Glossary

This page provides definitions for standard intercom terminology.
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Acoustical: A term used to differentiate a sound signal from its electrical signal counterpart or representation.
For example: A microphone converts an acoustical signal (from music or speech) to an electrical signal. A loudspeaker converts an electrical signal to an acoustical signal.
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Acoustics: The science of sound.
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Active Devices: Devices requiring operating power (battery or other) in addition to the signal. Examples are transistors, integrated circuits, amplifiers, and intercoms.
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AF: Audio Frequency. Within the range of 20Hz to 20,000Hz.
*Not to be confused with the Auto-Follow function in AZedit.
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AGC: Automatic Gain Control.
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All Call: For talk key assignment only. Activating an All Call key will also activate all talk keys to the left of the All Call key (up to, but not including another All Call key).
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Alpha: Alphas are the user-changeable names, which identify destinations (intercom ports, partylines, etc.). Change Alpha names for intercom ports using the Port Alpha button in AZedit Change Alpha names for everything else using the Other Alpha button. When you assign a destination to a talk key, the alpha name will appear in the alphanumeric display for that key (on keypanels so equipped).
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AM: Amplitude Modulation
*Not to be confused with the Auto-Mute function in AZedit.
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Ambience: Background noise or sounds.
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Ampere: The amount of electrical current when one volt is applied to 1Ω. Also, equal to one coulomb of electrical charge passing a point in one second.
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Amplifier: Usually an electronic device that increases the amplitude of an electrical signal. Examples include a microphone preamplifier that brings millivolt signals to volt levels. A power amplifier that makes a one-milliwatt signal into a 10, 100, 1000, or more watt signal.
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Amplitude: The size of analog electrical signal as opposed to its frequency or other parameters. Magnitude also indicates a size. Amplitudes focus more from the measurement viewpoint, for example: one-volt peak sine wave amplitude, one-volt average amplitude.
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Analog vs. Digital: Analog (as opposed to digital) here refers to the way information is put onto an electrical signal. An analog signal varies in voltage or current in step with the signal it represents. In the case of the acoustic pressure wave from speech, the pressure wave is converted to an electrical signal by a microphone. The voltage from the microphone varies as the sound pressure from the acoustic wave. A digital electrical signal either represents a binary number 0 or binary number 1. Combinations of numbers represent the amplitude of the pressure wave. The pressure wave is sampled at a rate two or more times the highest frequency to be transmitted. Therefore, there is a sequence of digital numbers representing the speech over a period of time. The advantage of analog circuitry is that it is conceptually simple and relatively easy to create. The disadvantage of analog circuitry is that it is sensitive to distortion and the quality of the circuit design and fabrication must be very high. Advantages of digital circuitry include:
1. Frequency response, and distortion are constant and independent of the circuitry (either it works or doesn't, the circuitry doesn't change the frequency response or distortion).
2. Physical aging, wear, and tear have little effect on the quality of the signal.
3. The circuit design and fabrication are very straightforward. The disadvantages of digital are that a substantial investment in system/circuit design must be made; the circuitry tends to produce and radiate interfering signals, more circuitry than analog is required in small units.
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Attenuation: The decrease in magnitude of a wave as it passes through a transmitting medium (including air, cables, circuitry). Attenuation is also used to indicate a numerical value of the attenuation through an electrical attenuator, for example: a 10-decibel attenuator (or "pad").
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Attenuator (Loss Pad): A device, usually passive, that decreases the amplitude of an electrical signal. For example: to prevent the overload of a sensitive microphone input when the signal is much larger than a microphone signal.
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Audio: 1. A term used to describe sounds within the frequency range of human hearing. Also used to describe devices that are designed to process signals generated from audio (acoustic) energy or to be used to generate audio (acoustic) energy.
2. In television, the sound portion of the program.
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Audio Frequency: Range of frequencies lying within the range of human hearing, often 20Hz to 20,000Hz, where hertz is cycles per second.
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Auto Follow (AF): A key assignment for listen keys only. Auto follow causes a key's listen assignment to always be the same as the talk assignment. Thus, if you change the talk assignment, you do not also have to change the listen assignment. You can manually activate an auto-follow listen key independently of the talk key. If you want auto-activation (or deactivation) of listen during talk, use one of the other auto key assignments, such as auto listen or auto mute.
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Auto Functions: Auto functions are special key assignments that work with other key assignments. For further information, see the glossary descriptions of individual auto functions: auto-follow, auto listen, auto-reciprocal, auto-mute, auto-table, all-call, DIM.
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Auto Listen (al): A key assignment for listen keys only. This assignment works like auto follow, except that listen automatically activates during talk, Auto listen is sometimes a good assignment for use with partylines or other non-keypanel devices that do not have talk-back control of matrix crosspoints.
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Auto Mute (AM): A key assignment for listen keys only. This assignment works like auto follow, except that listen automatically mutes during talk. Auto mute can help prevent feedback or echo when talking to certain destinations. In some cases, you may find it works better to disable talk latching for this type of key, because if you accidentally leave talk latched on you will never be able to hear the destination. To disable latching, in the Keypanels/Ports menu of AZedit, check the "D" check box for any talk key that has auto mute selected as the listen assignment.
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Auto Reciprocal (ar): A key assignment for listen keys only. This assignment forces you to continuously listen to whatever is assigned to the talk key. It is used commonly on keypanels, which are not equipped with listen keys, to allow listening to Party Lines. It is also useful to force listening when it is desirable to have an operator continuously hear a partyline or other source.
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Auto Table (AT): A key assignment for listen keys only, when the corresponding talk key is assigned to an IFB. Auto Table causes a listen key's assignment to always be the same as the Listen Source for whatever IFB is currently assigned to the talk key. (You define the Listen Source in AZedit during IFB setup.) Auto Table is convenient in a broadcast environment when a director needs two-way communication with the IFB talent, AND the IFB keys are frequently reassigned during the course of a program to talk to new talent locations. Using AZedit, several IFBs can be set up in advance, and their Listen Sources can be defined during setup. Then every time an IFB talk key is reassigned on a keypanel, the Listen Source for each new IFB will automatically become the listen key assignment for that key. For further information about Auto Tables, Listen Sources, and IFBs, search for "IFB" in AZedit help.
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AWG: American Wire Gauge. For example: the AWG wire size recommended by RTS® Systems for intercom wiring is 22 gauge.
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Balanced Line: A balanced two-conductor line carries audio that is differentially driven and balanced to ground. Neither conductor is tied to circuit common. Circuit common is either tied to a transformer center tap, is an electrical center point, or not tied at all. The signal (with respect to ground) on one conductor is equal and 180° out of phase with the other conductor. Balance Adjustment or Control In stereo audio, an adjustment to balance the left channel versus right channel. At RTS® Systems a name given to the null adjustment control. The null adjustment or balance control is used in two lines of products: user stations and interfaces — two to four-wire interfaces and two-wire to two-wire interfaces. In the headset user stations, the balance control (called sidetone in this case) is adjusted until the side tone heard in a headset is optimum. In a speaker user station, the control is adjusted for the best null so that a full duplex conversation can be held with both the panel microphone and loudspeaker enabled at the same time (without feedback).
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Bathtub Curve: A curve showing failure rate versus elapsed time. Typically, this curve is bathtub shaped. Initially a high failure rate occurs when active and passive parts fail ("infant mortality"). The parts fail under initial turn-on and burn-in stress. The flat part of the curve is the normal life of the equipment. The curve rises again when the equipment ages and is in the wear-out part of its life. Inspecting parts before they are used reduces the initial failure rate. Using higher quality components and proper derating of components in the equipment design, lengthens the equipment operating life. RTS® Systems burns-in power supplies and other equipment to catch early failures before the equipment goes to the end user.
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Bel: Originally a unit of measurement that meant that a sound was twice as loud. A more convenient unit for other reasons is a decibel, which is a tenth of a bel. Therefore, an increase of 10 decibels is twice as loud (and a decrease of 10 decibels is half as loud). Mathematically a unit that represents the logarithm of the ratio of two powers. See also decibel.
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Beltpack: Portable headset user station. This station is designed to be worn on a user's belt, but is also fastened to the underside of consoles, taped to a structure near the user, or mounted on a piece of equipment.
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Binaural: 1. A special process of using an artificial head and two microphones to closely emulate the spatial and frequency hearing of a human.
2. Two earphones, two signals, may be stereo or may be two different signals.
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Biscuit: A portable speaker station.
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Bit: Binary Digit. One eighth of a byte. One eighth of a dollar.
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Block Diagram /Single Line Diagram: A diagram to show the basic concepts of a device or system. Often the block diagram has system parameters such as transfer functions, gain, loss, level, DC voltage, inputs, outputs, and so on.
I. Block Diagrams are used on the Product Data Sheet to clarify the functions, show performance capabilities, and to show the input, output, control, and interconnection points. This diagram also defines and clarifies the specifications called out on the data sheet.
II. The diagrams called Block Diagrams are often, in fact, “Single Line Diagrams”. Single Line Diagrams are similar to the Block Diagrams but show more detail such as number of conductors in a cable, connector designations, connector details such as male/female, Equipment Model Numbers, and Equipment Designation Names/Numbers. At RTS® Systems, these single line diagrams are called “System Block Diagrams” and are used for several purposes:
1. Act as a checklist against the customer requirements.
2. Demonstrate to the customer the meeting of the customer’s requirements.
3. Are used to develop the equipment list (Lists the Quantities and Models numbers of equipment required to make the system).
4. Provide the information necessary to perform a system test.
5. Provide information to estimate wire and cable requirements.
6. Provide information to aid installation at the customer site. (Wiring Diagrams and Wire List can be generated from this information).
7. Graphically, give a measure of the size and complexity of a given communications system.
8. Provide a means of troubleshooting system problems during commissioning, during operation, and during maintenance.
9. Provide a documentation basis to expand the system in the future.
10. Provide documentation for telephone support of the customer from the factory.
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Blocking: A communication system blocks a requested call or access usually by a busy signal.
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Bridging: Bridging impedance means an impedance that when paralleled with a nominal impedance will have a non-significant effect on a circuit. For example: for a nominal impedance of 600Ω, a parallel impedance of 3,000Ω (5 times) would make the net impedance 500Ω, 17 percent less than 600Ω or 1.6dB. A parallel impedance of 6000Ω (10 times) would cause about a 9 percent change or about a 0.82dB difference. A parallel impedance of 12,000Ω (20 times) results in about a 3 percent change or 0.26dB. In present day audio systems, line level and power amplifiers have input impedances specified at 600Ω or 15,000Ω. Microphone preamplifiers are usually ten times the expected source impedances. For example: for 150Ω microphones the input impedance is 1,500Ω or greater. Earlier RTS® Systems intercoms also had this microphone input value, but a compromise value of 470Ω was necessary because of the crosstalk in headset cords. However, RTS® Systems professional audio equipment generally adheres to current audio standards.
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BW: Bandwidth.
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Byte: Eight binary digits or bits.
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Call light: A feature in intercoms that is used for two different purposes:
1. To get a user to put his headset back on (blinking call light). This method is the standard way for RTS® Systems equipment.
2. To generate a cue (steady call light). The usage in this case is often as follows: light on means standby, light off after light on means execute. This method is used by other manufacturers and is optional with RTS® Systems equipment. In some user stations, the call light feature is standard (BP-325, MCE-325) in other stations it is an option.
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Capacitance: The ability to store electrical charge between two conductors. Measured in farads (Named after Michael Faraday). A capacitance value of one farad can store one coulomb of charge at one volt. One farad permits one ampere of current when the voltage changes at the rate of one volt per second. Typical sizes are measured in: millifarad one-thousandth of a farad microfarad one-millionth of a farad nanofarad one-thousandth of a millionth of a farad picofarad one-millionth of a millionth of a farad.
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Capacitive Reactance: The opposition to alternating current through a capacitor. Capacitive reactance, Xc is measured in ohms and is equal to: 1/[2 × π × frequency × capacitance].
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Capacitor: Two conducting surfaces separated by a dielectric. The dielectric could be a material, air, or a vacuum. The capacitance of the capacitor is a function of the area of the surfaces, dielectric, and spacing between the conducting surfaces.
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Cardioid Pickup Pattern: The pick-up pattern of a directional microphone is frequently of cardioid (heart) shape. The maximum cancellation (minimum pick-up) occurs at an angle of 180°. The sound power concentration is approximately three times.
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CCU: Camera Control Unit. Usually located in an equipment room (studio) or a bay in a mobile truck (mobile). The CCU is connected to the camera "Camera Head" via a cable. The cable is either wire "multicore," triaxial cable "triax," or coaxial cable "coax."
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Channels and Buses: Channels and Buses are pathways for signals to travel. There are more than one channel or bus to allow for multiple conversations or information flows to occur simultaneously. Multiple buses separate signals using space and the process is sometimes called space multiplexing.
Analog Channels and Buses In the discussions here, analog Channels or buses carry signals representing audio. There is an exception; the call light signal is superimposed over the signals representing audio. Humans because of its 20.0-kilohertz frequency do not hear this signal. In this case, the voice audio and the call light signal are multiplexed using frequency separation. The words "channels" and "buses" are often used interchangeably. In a twelve channel or bus system, it is possible for a user station to be tied to say system bus 5 and system bus 3 when the user station channel selector switch reads 1 and 2 respectively. For purposes of distinction, discussions that talk about system channels or buses and user station channels, the word bus will refer to system buses and the word channel will refer to user station channels.
Digital Buses in the microprocessor units, addresses and data are moved on digital data buses. These buses vary in width from three to 16 bits. Some buses are bi-directional and the logic transmitting and receiving data on these buses is usually of the "three state" variety. Data is multiplexed on these buses using time division or separation.
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Characteristic Sound Pressure Level: The Characteristic Sound Pressure Level of a headphone is the sound pressure level that an electrical output of 1 milliwatt generates.
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Circuit: 1. A complete path for electrical power or an electrical signal (usually two conductors).
2. In a system, a channel for one or two way conversation may be called a circuit.
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Circumaural Headset: A headset where the earpieces surround the ear usually providing some isolation of outside noises from the ear.
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Clipping: A type of distortion resulting from overdriving an amplifier.
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Close-Up Effects: Found in a pressure gradient microphone, this effect causes strong low frequency pickup at near distances.
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Coil Effect: The inductance exhibited by a spiral-wrap shield at audio frequencies.
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Communication between Ports (Point-to-Point, or P-P): The audio signal from any input port can be routed to any output port. For example: during keypanel setup, you assign keypanel keys so that keypanel operators can talk and listen to other intercom ports. Communication of this type is called point-to-point communication. You can also route signals between intercom ports without keypanels. One way to do this is to force crosspoints in the Crosspoint Status screen of AZ™EDIT. Another way to do it is with a GPI input.
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Compression Force: Weight and the force of the earpieces on the head affect headset-wearing comfort. This "compression force" is measured in newtons, N. One newton is about the weight exhibited by a mass of 100 grams.
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Condenser Microphone: A microphone using a capacitor as the sound pressure-sensing element. Condenser microphones require a polarizing voltage. Condenser microphones outputs are high impedance and need to be buffered by an active device. The active device(s) needs power, so various phantom and A-B powering schemes are used to buffer the active device(s).
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Conductivity: The ease by which a material will support an electrical current. Mathematically the reciprocal of resistivity.
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Conductor: A material that will support an electrical current.
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Conference Intercom Systems, Conference Line Intercom Systems, Party- Line (PL) Systems: A conference system allows a group of people to intercommunicate. For example, one person can talk and all the others on the bus or channel can hear. When the system is full duplex, anyone can talk and the rest can hear or interrupt the speaker at any time. The conference and distributed matrix systems presently sold by RTS® Systems are full duplex and are non-blocking, which means that access to the channel is immediate and there is no busy signal. Conversations on conference systems are in general, non-private. A conference system can be two-wire or four-wire. RTS® Systems sells both two- and four- wire conference systems. The two-wire conference system (RTS® Systems “TW” system) is simple, economical, and very convenient to use. The four-wire conference system performs as well as the two-wire system, is easier to interface to other systems, but requires more equipment and is more costly. Conference systems can be distributed or centralized. Most of the systems that RTS® Systems makes are distributed conference systems. Distributed means that a station can be plugged-in at any arbitrary point along the bus or channel. Centralized means that all stations are tied to a central point where the conferencing function is actually accomplished.
Note: Sometimes the conference intercom system is called an interphone or headphone / headset system.
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Control Room: A room, usually adjacent to a studio, in which the producer, director, technical director, (and sometimes the audio mixer, lighting director, assistant director, production assistant, and Chyron operator) controls the production. In remote pickups, the control room is in the mobile unit, which may be several kilometers from the televised action.
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Coupling with the Ear: Differentiation between earpieces that are worn on the auricle (supra aural headsets), and those that envelop the auricle (circumaural headsets).
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CPS: Cycles Per Second. Obsolete designation replaced by Hertz (Hz).
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Crosspoint: The term "Crosspoint," like the term "Matrix" is inherited from intercom systems, such as the RTS® CS-9500, CS-9600, and CS-9700, that use a switching matrix to route intercom audio. In those systems, the crosspoints are the actual switches that close or open to connect or disconnect talk and listen paths. RTS® ADAM, ADAM-CS, and Zeus intercom systems do not actually use crosspoint switches, but use a technique called time division multiplexing (TDM), in which communications are routed as digital packets. However, use of the term "crosspoint" persists since packet routing accomplishes the same thing as conventional crosspoints: namely, connecting distinct talkers and listeners. In this sense, a crosspoint can be thought of simply as a communication link between any two points in the intercom system.
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Crosstalk: Interference caused by audio energy from one line coupling ("leaking") into adjacent or nearby lines.
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Current: A current is a flow of electrons past a point in a circuit and is measured in amperes (coulombs per second). Practical currents in electronics are measured in: amperes, milliamperes one thousandth of an ampere, microamperes one-millionth of an ampere, nanoamperes one-thousandth of one millionth of an ampere, picoamperes one-millionth of a millionth of an ampere, femtoamperes one-thousandth of a picoampere.
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Current Sources: RTS® Systems uses "Current Source" technology in many of its communications products. This technology allows the summing of signals on a single pair of conductors across a single system bus termination. This allows a distributed conference line system. Stations can be added arbitrarily anyplace in the system. The system allows two to 75 stations to be put on the system with only a maximum level difference of six decibels. The current source allows a signal to be put on the bus without shorting out the other signals.
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Daisy Chain: Some TW user stations allow the stringing together (or daisy chaining) of user stations. These stations have a "loop through" or "extension" connector as well as a "line" or "line input" connector. Connecting a TW system by connecting one user station to another via the line and loop through or "ext" connectors. This is as opposed to "home running," which is running a cable from each user station to a central point ("home").
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dB: Decibel, see definition for decibel.
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dBm: A reference level where 0dBm equals 1 milliwatt. In a 600Ω system, 1 milliwatt corresponds to a voltage of 0.775 volts.
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dBu: A reference level where 0 dBu equals the voltage as a dBm (0.775 volts) but without the 600Ω in the circuit.
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DC: Direct Current. Example: current as from a battery.
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Decibel (dB): 1. One-tenth of a bel. It is equal to 10 times the logarithm of the power ratio, 20 times the log of the ratio of voltages or currents. Three decibels increase represents a doubling of power, six decibels increase represents four times the power or a doubling of the voltage in a circuit.
2. A derived unit of loudness. The human ear perceives a 10-decibel increase as twice as loud, and a 10-decibel decrease as half as loud.
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Dedicated Line: 1. A term used by some to indicate a single path in a point-to-point system.
2. A term used instead of point-to-point or matrix system, for example: a dedicated line system. (This term seems to be more marketing than engineering oriented).
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Destination: A destination is anything that a talk key talks to or a listen key listens to. A destination can therefore be any port, Party Line, IFB, etc.
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Dielectric: An insulating (nonconducting) medium or material.
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Dim: "Dim" occurs in two contexts in RTS® Digital Matrix Intercom Systems. First, there is the Dim Table feature. Dim tables are used to correct a feedback problem that can occur between two keypanels operating in close proximity that have keys assigned to talk/listen to a common destination. Dim tables are set up in AZedit (search for keyword "dim" in AZedit help. Once a dim table is set up, it can be assigned as a level 2-talk assignment for those keys that are causing the feedback problem. For information about how to make this assignment from a programmable keypanel, search for "Dim Table" in the keypanel manual index. There is also an adjustable speaker dim feature available on the KP-32 Keypanel. This causes the speaker or headphone volume to diminish by a preset amount whenever a talk key is activated. This can help to prevent occasional feedback between the speaker and microphone due to volume settings, microphone placement, etc. For setup and usage, search for "Speaker Dim" in the keypanel manual index.
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Distortion: Distortion is the effect when the output of an electronic device contains undesired signals that were not present at the input. This is assuming that the electronic device is supposed to be a linear device. The undesired signals have a frequency or frequencies that are related to the input signal. If the frequency(ies) is/are harmonically related to a single frequency input, then the undesired signal is "harmonic" distortion. If the signal is the sum or difference of two input frequencies, then the distortion is called "intermodulation" distortion. If the distortion is the result of a pulse or step input, and the frequency(ies) is/are related to sums and differences of the frequencies determined by the Fourier transform of the input pulse or step input, the distortion is called "transient intermodulation distortion". Distortion can occur both in active devices (e.g. amplifiers) or passive devices (e.g. transformers). Harmonic Distortion is measured in percentages or decibels below the fundamental signal. For example: a distortion of 0.1 percent is "60dB down". Intermodulation Distortion requires two input signals (say 1000Hz and 400Hz) to be inserted and the sum and difference to be measured.
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Double Headset: Headset with intercom in one ear and program in the other.
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Double-Muff Headset: Headset with two earphones plus a microphone. It can be connected monaurally (same information, both ears) or binaurally (separate feed each ear). In binaural operation, the feed can be intercom in one ear and program in the other, or intercom channel A in one ear and intercom channel B in the other ear. Channels A and B are either conference line channels or other intercom feeds. To get a binaural feed requires a binaural/stereo capable user station such as BP-320, BP-325, Model 802, MCE-325, or any station so optioned.
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Drain Wire: An uninsulated wire in contact with a shield throughout its length, and used for connecting ("terminating") the shield.
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Dry Pair/Dry Line: A dry pair or dry line is a communications line that has audio signals but no direct current (DC) voltage or current.
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DSP: Digital Signal Processor. Usually a microprocessor with two memory addressing capability. One memory is the program memory, which tells the microprocessor what to do, and the second memory contains: data to be processed, intermediate results, and results. The advantage of a DSP is its speed. It is fast enough to process analog (or audio) signals in real time, and is often used in that application. Some applications are system-to-system interfaces (e.g. Telos "Link" for interfacing a standard telephone line to an RTS® Two-Wire Intercom line).
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DTMF: Dual-Tone Multi-Frequency
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Dual Listen: This is either an option or feature of intercom user stations. Dual listen permits an operator to listen to two channels at once. This may be a mix of two channels to one ear, or in a binaural or stereo user station, one channel can be assigned to one ear and the other channel to the other ear. Dual Listen could also be an intercom channel and a program audio source. The dual listen pots are functionally configured in one of three ways:
1. One pot controls the audio of the channel actively used, and the second pot controls the audio of a monitored channel.
2. One pot is always one channel and the other pot is always the other channel.
3. On three channel systems, operation is similar to 1 except if the active channel and the monitored channel coincide, the monitor feed is blanked out to prevent a 6dB increase in volume and feedback.
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Dual Listen Option: An option for user stations that allows a monaural mix of two channels. Usually the station has two volume controls, sometimes two concentric volume controls.
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Duplex/Simplex: See Full Duplex, Half Duplex, or Simplex.
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Dynamic Microphone: Converts sound pressure waves to electrical signals by means of a coil attached to a diaphragm moving in a magnetic field.
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Earphone: A device used to hear an electrical audio signal. The earphone converts electrical signals to acoustic signals that can be heard.
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Earth: British term for a reference ground. Earth may mean power line ground or a facility zero reference ground.
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EFP: Electronic Field Production. Production of television programming using field equipment (mobile trucks, portable gear, etcetera).
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EIA: Electronic Industries Association (formerly RMS or RETMA).
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EIA Sensitivity: Also called GM rating. Adding the EIA sensitivity to the SPL at the microphone gives the microphone power output in dBm into a matched load. Sensitivities for open-circuit can be considered as follows: -65dB re 1 volt/microbar = high sensitivity (usually results in better signal to noise ratio). -75dB re 1 volt I microbar = medium sensitivity -85dB re 1 volt/microbar = low sensitivity.
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Electret Microphone: A microphone using a capacitor as the sound pressure-sensing element. Electret microphones are a special case of condenser microphones in that they are permanently polarized and require no special polarizing voltage. Electret microphone outputs are high impedance and need to be buffered by an active device. The active device needs power so various battery, phantom, and AB powering schemes are used to buffer the active device, (which is very close to or on the microphone diaphragm).
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Electronic Switching Versus Mechanical Switching: Audio and other signals can be switched either electronically or mechanically. The electronic switching is generally faster and quieter, but usually has some losses. Mechanical switching is generally slower, noisier, but has less or little loss. In switching signals from current sources, electronic switching prevents loss of termination for a significant amount of time.
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EMF: Electromotive Force (voltage).
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EMI: Electromagnetic Interference. Interference caused by the radiation of electrical or magnetic fields from sources such as radio transmitters, light dimmers, computers, and transformers.
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Energy: The capability of doing work.
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Energy Dissipation: Loss of energy by conversion to other forms, usually heat.
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ENG: Electronic News Gathering. Accomplished using television and accessory equipment in a small van, with the capability of relaying pictures and sound back to a broadcast station or network control center. The equipment used may be of special design, for example smaller "ENG type" television cameras.
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Epsilon (ε): A symbol for voltage used in electronics, and engineering. Also used as the symbol for the electric field (volts per meter).
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Equalization (EQ): The ability to correct or adjust non-uniform frequency response in a sound system. The equalization may be applied to a signal to be recorded, that has been previously recorded or to a real time ("live") signal.
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Equalizer: An electronic device or circuit that allows for the adjustment of a signals frequency response.
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Farad: A measure of the ability to store electrical charge between two conductors. Farad is named after Michael Faraday. A capacitance value of one farad can store one coulomb of charge at one volt. One farad permits one ampere of current when the voltage changes at the rate of one volt per second. Practical sizes are: millifarad one-thousandth of a farad, microfarad one millionth of a farad, nanofarad one-thousandth millionth of a farad, picofarad one-millionth of a millionth of a farad.
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Feedback: 1. Audio deliberately fed back to a user, for example a monitor for a musician to hear his own instrument or voice.
2. Audio feedback to a headset or earset as in IFB operations. (see IFB)
3. An unintentional return of an electrical or acoustic signal to a microphone or amplifier input, the result of which is an oscillation.
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Film-Style Directing: Directing separate takes or scenes that are to be later edited in postproduction. These takes or scenes are not necessarily in the same sequence, as they will appear in the film or tape.
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Filter: A circuit that is sensitive to signal frequency and is capable of attenuating some signal frequencies and not attenuating others.
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FM: Frequency Modulation. A method of adding audio to a radio frequency carrier. FM signals are usually more noise free than amplitude modulation (AM) signals. Wireless intercom units usually use FM.
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Follow Spot: Used to accent or light action on stage, the follow spot is a focused high power light that focuses a beam from a large circle to a small spot. The operator of the follow spot is usually on the lighting intercom line, and sometimes in small productions on the primary intercom line. The follow spot operators have been known to tape their beltpack to the spotlight or a nearby metal structure. This practice can cause hum and noise in the intercom line because of the large currents involved in lighting. Some of the currents are induced into the metallic structure of the facility causing large "ground" currents. If a beltpack is to be taped to something, a layer of tape should be put around the beltpack first to insulate it from any metal. The newer BP-325 has a nonmetallic case, so adding tape to the case is unnecessary, but it is necessary to prevent contact of connector shells and other metal objects with ground or metallic structures.
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Four-Wire: A communications system where the path is different for talk and listen. In electrical pathways there are, in fact, four wires (two paths). Four-wire systems can be four-wire balanced and four-wire unbalanced.
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Four-Wire Balanced: Four-wire balanced is similar to four-wire unbalanced except that conductors are not tied to circuit common. Circuit common is either tied to a transformer center tap, or is an electrical center point, or not tied at all.
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Four-Wire Unbalanced: A four-wire system that uses a circuit common and two additional conductors. The talk pathway consists of one conductor plus circuit common. The listen pathway consists of another conductor and circuit common.
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Frequency: The number of times per second a periodic action occurs. Frequency is measured in Hertz (formerly cycles per second).
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Frequency Response: The range of useful frequencies for a particular device, circuit, or system. For example: a microphone frequency response of 20Hz to 20,000Hz ±3dB would be considered excellent. The design goal of the TW system is 75Hz to 20,000Hz (system), 75Hz to 10,000Hz (microphone preamplifier), and 75Hz to 8,000Hz (headphone/speaker amplifiers). The response on an actual system will vary according to the amount of cable in the system, various trade-offs, and the number of stations in the system.
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Full Duplex: Duplex communication allows a simultaneous two-way conversation, in which one person can interrupt the other. In data communications, full duplex permits confirmation of sent data by the receiving terminal echoing or sending back the same data or confirming data.
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Gain: 1. Level of amplification for audio/video signals. Operators may need to periodically adjust these levels during production (especially those gain controls on the audio mixer board).
2. An important parameter of a functional block or a circuit device. The gain is the output voltage divided by the input voltage, the output current divided by the input current, or the output power divided by the input power. For example: a microphone preamplifier in a TW user station may have a maximum gain of 54dB (a voltage ratio of 500).
Note that, in the case of the bilateral current source, it is a voltage controlled current source, and is characterized not by gain, but by transconductance. The output amperes divided by the input volts give Transconductance. The units of transconductance are siemens (formerly the units were mhos). The bilateral current source used in RTS® Systems user stations usually has a transconductance of 5 milliamperes divided by 1.5 volts or 3.3 millisiemens.
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GND: An abbreviation for ground.
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GPI (or GPI/O): General Purpose Interface or General Purpose Input/Output. This refers to logical inputs and outputs that can be wired to external devices for various purposes (hence the term "General Purpose"). Typically, these are optically isolated logical inputs and relay outputs. However, other variations exist.
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GPIO: General Purpose Input/Output. (You may also see this referred to simply as "GPI".) GPIO is a means of controlling devices using switch contact closures, DC voltages, or similar methods. For example: you can control a lighting system from keypanel keys, or key transmitters from a talk key during transmit, or simply operate a light or buzzer for cueing. In ADAM, ADAM-CS, and Zeus intercom systems, you can also control intercom events from external switches. For example: you can activate key assignments, close or open crosspoints, activate GPI outputs, etc. In CS-9000 Series intercom systems, general-purpose control outputs are provided by optional FR-9528 Relay Frames (8 relays each). In those systems, a relay may be assigned to an intercom key on a keypanel using the Relay key assignment type. Pressing the intercom key activates the relay. ADAM, ADAM-CS, and Zeus intercom systems all have a dedicated GPIO connector (J27 on a Zeus Frame, J903 on an ADAM-CS Frame, and J11 on the XCPADAM-MC Master Controller Breakout Panel in an ADAM Intercom System). This connector supports 8 control inputs and 8 control outputs. Additionally, one or more UIO-256 Universal Input/Output frames may be connected to the intercom system. Each UIO-256 provides another 16 control inputs and 16 control outputs. Control outputs may be assigned to intercom keys using the Relay key assignment type, and the intercom keys can then control external devices the same as the FR-9528. Control inputs can be assigned to activate "virtual" key assignments. (A virtual key assignment is a key assignment at an intercom port where there is not actually any keypanel connected. In summary, use an external switch to act like a talk or listen key.) The control inputs and outputs can also be used as conditions for UPL statements in AZedit. Finally, there is a GPIO option available for the KP-12 keypanel, and a connector module option for the KP-32, which includes GPIO. These are referred to as "Local" GPIO, since they are assigned and used locally at the keypanel. Each local GPIO includes 4 control inputs and 4 control outputs.
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Green Room: A room for performers/talent to stay just before making their appearance on stage. This room is usually close to the stage, and has amenities plus a video and audio monitor.
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Ground: The term ground has several meanings. One meaning is a circuit common point potential. Another meaning is a 0 volts point. Another meaning is a connection to the earth. Another meaning is the chassis of radio equipment. Radio Frequency engineers usually connect circuit return to the chassis. This can cause a ground loop in systems if the chassis is connected to earth ground as well, and the circuit return in the system encounters another earth ground. The TW System circuit return is bypassed to earth ground and tied to earth ground through a 10,000Ω or 22,000Ω resistor, in order to prevent ground noises or hums from being introduced into the intercom system. Connection of a chassis grounded device to the TW System should be done through an audio isolation transformer.
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Ground Loop: A ground loop occurs when a system circuit common is tied to earth ground or another ground or another conductor at two places in the system. This allows, "Ground currents" to be superimposed on the intercom system circuit common, causing hum and spurious noises.
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Ground Potential: Often the potential of the earth, but also the potential at a zero voltage point in a system or an electrical/electronic circuit.
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Half Duplex: Half Duplex communication allows two-way conversations, one-way at a time, such that one person cannot interrupt the other. In data communications, half duplex means sent data is not confirmable by the receiving end on a continuous basis.
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Harmonic Distortion: A distortion at the output of a device where the amplified input signal is accompanied by the sum of unwanted signals that are harmonics o the input signal. Harmonic distortion can be expressed as a percentage of the total output intensity, or in decibels. See also Distortion.
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Headphones/Headsets: Headsets are headphones with microphones added. Headphones and headsets are available in a wide range of variations. Some of the variations include: Lightweight, Heavyweight, Medium Weight: Lightweight can often be used or worn for a ten hour shift with only mild discomfort; medium weight usage ranges from two to six hours continuous, and heavy weight usage ranges from 15 minutes to 2 hours. Acoustic Isolation: which varies from 0dB to 40dB. Usually more isolation means a heavier headset. Acoustic Isolation (30dB to 40dB) is required in high ambient noise environments such as concerts, auto racing, construction areas, aircraft engine run-up, near machinery such as printing presses. Medium isolation (10dB to 20dB) is required in quieter concerts, near crowds, near quieter machinery. Low acoustic isolation can be tolerated in environments such as television studios (news). Impedances: Impedances of headphones range typically from 2000Ω to 2Ω. Common impedances per earphone are 300Ω, 150Ω, 50Ω, and 25Ω. Headphone total impedances depend on the earphone impedance and whether they are connected in series or parallel. The headphones in standard headsets manufactured by Telex® range from 25Ω to 300Ω. Military headphones may be very low impedance, 10Ω or less. A fuel tank entry system sold by RTS® Systems has 2000Ω headphones. Lower impedance headphones allow a louder sound (up to 110dB SPL) to be generated with relatively low voltage in the user station (say 12 volts DC). Microphone Types: (for headsets) The microphones types may be carbon, carbon emulate, dynamic, electret. The carbon types produce high output levels but have higher distortion, the carbon emulate types, put out high levels with low to moderate distortion but require special electronics and a way to power the electronics. The electrets usually have electronics built on the microphone, but there is no voltage gain from this electronics, just impedance matching (from megohms to kilohms). Electrets have about 10dB more level than dynamics, but are very prone to "popping". To prevent popping, windscreens need to be installed or placed over the microphone element, and the following circuit should have a circa 500Hz high pass roll off. Dynamic and electret microphones usually have low distortion and good frequency response (100 to 8,000Hz). Some dynamic microphones made with low technology may have poor frequency response. Some typical microphones impedances are as follows: carbon: small button 600Ω, large button, 50Ω; dynamic: 2Ω (military), 150-200Ω (RTS® Systems recommends), 600 1000 (lower cost push-to-talk and others). Microphone impedances can also be higher such as 50 kΩ, but these usually are not on headsets. Most RTS® Systems User Stations microphone inputs allow for an impedance range of 50Ω to 1000Ω for dynamic microphones, 1000Ω to 2000Ω for electrets, 50Ω to 200Ω for carbon or carbon emulate.
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Headroom: The difference between the instantaneous level of a signal and the peak signal possible in a given system. Headroom is often expressed in decibels. System headroom in the TW System is about eight to ten dB. Headroom for the microphone input is an apparent 40dB because of the 30dB limiter compression ratio. Because of the design of the TW and 800 series systems, and the consistency of levels, the peak to average speech ratio is close to 10dB.
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Hertz: The unit of frequency, cycles per second. One thousand hertz equals one kilohertz equals one thousand cycles per second.
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Home Run: Running the user station system connection cables to a central point (as opposed to Daisy Chaining).
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Hot: 1. A wire actively carrying power or signals.
2. Equipment that is turned on, for example a "hot" microphone.
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Hum: Hum is an interfering addition to audio. Its frequency is within that of human hearing and it is at the frequency of the power line or its harmonics. For example: a pickup of the fundamental will result in a 50Hz, 60Hz, or 400Hz tone in the audio. If the hum is due to excess ripple in a full wave rectified supply, the frequency will be 100Hz, 120Hz, 800Hz. If the power line waveform is distorted (which it often is), other harmonics will be heard. Hum is induced electrostatically via unshielded wires in high impedance circuits, or electromagnetically via unshielded dynamic microphones, transformers, tape recorder heads, or ground loops.
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Hypercardioid: A microphone pick-up pattern. This pattern has its maximum rejection at 100° off axis. This pattern has good rejection of far field sound and room reverberation. Good in house speaker systems.
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I: Symbol used to designate current.
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IBEW: International Brotherhood of Electrical Workers
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IFB: The IFB* System is a special intercom system used for television shows with highly flexible formats or where important program changes are likely, for example, newscasts or special events telecasts. The IFB system connects control room personnel such as the director, producer, audio mixer, and technical director directly with the performers or "talent". The performer wears either a small earpiece or headset** that carries the program sound unless the director or another member of the production team operates the IFB and interrupts the program sound with special instructions.
*IFB means Interrupted Feedback, or Interrupted Fold-Back. This system is also called Interrupted Return Feed (IRF); program Interrupt, or prompt mute.
** In sports, stadium, and parade remotes, a double muff headset is used. Impedance is the resistance to an alternating current.
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Impedance: Impedance is composed of resistance and reactance (rectangular coordinate representation). Impedance can also be viewed as a vector quantity with a magnitude and a phase angle. Impedance can be measured with an impedance meter. Impedance may vary with frequency. In the discussions in other sections, the impedance is usually that at one kilohertz, unless otherwise specified. The unit of impedance is the ohm (Ω). An impedance stated in rectangular coordinates is a complex number. In RTS® Systems, equipment the impedance is important over a band of frequencies and this band is normally stated in the specifications.
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Insertion Loss: A measure of the attenuation of a device by determining the output of a system before and after the device is inserted into the system.
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Intercom: 1. A means of organizational communications. The design of the intercoms systems produced by RTS® Systems focuses on the concept of team communications. A team is an organization of members who perform individual tasks to accomplish a team goal or objective. The intercom is the pathway or means for the voice communications used to coordinate the team activity.
2. In larger systems, intercom refers to the matrix or point-to-point communications equipment, and interphone refers to the conference type equipment.
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Intercom Data Groups and Port Number Calculation: For data routing purposes, port numbers are arranged in groups of 8 sequential intercom ports. In an ADAM™ or ADAM™ CS Intercom System, each Audio I/O card comprises one data group. In a Zeus™ Intercom System, each group of 8 port connectors comprises a data group. Within each data group, its address setting uniquely identifies each keypanel. Whenever you display the Panel ID, the intercom system determines which data group the keypanel is connected to, and the address setting. It then reports the calculated address. For example: suppose a keypanel is connected to data group 3 and the keypanel address is set to 5. Since each data group consists of 8 sequential intercom ports, the calculated port number for this keypanel will be (2 × 8) + 5, or 21. This is the total of all intercom port numbers on the first 2 data groups, plus the offset of 5 ports into the third data group.
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Interconnect: A cable, device, or method of connecting one device to another, or one system to another.
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Interface: The place where two systems or a system and a subsystem meet. Also the device that adjusts levels and other parameters such that one system appears to the other system as a compatible extension.
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Intermodulation Distortion: See Distortion.
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Inverse Square Law: The decrease in level as a listener moves away from a loudspeaker, or a microphone is moved away from an acoustic source. The law says that the sound pressure will decrease six dB every time the distance is doubled. This law applies to the outdoors, and to the indoors where reverberation and room effects are negligible.
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IR Drop: Applies to the voltage drop along a wire as a function of the current (I) and the resistance of the wire (R). For example, the resistance of 10,000 feet of a number 22 gage pair is 320Ω. The DC voltage drop at the end of the wire due to a user station using 50 milliamperes of current is 0.040 amperes times 320Ω equals 12.8 volts. If the power supply is 32 volts and the drop is 12.8 volts, the voltage at the end of the wire is 19.2 volts. The minimum operating voltage for a user station operating in the high impedance mode is 18 volts. Therefore, a beltpack user station such as the BP-317, or BP-300 has enough DC voltage to work at the end of 10,000 feet of a 22 AWG wire pair.
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ISO (Camera ISO): ISO is a means for a keypanel operator to isolate a particular intercom port for private communication. While the intercom port is isolated, it can only hear audio from the keypanel operator. ISO is frequently used in television broadcasting to temporarily isolate a member of a camera Party Line. The isolated camera operator can then receive directions without interference from other audio traffic on the Party Line. ISOs are setup using the intercom system configuration software. Each ISO can also be given a name, which is meaningful to keypanel operators. Once an ISO has been set up and named, it can be assigned to any keypanel key (provided that ISO assignment has not been restricted or disabled in the intercom system configuration software). For further information about ISOs, search for "ISO" in AZedit help.
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Isolation: The ability of a circuit or component to reject interference, usually expressed in dB.
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K: (Kilobyte) prefix symbol for 1024 (common usage).
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k: (Kilo) metric prefix symbol for 1000.
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L: Symbol for inductance.
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Lavaliere: A small microphone. There are two types:
1. A very miniature type that clips onto clothing on the front of a performer below his head, and
2. A larger microphone on a cord worn around the neck of the performer with the microphone hanging below the neck on the chest.
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LCD: A liquid crystal display (commonly abbreviated LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector.
The CLD series RTS® keypanels feature LCD displays that host an advanced graphic interface.
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Leakage: The undesired leakage of a current or signal into another path.
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Level: The amplitude of power of a signal. If in decibels, the level has to be stated relative to a reference, and the reference has to be made clear.
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Light Signaling: See Signaling. Accomplished on the intercom line, using DC levels (Clear-Com®, HME, Theatre Visions) or a 20-kilohertz tone (RTS® Systems, Telex® Audiocom®).
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Limiter: An effective communications system needs to limit dynamic range to ensure adequate intelligibility to the listener. The limiter/compressor in the TW system user stations has three functions:
1. It helps loud talkers and soft talkers to be heard equally well,
2. It prevents a loud voice from being severely distorted,
3. It keeps the voltage levels from exceeding system limits. Function 3 is important because the user station must operate over a wide range of power voltages, and the limiter makes a practical system possible.
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Line: A single communication path.
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Line Level: Line Level depends on the system and the reference. It is often used to differentiate microphone level (-40 to -60dBu) and a higher level (often 0dBu).
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Local Power Option: Local Power Source is a small AC converter that converts AC line power to low voltage in order to power a user station -a separate connector is provided. User stations usually get DC from the converter, although occasionally low voltage AC power is used.
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Loop-Through: See "Daisy Chain".
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Loudspeaker: A transducer that converts the electrical output of an amplifier to an audible sound.
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mA: Shorthand for milliamperes or thousandths of an ampere.
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Main Station: A user station where a user station and a system power supply are combined into one package.
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Master Station: A multichannel user station. There may be one or more of these stations in a system. Another definition is the primary station in a system.
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Matrix: "Matrix" is a term inherited from earlier point-to-point intercom systems, where all point-to-point communication was accomplished by closing specific switches in a switching matrix. Examples include the RTS® CS-9500, CS-9600, and CS-9700 Intercom Systems. In many instances, "Matrix" is used interchangeably with "Intercom System". RTS® ADAM, ADAM-CS, and Zeus Intercom Systems, on the other hand, do not use a switching matrix, but use a method called Time Division Multiplexing (TDM), in which communications are routed as digital packets. However, use of the term "matrix" persists since packet routing accomplishes the same thing as a conventional switching matrix: namely, connecting distinct talkers and listeners.
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Maximum SPL: The acoustic level above which operation changes from linear to nonlinear. This is a specification usually for microphones.
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Mho (℧): The old unit of conductance or transconductance, now a siemen. The more familiar units of transconductance are amperes (output) per volts (input). For electronic devices, the units are usually millisiemens or milliamperes per volt.
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Mic: Short for Microphone
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Micro (μ): Micro is a prefix meaning one millionth. For example, a one-microfarad capacitor has a capacitance of a millionth of a farad.
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Microcontroller: A Microprocessor that has a built in RAM (Random Access Memory), built in ROM (Read Only Memory), parallel type inputs/outputs, and often a serial input/output.
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Microphone: A transducer that converts sound into an electrical output or voltage.
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Microprocessor: The heart of a computer on a chip. Has inputs and outputs and can read RAM (Random Access Memory) and ROM (Read Only Memory). Used in the Model 802 to process stimuli such as button pushing and incoming tally signals and produce reactions such as blinking or steady lamp illumination, crosspoint closure, tally generation, relay control, or audible chime signal.
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milli (m): A prefix that means one-thousandth.
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Mix-Minus Bus/feed: 1. In the studio, a mix-minus feed can be fed to a singer on stage. The mix- minus consists of a prerecorded orchestra. The performers microphone signal and the mix-minus feed are combined in another mixer output for the final air or recorded feed. This method is used for reasons of economy and to simplify production.
2. In ENG operations, a mix-minus feed is used for the IFB. The mix-minus allows the talent to hear the program audio that includes the voices of other talents at other venues, but not the talents own voice. The effect is to allow normal conversations, on air, among the performers. The bus feed refers to the mixer mix-minus feed available to one or more IFB program inputs.
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Mixer: An electronic device used to combine several signals inputs to a single output or to stereo outputs. Often other features are added to make it easy to achieve the basic goal.
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Monaural: Containing one source of audio although the source may be a summation of two or more original sources.
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Monitor: An audio speaker used to supply program audio to the control room, audio mixer, and to others who need an acoustic audio feed. Some special monitors are used for musicians to hear their own instrument or voice. Usually a monitor is placed in the Green Room.
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Mu (μ): Greek letter, mu, symbol for permeability (magnetic), amplification factor, prefix for micro (one-millionth).
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Mu Metal Shield: A highly effective magnetic shielding material.
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Multiplexing: A method of carrying more than one signal on a single "path." Multiplexing may be by means of frequency, time division, and/or space. The TW system frequency multiplexes DC power, speech signals, and a 20-kilohertz call signal on a single pair of wires. The Models 848A/DC848 use time multiplexing in a digital RS485 signal to send data for all 24 stations down a single path.
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mV: Millivolt or one thousandth of a volt.
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mW: Milliwatt or one thousandth of a watt.
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NAB: National Association of Broadcasters.
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NABET: National Association of Broadcast Employees and Technicians.
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NEC: National Electrical Code
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NEMA: National Electrical Manufacturers Association
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Nibble: A nibble is half a byte or four bits.
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Noise: Usually an unwanted sound or signal that interferes with a sound or signal normally present in a system, device, or circuit. Sometimes a special noise source such as a pink noise source or a white noise source is used to test a system or acoustically test a room.
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Ohm (Ω): The electrical unit of resistance. One volt will maintain one ampere of current through one ohm.
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Ohm's Law: This law relates the electrical parameters of voltage, current, and resistance. The symbol for voltage is V*, current is I, and resistance is ρ. Voltage, V=I×ρ. Current, I=V/ρ. Resistance, ρ=V/I.
*An older symbol or term for voltage is ε. ε is also the symbol for the Electric field, which has units of volts per meter.
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Omega (Ω): Symbol for ohm.
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Omnidirectional Microphone: A microphone that picks up sound from all directions with the same amplitude.
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Option: Options are extra features available (for a price) on intercom and pro-audio equipment.
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Output: The useful signal (voltage, current, power) produced by a system, device, or circuit.
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Paging: Making a voice announcement over a sound system. The sound system is "PA" in the sound contractor world, and "SA", Stage Announce, in the television/theater world.
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Parallel Circuit or Connection: In a circuit, the paralleled elements would be across the same voltage and the currents would divide amongst the elements. This kind of connection can apply to circuits, devices, or systems. For example: two RTS® Systems TW Intercom Systems can be paralleled, by coupling with the appropriate capacitors, and switching each system power supply(ies) from 200 ohms to 400 ohms on the channels to be paralleled.
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Party-Line (PL): A Party-Line (also called a conference line) is a group of intercom ports, which can always talk and/or listen to each other. Party Lines have default names PL01, PL02 etc. These names can be changed to more meaningful names using Other Alpha setup in AZedit. Members are assigned to a Party Line using Party-Line setup in AZedit. Once a Party Line has been set up, it can also be assigned to a keypanel key either from the configuration software or at a programmable keypanel. This allows the keypanel operator to talk and/or listen to the Party Line without being a member.
IMPORTANT: Do not confuse special lists and Party Lines. A special list is used when a keypanel operator needs to occasionally talk or listen to a group of intercom ports that are otherwise unrelated. A Party Line is typically used when several users of nonkeypanel devices (such as belt packs or camera intercoms) are engaged in a specific common activity and they need to talk and/or listen to each other all the time. Keypanels are almost never members of Party-Lines (although they can be). However, a keypanel key can be assigned to occasionally talk or listen to a Party Line if desired. Just remember: Party-Lines are primarily set up for Party-Line members, with occasional access by keypanel operators, while special lists are set up exclusively for keypanel operators to talk or listen to several unrelated intercom ports. For specific information about Party-Line setup, search for "PL" or "Party Line" in AZedit help.
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Patch Bay/Patchboard: A system of interconnecting audio signals. Consists of fixed connectors interconnected with flexible "patch" cords that are cords usually with a male connector on each end.
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Peak: The crest value of a voltage, current, or power.
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Phantom Power: There are three standard voltages: 12, 24, and 48, according to DIN 45 596. Voltage is applied to the circuit in a balanced fashion using a center tapped transformer or two resistors. The size of the resistors depends on the voltage.
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Phase, Phase Shift: Comparing the reference of one waveform to the reference point of another waveform. With periodic waveforms, the phase varies from 0 degrees (waveforms line up), to 180 degrees (waveforms opposite), to 360 degrees (waveforms line up but one is delayed by the time of one waveform).
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Pi (π): The mathematical constant π is an irrational number, approximately equal to 3.14159, which is the ratio of a circle's circumference to its diameter in Euclidean geometry. It is also known as Archimedes' constant (not to be confused with Archimedes number) and as Ludolph's number.
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Pickup Pattern: Refers to the sensitivity of a microphone to acoustic audio signals originating from different spatial directions.
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Pink Noise: Equal noise energy per octave.
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PL: See Conference Intercom Systems.
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PLL: Phase Lock Loop. A tone decoder utilizing a phase lock loop is used in many of the TW System stations.
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Point-to-Point (Matrix) Systems: A point-to-point system allows two or more people to intercommunicate. However, the conversations are limited to those selected by the originator of the call. This system normally includes a “tally” subsystem. The “tally” subsystem tells the called station where the originator is so that the called station operator can press a button to answer. Some systems automatically press the button and complete the return path. Most systems made by RTS® Systems are full duplex (one can interrupt the speaker), and non- blocking (access to the channel is immediate and there is no busy signal). Conversations on point-to-point systems are in general, private. There are two kinds of point-to-point systems available. One is a distributed matrix system; the other is a central matrix system. The Models 848A and DC848 are modules in a distributed matrix system. The McCurdy Models 9500 and 9400 are examples of central matrix system.
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Pop: An undesired effect on a microphone output when a puff of air hits the microphone diaphragm. The effect sounds like a thump or pop. The effect is noticed with the following sounds: "p", "b", and "t".
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Pop Filter: Material placed between a sound source and a microphone that reduces the "pop" effects. It slightly affects microphone performance.
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Port: Ports are the individual channels that devices are connected to. Devices include: 2-way communication devices, such as keypanels, belt packs etc. Audio sources, such as broadcast feeds or background music. Miscellaneous audio output devices, such as powered loudspeakers, PA systems etc.
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Port Gains: RTS® keypanels are calibrated to send and receive audio at the standard operating levels of the intercom system. No audio gain adjustment is normally required when connecting these. However, many other types of devices may not operate at the standard intercom system levels. To assure signal level compatibility between the various types of audio devices connected to the intercom system, there are separate analog input and output gain adjustments for each intercom port. It is also possible to adjust the listen gain for any specific intercom port when listening to any other specific intercom port. This is called the point-to-point listen gain, or crosspoint gain. For example, a keypanel operator might want to monitor a music source connected at some intercom port, but at a reduced audio level so that it does not interfere with normal intercom communications. The crosspoint gain can be reduced for the keypanel port listening to the port where the music source is connected. Analog gain adjustment is only available using AZedit. Crosspoint gains can be adjusted either within AZedit or from a programmable keypanel. For further information on any gain adjustment in AZedit, search for keyword "gain" in AZedit help. For procedures to adjust gain from a programmable keypanel, look for "gain" in the manual index.
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Port ID Numbers and Alphas: Intercom ports have identification numbers 001, 002 etc. These numbers cannot be changed, but may not be commonly known to intercom system users. Each intercom port also has a default name, called an “alpha”, because this name appears in the alphanumeric displays on keypanels when you assign the ports to keys for talking and listening. The default alpha names are N001, N002 etc. These default alpha names can be changed to ones that are meaningful to keypanel operators using Port Alpha setup In AZ™EDIT. (Click the “Port Alpha” button in AZ™EDIT, and then press F1 on the computer keyboard if you need help.)
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Postproduction: Production activity that occurs after the actual production phase. For example the editing of a television or motion picture production.
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Postproduction Editing: The process of making decisions and actually manipulating the media (film or tape) to change action sequences, delete, insert, and modify images and sound.
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Pot (Potentiometer): A device to electrically change audio or video levels. Potting up means increasing a level from a control panel. An audio mixing console is an audio control panel.
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Power Amplifier: An amplifier used for driving lower impedance (8 to 500Ω) headphones or speakers (2 to 45Ω).
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Power Ratio: See decibel.
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Power Supply: 1. The source of electrical power ("power outlet"). In North America, this source is generally 120 volts AC, 60Hz. In Japan, the source is generally 100 volts, 50Hz or 60Hz. In Britain, the source is 240 volts, 50Hz. In Europe, the power is usually 220 volts, 50Hz. There are exceptions in every location, and there are still isolated odd systems throughout the world. RTS® Systems equipment has been designed to operate at these various voltages. In addition, some equipment is operable off of DC sources such as batteries, automobile 12 volt power, aircraft 28 volts, and aircraft 120 volts, 400Hz.
2. A unit used for converting power outlet power to DC power.
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Power Supply, TW: A special power supply to run user stations on the RTS® Two-Wire Intercom System. This supply provides low noise DC power (nominally 32 VDC) and an audio impedance of 200Ω or 400Ω. This impedance extends from 100Hz to 20000Hz.
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Preamplifier: An amplifier usually used to raise the small signal from a microphone to a "line level" sized signal.
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Presence Peak: A rise in the response of a microphone in the range of 2000Hz to 10,000Hz. In circuits, a deliberate alteration of the frequency response in the range of 1000Hz to 10,000Hz. RTS® Systems model 802 has a small presence boost in the speaker amplifier change in the 1000Hz to 2000Hz range.
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Pressure Zone Microphone (PZM): Used to pick up audiences or groups. Microphones with a reflecting surface such that the sound waves arrive in phase at the microphone element, providing good frequency response. Also used for orchestral pickup.
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Program, Program Audio: In television, the audio signal that is being sent out with the picture to be broadcast.
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Push-to-Talk (PTT): Usually used on handsets or push-to-talk microphones. Pushing the button enables the microphone and often also enables an electronic switch in an intercom station. The electronic switch prevents amplifier and cable pickup from going on the intercom line as undesired noise.
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Rack Unit(s) (RU): A standard unit of measure used when dealing with electronic equipment racks. 1RU = 1.75" (44.45 mm). For example: a particular piece of equipment is described as being 3RU in height. This means that it is 5.25" (3 x 1.75") in height.
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Reactance: A property of an inductor or capacitor that is frequency dependent. Capacitive Reactance is opposite to Inductive Reactance. Inductive reactance increases with frequency. Capacitive reactance decreases with frequency. See Capacitance and Inductance.
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Relay: Relay is used interchangeable with GPI output. The relay feature works with the 16 GPI outputs of an optional UIO-256 Universal Input/Output Frame, and with the relay outputs of an FR9528 Relay Frame. The relay feature also works with the 8 GPI outputs of an ADAM, ADAM-CS, or Zeus intercom system (J27 on a Zeus frame, J903 on an ADAM-CS frame, and J11 on the XCP-ADAM-MC Master Controller Breakout Panel in an ADAM intercom system). You can assign a keypanel key to control a GPI output from any of these devices, and then use that key and output to control an external device. For example: you could use a keypanel key to control lighting. Or, you could assign a relay as a level 2 talk key assignment in a stacked talk key arrangement to both send audio and key a device, such as a paging amplifier or a two-way radio.
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Remote Station: A user station located at a distance from the master station.
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Remote Truck, Remote Unit: A mobile television studio. Supports television productions with equipment and production personnel operating positions. Carries cameras, CCUs, switcher, monitors, audio console and ancillary equipment, VTRs, and last, but not least, intercom systems.
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Resistance: In DC circuits, the opposition to current, in AC circuits, the real part of the opposition to current.
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Resonance: A condition where an applied signal's frequency coincides with a natural response frequency of a circuit, device, or system. There must be reactances in the circuit for a resonance; a pure resistance does not resonate.
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Retractile: A cord whose jacket is treated and formed to retract as a spring.
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RF: Radio Frequency. Frequencies generally ranging from 15kHz to 150gHz. The electrical energy at these frequencies is often converted to electromagnetic waves that are propagated through space. These waves are the basis of the wireless intercom, radio broadcasting, television broadcasting, microwave ovens, industrial processes. Frequency Name of Band Examples: 3kHz to 30kHz Very Low Frequencies (VLF) Underwater Communications 30kHz to 300kHz Low Frequency (LF) Navigation 300 to 300kHz Medium Frequency (MF) AM Radio Broadcasting 3 to 30mHz High Frequency (HF) Short Wave Radio, Long Range Terrestrial Communications 30 to 300mHz Very High Frequency (VHF) TV, FM Broadcast, Fixed I Mobile Communications, Walkie Talkie, Wireless IFB, Wireless Intercom, Airborne Communications 300 to 300mHz Ultra High Frequency (UHF) TV Broadcast, Mobile Communications, Walkie Talkie, 3 to 30gHz Super High Frequency (SHF) Satellite Uplink/Downlink 30 to 300gHz Extremely High Frequency (EHF) Satellite Uplink/Downlink kilohertz = 1000Hz megahertz = 1000000Hz gigahertz = 1000000000Hz
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RFI: Radio Frequency Interference. This interference may originate from AM and FM radio stations, television stations, light dimmers, electric motors, intermittent incandescent or fluorescent lamps, doorbells, et cetera. It results in either direct demodulation into audio circuits or position sensitive effects.
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Rho (ρ): Abbreviation for resistance, and the symbol for a resistor.
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RIB: Racks in a Box. A RIB is a large-scale intercom system that is delivered to the customer in a preconfigured rackmount array.
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RMS: The abbreviation for root-mean-square. The effective value of an alternating current waveform. The root-mean-square current, power, or voltage is as follows: Square the amplitude, so that the positive and negative halves of a waveform are the same polarity. Then the value is averaged over time. Finally, the square root of the average or mean is taken. The RMS value of a one-volt peak sine wave is 0.707
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Roll-off: The frequency at which the response of a filter, circuit, network, device, or system changes from its center value by 3dB.
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RU: See Rack Unit(s).
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SA or S.A.: Stage Announce. A public address system originating in a control room and ending up on the stage. The SA may also have the functionality of an IFB. This allows the director to interrupt dance music and address the dancers. The SA function is a standard function on the Series 4000 IFB system, the Model 801/Model 860 system, and the

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Glossary