HANDBOOK OF INTERCOM SYSTEMS ENGINEERING FIRST EDITION 38109-977 Preliminary Rev.
The Fine Print The Handbook of Intercom Systems Engineering, first edition, Copyright© 2000 by Telex Communications, Inc. All rights reserved. Printed in the United States of America.
TABLE OF CONTENTS Preface- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -3 About the Authors - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -5 Intercoms—An Overview- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -1 Introduction . . . . . .
(Limitations of Each System). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Design of Party-Line Intercom Systems - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -21 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . Defining And Meeting Your Needs . . . . . . . . . . . . . . Application 1 Generic Single Channel Systems . . . . . .
(Connecting (Interfacing to Other Communications Systems)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 (Some Practical Considerations) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Introduction to Matrix Intercom Systems - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -45 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Definitions. . . . . .
Determining Intercom Needs - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 113 Conference Versus Point-to-Point Requirements . . . . . . . Fixed vs. Mobile Requirements. . . . . . . . . . . . . . . . . A General Overview . . . . . . . . . . . . . . . . . . . . . Determining Intercom Needs, two-wire, four-wire, or both? . Small Studio or ENG Vehicle. . . . . . . . . . . . . . . MCE325 Modular Programmable Station PS15 Power Supply/MCP2 Rack Kit .
Glossary - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -129 Index - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -151 v
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LIST OF FIGURES Simple Party-Line System - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Simple Matrix System - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2 Wireless Intercom Examples - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 Example of Interfacing a TW System to a Matrix System - - - - - - - - - - - - - - - - - - - - 4 Complex Matrix Intercom System - - - - - - - - - - - - - - - - - - - - - -
A Comparison of Relative System Sizes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -70 Separate Studios, Separate Intercom - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -71 Fixed Trunking - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -72 Intelligent Trunking - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -74 Cascaded Trunking - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CHAPTER0 CHAPTER0 CHAPTER0 PREFACE CHAPTER0 Welcome to the Telex Communications, Inc. Handbook of Intercom Systems Engineering. The idea for this book came, as it does with many books and inventions, over drinks at a bar. A few of us “intercom types” were discussing our varied histories and experiences. We added up the years each of us had in the intercom system industry and between the four of us we hit the 75 year mark.
installation and support of intercom systems. In other words, we hope this book helps you get the absolute most out of your communications systems. Apart from the story of the bar and the trade show, there is another serious reason why we have written this book. Intercoms (in our opinion) are a neglected, underrated, taken for granted part of the technical world – they are not glamorous nor interesting.
CHAPTER0 CHAPTER0 CHAPTER0 ABOUT THE AUTHORS CHAPTER0 This handbook is the work of a number of past and present Telex employees, as well as, some outside experts (such as Stan Hubler). Among the contributors (in alphabetical order) are: Talal Aly-Youssef, Gene Behrend, Larry Benedict (contributor and editor), Rick Fisher, Stan Hubler, John King, Murray Porteous, Dave Richardson, Ralph Strader, and Tom Turkington.
6 Handbook of Intercom Systems Engineering
C H A P T E R 1 INTERCOMS—AN OVERVIEW CHAPTER1 RALPH STRADER Introduction Intercom systems, by definition, may be comprised of many different types of intercoms and subsystems. The basic building blocks can be categorized into four basic types or elements: Party-Line Systems, Matrix Systems, Wireless Systems, and Accessories. Party-Line Systems Wired Party-Line systems are systems in which a number of participants are all involved in the same conversation.
Matrix Systems Wired Matrix systems are systems in which a large number of individuals have the ability to establish private individual conversations from point A to point B. Again, going back to the telephone system in your neighborhood, you, your next door neighbor, the pizza joint down the street and the local gas station are all connected to the same central office by wires from each location back to the telephone company.
intercom system at some point. They can range from as simple as a single pair of units talking to one another, to a system in which 24 or more different portable units are dynamically switched between conversations. Figure 1.
Figure 1.4 Example of Interfacing a TW System to a Matrix System To connect a matrix intercom system to a Two-way radio system, a contact closure may be required to activate the radio transmitter. A GPI (General Purpose Interface) between the matrix and the base station of the radio can solve this problem easily. To do intelligent trunking between matrix systems, across campus or across the country, the audio and control signals between the matrices could be transported over fixed pairs of wires.
Figure 1.
ISO Camera Isolate – This is not reserved strictly for the domain of cameras anymore. This is truly an isolate function, not unlike the action at a party of grabbing the arm of a fellow guest, dragging them off to a corner for a private conversation, and then returning them to their group. There are instances where it is necessary in an intercom system to establish a momentary private conversation with someone who may be talking and listening to a number of other people.
C H A P T E R 2 INTRODUCTION TO PARTY-LINE INTERCOM SYSTEMS CHAPTER2 STAN HUBLER Introduction Leading off this chapter, Some Definitions that may help you understand Party-Line intercoms terms (and buzz-words). Then, a Short History of Party-Line intercoms will be presented, leading into a discussion of Present Day Systems and Manufacturers. The System Components and Their Function will explore the main components of these systems and what they do.
Balanced Line The balanced line concept reduces noise pickup by outside sources. A balanced two conductor line carries audio that is differentially driven and balanced to ground. Full Duplex This is communication that allows simultaneous two-way conversations, that is, one person can interrupt the other. In data communications, full duplex permits confirmation of sent data by the receiving terminal echoing, sending back the same data, or confirming data. Decibel (dB) A derived unit of loudness.
stage directors, director, assistant director, production assistant, and others. Originally, these crews shared one intercom channel where the director called the shots. Later, as intercom developed, additional channels were added so each crew could still listen to the director, then could switch to their own channels to coordinate activities without conflict with the director.
sound powered system, but we do not discuss it here. Present day Party-Line intercom systems may be wired or wireless or both. System Components and Their Function The system components for most Party-Line intercoms consist of power supplies (or master stations), user stations (e.g. belt packs, speaker stations, main stations, etc.), interconnecting cable, headsets, panel microphones, push-to-talk microphones, and a system termination.
Table 2.2 Intercom connector wiring by various manufacturers. Clear-Com Pin # Function 1 Common for Audio, Power, & Shield 2 DC power: 30 volts nominal 3 Unbalanced Audio Audiocom Pin # Function 1 Common for Audio, Power, & Shield 2 Audio + DC Power 3 Audio + DC Power RTS TW Pin # Function 1 Common for Audio, Power & Shield 2 Channel 1 Audio + DC Power 3 Channel 2 Audio The wireless systems usually include an interface to the wired systems.
Alternately, newer units have two talk buttons, two volume controls, and two status indicators to tell which talk button is engaged. Examples: RTS™ BP325, BP351, ClearCom® RS-522-TW, or Audiocom® IC-2B. Speaker User Station Functional Description A typical speaker station can function with either a headset or a speaker/microphone. A power amplifier, a speaker, and a speaker on/off switch are added to the electronics of a belt pack. In addition, a nulling adjustment is easily accessible.
4 The pin out of the headset connectors is as follows: Four pin XLR Pin 1 - Microphone common Pin 2 - Microphone “hot” Pin 3 - Headphone common Pin 4 - Headphone “hot” Five pin XLR Pin 1 - Microphone common Pin 2 - Microphone “hot” Pin 3 - Headphone common Pin 4 - Left Headphone “hot” Pin 5 - Right Headphone “hot” 5 Since the power supply has a limited amount of XLR-3 connectors, splitter boxes are used to expand the system. These boxes have all the connectors wired in parallel.
System Powering Systems can be centrally powered with a power supply or they may be individually powered with “local power” modules, also known as built-in power supplies. The systems can also be a mixture of central and local power. In the cases of Audiocom® systems and RTS™ TW systems, the power and signal share the same wire(s). This means, for those two systems, the power supplies DC source must be ultra low noise/quiet, circa -70dBu or better.
Master Stations These are multichannel stations. Some Master Stations are balanced (RTS™ TW Model 802/803) and require an interface (RTS™ TW Model 862 or 4012) to work with unbalanced channels. Master Stations can be configured to work with their respective systems with a minimum of interfacing. Master Stations have many functions which we go into to detail later. Cabling Usually the intercom system’s specifications are based on the use of 22 AWG microphone cable.
strobe is powered from the RTS line but only draws 10 milliamperes. It also supplies a relay closure and a logic signal. Limitations of Each System Cable capacitance, resistance, and crosstalk affect all three systems. The longer cables (over 2000 feet) limit the number of belt packs at the end. A system with cumulative cables adding up to 10,000 feet will have a reduction in frequency response due to cable capacitance. Both resistance and capacitance affect crosstalk.
3 This format allows louder and clearer communication. Party-Line intercoms can be wired or wireless or both. (System Components and Their Function) 1 The system components for most Party-Line intercoms consist of power supplies (or main stations), user stations, interconnecting cable, headsets, panel microphones, push-to-talk microphones, and a system termination. 2 The power supply (normally centralized) generates DC power for the entire system (exception: self powered user stations).
2 Systems can be powered from a central power supply or local powered modules. Using local power modules allows more stations to be on the system. 3 If a station is too far away to get enough DC power, batteries can be used as a workaround. 4 Headset User Stations have a microphone preamplifier with a maximum gain around 53dB. Many stations have an AGC (Automatic Gain Control) that adjust the gain to the incoming microphone signal level.
Figure 2.1 Audiocom® intercom concept. Figure 2.2 Clear-Com® intercom concept.
20 Figure 2.3 RTS™ TW intercom concept. Figure 2.4 RTS™ TW user station block diagram.
C H A P T E R 3 DESIGN OF PARTY-LINE INTERCOM SYSTEMS CHAPTER 3 STAN HUBLER Overview In this chapter, designing a system based on your needs is first approached by Defining And Meeting Your Needs. This topic is designed to help you choose or at least understand the system. IFB is described in The IFB System (One Way Communications System). Then Connecting (Interfacing) to Other Communications Systems discusses real world solutions to interfacing these systems.
Audiocom Party-Line Intercom Equipment Listing #1 Figure 3.1 Generic single channel Audiocom® system. Power Supply: PS2001L Splitters: TW5W Belt Packs, Single Channel: BP1002 Headsets: Leader Person: Single Muff PH-1; rest of crew: Double Muff PH-2 Cables: Standard Microphone Cables with XLR-3 connectors Note 22 The first block diagram, Figure 3-1 shows a simple single channel Audiocom intercom system.
Clear-Com Party-Line Intercom Equipment Listing #1 Figure 3.2 Generic single channel Clear-Com® system. Power Supply: PK-5 Splitters: TWC-10A Belt Packs, Single Channel: RS501 Headsets: Leader Person: Single Muff CC-95; rest of crew: Double Muff CC-260 Cables: Standard Microphone Cables with XLR-3 connectors.
RTS TW Party-Line Intercom Equipment Listing #1 Figure 3.3 Generic single channel RTS™ TW system. Power Supply: PS15 Splitters: TW5W Belt Packs, Single Channel BP319 Headsets: Leader Person: Single Muff PH-1R; rest of crew: Double Muff PH-2R Cables: Standard Microphone Cables with XLR-3 connectors. Application 2 Two-Channel System: TV, School, Cable The second application is a two-channel system for a small TV operation (Studio or Truck), school or cable access.
Figure 3.4 Small TV operation. Audiocom Party-Line Equipment Listing #2 Power Supply: PS2001L (Rack Mount, 1RU) Director’s Station: US2002 (Rack Mount, 1RU) Video: WM2000 (Wall Mount) Graphics: WM2000 (Wall Mount) Cameras and Floor Manager: BP1002 (Belt Packs) Headsets Director, Switcher, Floor Manager, Video, Graphics: Single Muff PH1 Headsets: Cameras: Double Muff PH2 Splitter: TW5W IFBs: IFB-1000 Earphones (Earsets): CES-1 Note Cables: Standard Microphone Cables with XLR-3 connectors.
Headsets: Cameras: Double Muff CC60 IFBs: TR-50 (Includes earset) Splitter: TWC-10A Note Cables: Standard Microphone Cables with XLR-3 connectors. One cable per channel. /2 indicates two microphone cables required.
Audiocom Party-Line Equipment Listing #3 Power Supply: PS2001L (Rack Mount, 1RU) Stage Manager’s Station: US2002 (Rack Mount, 1RU) Dressing Rooms and Green Room: SS1002 (Single channel wall mount station; if a portable speaker station is desired, add an S, U, or P box). Crew: BP1002 (Single Channel Belt Packs) Headset: Stage Manager Single Muff PH1 Headsets: Crew: PH2 Cables: Standard Microphone Cables with XLR-3 connectors. One cable per channel.
Application 4 Training Systems Audiocom Figure 3.6 Audiocom® based training intercom system. The training system consists of an instructor and multiple two-student crews. In the case of Audiocom, each of the six two-student groups are independently addressable by the instructor. When the student groups are not talking to the instructor, each twostudent group can have semi-private conversations. The call light tells the instructor which group is paging.
Clear-Com Figure 3.7 Clear-Com® based training intercom system. It just happens that the Clear-Com® system is the simplest for this application, since the Master Station, MS-812A has the three pin XLR connectors for 12 channels on the rear panel. The MS-812 has several configurations, and will have to be specified for this application (No IFB, 12 Clear-Com standard PL channels). Power Supply: PS-464. Instructor’s Station: MS812A. Students’ Stations: Single Channel Belt Packs RS-501.
RTS™ TW Figure 3.8 RTS™TW based training intercom system. The RTS™ TW system for this application is the next simplest, and has added features. The student crews can have completely private conversations, yet are still reachable via the call light paging system. Each BP325 belt pack can be configured to accept an individual program source (but the loop-through is lost and the two students line connection will be through a simple one to two splitter).
Application 5 Medium System for Television Figure 3.9 Medium intercom system for television. This shows an RTS™ TW large 12-channel system. This is a system that is in medium trucks that haven’t yet switched over to a combination matrix and Party-Line system.
output of a Master Station or User Station with a “Hot Mic” output. The IFB electronics receives its program audio from the audio mixer board. The IFB System (One Way Communications System) IFB is a television acronym for Interrupted FeedBack, Interrupted FoldBack, Interrupted Return Feed (IRF). An IFB system permits a director or producer to talk to the talent, typically an “on air” announcer, newscaster, or sportscaster. Normally the talent hears the broadcast program audio.
In some more extreme cases, only a single pair of wires may be available. In this case, plug the talent’s stereo headset into the stereo connection on the talent receiver, then connect the high side of the pair to pins 2 and 3 of the XLR3 connector and the low side to pin 1 (pseudo-stereo mode). This will give a mono feed with each ear individually adjustable and both ears interrupted. For runs of two miles of number 22 gage twisted pair, at least one talent receiver station should be operable.
Some of these are: 1 Mode differences. There are several not directly compatible modes of operation: two wire mode, four wire mode, full duplex mode, half duplex mode, simplex mode.
Modes The following modes exist in intercom systems: M2) Two-Wire. M4) Four-Wire. The following sub-modes are considered for two-wire and four-wire: M2F) Two-Wire, Full Duplex. M2H) Two-Wire, Simplex. M4F) Four-Wire, Full Duplex. M4H) Four-Wire, Simplex. Level Problems One problem in interfacing from two-wire to two-wire is caused by the 2 wire systems’ use of 2 to 4 wire hybrids. Interfacing requires conversion from two-wire to four-wire twice to allow level adjustments to and from systems.
Interfacing Practice Interfacing Television Camera Intercom Systems to TW Systems General Camera Configuration Information for Television Cameras (except ENG units) Television cameras used in broadcast and industry usually have two parts: a camera head and a camera control unit (CCU). The camera head assembly usually contains the lens equipment, camera electronics, and triax adapter (if used).
Table 3.2 Intercom comparisons. Intercom Type Nominal Impedance Impedance Range Output (Ohms) (Ohms) Type Mode Estimated TX/RX Peak TX Levels Power (mW) (dBu) TW 200 50 to 400 Un-Bal 5 TELCO 600 600 to 900 Bal two-wire 1 0 to -10 Two-Wire 150 to 200 100 to 1k Un-Bal two-wire 0.
Headphone Impedances Low impedance headphones are louder, causing the user station to draw more current from its power source. High impedance headphones are not as loud, drawing less current. Many user stations have a headphone impedance range from 25 - 600 ohms. Headphones up to 2,000 ohms will function but greatly reduced levels. In a double muff headset such as a Beyer DT-109, there are two 50 ohm headphones connected in parallel resulting in an impedance of 25 ohms.
Cable Considerations Crosstalk Use shielded cable to interconnect user stations in areas of possible electrical interference, (areas such as those near: digital equipment, high current primary power conductors “power outlets”, transformers, transmitters, and lighting dimmers. Do not run TW Intercom System cables along the same ductways and pathways as these cables. Standard wire size for the an intercom system interconnection is #22 gauge shielded cable, such as Belden 8761, 8723, 9406.
System Current/System Capacitances/Loading The system currents are determined by several parameters: 1 The current required to supply standby current for each user station. 2 The current required to supply the dynamic current to generate line signal, headphone signals, speaker signals and call lamp signals. 3 The current required to start up a system (inrush current) by charging up to (50) 4000 microfarad capacitors or 0.2 farad. 4 The current limit imposed by the power supply to protect itself.
user stations will normally continue to operate if one can only figure out a way to flip the switches and touch only the knobs. Moisture / Contamination Protection If, in the field, a soft drink or something like it is spilled into the equipment, the equipment can be dismantled and cleaned gently with clean water. After the equipment is dry it can be returned to service. If this happens fairly often, residues in the water can be deposited on the equipment.
9 A training system usually consists of a station for the instructor and multiple, independently addressable student stations. 10 In a large system for television production, additional accessory equipment allow expanding the Party-Line into 12 or more Party-Line channels, isolated camera channels, IFB capable stations, and wireless intercoms.
8 Extending the range and using “local powering” may reduce a two-channel system to one channel at the remote station. 9 Crosstalk in a two channel system such as the RTS TW system can be reduced by “home running” the cables to a central point where the splitters and power supply are. 10 Crosstalk can also occur across the ground connection, especially where long cables have built up the ground resistance.
44 Handbook of Intercom Systems Engineering
C H A P T E R 4 INTRODUCTION TO MATRIX INTERCOM SYSTEMS CHAPTER4 RALPH STRADER Introduction While there is an extensive glossary in the back of this book, some definitions will be given here to aid in the following chapter. Definitions Ports Matrix User Station Refers to the number of connections available to external devices from the matrix.
Figure 4.1 GPI (or GPI/O) Rack Unit(s) (RU) The KP-32 is a good example of an advanced user station (keypanel). 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. A standard unit of measure used when dealing with electronic equipment racks. 1 RU = 1.
Figure 4.2 Example of Matrix Ports ADAM / ADAM-CS / ZEUS MATRIX Data 1-8 Data 9 -16 Data 17 - 24 1 2 3 4 1 2 3 4 Out 4 In 4 Data 1 - 8 Out 1 In 1 Data 1 - 8 PORT #4 PORT #1 History of Matrix Intercoms Properly, it can be said that matrix intercom systems go back to the advent of automated central office telephone switching systems in 1892. Matrix intercoms, even today, owe a great deal to the concepts and technologies of those systems.
In the late 1970’s, microprocessors became available and the first truly intelligent intercom system, the McCurdy 9400, was delivered. This was the first system that used data sent from the user stations as opposed to one wire per intercom key. As microprocessor technology improved, the 9400 was replaced by the 9500 series. This series was more dense, allowing a 50 X 50 system in 3RU.
Table 4.1 Number of Users vs. Number of Crosspoints Number of Users Number of Crosspoints 10 100 25 625 50 2,500 100 10,000 200 40,000 400 160,000 As you can see in Table 4.1, while a ten-user system “only” requires 100 crosspoints for all possible communications paths, a 100-user system requires 10,000 crosspoints. Now, realize the number of crosspoints has a direct correlation to power consumption, physical size, and cost.
Figure 4.4 A comparison of the 9400 Intercom System to the 9500 Intercom System (see inset). The 9500 represented a tremendous reduction in physical size. By 1988, the limits of the square architecture were beginning to show. The 350 port McCurdy 9700 matrix intercom systems that NBC commissioned for the 1988 Seoul Olympics required 10 full racks, over 20 kW of power, and weighed in at over 2 tons. The 9700 matrix was the largest matrix intercom of its day.
and switching systems much earlier, and now it would be applied to matrix intercom systems. In a TDM matrix, the incoming signals from users (microphones or headsets) are run through an A/D converter and assigned a “time slot” on a TDM backplane. A good (although not strictly accurate) analogy would be the signals on a cable TV system. Whereas on the cable system you might have ESPN, HBO, and MTV, on a TDM backplane you would have the timeslots for Director, Producer, and Camera1.
Figure 4.6 Conventional Matrix vs. TDM Matrix Today, nearly all matrix intercoms are based on TDM or similar technology. Telex manufactures the RTS™ Zeus™, ADAM™-CS and ADAM™ TDM Matrix intercoms, Clear-Com has the MatrixPlus3, and other manufacturers in Europe offer TDM-based solutions to their markets. Modern Day Matrix Intercoms As discussed in the last section, today’s matrix intercoms are TDM based.
Special Considerations When considering the type of intercom system to install for a given application, there are many factors to take into account and many of these have been discussed in an earlier chapter. These factors are discussed in detail in the following section on advantages and disadvantages of matrix intercom systems versus the other types of systems available. Advantages Matrix intercom systems have numerous advantages over other types of intercoms.
your telephone; Call Bill, press the “Conf” button again; call Chuck, then press the “CONF button, and you have a conference with all parties involved. With a matrix intercom system, you press the talk keys assigned to Alice, Bill and Chuck and say “Meet me on Tech PL”. You, Alice, Bill and Chuck each press “Tech PL” on your user station, and instant conference. Other types of specialized communications can be established as easily (or easier) in a matrix intercom system.
Figure 4.7 Typical Keypanel Typical User Station (Keypanel) + 8 dBu Audio From Matrix (Listen) Speaker CPU Serial Data Rs485 Data To Matrix Headset Microphone Switches Indicators + 8 dBu Audio To Matrix (Talk) Normally, a user station provided by the manufacturer of the intercom performs all of these functions. However, suppose the user requires a user station to be very small, low cost, and mounted in a single gang electrical box, and that the station only needs to call a security desk.
Output from a Previous UPL Statement GPI Input Local GPI Input Status of a GPI Output Status of a Local GPI Output Talk Key Status Listen Key Status UPL Resource Crosspoint Status Input Talking Output Listening Headset Transfer Switch Status Current Date Current Time IFB Interrupted Counter This allows the test to be chained with other conditions via AND, OR, NOT and XOR to be tested and cause one of the following (or multiple of the following) actions to take place: Close Crosspoint Inhibit Crosspoint Asse
input 1 --> outputs 43, 44, 45 input 3 --> output 43 program input 1 --> output 45 also inhibit the following crosspoints: program input 1 --> output 1 Issue the following ASCII Command String to the Matrix: IN1FI43F44F45F1IIN3FI43FINPG1FI45F The simplified ASCII command line protocol still requires some programming to take place external to the matrix to either translate the native language of the external control system to Telex® Command Line Protocol, or to modify the internal code of the third party dev
You are in your kitchen – QUICK, multiply 347.2 times 15.8 – Well let’s see, I could go down to the den, turn on the computer, wait for Windows® to boot up (have a cup of coffee), start my spreadsheet program, and type in “=347.2*15.8,” read the answer – “oops, no pencil -%(&#@) Select File, Page Setup, Set Print Area highlight the cell with the answer, Print, wait for the Laser Printer to warm up, take the print out, tell the computer to shut down, go back upstairs….” elapsed time 9 minutes.
So now…Quick! You need to setup an intercom on the roof of your facility to cover a local parade. You can go to your matrix intercom, locate two unused ports, assemble appropriate length three pair cables, fish the cables up to the roof. Then fish a power cord to the roof, take two keypanels up there (hope it’s not raining), and connect the panels. Now go down to the configuration PC, assign appropriate keys to those panels. Go back to the roof and verify that you have communications.
60 Handbook of Intercom Systems Engineering
C H A P T E R 5 DESIGN OF MATRIX INTERCOM SYSTEMS CHAPTER5 RALPH STRADER Introduction In this chapter, we will address the major issues and considerations for designing a matrix intercom system. At the end of the chapter, you will not know everything to specify, plan, design, and install a matrix intercom system. Nevertheless, you will have a good idea of the basic requirements, pitfalls, and opportunities involved in the design and installation of a matrix intercom system.
unless otherwise noted, the comments also apply to ADAM™-CS and Zeus™ intercom systems. Previously, we discussed the analogy between telephone systems and matrix intercom systems – the analogy is not correct in all cases, here are some exceptions. Figure 5.1 IMPORTANT Typical ADAM™ Matrix Connections In ADAM™ matrix intercom systems, the connection between the matrix and keypanel is normally via three twisted pairs of unshielded cable. As shown in Figure 5.
As received “out of the box,” a matrix intercom system needs to be configured (programmed). This can include how many users are connected, how many conferences are expected, what you wish to name the users, who can talk to whom, and, just as importantly, who cannot talk to whom. In some cases, the default configuration upon first operation is adequate and may allow enough communications to meet your needs, but it is unlikely, and frankly, a tremendous waste of capabilities.
Camera 2 Camera 3 Floor Director TelePrompTer Anchor A Anchor B Anchor C Weather Control Room Director Producer TD PA 1 PA 2 Segment Producer Audio Operator News Computer Operator Font Operator Other Green Room Makeup Do this for all locations; it will give you a quick “port count” for your system, which will have a significant impact on size of the matrix, and, as a result, the cost. I presume that even if you do work for MegaMedia Corporate Conglomerate Entertainment Enterprises Ltd.
• Does the user regularly need the ability to adjust individual volumes of the keys (not to be confused with the overall volume control which all panels have)? If yes, a Level Control Panel should be added to their station.
Figure 5.2 66 A wide variety of keypanel options exist. Here we have a selection of RTS™ keypanels that fit a range of needs. Small keypanels such as the (A) KP-12LK and (B) WKP-4 provide an interface for those with limited keypanel needs. The (G) KP-96-7, a medium sized unit, was the workhorse of the RTS™ keypanel line until the 1980’s and 1990’s.
Let’s proceed on the basis that you have now compiled a list of needed equipment, have gotten approvals, placed the order, and are now ready to begin the installation of your system. Cable Considerations Cabling types do vary considerably among the manufacturers of matrix intercom products, as do the signals transported by them. For that reason, the following discussion is somewhat specific to RTS™ Zeus™, ADAM™-CS and ADAM™ matrix intercom systems.
buzz” audible in that audio signal. The data signal would not carry for as great of distances. This type of error is second in the top ten of initial installation problems, after addressing mistakes. ADAM™ and ADAM™-CS systems are also available with other wiring schemes, including multi-pin breakout to jackfields for monitoring and rapid changes and for use of 25 pair “Telco cable” for distribution.
We talked earlier about how addressing of keypanels is critical in the matrix intercom system. The way in which addresses work is as follows: In a given group of 8 panels sharing a common data line, the data gets sent from a keypanel to and from a matrix by a process called polling.
Figure 5.4 A Comparison of Relative System Sizes These are the numbers of ports that are available in a single RTS™ intercom matrix from Telex. Other manufacturers offer systems in sizes from eight to approximately 500 ports. As you can see, size is not a limitation in most cases. At the time of this writing, the largest known single matrix intercom system in service is a RTS™ ADAM™ system which consists of 784 ports at both ESPN and NBC. Size and capability are not the limiting factor in most cases.
Now, let’s take the opposite tack; what would be the reasons for going to a single large matrix? Some of the reasons might include: • Operations require ability for any of the 512 users to communicate with any of the other users. • Desire for single point of administration, control, troubleshooting and monitoring. • Design of the facility is highly decentralized operationally, and day to day, different portions of the facility must work together.
jackfield. Then, simply connect the output of Production PL from Studio A to the input of Production PL for Studio B, and conversely, connect the output of Production PL from Studio B to the input of Production PL for Studio A. Do the same for Technical PLs. Figure 5.6 Fixed Trunking Now, any conversations on Production PL for A control will also be available to the Studio B cameras for both talking and listening, and the same is true for the Technical PL. Our problem is solved.
The technique described is called trunking; the two ports of each system assigned to PLs have been “trunked” to one another. For reasons that will become clear later, we refer to this as “dumb” or unintelligent trunking. That isn’t to say that it isn’t a brilliant idea or solution. It means that no system intelligence was employed in establishing the trunks.
Figure 5.
“Great” you say, “Why not always trunk and avoid HUGE matrices?” I’m glad you asked that question. First, there is what I refer to as the “Mother’s Day Syndrome.” Mother’s Day rolls around, and all good sons and daughters decide to call their dear, sweet mom and wish her the best, and many of them don’t get through. They hear a nice recording of someone saying, “All circuits are busy, please try your call again later.
exists for the trunk master to route a signal from A to C and from C to B, thereby bypassing the bottleneck. Figure 5.8 Note Cascaded Trunking Another advantage of trunking is that there is no requirement for the individual matrices involved to be in close proximity. Systems, which are hundreds or even thousands of miles away, have been successfully trunked using techniques described earlier with respect to remote keypanels.
By using the Bus Expander with multiple ADAM™ frames, a single electrical matrix can be located floors or buildings apart within a complex, and yet function as a single large matrix. Now that we have discussed a number of different methods used to create large intercoms, and how to interconnect smaller intercoms into a single system, let’s move onto interfacing and accessories. Interfacing It is rare that an intercom system is an island unto itself.
Figure 5.9 TW and Matrix Signal Flows User Station TW Signal Flow “Generic” Microphone Speaker Bidirectional Audio to Other Stations Sidetone + + User Station Matrix Signal Flow “Generic” Microphone Balanced Audio To Matrix Volume Balanced Audio From Matrix Speaker BASIC SIGNAL FLOW DIFFERENCES BETWEEN TW & MATRIX INTERCOMS In a wireless intercom system, the communication may be full duplex, with the two sides of the conversation carried on two separate frequencies.
Figure 5.10 Wireless Intercom Interfaced to Matrix Intercom Since the RadioCom™ system is full duplex, with the base station transmitting continuously, there is no need for the matrix intercom to provide a PTT (Push To Talk) signal to the base. In the case of radio systems where the base station is not transmitting continuously, the matrix must provide a logic signal corresponding to a user pushing an intercom key to talk to that wireless system.
Figure 5.11 GPI/O Implemented PTT (Push-To-Talk) 2 Way Radio Base Station In Out +- +- GP I/O Interface PTT(n/o) Relay Closes Upon “Talk” Signal to 2 Way Radio “PTT” (Push-to-Talk) As mentioned earlier, TW systems are, by definition, two-wire (one pair) communications systems, having both talk and listen present at the same time on the same conductors. In order to connect a TW intercom system to a four-wire system an interface is required.
Figure 5.12 TW to Matrix Interface The hybrid, in Figure 5.12, acts as a “traffic cop” allowing the talk signal from the matrix to be applied to the bi-directional TW line while blocking its return when the talk signal from the TW is presented to the matrix. The effect of the blocking is termed “nulling”, as it cancels of the return signal. The effectiveness of the cancellation is driven by many factors.
here is specific to RTS™ ADAM, ADAM™-CS and Zeus. The basic concepts hold for other matrix intercoms on the market. A brief word on the architecture of the ADAM™, ADAM™-CS and Zeus™ matrix intercom systems will set the stage. Zeus is the entry-level matrix and is configured as 24 ports, and does not include power supply or controller redundancy. ADAM and ADAMCS are expandable systems, and are standard with redundant power supplies and redundant auto-switching controllers.
a connected matrix and the best way to learn the programs is to install them. An extensive help file is provided and the program is laid out in a logical manner. Because the configuration software is run on a standard Windows PC, and communicates with the matrix via a standard serial RS-232 port, a number of possibilities exist for remote configuration, control, and monitoring. One option is to replace the PC with an autoanswering modem.
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C H A P T E R 6 INTRODUCTION TO WIRELESS INTERCOM SYSTEMS CHAPTER6 TOM TURKINGTON Introduction to Wireless Intercoms Wireless intercoms have a long and important history as part of the communication professional’s repertoire. They have gone through many changes and technological improvements over the years to bring us to where we are today. The purpose of this chapter is to allow you to become familiar with the history, general workings, and special considerations of wireless intercoms.
(now often called HTs or Handie-Talkies) have higher operating power which affords substantially increased operating range of over a mile or more in some cases. This range can be increased to cover an entire city by the use of repeater stations located at the top of centrally located buildings. Two-way radios did not, however, do as well for the rigors of live television production. In live TV, the restrictive nature of HTs was only too evident. First, HTs utilize a half-duplex communication scheme.
Figure 6.1 The first beltpack based wireless intercom system. RECEIVER FOR WALK AROUND 1 TRANSMITTER FOR WALK AROUND 1 2 3 TRANSMIT ANTENNA TO ALL WALK AROUND RX’S 4 RECEIVER ANTENNA FROM WALK AROUND TX’S ANTENNA SPLITTER COMMON TX FOR ALL WALK AROUND PACKS RX FOR WALK AROUND 1 RX FOR WALK AROUND 2 RX FOR WALK AROUND 3 RX FOR WALK AROUND 4 Each user station in the system consisted of two beltpacks, one for transmit and one for receive.
duplex operation. This enables all users on the system to speak and hear other users simultaneously without “covering” other users’ transmissions. The demands of modern broadcast productions make the full-duplex operation of wireless intercom systems an absolute necessity for stage managers, lighting and audio technicians, or any professional who has to deal with the breakneck speed and complexity of television productions.
The answer to the frequency problem is to utilize a digitally synthesized, frequency agile system. That may sound simple enough in theory, but in reality, designing such a product is a totally different matter. A digitally synthesized, frequency agile system must not only incorporate a superior design with high-quality filtering to withstand the rigors of an overcrowded frequency spectrum, but it must also offer an ergonomically designed user interface that allows ease of frequency selection and operation.
Special Considerations Wireless communications are here to stay. They have become an integral part of the total professional communications package. There are, however, many factors associated with wireless that need to be understood and addressed that do not come into play with hardwired communications systems. In this section, we look at the special considerations that must be considered when deciding whether or not to implement a wireless system.
Table 6.1 Standard US television channel allocations. Chan Start Video Chroma Audio 2 54 55.250 58.8295 59.750 3 60 61.250 64.8295 65.750 4 66 67.250 70.8295 71.750 5 72 73.250 76.8295 77.750 6 78 79.250 82.8295 83.750 7 174 175.250 178.8295 179.750 8 180 181.250 184.8295 185.750 9 186 187.250 190.8295 191.750 10 192 193.250 196.8295 197.750 11 198 199.250 202.8295 203.750 12 204 205.250 208.8295 209.750 13 210 211.250 214.8295 215.
Table 6.1 Standard US television channel allocations. Chan Start Video Chroma Audio 46 662 663.250 666.8295 667.750 47 668 669.250 672.8295 673.750 48 674 675.250 678.8295 679.750 49 680 681.250 684.8295 685.750 50 686 687.250 690.8295 691.750 51 692 693.250 696.8295 697.750 52 698 699.250 702.8295 703.750 53 704 705.250 708.8295 709.750 54 710 711.250 714.8295 715.750 55 716 717.250 720.8295 721.750 56 722 723.250 726.8295 727.750 57 728 729.
(IM) or intermod as it is often called, happens when two or more frequencies mix in a nonlinear device and produce a number of related different frequencies known as intermodulation products. We look at intermodulation in more detail in the next chapter, but suffice to say, choosing a manufacturer or dealer that is qualified to pick intermodulation free frequencies is a must. Now let’s look at cost.
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C H A P T E R 7 DESIGN OF WIRELESS INTERCOM SYSTEMS CHAPTER7 TOM TURKINGTON Introduction The design, and subsequent operation, of a wireless intercom system is, like any wireless network, highly dependent on numerous factors. Some of these factors you will have control over, but many you will not.
A brief look at the properties of the electromagnetic spectrum can tell us a lot about the RF signals that move through it. As you can see, the name electro-magnetic is really a combination of two words, electron (or electronic) and magnet (or magnetic). The reason for this is that waves that propagate in the electromagnetic spectrum have two separate and distinct components, an electrical and a magnetic. As you can see in Figure 7.
Figure 7.2 An example of wireless transmission and reception. TRANSMIT ANTENNA RECEIVER ANTENNA TRANSMISSION LINE SOURCE SIGNAL TRANSMITTER TRANSMISSION LINE RECEIVER COPY OF SOURCE SIGNAL In Figure 7.2, the transmitter is a device that has an input for information, audio, data, or some other form of intelligence called a source signal, that needs to get from here to there. The transmitter then takes that information and puts it onto an RF signal.
because it shows why a wave that travels twice as far as another wave of equal magnitude is not half as strong. Take the following example: Two transmitters TXA and TXB both emit signals that are exactly the same at 1 Watt of power. The signal from TXA travels 10 units. Power at that point can be calculated by 1/102 x 1W or 0.01 x 1W. That means there is 0.01W of the TXA signal left after it has traveled 10 units. Now let’s say that the TXB signal travels twice the distance of TXA or 20 units.
Figure 7.5 The orientation of the radiator (antenna) determines the polarization, and therefore, the orientation of the E and H fields. E Field Vertical H Field Vertical H Field Horizontal E Field Horizontal VERTICALLY POLARIZED WAVE HORIZONTALLY POLARIZED WAVE Transmit and receive antennas of the same system must be oriented in the same direction (plane) to have a proper transfer of the carrier.
Figure 7.8 An example of combining waves that are not 180° out of phase. Interference As mentioned earlier, multipath can be described as a form of self interference caused when a reflected RF carrier arrives at the receive antenna along with an RF carrier that has taken a direct path. See Figure 7.9. The reason multipath is so detrimental to the successful operation of an RF system has to do with the nature of the relationship of the reflected signal to the direct path signal. Figure 7.
greatly. As these levels are changed over a wide range, the receiver performance will be greatly degraded. The greater the physical distance between transmitter and receiver, the less the receiver will be affected. Likewise, the greater the frequency separation between the two, the less the receiver performance will be affected. Selecting frequencies that are “clean,” or free from the effects of intermodulation products, is essential to good wireless communications.
Reducing the effect that intermodulation can have on your wireless intercom system comes down to a few important principles. First, and foremost, you must pick frequencies that are intermod free with each other and with surrounding transmitters. Second, you should pick wireless intercom systems that have well designed receivers and transmitters with appropriate passive filtering. Third, you must manage the positioning of antennas and beltpacks within the system to optimize operational potential.
occur. In some situations, it is possible for this to cause damage to either the transmitter, transmission line, and/or antenna. Now let’s look at the receiver and it’s primary functional aspects (see Figure 7.11). The receiver in a wireless system is the exact compliment of the transmitter, but is usually much more sophisticated and complex in design. Its job is to receive the signal from the receive antenna and extract the source signal so that it matches the original exactly.
Figure 7.12 Good linearity is a must for faithful signal reproduction. r inea nL No Lin ea r Lin ea r Se Se ctio n ctio n r inea nL No GOOD COPY L Non ar ine L Non ar ine DISTORTED COPY The next receiver section we look at is the first local oscillator (LO). The job of the first LO is to provide a reference signal that is a fixed distance from the operating frequency of the system. It is very important the first LO be stable over a wide range of temperatures.
Antenna & Cable Considerations Antennas and cables (transmission lines) are one of the least thought about aspects of a wireless system among RF novices. Good quality antennas and cables, however, are some of the most important aspects to establishing and maintaining a quality RF link. In addition, because antennas and cables are more easily changed and in general are less expensive than other system components, they can be a “quick fix” for many RF problems found in common wireless communications systems.
squeezed the balloon’s center with your hands, a corresponding bulge would appear on either end. The balloon is not any larger or smaller than it was, it has only changed shape. This is how a real world antenna works. When energy is focused in one direction, it must always be at the expense of energy going in another direction. Important: The most basic form of real world antenna is the dipole. The dipole has 2.15 dBi of antenna gain over an isotropic radiator. That means there is 2.
Figure 7.14 An example of a Yagi antenna. There are two very commonly used directional antennas in wireless communications systems today, Yagi and Log Periodic antennas. We will not cover the technical differences of these antennas here, but we will discuss the functional differences. Just as in omni directional antennas, directional antennas must be tuned or “cut” to a specific frequency range.
can greatly improve system performance and decrease harmful interference. In general, it is a good idea to choose an antenna that is just wide enough to handle the desired operating frequencies. One more note on directional antennas. Because FCC rules concerning transmit power (Effective Radiated Power or ERP) take into account the antenna gain of the transmit antenna, high gain transmit antennas may not be used on transmitters in most wireless communications applications.
Table 7.1 Coaxial Cable Loss Chart Attenuation (dB per 100 feet) at the frequency given 220 MHz 450MHz 700MHz 900MHz Times LMR-400 1.8 2.7 3.4 3.9 RG-8/U 2.9 4.5 5.8 6.7 RG-213/U 3.5 5.2 6.7 8.0 Times LMR-240 3.7 5.3 6.6 7.6 RG-8/X 6.0 8.6 10.7 12.8 Results are calculated and can vary. Figure 7.16 The typical parts of coaxial cable.
wireless beltpacks, it is important to locate the base antennas as high as possible. Getting a few extra feet up will often make a large difference in overall system performance. When installing the wireless base station it is important to avoid locating it near computer or other microprocessor controlled equipment. All computer type equipment radiates RF energy that can cause harmful interference in even the best wireless equipment.
pinched in a door, or bent sharply around a corner, the characteristics of the cable can be changed dramatically and have a significant negative affect on system performance. Electromagnetic fields generated by other radios, AC power, arc welders or…, well you get the idea, can also have a negative affect on your wireless communications system. Avoid placing antennas near any device that has a strong electromagnetic field associated with it.
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C H A P T E R 8 DETERMINING INTERCOM NEEDS CHAPTER8 DAVE RICHARDSON Conference Versus Point-to-Point Requirements As previously discussed in this book, there are at least two types of wired intercom systems: conference (two-wire) and point-to-point (four-wire). Although the conference style provides sufficient communications capabilities for some facilities, the point-to-point four-wire matrix offers not only functions of the conference style, but, also other advantageous modes.
subconscious panel differentiation. With a separate module used for every form of communication, a Director’s station may have separate panels for PL, ISO, point-to point, and IFB control. A minimal link exists between the control stations and sub-systems. The link is provided by an un-switched microphone connection on the control station. Therefore, in the heat of a production, the director knows which panel does what, and may quickly access IFB to a specified talent.
the choice, but digital interfaces, such as the SSA424, yield good intersystem transparency. As a result, an initial two-wire purchase can interconnect to an ADAM or Zeus four-wire host later without significant trans-hybrid losses. Fixed vs. Mobile Requirements A General Overview In the age of the portable control room, fixed and mobile requirements in larger systems are surprisingly similar to each other.
Determining Intercom Needs, two-wire, four-wire, or both? In determining intercom needs for a specific application, we begin by first giving examples of intercom requirements. Then, we will attempt to specify an RTS™ intercom system to fill that requirement. Although specific applications are presented, we finish with a general discussion of how to determine whether a given system should be two-wire, four-wire, or some combination of each system.
TW5W Splitter This rugged unit allows up to five BP-325’s to connect to a central location. It can be used outside the truck and placed directly on the ground. Using it, only one microphone cable needs to be connected from the truck to the cameramen, which is useful when the shoot is several hundred feet away. In the small studio scenario, the TW5W can be replaced with the TW7W 1x7 splitter mounted in the rack.
We briefly touched upon the primary forms of communication used in television broadcast. These are PL, IFB, ISO, and PP, with the first two (PL and IFB) being the most important in order to produce a television program such as the news. Let’s take the example of the medium size system and specify first a two-wire intercom and later a fourwire intercom. The positional needs for our example medium studio intercom are shown in Table 8.1. Table 8.
Figure 8.2 Figure 3. Block diagram of a medium sized intercom system using two-wire. The forms of communications depicted here are six conference lines and eight IFB circuits. 862 System Interconnect The Model 862 System Interconnect Panel is the bridge between the Series 800 two-wire balanced portion and the unbalanced TW section. PS31 Power Supply The PS31 TW Power Supplies provide six powered conference channels (three each).
4025A Splitter The 4025A combining device parallels up to four, 25 pair cables to yield one cable to connect to the 4010 IFB Central Electronics Unit. 4030 Talent User Station The 4030 talent user station is a distributed amplifier with interrupt and non-interrupt volume controls. Studio talent personnel use a Model 2234 earset (previously described), which plugs into the 4030. Sports commentators wearing headphones or headsets use the stereo jack on the 4030.
Zeus™ DSP2400 Matrix The Zeus™ Matrix is lightweight, rugged, powerful, and easy to interconnect. It also comes with a wonderful manual and has terrific specifications. It contains 24 ports for connecting to the four-wire devices. The connectors are already installed on the back plane of the unit. All forms of communication are integrated within the Zeus; no subsystems are required.
matrix panels, these keys can be programmed either at the panel itself, or from the configuration computer (not shown) that is attached to the Zeus. IFB828 IFB Power Supply This unit is the Model 4010’s matrix brother. Since all priority, tally, and interrupt chores and handled by the Zeus™ matrix, the IFB828 acts simply as a power center for the 4030 talent stations. There are eight of these circuits available.
Large Studio or Mobile Vehicle Before the advent of the digitally controlled matrix system, large intercom systems were cumbersome to specify. The engineer had to know precisely how many forms of communication to obtain for the system. Any increase in these after the initial sale would mean major physical changes in equipment. Also, to accommodate the special needs of customers, manufacturers were driven to produce special, one of a kind intercoms that were difficult to test, install, and provide support.
large design effortless. Apparent in our sample system is the ADAM here is a storehouse for 10 separate intercom systems! These internal intercom systems are configured to work separately or concurrently with each other. With the new automated server feature in AZEdit, files can be downloaded without human intervention by the powerful new UPL (User Programmable Language).
In our large intercom system, we find 4 IFB x 6 large control rooms plus 4 IFB x 4 small control rooms. This makes our IFB count 40, which brings our total count so far to 100. This means we cannot use an ADAM™-CS 64x64 for this application. Cameras Most high-end cameras are capable of operating in the four-wire intercom mode. In our sample large intercom system, the engineering staff has chosen the best cameras available and purchased a great quantity of them.
KP96-7 Keypanel The KP96-7 matrix intercom panel has 15 talk and 15 listen keys with alphanumeric displays. This is a perfect quantity for the Director and Producer positions. In the large control rooms, we have added the EKP96-8 Expansion Panel to these positions which gives us an additional 16 talk and 16 listen keys with alphanumeric displays. These extra keys are used for the IFB circuits.
How old is Too Old? Should you completely replace your existing system? Probably not! The RTS™ TW system has been around for a long time. As such, there are products that have been in constant service for 20-25 years. The good news is the newer two-wire conference products are completely compatible with the older two-wire products, as long as the older units are Phase 3. Phase 3 (circa 1979) means that operating power is required on only one channel, not both.
Keypanels in RTS™ matrix systems do not store configurations. Therefore, if a panel needs to be replaced at any location, the new panel will assume the identity of the old one. On the matrix, there are diagnostic LEDs on the hardware that show if there is a problem or fault. Budget Getting back to reality, budget is always the determining factor whether you will purchase a two-wire, four-wire, or some combination of both.
CHAPTER0 CHAPTER0 CHAPTER0 GLOSSARY CHAPTER 0 A Acoustics Acoustical Active Devices AF AGC All Call Alpha AM Ambient Ambience Ampere Amplitude Amplifier Analog vs. Digital The science of sound. 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.
Attenuation Attenuator (Loss Pad) Audio Audio Frequency Auto Follow (AF) Auto Functions Auto Listen (AL) Auto Mute (AM) Auto Reciprocal (AR) Auto Table (AT) AWG 130 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.
B Balanced line Bathtub Curve Bel Beltpack Binaural Biscuit Bit Block Diagram / Single Line Diagram Blocking 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, or 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.
Bridging BW Byte Bridging impedance means an impedance that when paralleled with a nominal impedance will have an non-significant effect on a circuit. For example: for a nominal impedance of 600 ohms, a parallel impedance of 3,000 ohms (5 times) would make the net impedance 500 ohms, 17 percent less than 600 ohms or 1.6 dB. A parallel impedance of 6000 ohms (10 times) would cause about a 9 percent change or about a 0.82 dB difference.
Characteristic Sound Pressure Level Circuit Circumaural Headset Clipping Close-Up Effects Coil Effect .Communicatio n between Ports (Point-to-Point, or P-P) Compression Force Condenser Microphone Conductivity Conductor Conference Intercom Systems, Conference Line Intercom Systems, PartyLine (PL) Systems Control Room Coupling with the Ear CPS Crosspoint 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.
Crosstalk Current Current Sources 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.
Distortion Double Headset Double-Muff Headset Drain Wire Dry Pair / Dry Line DSP Dual Listen Dual Listen Option Duplex / Simplex Dynamic Microphone 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.
Earth Earphone EFP EIA EIA Sensitivity Electret Microphone Electronic Switching versus Mechanical Switching EMF Energy Energy Dissipation ENG EMI Equalization (EQ) Equalizer British term for a reference ground. Earth may mean power line ground or a facility zeroreference ground. A device used to hear an electrical audio signal. The earphone converts electrical signals to acoustic signals that can be heard. Electronic Field Production.
Film-Style Directing FM Follow Spot Four-Wire Four-Wire Balanced Four-Wire Unbalanced Full Duplex Frequency Frequency Response 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. Frequency Modulation. A method of adding audio to a radio frequency carrier. FM signals are usually more noise free than amplitude modulation (AM) signals.
Green Room Ground Ground Loop Ground Potential 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 CS9000 Series intercom systems, general purpose control outputs are provided by optional FR9528 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.
Headroom Hertz Home Run Hot Hum Hypercardioid environments such as television studios (news). Impedances: Impedances of headphones range typically from 2000 ohms to 2 ohms. Common impedances per earphone are 300 ohms, 150 ohms, 50 ohms, 25 ohms. Headphone total impedances depend on the earphone impedance and whether they are connected in series or parallel. The headphones in standard headsets sold by RTS™ Systems ranges from 25 ohms to 300 ohms.
Impedance Inductance Insertion Loss Intercom Intercom Data Groups and Port Number Calculation Interconnect Interface Intermodulation Distortion Inverse Square Law IR Drop Isolation 140 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.
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.
Matrix Maximum SPL Mho Mic Micro (µ) Microcontroller Microphone Microprocessor milli (m) Mixer Mix-Minus Bus / feed Monaural Monitor Mu (µ) Mu Metal Shield Multiplexing mV mW 142 “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™ CS9500, CS9600, and CS9700 Intercom Systems.
N NAB NABET NEC NEMA Nibble Noise National Association of Broadcasters. National Association of Broadcast Employees and Technicians. National Electrical Code National Electrical Manufacturers Association A nibble is half a byte or four bits. 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.
Peak Phantom Power Phase, Phase Shift Pi (π) Pickup Pattern Pink Noise PL PLL Point-to-Point (Matrix) Systems Pop Pop Filter Port Port Gains Port ID Numbers and Alphas 144 The crest value of a voltage, current, or 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 depend on the voltage.
Postproduction Postproduction Editing Pot (Potentiometer) Power Amplifier Power Supply Power Supply, TW Power Ratio Preamplifier Presence Peak Pressure Zone Microphone (PZM) Program, Program Audio Push- To- Talk (PTT) operators using Port Alpha setup In AZ™EDIT. (Click the “Port Alpha” button in AZ™EDIT, then press F1 on the computer keyboard if you need help.) Production activity that occurs after the actual production phase. For example the editing of a television or motion picture production.
Remote Station Remote Truck, Remote Unit Resistance Resonance Retractile RF RFI RMS Roll-off RU 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.
Sensitivity Series Circuit Shield Shotgun Microphone Sidetone Signal Signal to Noise Ratio (S/N or [S+N]/N) Sigma Signaling Simplex Single-ended Single Channel / Two Channel SMPTE include compounds. Some examples are semiconductor diodes, transistors, integrated circuits, transector overvoltage devices, thyristors, and carbonized substances. 1. The electrical output of a microphone for a given SPL input.
SMPTE/EBU Time Code Sound Sound System Special List SPL Squawk (Versus Matrix) Stacked Key Stereo Studio Camera Studio Talkback Supra Aural Headset Supercardioid Switcher (usually the Technical Director) System 148 Recorded on videotape or audiotape. Provides a time address for each video frame in hours, minutes, seconds, and frame numbers. Requires a SMPTE code generator to create. Some RTS™ Systems audio equipment can be used to distribute SMPTE time code.
T Talent Talk Level 1 Talk Level 2 Tally Telco Tone Signaling Transducer Transformer Transient Transient Intermodulation Distortion Transient Response Trunking Two-Wire Two-Wire Balanced Two-Wire Unbalanced Unbalanced Line Collective name for all performers and actors who appear regularly on television. Talk level 1 is the normal talk key assignment. This is the assignment that normally appears in the alphanumeric display (on keypanels so equipped).
supply operates a string of belt pack or other user stations in an isolated, balanced mode. The balanced system is transformer coupled into the regular unbalanced system. V V VA Voltage Voltage Drop VU VU Meter The symbol for volt. The symbol for volt-ampere. A volt-ampere describes the demand on the power line without regard to power factor or true power. This figure is more helpful in determining the maximum load on a circuit, that has a given ampere rating.
INDEX Numerics 4010 IFB Central Electronics Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 4025A Splitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4030 Talent User Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
demodulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 desensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Design of Matrix Intercom Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
intermodulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Intermodulation (IM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 intermodulation products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 interrupt fold back (IFB) . . .
polling window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Present Day Systems and Manufacturers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 propagation path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 PS15 Power Supply . . . . . . . . .
TW and Matrix Signal Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 TW systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 TW to Matrix Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 TW5W Splitter . . . . . . . . .
