Telex 38109-977 manual Design of Party-Line

(Limitations of Each System). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Design of Party-Line

Intercom Systems - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -21

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Defining And Meeting Your Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Application 1 Generic Single Channel Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Audiocom Party-Line Intercom Equipment Listing #1	. . . . . . . . . . . . . . . 22
Clear-ComParty-Line Intercom Equipment Listing #1	. . . . . . . . . . . . . . . 23
RTS TW Party-Line Intercom Equipment Listing #1	. . . . . . . . . . . . . . . 24
Application 2 Two-Channel System: TV, School, Cable	. . . . . . . . . . . . . . . 24
Audiocom Party-Line Equipment Listing #2	. . . . . . . . . . . . . . . 25
Clear-ComParty-Line Equipment Listing #2	. . . . . . . . . . . . . . . 25
RTS TW Party-Line Equipment Listing #2	. . . . . . . . . . . . . . . 26
Application 3 Theater System	. . . .	. . . . . . . . . . . 26
Audiocom Party-Line Equipment Listing #3	. . . . . . . . . . . . . . . 27
Clear-ComParty-Line Equipment Listing #3	. . . . . . . . . . . . . . . 27
RTS TW Party-Line Equipment Listing #3	. . . . . . . . . . . . . . . 27
Application 4 Training Systems	. . . . . . . . . . . . . . . 28
Audiocom	. . . .	. . . . . . . . . . . 28
Clear-Com	. . . . . . . . . . . . . . . 29
RTS™ TW	. . . . . . . . . . . . . . . 30
Application 5 Medium System for Television	. . . .	. . . . . . . . . . . 31
The IFB System (One Way Communications System)	. . . .	. . . . . . . . . . . 32
How an IFB Works	. . . .	. . . . . . . . . . . 32
Studio and Some Field Applications	. . . .	. . . . . . . . . . . 32
Field Application, Sports	. . . .	. . . . . . . . . . . 32
Field Application, ENG (Electronic News Gathering)	. . . . . . . . . . . . . . . 33
Connecting (Interfacing) to Other Communications Systems	. . . . . . . . . . . . . . . 33
A Typical Interfacing Problem	. . . .	. . . . . . . . . . . 34
Interfacing Issues	. . . .	. . . . . . . . . . . 34
Modes	. . . .	. . . . . . . . . . . 35
Level Problems	. . . .	. . . . . . . . . . . 35
Signal / Data Conversion	. . . .	. . . . . . . . . . . 35
Call Light	. . . .	. . . . . . . . . . . . . 35
Data	. . . .	. . . . . . . . . . . . . 35
Interfacing Practice	. . . .	. . . . . . . . . . . 36
Interfacing Television Camera Intercom Systems to TW Systems	. . . .	. . . . . . . . . . . 36

General Camera Configuration Information for Television Cameras (except ENG units) . . . . . . . . . . . . . . . . . . . . . 36 The Problems in Interfacing to Cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Alternatives for Interfacing to Television Cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Some Practical Considerations	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Headset Cable Lengths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Headphone Impedances	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Wiring Practices/Workmanship Standards . . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Unbalanced vs. Balanced	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Extended Range On Part Or All Of The System	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Cable Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Crosstalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Crosstalk Through A Common Circuit Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Crosstalk Through A Mutual Capacitance Of Two Conductors . . . .	. . . . . . . . . . . . . . . . . .	. .	. .	.	. 39
A Low Crosstalk Approach To Interconnection	. . . . . . . . . . . . . . . . . .	. .	. .	.	. 39

Distances/Conductor Sizes/Distributed vs. Central Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 System Current/System Capacitances/Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Temperature Range Consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Cooling Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Moisture / Contamination Protection		. . . . . . . . 41
Magnetic Fields: Hum Problems		. . . . . . . . 41
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
(Defining and Meeting Your Needs)	. . . . .		. .	. .	. . 41
(The IFB System (One Way Communications System))	. . . . .		. .	. .	. . 42

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