Channel Select Input/Output; Dc Remote Keying; Ptt In; Programmable No-Tone Period - RF Technology Eclipse Series Operation And Maintenance Manual

7 SPECIFICATIONS

7.4.20 Channel Select Input/Output

7.4.18 Channel Select Input/Output
Coding - 8 lines, BCD coded 00 - 99
Logic Input Levels - Low for <1.5V, High for >3.5V
Internal 10K pull down resistors select channel 00 when all inputs are O/C.

7.4.19 DC Remote Keying

An opto-coupler input is provided to enable dc loop keying over balanced lines or local
connections. The circuit can be connected to operate through the 600 Ω line.

7.4.20 PTT in

An external input that when "grounded" with at least 1mA of current, will cause the
exciter to key up. The current is drawn from the PTT in input which attempts to "pull
up" anything that "grounds" it. It can be "grounded" with a short to 0V, or any
resistance up to 3.9k ohm. If the resistance of the "ground connection" is less than 2.2k
ohms, then up to three diodes in series can be part of the grounding path. This allows
systems installers to use quite complex diode logic to enable or disable exciters.
It would normally be "grounded" by the COS output of a receiver.

7.4.21 Programmable No-Tone Period

A No-Tone period can be appended to the end of each transmission to aid in eliminating
squelch tail noise which may be heard in mobiles with slow turn off decoders. The No-
Tone period can be set from 0-99.9 seconds in 0.1 second increments.

7.4.22 Firmware Timers

The controller firmware includes some programmable timer functions.
Repeater Hang Time(Transmit Tail) - A short delay or ``Hang Time'' can be
programmed to be added to the end of transmissions. This is usually used in talk
through repeater applications to prevent the repeater from dropping out between mobile
transmissions. The Hang Time can be individually set on each channel for 0 - 999
seconds.
Time Out Timer - A time-out or transmission time limit can be programmed to
automatically turn the transmitter off. The time limit can be set from 0-10million
seconds. The timer is automatically reset when the PTT input is released. Zero seconds
disables the timer, and allows continuous transmission.
RF Technology T50 Page 41