8
SYSTEM SETUP
Simplex:
It will be necessary to program the “Front Porch Time” on the TVS 2 long enough for the sync packet to open the
repeaters’ CTCSS/DCS and let the repeater come up to full power and then to open the portable and mobile
radios CTCSS/DCS so the sync is not blocked at the receiving radios. EIA spec states that a 100 Hz CTCSS tone
should open in 250 msec. 67 Hz tone will take longer and a 250 Hz tone will be half the decode time.
Repeater:
If the repeater’s repeat audio levels are not properly aligned it is possible the synchronization packet could be
distorted. Flat audio is preferred. Pre-emphasis and de-emphasis should be disabled via the repeaters internal
programming. To correctly align the repeat audio levels of the repeater use the following procedure.
1. Connect a microphone to the repeater’s TX radio.
2. While monitoring the TX signal with a service monitor set the TX modulation for 4.8 – 5.0 kHz of deviation in a
wide band system or 2.4 – 2.5 kHz in a narrow band system. This should be done while speaking loudly into
the microphone with a constant voice.
NOTE:
For military radio systems operating in the 36 -88 MHz range set the modulation to 13kHz out of a
maximum of 15kHz
3. Adjust the RX repeat audio using 1.5 – 2.0 kHz deviation of a 1 kHz tone at the RX input with a strong RF
signal and adjust the repeat level to the transmitter for the same level of 1.5 – 2.0 kHz while monitoring the TX
signal with a service monitor. For a narrow band system use 0.75 – 1.0 kHz deviation.
4. Ensure that compression and expansion are turned off in the repeater. Do not enable de-emphasis or pre-
emphasis.
It will be necessary to program the “Front Porch Time” on the TVS-2 long enough for the sync packet to be
decoded by the receiving radio. Time should be given for CTCSS or DCS signaling to be decoded and for the
repeater to rise prior to the synchronization being transmitted by the scrambler.
Trunking Systems:
Midian’s TVS-2 has a trunking delay input. Connect this input to a point in the radio that will give the scrambler a
strobe upon acquisition of a channel. This can either be high or low. Program the “Trunking Delay Polarity” to the
active state of the strobe. Upon indication that the channel has been acquired the TVS-2 will go through the
programmed “Front Porch Time” and send the synchronization. If a channel is not acquired within 5 seconds the
PTT will need to be reset.
Voted Systems:
When using the TVS-2 in a voted system please observe the following:
1. The voting receivers should be programmed to “Scan and Lock”, not “Scan and Re-Scan”.
2. Set the “Front Porch Type” on the TVS-2 to “Preamble”.
