Digitac Questions

[quint 18]

Hello all

I am working on a radio system that is using a digitac voter the system is voted at 4 sites all linked via microwave. I am hearing complaints from the field that the audio is lower than the dispatcher. One of the satellite receivers was recently moved from a telco line on to the microwave. My initial suspicion is that all of the bases need to be adjusted for proper levels as they have not been maintained. So with that I have the following questions.

What are the proper levels for the voice and status tone on the base? I think status should be -13db down from voice. so if voice is -10db at 1khz tone with 1.65khz of mod that would make the status -23. is this correct or have I been incorrectly informed?

Can the levels only be adjusted on the bases? I can see no adjustment on the voter itself.

Can the voted output audio be different from the voted field audio? If so how do I adjust to make them equal?

The system is comprised of 4 mtr2000 and a digitac voter on a gold elite console all audio is clear analog ( nothing fancy)

Thanks for the help and direction. I am also in the process of looking for a manual that was in the center but, as usual no one can seem to locate it.

Fred

[Birken Vogt]

I have to run so I can't type a long reply but the standard offset I was taught was 8 dB from 60% deviation to status tone. So my standard adjustment is 1.5kc mod 1000 hz tone = -10 dBm and status tone = -18 dBm.

The 13 dB offset is for full deviation to status tone but because of headroom issues, I do not set it up that way. So full deviation 2.5 kc would give -5 dBm on the line but I only measure that as a quick check, not the parameter I actually use for setting up.

[The Pager Geek]

The beauty of the Digitac is the AGC circuits. To make a VERY long story short, as long as they are all the same... the digitac will sort it out.

I use -13 from avg voice for status tone. I use a combination of telco and microwave (not ideal, but that's what it is.) The ideal way is to measure at the digitac while aligning the station in the field.

- Levels from the receivers into the digitac can only be adjusted at the receiver sites. However, your complaint about dispatch audio is controlled at the digitac. I assume you are using a Tone Keying Module with Priority? (2 cards, QRN4515 and QRN4516) The console input audio can be adjusted on the transmit board (input 1 level adjustment pot). This is all assuming you are using the proper transmit station wiring (Line Output 5, P806, Pins 10,35) and console input (Console In, P805, Pins 24,49)

- Yes, Voted audio and console audio can be different. See above. The best way to align it (assuming programming is correct) is to use a receiver site with a test tone to generate your optimal transmitter tone levels. Then, use Input Level 1 to match the console the console audio to the receiver audio.

Hope that helps.

TPG