[App_rpt-users] Simulcasting with RTCM/voter

[Hayden Honeywood]

Thanks for the information Joe.

The RTCM generates the CTCSS in the main audio path with an entry in
voter.conf.

There is no separate deviation adjustment on the board, you set a global
level in that config file.
OK on the delays between sites etc. I think I understand whats going on
there. As I mentioned beforehand I think a lot of my issue is that the 2nd
site radio is on the bench and the delay from the main site TX is causing
distortion problems. I'm hoping to document a lot of the simulcast
information on my blog in time.

In answer to some of your points -

1) I've played with the offset mainly because at low band 50MHz due to the
propagation effects, complete cancellations happen in overlap when both
signals from the transmitters are approx the same. Whereas on UHF I believe
this is not to much of an issue due to reflections, doppler etc. Only
really an issue with fixed stations I believe. Offsetting by a few Hz I can
hear the null move around, and cancellation is not so bad.

2) The exciters have been set the same - same model, same inputs etc.

3) Yes. The only differences may be is that the VCO of the units is
modified to 50MHz from 70 by adding capacitance in various places. The
alignment of both VCO's is the same however - set to 3V on a specific test
point.

4) Yep all the same. I've used a CTCSS encoder input which is post
pre-emphasis and limiting. Limiting is done by the RTCM.

5) As above - although I've noticed that the CTCSS's deviation on the bench
test transmitter is about 50Hz low when aligning for a 1K = 3K deviation.
I've tried turning up the TX level pot to equal it, but it still sounds the
same.

Hayden
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