[App_rpt-users] RTCM RSSI calibration

[Tim Sawyer]

Some things to consider:

 - Install JP1 on the Quantar's RTCM. The squelch should calibrate at
around 4 blinks rather than the 12 blinks or so without JP1.

 - Be sure you've done the diode and squelch calibration with the actual
attached radio (no antenna).

 - The Quantar firmware should be 20.14.48 as later versions have better
noise output.

 - Try the "Chuck Squelch" RTCM version. They say it's better. I'm not sure
I can tell the difference.

 - Each RTCM should have 3 to 5 turns past threshold to prevent the squelch
form being too loose. Somewhere around the 350 level seems about right.
Chuck Squelch seems to need fewer turns but YMMV.

 - Don't "and" CTCSS with squelch. That may override the RTCM's squelch
detection. Compare with CTCSS on and off to see effect if any.

 - See our new wiki.allstarlink.org. There's a lot of good RTCM information
there.

Hope this helps.

On Sun, Oct 22, 2017 at 12:39 PM, Skyler F <electricity440 at gmail.com> wrote:

> For one voted site, we are using a Motorola Maxtrac 900 and for the master
> we are using a quantar receiver.
>
> Unfortunately, the RSSI levels don't really mean the same thing between
> the two receivers. The Maxtrac Voter will be almost full quieting and then
> the Quantar will pick it up relatively very noisy.
>
> I know it is not the best idea to use two separate models of receivers for
> voting, but other then the signal strength, the audio seems to sound the
> same. The problem with the Quantar is that it is a "Virtual Discriminator
> Audio" which needed BEW mode on the RTCM to be enabled and that is what
> seems like is messing up the measurements.
>
> Is there a way to tune these RSSI levels so the perceived signal strength
> has the same correlation on the numbers 0 - 255.
>
> In addition, we would like to disable the master receiver at some points,
> like only have the voter turned on for receive just to test it's coverage.
> Is this possible?
>
> Thank you,
> Skyler
>
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-- 
--
Tim
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