These are possible fixes for scanners based on the Grecom PSR-500, PSR-600 (radio shack pro-651, pro-652, pro-106, pro-197), and whistler WS1040, plus the non GRE based scanners WS1080, WS1088, and possibly the TRX-1, TRX-2. These are mostly meant for scanning inside your house. They may help for Apco P25 Phase I and/or Phase II.
I will not give details on how to find and change the settings do not ask. Google exists.
When testing it can help to have a known working scanner set to the system you are trying to get working so you know when the system is transmitting (I have a WS1088 and PSR-651). Make one change at a time, and then wait for results. this includes adjusting settings on any external antenna amplifier.
Here are the settings that seem to help receiving in a simulcast environment:
for the GRECOM based scanners:
Check that NFM is on or not on TSYS. for some systems this matters and for others not so much.
Squelch setting can be an issue. I turn it all the way down with only that system enabled, and then adjust it up until the S disappears.
Enabling CC Dump on win500 can help as you can see when it is receiving a control channel.
try setting MultiSite Mode to Roam, and set Threshold Hi to 85, and Threshold Lo to 50 or 55.
Enable or Disable AGC for the TSYS System.
Try using a rubber duck antenna, or your roof antenna. see which one works better.
Try different roof antennas. For my Grecom scanner a whip antenna seems to work better, but for my Whistler my discone seems to work better.
For the Whistler (newer than WS1040) scanners:
Check that NFM is on or not. for some systems this matters and for others not so much.
Set Multi-Site Settings Data Decode Threshold: Low:50 and High:85 (this setting made the most dramatic change)
Set AGC (as far as I know this is not Digital AGC) on either globally or for individual Talk group ID's.
Try using a rubber duck antenna, or your roof antenna. see which one works better.
Try
different roof antennas. For my Grecom scanner a whip antenna seems to
work better, but for my Whistler my discone seems to work better.
For my Whistler WS1088 Turning AGC on and setting the decode thresholds greatly improved my ability to receive P25 Phase I, as well as using my roof discone.
I have experimented with various combinations of antennas, and using a Jim M-75 signal amplifier with mixed results. it helps for some systems, and makes things worse for others.
I did not have much trouble receive P25 systems when using the rubber duck antenna and driving around.
