Problems with Grecom PSR-600 not hearing P25 Talk Groups

jim202

Member
Joined
Mar 7, 2002
Messages
2,735
Location
New Orleans region
I put the local NOAA frequency of 162.525 in the second scan list. Manually went to it and it hears the broadcast fine. So the receiver and audio system is OK in the carrier mode.
 

tvengr

Well Known Member
Joined
Feb 10, 2019
Messages
10,429
Location
Baltimore County, MD
That also means the antenna is OK. This is starting to sound more like a simulcast distortion problem. If you have a 12-volt cable with a cigarette lighter adapter, it's time to take a ride to see if you can find a place where it works. When you are very close to one of the towers, it can override the out of phase signals from the other towers. If you are just using the scanner at home, you can try a directional antenna which will reduce the interference from the other towers.
 

jim202

Member
Joined
Mar 7, 2002
Messages
2,735
Location
New Orleans region
I already looked at your file and didn't see any problems.
I find it almost impossible that I am having a simulcast problem. With the nearest tower only about a mile away, I have a very strong signal. If I take the antenna right off the scanner, it is still hearing the control channel at 2 to 3 bars on the signal indicator. Only have been using the pull up antenna that comes with the scanner with it all way down.

I was working for the Parish radio consultant working with Motorola when the simulcast LWIN system was installed in the Saint Tammany Parish. Stood there at each tower shelter while Motorola was doing their system setup and adjustments. Caught them for using test equipment that was out of calibration. They had to send out all the equipment they used to set up and adjust the system for calibration. When their test equipment came back, we started the alignment of the system all over again.

So I know where all the tower sites are. The local one to me is a 500 foot tall one with the receive antenna at the top and 2 transmit omni antennas about 30 feet below the top on 2 sides of the tower. Both transmit antennas are not shaded by the tower to my location. Hard to be located any better to stay out of any simulcast distortion issues.

Any other ideas on what might be the problem with this scanner is not decoding any of the programmed talk groups?
 

gmclam

Member
Premium Subscriber
Joined
Sep 15, 2006
Messages
6,406
Location
Fair Oaks, CA
I find it almost impossible that I am having a simulcast problem.
I have base and mobile versions of this model. I've traveled around the west coast and tried to monitor systems with each the P25 GRE and an SDS-100, each on their own antenna. It's quite interesting to witness the difference in performance. If you get the system at all, the issue I've witnessed is some conversations are just missed on a non-simulcast capable receiver. Everything you've mentioned here points that way. Continue to fight the obvious and miss stuff. I know the SDS price is more than what most want to pay, but it's the only scanner choice that deals with this issue at this point in time.

I guess you could dedicate a receiver and a directional antenna. Attenuate the signal to be the minimum needed to get a good decode rate. That's the best you can do with the GRE. The thing is, we truly never know what we've missed.
 

KevinC

The big K
Super Moderator
Joined
Jan 7, 2001
Messages
12,399
Location
Home
I have base and mobile versions of this model. I've traveled around the west coast and tried to monitor systems with each the P25 GRE and an SDS-100, each on their own antenna. It's quite interesting to witness the difference in performance. If you get the system at all, the issue I've witnessed is some conversations are just missed on a non-simulcast capable receiver. Everything you've mentioned here points that way. Continue to fight the obvious and miss stuff. I know the SDS price is more than what most want to pay, but it's the only scanner choice that deals with this issue at this point in time.

I guess you could dedicate a receiver and a directional antenna. Attenuate the signal to be the minimum needed to get a good decode rate. That's the best you can do with the GRE. The thing is, we truly never know what we've missed.
Just to add to this. GRE-based scanners do a lot of things very well (like conventional P25 audio), but P25 simulcast/LSM/CQPSK isn’t one of those things.
 
Top