PSR-800: tdma fails on UHF

[bcorbin]

Hi folks -

Los Angeles has a relatively new Phase 2 system stretched out across 470 and 770 MHz, multiple sites, *no* simulcasting...

What I have discovered is that my PSR-800, which does a wonderful job decoding tdma on 770 and 900 MHz, fails miserably on 470 MHz. I can make out audio in the clear, but there is a very strong, ~3-5 Hz "beat" superimposed on the audio that makes it all-but-impossible to actually understand anything.

This is independent of monitoring location, signal strength and 470 MHz site. My suspicion is that the signal feeding the codec is not set at the the right level. I've fiddled around a bit with the ADC gain, but to no avail.

I believe I have the current firmware - CPU:2.0 and DSP:1.3

Has anyone experienced anything similar? Any ideas?

Thanks...

 

[BaLa]

Wonder if the Unidens do any better or if it's somehow the system.

 

[bcorbin]

Wonder if the Unidens do any better or if it's somehow the system.

I spent a lot of time hoping it was the system - there's no 700 MHz coverage up where I am... With no improvement on the local site, I started paying enough attention to isolate it to 470 MHz and on asking around, determined that the 470 MHz sites sound fine on other radios (possibly Unidens, didn't ask). Have seen similar problem reports on the Whistler forum...

Needless to say, I could be happier - I paid just a little too much for a radio that works well on everything BUT the local public-safety trunk... 8*(

It sounds like an issue, internally, with levels - almost like what you'd get if you weren't driving DSD or similar correctly - but it seems strange that 470 would be coming out the IF into the detector any differently than anything else...

Kinda hoping DonS or someone else with intimate knowledge of the innards might have some ideas - I'm certainly open to any ideas anyone else has, and would still definitely like hear from anyone else who's experiencing similar...

Thanks, all...