Unitrunker works on 700 MHz P25 but not VHF P25

[nd5y]

This is weird.
I have been having problems for years with Unitrunker not decoding the local VHF P25 system.
Now there is a new 700 MHz P25 control channel that is relatevely weak. A lot weaker and noisier than the VHF system.
Unitrunker is decoding it just fine. About as good as it does with the weak 900 MHz Narrow EDACS systems.

This is with a tapped Pro-2006

 

[nd5y]

Here are a couple log files

 

[SCPD]

Sorry Tom; I have no idea why the two are so different.

 

[millam]

I have the same problem. A VHF P25 system that has 5 bars of signal, clean disc audio but UT will only get up to 50-55 with its health reading. It will not auto start when I tune my scanner to it. I have to stop UT
and restart it and it may start decoding. UT does not show the radio numbers on the screen only group numbers or the radio numbers when they are logging in.

Mil

 

[nd5y]

My health never goes above about 20 even with a full quieting signal on two different sites.
I thought I had some kind of hardware problem with the sound card or something or a bug that only happens on P25.
Moto type II and EDACS wide and narrow systems always decode perfectly even when weak and with lower health readings.

 

[fwradio]

I know exactly why... Every channel on the Parker County VHF P25 system is off-freq on the symbols. None of the channels I looked at (and I looked at all of them) hit the marks on the Aeroflex 3920 service monitor. I thought it was strange so I looked at the 700/800 systems around Dallas and Fort Worth and every one of them was right on the mark.

Tom, maybe that's why both of us have had so many problems with getting Unitrunker to properly decode, and maybe that's why they have so many problems with system access out there on the radios.

Rick- if you'd like, I have a printout of the screenshot from the Aeroflex that I can scan and send to you. It was taken from the 152.06 control channel at the Weatherford site with a -55 dB received signal, so it is a clean signal.

 

[SCPD]

Please do. Even better could you post here for everyone?

 

[fwradio]

The distribution screen shot shows how most of the symbols are a little off frequency. The second shot is the eye pattern, which looks pretty ugly when compared to any other system out there.

 

[SCPD]

That's actually a decent eye pattern as all three openings are clear. I see how the symbols are over-deviated but that shouldn't hurt as long as the signal isn't clipped by the computer's audio input.

 

[fwradio]

The best decoding I have gotten was by taking my laptop and service monitor out to the Weatherford tower and the best I could get there was about 34% while playing with the input levels. That was pretty dependable decoding, but the best I get away from there is about 10-15%.

I have also heard that the range on the radios is not that good either, which is suprising considering the distance from the tower that you can still hear the signal clearly.

 

[nd5y]

What does it mean in the log file when some lines begin with a dash (or minus sign) and others with E?

 

[SCPD]

What does it mean in the log file when some lines begin with a dash (or minus sign) and others with E?

E marks bad frames. The dash marks last OSP in a group (usually three).