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BCD536HP: Chicago FD P25 Audio Dropout

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#1
Chicago FD uses a simulcast uhf p25 non trunked system... I am randomly getting audio dropouts on the signal. I have tried: attenuator on and off, changing audio settings from search to NAC, also tried modulation of NFM and auto...still no improvement. The dropouts come and go..seem worse at night for some reason. Signal strength is excellent. I'm wondering if I need to adjust p25 settings manually or if I have a bad radio..any ideas??
 
Joined
Jun 5, 2006
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822
Location
Palatine, IL.
#2
What radio do you have?

I live in Palatine. I can pick up Chicago cops very clear on certain days; on others they may be a bit scratchy.

For the Fire Department, I do not monitor them anymore. I to would get drop outs all the time. I also get unintelligible hits as well, and they also eventually drop out.

I don't know how far you are from them, but I've been told that they use a very old system with low power. FWIW.
 
Joined
Feb 7, 2008
Messages
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Location
Chicago, IL
#3
Hey Steve. I have a 436 not a 536 but I have had the digital threshold settings at Auto & 10 since I got it and had very good reception with only a few drop-offs.
 

Blunt630

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Apr 15, 2009
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#4
I live in Naperville, I can clearly hear CPD... CFD on the other hand comes and goes depending on weather.. 396xt here,
 
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#5
I live in Joliet and use outside antennas with 9913 and LMR400 coax, some days when UHF is at its best i hear CFD 75% so i dont think your radio is the fault...I use the 996P2......
 
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Messages
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#6
I am still having the issue with dropouts when monitoring Chicago fire digital...I have both the 436 and 536 and both miss many transmissions altogether and my friends with these same radios report the same. I have updated the firmware on a regular basis and the problem is no better. I am no longer using the 536 or 436 as they do not receive these signals as they should. My 2 older radios of a different brand work far better. I kept these unidens in the hope they would admit to and correct the problem but it’s been years now..I believe I have tried all the tweaks to the settings that I have heard of to no avail. I am very unhappy with these products and M GOING TO TRY A NEW BRAND IN THE FUTURE.I am writing this in a last ditch effort to see if anyone knows of or has come up with a solution.
 
Joined
Jul 18, 2014
Messages
8,884
Location
PA
#7
The only scanner capable of reliably receiving simulcast is the Uniden SDS100, because it has the correct I/Q demodulator circuitry in the receiver needed to decode the signal. No other scanner brand has a model designed to receive simulcast.

Upman has posted some direct comparisons between the SDS100 and the 436 in challenging simulcast environments:
https://forums.radioreference.com/u...eak-simulcast-dense-rf-drive.html#post2919455
 

RBMTS

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Apr 28, 2002
Messages
606
Location
Naperville, IL
#8
I wouldn't blame the radio or the brand. There are lots of variables that could be causing the problem. Simulcast distortion for one.

I noticed some of the same problems with I visit Chicago and try to listen to CFD. Here are a few things to try (if you haven't experimented with them yet).

1) Try locking into ONLY the main or englewood dispatch frequencies. Don't scan. See if that helps. It could be that the scanner is missing the initial digital preamble to the digital channel during a scan sequence.

2) Try a smaller antenna - even to the point of using a paperclip if necessary. Sometimes less is better to reduce simulcast problems.

3) Reversely try a different higher gain antenna to boost the digital signal.

4) Try moving the scanner to a different location in the room or even a different room. Sometimes small changes can make huge improvements with digital reception.

5) Continue to adjust the P25 threshold settings to finely tune in.

Just a couple of idle thoughts for you. Again, maybe you tried these but wanted to mention them anyway.
 
Joined
Jan 20, 2003
Messages
3,679
Location
Washington Pennsylvania
#11
I am still having the issue with dropouts when monitoring Chicago fire digital...I have both the 436 and 536 and both miss many transmissions altogether and my friends with these same radios report the same. I have updated the firmware on a regular basis and the problem is no better. I am no longer using the 536 or 436 as they do not receive these signals as they should. My 2 older radios of a different brand work far better. I kept these unidens in the hope they would admit to and correct the problem but it’s been years now..I believe I have tried all the tweaks to the settings that I have heard of to no avail. I am very unhappy with these products and M GOING TO TRY A NEW BRAND IN THE FUTURE.I am writing this in a last ditch effort to see if anyone knows of or has come up with a solution.
They should have given you a radio when you retired Steve.
 
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