• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

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Phx PD problems

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kc7vtr

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Dec 27, 2005
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39
I got a used Pro-96 a couple of days ago and am not impressed with the quality of reception of Phoenix PD. I frequently (maybe 30% or more of the time) get garbled transmissions. Voice cuts in and out, wierd noise effects, etc. It seems to happen mostly on A deck and more often with the dispatchers than the officers. B deck and other systems, MCSO, DPS and Mesa (Only listen to this in the car as I approach/leave work) are much better. (Yes I know that MCSO and DPS are analog. :) )

I've tried both the standard rubber duck and the RS 800 MHz antenna at home (I-17 & Greenway). Neither antenna nor moving around in the house seem to make a difference. I've tried both antennas and a mag mount tri-band scanner antenna in the car but no difference. I still get garbled reception.

Suggestions?
 

AZScanner

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Joined
Dec 19, 2002
Messages
3,352
Location
Somewhere in this room. Right now, you're very col
There's a limited amount of things you can do. Make sure you have the DSP upgrade that allows CQPSK reception (do a search in the forums and you should be able to find a link to it) Another thing I do with mine is turn squelch all the way down. Also experiment with the attenuator. I've found in some locations I get better reception with the attenuator on.

Other than that, there's not a whole lot you can do. My scanner feed on SBN is run from an antenna strung up in my loft - my apartment is already on the second floor, so with the loft, the antenna is about 3 stories off the ground, and I still sometimes get garbled transmissions. I think much of it is adjacent channel interference. Once rebanding occurs and the system moves to 700 megs, things will hopefully improve.

-AZ
 

InlandAZ

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Joined
May 16, 2005
Messages
633
Location
Chandler AZ
"Once rebanding occurs and the system moves to 700 megs, things will hopefully improve."

I have no problem with MCSO or Phoenix, but I won't hold my breath with Mesa... I wasn't aware DPS shared the system (I have them programmed in a separate bank - UHF I think)...

So.. 700 is a done deal eh?
 

mesocyclone

Member
Joined
Nov 5, 2005
Messages
78
Location
Phoenix, AZ
Intermodulation and Desense

One thing to watch out for is getting signals that are too strong - that are not the ones you want. Unfortunately, with digital signals, these are MUCH harder to diagnose.

This causes two effects:

1) Intermodulation - signals can mix in the front end of your scanner (or, for that matter, other non-linear nearby devices or even far away transmitters). The result is a signal on the frequency your scanner wants to listen to - one that interferes with the desired signal.

2) Desense - a strong signal within the front end passband of your scanner, even if it is a ways from the signal you want to hear, can saturate the front end and strongly attenuate all other signals. For example, the Radio Shack 2004-2006 scanners, at my house about 10 miles from South Mountain, will knock down all VHF public safety frequencies by 30dB (a factor of 1000!). This happens if I put a good antenna on the scanner. Hence I use a Grove Enterprises pre-filter and an attenuator. When you reduce the power of all signals coming in, perversely the signal you want can get stronger in this situation.

Thus I would suggest fiddling with attenuators (if you suspect you have good reception of interfering signals) and better antennas (otherwise) - or both if you don't know.
 
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