Noise on RCS analog talkgroups

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LauraQ

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Has anyone noticed noise on the RCS analog talkgroups? Specifically, I'm listening to the North Zone. The noise is heard only on analog TGs and is heard on three different scanners.

Thanks,
Laura
 

MtnBiker2005

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Watch what freqs you are hearing the noise on. That's the type of info Don wants to know from us.

Heard it this evening...
857.2000 - Analog sounds noisy/crappy.
857.2000 - P25 digital sounds very good.
 
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K6CDO

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If the noise is static-like, it often is an artifact of the simulcast. With 10 transmitters all transmitting at the same time, there are very slight differences in the arrival of the signals to your antenna. Instead of hearing what sounds like two (or more) transmitters keying up on top of each other, the static-like noise is present. Moving the radio slightly may make it better.
 

LauraQ

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This noise is actually almost like a control channel type sound behind the transmissions. Very strange. I'll try to record it tomorrow. I'll also make note of what TG's I hear it on. It's intermittent, but I've heard it on a couple of EMS TG's, as well as Escondido Fire Dispatch.
 

Mike_G_D

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This noise is actually almost like a control channel type sound behind the transmissions. Very strange. I'll try to record it tomorrow. I'll also make note of what TG's I hear it on. It's intermittent, but I've heard it on a couple of EMS TG's, as well as Escondido Fire Dispatch.
The talkgroups are less important than the actual voice frequencies used in this case. So note the voice frequencies that show up on your scanners' display when you hear the noise. Also, your description of the noise sounds like it could be from your scanner's overloading due to nearby NEXTEL sites and/or possibly other cellular telephone 800MHz sites. GRE-based designs are particularly prone to this; this includes many Radio Shack units (like the Pro-197 and the handheld equivalent that I can't currently remember the number of right now). You stated that you noted it on several scanners - what models were these? If any were Uniden models and you still heard the noise then that is very relevant as the Unidens are less prone (though certainly not immune) to this overloading issue.

So next time it happens pay attention to the display and note the voice frequencies used and let us know what models of scanners you are using that you hear the noise on as well as any differences in degree between them. Also, indicate your antenna type and installation.

And just FYI - digital modulation will mask any interference such that you will not be able to tell if any is there at all unless it is severe enough to cause significant bit errors in which case all you will note is, depending on the receiver design, garbled digital audio (like the "R2D2" sound) dropped audio or no audio period. That's the "mixed blessing" of digital - when debugging using human ear only one usually cannot tell what interference type is present such as adjacent or alternate channel interference, intermodulation, images, etc., whereas with an analog FM signal an experienced ear can often lead to a good diagnosis (I'm pretty good at it myself but I've been listening for over 35 years total and have over 12 years professional lab experience). So you will not necessarily hear any issue with a digital signal on the same voice frequency as you did with an analog FM signal previously unless it is severe enough to cause significant bit errors leading to garbling, dropouts, or no audio at all, etc.

-Mike
 
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MtnBiker2005

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Per the RCS Radio Techs testing at 4pm Saturday.
Channel 11 is the bad channel(857.20000). They talked about turning it off.
Channel 16 has some noise in the background.
 
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inigo88

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Haha way to save the day Brian! I tried to listen to North Zone last night for a little while to see if I could corroborate the issues on 857.200, but I was only hearing digital talkgroups. Go figure. :)
 

LauraQ

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You gentlemen are correct...857.200....is the problem frequency. I heard the noise again this morning during an ALS call to Palomar on the frequency. The MICN even commented on not understanding part of the transmission because of the interference.

Glad to hear the techs are working the problem. All I can say is...thanks a million!
 
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