Something wrong with the AGC on the BCD436HP

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kikito

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What I'm seeing is reminiscing of the same AGC problem when the BCD396XT first came out. Sometimes it feels like is not doing anything. Sometimes on an already loud transmission, it actually gets even louder and clipping when AGC is turned on. At lower volumes, it sounds kind of "scratchy" and varies between sounding under and over modulated. This is on a P25 VHF Trunked system (Alaska ALMR) and I have all kinds of radios to compare to. Most sites show full signal on the meter for the control channel. The P25 Decode Error rate is almost always in the very low single digits, in fact, many times it shows a steady 0 on the error rate.

I will continue comparing and judging the performance but I really think the AGC feature could use some tweaking.
 

greggk

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Rather than start a new thread, this relates to AGC as well. All of my trunked systems sound very good. Yesterday, however, I programmed the Illinois Statewide p25 system to pick up NW Central Dispatch. It dispatches many cities here in Northern Ilinois. It is a TDMA system (Project 25 Phase II)

The disptacher is always the same female robotic voice. Almost sound like the NWS does. Following that voice, an apparently "live" person comes on and clarifies the message.

Its often very hard to hear. Volume is good, but voice is often to garbled to understand. I turned on AGC, which may help a bit, but not a lot.

Has anyone had any experience with this? Has anyone been able to get better sound?

Thank you.

Greg
 

policefreak

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greggk said:
Rather than start a new thread, this relates to AGC as well. All of my trunked systems sound very good. Yesterday, however, I programmed the Illinois Statewide p25 system to pick up NW Central Dispatch. It dispatches many cities here in Northern Ilinois. It is a TDMA system (Project 25 Phase II)

The disptacher is always the same female robotic voice. Almost sound like the NWS does. Following that voice, an apparently "live" person comes on and clarifies the message.

Its often very hard to hear. Volume is good, but voice is often to garbled to understand. I turned on AGC, which may help a bit, but not a lot.

Has anyone had any experience with this? Has anyone been able to get better sound?

Thank you.

Greg
That sounds more like a reception issue to me. AGC may hone in on that audio a bit to make it sound less crappy but it can only do so much. In my experience (theres a thread dedicated to this issue) with Phase 2, when reception gets weak I begin to hear a crackling sound. I think because the digital processor slows way down to recover the garbled audio better. Sort of like the old tracking concept on VHF tapes going through a VCR (wow, who else even knows what I am talking about?). For me, where AGC doesnt do much for me, I have turned the volume offset up +1 on phase 2 talkgroups and that seems to help them sound clearer.
 
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greggk

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Thanks. I get the crackling sound also, but not all the time. I tried doing the manual instructions of checking error rate etc. No luck there. I remember now reading somewhere about this being a possible reception error. I'll turn the off set up by +1. Thanks for the help!

Greg
 

greggk

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Policefreak..I turned off the AGC and set the primary dispatch channels to +1. I get some benefit, but some transmissions are just not intelligible at all. However, when I really cannot understand them, neither can the dispatch/ patrols. They always ask for a repeat.

Its my understanding that since simulcasting sends the same transmission to two different towers, at different distances from my radio, that the two transmissions don't line up with each other and therefore the garble. And as you said, if one tower is really far from me..I have the Garble as well.

Thanks again.

Greg
 

pratzert

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I too, think that there is some sort of AGC problem. Some transmission normal, and other so loud it is startling
 

N0UDG

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I too, think that there is some sort of AGC problem. Some transmission normal, and other so loud it is startling
Also, some people do not seem to have the proper "mic etiquette".

For a while one dispatcher seemed to be having a "whispering contest & no doubt winning" and one of the cars talked so loud and close to the mic that it was actually not only too loud but distorted as well.

I don't think AGC can handle this but the "shift Commander" or "Chief" probably can.
 
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