interference on digital

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johnny1225
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interference on digital

Post by johnny1225 »

We put in a XPR8400 UHF Repeater in to a very large scale hotel, complete with XPR6350 radios. They are working in capacity plus with about 5 talkgroups. 4 out of the 5 talkgroups are working fine but security says that they are getting alot of interference on their talkgroup only. Does it make sense that only one talkgroup all on the same freq in cap plus could be getting interference? Any suggestions would be greatly appreciated.

Thanks

John
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Astro Spectra
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Re: interference on digital

Post by Astro Spectra »

Are you running enhanced privacy on that TG?
johnny1225
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Re: interference on digital

Post by johnny1225 »

no it is just basic on all the talkgroups
RFguy
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Re: interference on digital

Post by RFguy »

Corupt codeplug?
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wavetar
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Re: interference on digital

Post by wavetar »

johnny1225 wrote: 4 out of the 5 talkgroups are working fine but security says that they are getting alot of interference on their talkgroup only. Does it make sense that only one talkgroup all on the same freq in cap plus could be getting interference?
No, it doesn't make sense. But, perhaps they are the heaviest user and are the only group to notice so far? We need more detail about the "interference". How do they know there is interference? What exactly do they mean? Are they hearing somebody else's Cap+ system? Are they getting a lot of distorted/garbled audio? A lot of trouble accessing the system?
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Bill_G
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Re: interference on digital

Post by Bill_G »

Welcome to the club. We have a new Trbo trunking system with a few hundred users distributed over a large industrial area, and there is one small group that just can't be satisfied. Everyone else is loving it. So far it looks like mic gain versus background noise versus user mic technique.
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Bill_G
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Re: interference on digital

Post by Bill_G »

While we are talking about digital interference, it show up in a Trbo or P25 as rcvr desense. An analog signal does nothing more than raise the noise floor of the receiver that the valid digital signal must overcome. The users will experience busies and/or high BER which brings it's own form of distortion. The best you can do is try to determine if the customer has areas of poor coverage, or cochannel users that are clobbering the input.
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wavetar
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Re: interference on digital

Post by wavetar »

Bill_G wrote:Welcome to the club. We have a new Trbo trunking system with a few hundred users distributed over a large industrial area, and there is one small group that just can't be satisfied. Everyone else is loving it. So far it looks like mic gain versus background noise versus user mic technique.
I saw at the Motorola CPE in Vegas this week that there is a new "INC" Industrial Noise Cancelling remote speaker mic coming out in June. It's supposed to do a much better job of reducing high levels of background noise, and they claim you don't need to speak directly into this one. Might help your issue.
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RFguy
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Re: interference on digital

Post by RFguy »

wavetar wrote: I saw at the Motorola CPE in Vegas this week that there is a new "INC" Industrial Noise Cancelling remote speaker mic coming out in June. It's supposed to do a much better job of reducing high levels of background noise, and they claim you don't need to speak directly into this one.
I tried out that mic at CPE and was extremely impressed by it (or should I say IMPRES-ed). It uses the same dual mic technology they use in the APX speaker mics. It also has 1 watt audio so will be much louder on RX. It won't be cheap, but in the right application, it will be well worth it. Part# when it comes out is NNTN8383A. Expected release is June.
johnny1225
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Re: interference on digital

Post by johnny1225 »

Just talking to the customer and they said they can hear full conversations of another hotel specially in the east part of the building. I am wondering if changing the color code to a different one that is set now would correct the problem?
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wavetar
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Re: interference on digital

Post by wavetar »

johnny1225 wrote:Just talking to the customer and they said they can hear full conversations of another hotel specially in the east part of the building. I am wondering if changing the color code to a different one that is set now would correct the problem?
Changing the color code may help from hearing the interference, but this is a case of full on-channel interference, and it will continue to cause havoc with system access and garbled digital sound (or no sound at all) when the interference mixes with your customer's signal. I don't know the spectrum landscape in Toronto, but I find it strange that hotels would be sharing the same system frequencies. It would also mean they just happened to choose the same color code, the same talkgroup(s), and the same basic privacy key as your system...another thing I find very strange. Are both customers legally on the air?

Did your customer in question have an analog repeater on the same frequencies before the switch to TRBO? Did they experience interference on it?
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johnny1225
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Re: interference on digital

Post by johnny1225 »

no they didnt have a repeater before or radios because it is a new hotel that was build. I guess i should get industry canada involved to just seems very weird to me that they would hear full conversations in a cap + system
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Bill_G
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Re: interference on digital

Post by Bill_G »

Ah! Co-channel user. Yep. Seen that happen even before digital. Time to check everybody's license.
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escomm
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Re: interference on digital

Post by escomm »

johnny1225 wrote:no they didnt have a repeater before or radios because it is a new hotel that was build. I guess i should get industry canada involved to just seems very weird to me that they would hear full conversations in a cap + system
Is your customer licensed on the frequency? If so, did you monitor the frequencies the coordinator gave you before constructing the system? And these radios are programmed for capacity plus and your customer can here another hotel as though the other hotel were running a capacity plus system, with the same system parameters and talk groups?

Really?
johnny1225
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Re: interference on digital

Post by johnny1225 »

yes they can hear so they say only on the security talkgroup full conversations specially on the east side of the building, which i find very weird!
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FatBoy
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Re: interference on digital

Post by FatBoy »

I could understand hearing another hotel on trbo with no trunking or no privacy, but only 1 of the talkgroups is hearing an adjacent hotel......... on trunking (CAP+) AND privacy enabled? That seems to fail the logic test to me. Would it be possible to put a radio on that group and record it? I have used a trbo radio sitting in a charger with a speaker mic that has the 3.5mm jack on it. I plug an audio cable from the 3.5mm jack to the line in on the computer and run a program called SCANREC or Scanner Recorder with only records when it hears actual audio, thereby compressing your listening time significantly. Adjust radio volume for best quality on recording. FB
......I understand what the package says sir, but you cannot talk 28 miles with 3 AA batteries.......
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