Department of Natural Resources

[cobra]

Is anyone listening to the DNR repeaters ?

Can anyone tell me what is going on with the buzzing noises that seem to be taking over the clear voice transmissions ? Is it P-25 phase II, NXDN, MotoTrbo, MDT transmissions, AVL, or just what ?

Tnx, Cobra

 

[LarrySC]

Here in the upstate they are just using Digital PL Tones for the squelch. Would figure MotoTRBO for other areas.

 

[trumpetman]

It's P25. There was a thread on this very topic a few weeks/months ago. SCDNR is running Quantars and Motorola XTS5000s last I checked....I imagine they're secure capable as well.

 

[cobra]

SC DNR Signals

Thanks to all who responded, but there is something else and something new going on in the last few weeks. There are new sounds on the Little Mountain repeater (151.160) that are different than those noted on the Santee and Georgetown repeaters the last few years.

I gave in and contacted the DNR radio maintenance foreman a couple of weeks ago to politely asked the question about what they were doing. I told him that I was a former law enforcement officer with other credentials, and would only like to listen to their system, and not use anything that I heard for other purposes. He gave me me a "baby faced" answer by saying that: "Gee, we hear those same sounds on our radio system too, and we don't know what they are! We even contacted the FCC to find out where they were coming from and they couldn't help us" . DUH.... I guess he thought I would just pack up and go away.

I am still digging. Any help from any of you would be appreciated.

TNX...j

 

[trumpetman]

Not sure why you don't believe the guy....harmful interference is a real thing and sometimes the people in charge just don't have answers.

There's been more than one occasion where I've talked to those involved with maintaining/managing systems and pointed something out that didn't sound right or didn't sound like it belonged and either they hadn't noticed it up to that point or are just as confused as I am and trying to figure it out as well.

At least he was kind enough to offer a response...and even kinder to not flat out tell you to bug off like most would do these days.

 

[cobra]

Chris, If you heard what we are hearing you would know (or at least you should know), that this is not "harmful interference." There is traffic being passed and I would have much rather have him tell me so, realizing that if it is indeed secure, I wouldn't have a chance of copying it in the clear. A kind response, sure it was. A truthful one, I seriously doubt it.

 

[Quantar22]

There is a known bug in the Quantar Epic firmware that if you run Multi-NAC that it will sometimes pass weak signals regardless of the NAC being in the access table. Whether or not this is the case here I have no idea. All I know is that from speaking with someone I work with they have seen this first hand. The weird thing is it only happens when running the repeater in mixed mode and Multi-NAC. Haven't tried running it Astro only with Multi-NAC access table to see if it does it that way or not... The above being said the guy may actually be truthful if he doesn't know about this firmware problem as it isn't highly publicized.

 

[trumpetman]

There is a known bug in the Quantar Epic firmware that if you run Multi-NAC that it will sometimes pass weak signals regardless of the NAC being in the access table. Whether or not this is the case here I have no idea. All I know is that from speaking with someone I work with they have seen this first hand. The weird thing is it only happens when running the repeater in mixed mode and Multi-NAC. Haven't tried running it Astro only with Multi-NAC access table to see if it does it that way or not... The above being said the guy may actually be truthful if he doesn't know about this firmware problem as it isn't highly publicized.

ASTRO only still has the same bug. We've been battling that exact issue here with a Quantar and finally just went to a single NAC & PL tone and left it at that; no problems since then. Surprisingly not very well documented from what I could find, that was our best guess was that the multi-NAC mixed mode was the issue.

 

[cobra]

Thanks to both of you, Quantar and Trumpetman. I appreciate the civil responses. I will keep digging into this for a little while longer and would appreciate what you can offer and I will post the same.

Cobra

 

[bigfoot317]

It is data transmissons from an unknown source. Its been going on fot several years. He cant figure out where its coming from. Sewer plant, power grid....anyones guess. Switching to digital soon will help.

 

[Quantar22]

It is data transmissons from an unknown source. Its been going on fot several years. He cant figure out where its coming from. Sewer plant, power grid....anyones guess. Switching to digital soon will help.

Not exactly sure how that will help with an interference issue. Might pay to find the interference issue instead of doing a cover up. If a signal is lets say -110 dBm into a receiver running in analog it will still be -110 dBm into a receiver regardless if it is analog or digital. Receivers do not care what the type of modulation are if they are being interfered with. That is what the capture effect in the receiver is all about. A carrier at -110 dBm in C4FM is the same as a - 110 dBm signal running in plain ole 12.5 KHz analog. When a valid subscriber unit is using the system with a signal less than the interference signals level you are still going to have problems. This is the equivalent of switching PL tones just to keep the repeater from keying due to interference. Not a fix at all. Sorry to rant but I don't get the idea that people do this and say the issue is repaired when it really isn't.

 

[KE4SZT]

Heard DNR units a couple months ago on the Pee Dee Repeater, CH-17 151.160, in analog saying to change to another channel, think it was 47. When they switched over, they were on the same frequency, but it was the "buzzing" that everyone has been hearing. 99.9% sure it isn't interferance. Most likely encrypted P25 for unit to unit and analog back to Columbia.

 

[SCPD]

Great Comment! KE4SZT