165.2875 digital pulses with no NAC

[SOFA_KING]

My local 165.2875 P25 repeater has been sending constant digital noise without a NAC (ctcss search says 67.0 Hz...can't be) for a month now. Maybe the data is near 67 Hz. Like four frames of data that just keep repeating in a never-ending string. I was wondring if this was some new form of emmission, but I think it is just broken or hung. I listened to the MotoTRBO samples and that is not it. This repeater is jamming that freq over a very large area!

What would you do? Call the agency and let them know? Let them discover it on their own? Maybe it is some new technology I know nothing about!

Phil

 

[ocscan]

Are you getting the same results with different scanner? That's always my first "check"

 

[Squad10]

My local 165.2875 P25 repeater has been sending constant digital noise without a NAC (ctcss search says 67.0 Hz...can't be) for a month now. Maybe the data is near 67 Hz. Like four frames of data that just keep repeating in a never-ending string. I was wondring if this was some new form of emmission, but I think it is just broken or hung. I listened to the MotoTRBO samples and that is not it. This repeater is jamming that freq over a very large area!

What would you do? Call the agency and let them know? Let them discover it on their own? Maybe it is some new technology I know nothing about!

Phil

The new Motorola APX series portable and mobile radios have integrated GPS. Maybe this is what you are hearing??? I wouldn't know if I actually heard an ATX GPS position report.

The Chicago 165.2875 P25 repeater keys up with short (1 sec.) bursts frequently every day, with no NAC, but it is not constant as you mention. You might want to dedicate one P25 radio to the input frequency, and another to the output and see if the two coincide.

My opinion, let them discover it on their own, unless you know somebody with ATF really well.

 

[SOFA_KING]

Are you getting the same results with different scanner? That's always my first "check"

Yes. Not an image. I have been at the site. It is "them". What to do about it?

Phil

 

[Squad10]

Yes. Not an image. I have been at the site. It is "them". What to do about it?

Phil

Try the ol 2135 on the cabinet and fix it!!!!

 

[SOFA_KING]

Try the ol 2135 on the cabinet and fix it!!!!

I have the keys and I thought about that! Most are alarmed and I do NOT want that kind of trouble. Let them take care of it.

Oh...and I just caught your post about the GPS feature. I have seen that stuff! A couple of USSS freqs broadcast that. So far I have detected several freqs that are broadcasting that GPS info, but from different agencies, and it is muted with a NAC code also being sent. This is not it. I think it is just hosed.

Boy, those TRBO radios look nice!

Phil

 

[Squad10]

<<<<< I have seen that stuff! A couple of USSS freqs broadcast that. So far I have detected several freqs that are broadcasting that GPS info, but from different agencies, and it is muted with a NAC code also being sent >>>>>

Do you know if:a GPS position update is interleaved with a P25 voice transmission, or does the position update occur by itself as a short burst?

 

[SOFA_KING]

I do not know. I heard one agency testing the feature and that is how I found out about it. Their repeaters were belching that stuff all night long even when no one was talking on the system.

Phil

 

[ecps92]

Curious, where? and What Freq/Agencies

<<<<< I have seen that stuff! A couple of USSS freqs broadcast that. So far I have detected several freqs that are broadcasting that GPS info, but from different agencies, and it is muted with a NAC code also being sent >>>>>

Do you know if:a GPS position update is interleaved with a P25 voice transmission, or does the position update occur by itself as a short burst?

 

[MaizeBlueFlyover]

There is a local USSS repeater in my area that I have heard these "key-ups" on. They do broadcast with a NAC though. Always wondered what it was, perhaps this is it.

 

[WayneH]

There is a local USSS repeater in my area that I have heard these "key-ups" on. They do broadcast with a NAC though. Always wondered what it was, perhaps this is it.

I see/hear this a lot on various systems. Generally when I do it's a voted or more complex system. I don't know if it's a voter thing or if there's some other form of path testing that's going on. All the times I've heard them there is a NAC. It's basically idle data/null voice (like what exists in a P25 repeater tail). I think it happens every 2 minutes like clock work.

Since a P25 stream always includes a NAC what these are is something different.

 

[Squad10]

I see/hear this a lot on various systems. Generally when I do it's a voted or more complex system. I don't know if it's a voter thing or if there's some other form of path testing that's going on. All the times I've heard them there is a NAC. It's basically idle data/null voice (like what exists in a P25 repeater tail). I think it happens every 2 minutes like clock work.

Since a P25 stream always includes a NAC what these are is something different.

Before the USSS went P25 in Chicago, I would hear a data burst every 2 minutes like clock work from a transmiitter at a suburban location. Since P25 was put in, I no longer hear the data burst. Never figured out its purpose. I don't hear anything out of the ordinary with the P25 system. Just encryption when the POTUS is in Chicago.

 

[SOFA_KING]

Maybe this data burst has multiple uses. I can confirm the GPS feature, but nothing else. If there is a voting feature for USSS, it is only being broadcast on Tango and Papa here. How would that work? What about Bravo and Charlie?

Phil

 

[fineshot1]

How often are the data bursts? I know if its a fed its probably not but it sounds like LTR Passport or similar.

 

[SOFA_KING]

How often are the data bursts? I know if its a fed its probably not but it sounds like LTR Passport or similar.

This is all fed stuff. It is also all P25. About 2 minutes as others have said is right. I doubt it is LTR, and on the system I heard the GPS info it was definitely not LTR.

Phil

 

[WayneH]

This is all fed stuff. It is also all P25. About 2 minutes as others have said is right. I doubt it is LTR, and on the system I heard the GPS info it was definitely not LTR.

So if you set your GRE on the channel in P25 Search mode no NAC is decoded when a burst hits the receiver? I can easily get a NAC with the P25 pulses I've heard occur. I do set my DG Int Prime setting pretty low though; makes the receiver open faster.

 

[SOFA_KING]

So if you set your GRE on the channel in P25 Search mode no NAC is decoded when a burst hits the receiver? I can easily get a NAC with the P25 pulses I've heard occur. I do set my DG Int Prime setting pretty low though; makes the receiver open faster.

Yes I do. I get the NAC. I too set my DG Int Prime low at 48. I have yet to verify if my P25 reception is degraded by doing so. It takes just about S-2 to decode P25 now. I will have to play more with that setting when activity is up. It has been very slow around my area. But that ATF repeater is still "jamming"!

Phil

 

[WayneH]

Yes I do. I get the NAC.

But not on 165.2875? You've confused me now since your subject says you don't receive one.

 

[SOFA_KING]

But not on 165.2875? You've confused me now since your subject says you don't receive one.

No, not on this freq. This is a whole different thing than the GPS (or whatever it is) belching on the other systems. The 165.2875 repeater around here is just hung on what sounds like idle data. Again, the topic drifted into some other direction. It happens.

I would bet the TX got stuck on when it shouldn't be, but with all the new technology coming out I thought it could have been something new I never heard of.

Phil

 

[KE7JFF]

Maybe the feds just invented a P25 LTR system