172.3000 $A70 Control Channel eh?

spacellamaman

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Central NC, 8-10am 6-26-20. Walking the dog this morning, running limit search and hit 172.3000 as a control channel $A70. Definitely some ducting or something as I was receiving Shaw AFB 160mhz trunked system, 381.425 $581 a SC army base CC briefly, as well as quite a range of VaSTARS stuff in the 150-160's that is not normally rx'd here. Have failed so far to find much on here other than a TX report of $A70 used by CBP, and didn't have time to further investigate via other scanner functions.

A couple of years ago 172.300 popped up in similar circumstances as a P25 system, it was investigated inconclusively with a different NAC, see:


anyway, anyone have an idea as to what 172.3000 $A70 belongs to?
 

ecps92

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172.3000 has been reported in the NC/SC/GA area in use with $A30, $A70 and $B20 over the years

Any RID's ??
Central NC, 8-10am 6-26-20. Walking the dog this morning, running limit search and hit 172.3000 as a control channel $A70. Definitely some ducting or something as I was receiving Shaw AFB 160mhz trunked system, 381.425 $581 a SC army base CC briefly, as well as quite a range of VaSTARS stuff in the 150-160's that is not normally rx'd here. Have failed so far to find much on here other than a TX report of $A70 used by CBP, and didn't have time to further investigate via other scanner functions.

A couple of years ago 172.300 popped up in similar circumstances as a P25 system, it was investigated inconclusively with a different NAC, see:


anyway, anyone have an idea as to what 172.3000 $A70 belongs to?
 

spacellamaman

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no RIDs, at the time i was walking around in the yard with a PRO668, so in search when it locks on, there is no audio and it just displays the NAC, so i turned down the squelch and removed the antenna, and immediately replaced it, to keep the scanner from having a chance to decode and cut the audio, to actually hear what it was recieving, and it was just your standard constant, P25 control channel audio/noise.

the $B20 incident from a while back, i picked that up under similar conditions in basically the same location as this time, not that that matters too much. i wasn't aware of the $A30 report tho.

so now my question is, how in the world has this yet to be tracked down?

if both incidents are the same system, which may or may not be the case, there is at least one, possibly two towers minimum, broadcasting a steady signal, somewhere in the southeast, almost certainly co-located in a high density population center, that has, inevitably at least a few scanners chasing any and everything down.

i'll have to track down my old posts to confirm, but i am pretty sure the first go-round i was picking up SC stuff then too, either Shaw AFB or Ft Jackson or something like that. i had kinda written off the Unidentified Project 25 BEE00-B25 as a weird fluke cause i essentially was able to recieve only one of the freqs, for less than a day i think, and then never again. others far more technically inclined than I made further efforts to no avail, and nothing mentioned since. this makes me think its the same thing and wherever it is, its prob been there the whole time.

if random schmucks like me, presumably hundreds of miles away are stumbling upon it, where are the reports from the folks that can see the transmitter out their kitchen window?

all right, i guess i am done now.
 

nd5y

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if random schmucks like me, presumably hundreds of miles away are stumbling upon it, where are the reports from the folks that can see the transmitter out their kitchen window?
They are dumbed down from using recent Uniden and Whistler products and don't know anything exists except for what they can download from RR.
 

spacellamaman

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If this is indeed a control channel, there should be additional useful information besides the NAC that can be determined, such as Site ID, WACN, and any connected trunked sites, etc.

- Chris
very true, which made it all the more frustrating when i found it using the pro668, which is not useful in that area. needless to say the signal was long gone before i had a chance to investigate hours later with a 436 and a 1040.

btw if anyone is interested here is the thread for the $B20 system

 

nd5y

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172.300 $167 is an FBI repeater somewhere west of Fort Worth and south or west of Wichita Falls.
Wherever the cc is probably isn't this far west (TX or OK).
I don't think I have ever seen a cc in the 162-174 band.
 

spacellamaman

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172.300 $167 is an FBI repeater somewhere west of Fort Worth and south or west of Wichita Falls.
Wherever the cc is probably isn't this far west (TX or OK).
I don't think I have ever seen a cc in the 162-174 band.
yeah its hard to imagine it being that far out, but it is interesting to note, searching the forums here, the only other reports i could find of the NACs being used so far, just happen to be in the TX area, though in totally different contexts.

Purely based on the other systems recieved during these two instances, i feel like it probably is the far side of SC from NC or in Georgia, tho somewhere in VA or TN mountain country seems likely too. I would say that 2-3 times a year, conditions will be such that i can recieve 380mhz sites in central SC and 1-2 times a year I'll catch Shaw AFB. Enhanced Rx of VaSTARS sites, maybe once a year. this 172.3 rx is now twice in a total of 6 years.

as for 162-174 CCs, they are few and far between for sure, Shaw AFB in SC is the only one I have been able to recieve in 6 years (not counting the VaStars stuff cause its more like 150ish to 162ish, odd in itself) even then under very rare conditions. Frankly, its an odd choice of bands to begin with, and must be chosen for some sort of reason that is beyond my understanding.
 
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nd5y

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I should have worded that differently. I have never actually received a cc in the 162-174 band at my location.
All of the military VHF systems anywhere near here are all in the 138-151 part.
 

ecps92

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As GTR pointed out, there are plenty of them, especially if the UHF Bands are already full
and/or you are near a Pave Paws site [not just Amateur Radio is impacted] and then you have the
Part 90 Public Safety who have gone VHF and borrowed from the NTIA

See Maine, KY, PA [off the top of my heard] as well as some other Central US Statewide networks

And one or two threads from the West Coast on some networks being brought on-line for VHF TRS

172.300 $167 is an FBI repeater somewhere west of Fort Worth and south or west of Wichita Falls.
Wherever the cc is probably isn't this far west (TX or OK).
I don't think I have ever seen a cc in the 162-174 band.
 

nd5y

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Part 90 Public Safety who have gone VHF and borrowed from the NTIA
See Maine, KY, PA [off the top of my heard] as well as some other Central US Statewide networks
There are none of those in TX, NM, OK, AR or LA. I think the closest to me is MO.
 

signal500

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172.300 $156 is part of a wide area DOJ system here in the Panhandle of Florida. 172.300 $301 is also used by the CBP in Webb County, TX. I have monitored similar NAC's used ($A30, $A70, $B20) by CBP all along the southern border during band openings. Maybe it's part of a VHF TRS for CBP?

172.300 $167 is an FBI repeater somewhere west of Fort Worth and south or west of Wichita Falls.
Wherever the cc is probably isn't this far west (TX or OK).
I don't think I have ever seen a cc in the 162-174 band.
172.300 $156 is part of a wide area DOJ system here in the Panhandle of Florida. 172.300 $301 is also used by the CBP in Webb County, TX. I have monitored similar NAC's used ($A30, $A70, $B20) by CBP all along the southern border during band openings. Maybe it's part of a VHF TRS for CBP?
 

spacellamaman

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well anyway ya look at it guys, this thing ain't an elusively chirpin ivory billed woodpecker vote-scan set-up. Its a piliated-trunking-woodpecker pounding on the aluminum siding of someones house! And nobody has seemed to notice! It just blows my mind.
 

ChrisP

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needless to say the signal was long gone before i had a chance to investigate hours later with a 436 and a 1040.
Which makes me wonder if it is really a trunking control channel. Normally there would be some evidence of the control channel 24-7 for the system to be useful. But this one keeps disappearing.

There are P-25 test signals that are used for coverage testing and Bit Error Rate information that look and sound a lot like control channels, but only show NAC data and not much else.

- Chris
 

spacellamaman

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Which makes me wonder if it is really a trunking control channel. Normally there would be some evidence of the control channel 24-7 for the system to be useful. But this one keeps disappearing.

There are P-25 test signals that are used for coverage testing and Bit Error Rate information that look and sound a lot like control channels, but only show NAC data and not much else.

- Chris
that is certainly a good possibility, not that i was necessarily aware of that per se. the only experience i have had with anything like that was a few years ago where apparently a tech did a oopsie on a rarely used tower for a system in my area, but it was not broadcastiing a NAC at the time, just this weird noise that i presumed was of a completely different nature, on the CC and VC's for that tower simultainiously. i would have to refer to trumpetman for details on whether that was the same type of thing you are suggesting, but he indicated it was somesort of test mode.

anyhoo, the signal disappearing, at least from my locale is just due to the conditions coming and going as far as i can tell.

i haven't mentioned this yet, due to the dark comedy of errors, and hard learned lessons of unmentionable situation, but i was able to briefly receive the same (audible same) from a high elevation point two nights ago, most unfortunately, with a bc125at. i had no intention of doing any scanning that night, only take pics of a storm system approaching, overtaking my position and soaking me wet in the process.

i threw the cheapest scanner in a ziplock in my backpack as an after thought, knowing i wouldnt use it. it takes 45 minutes hiking up to this place, so of course, the storm system halted and petered out. boredom quickly set in. long story somewhat shorter, i received what sounded like a CC on 172.3, very variable fade, from approx 2000-2010h local. first time since fri morning. ugggghhh... back to the car, dump camera gear, grab all radio gear, back to the top, 1.5 gallons of sweat and an hour and a half later back at the top, there wasn't even a whisp of the signal to be found.

not to be simply satisfied with failure, disappointment and all sorts of exhaustion, just in case the signal faded back in, i wanted to be ready. i decided to whip-out a quick P25 system, so i could use the T-Sys analyze mode, in my new-to-me and rather confusing WS1040, doing the programming by memory, of which i have little. (1040 manual didn't make it out of the car on trip #2)

and while it hardly needs to be mentioned, as you may have already guessed, i heap error-ed myself, bricking the Ws1040 (unforgiving little goomer) in the process. ....yeeeeaaaa.... Running low on things left that could go wrong (others omitted here for brevity) I finally decided, this was not going to be the day, trudged back down, and was home by midnight.....

i really have no clue if there is any advantage to that location in this particular situation, but my next trip i will packing 2 kitchen sinks, just in case, and will report any findings.
 

rkm1215

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Wow, an adventure for sure! Wonder if it could be a Site on Wheels or maybe some sort of standup TRS in a box kind of thing. Just speculation.
 

ecps92

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Might be Correct for your area - however the user Agency will vary by Region and/or State
ie: However, just in the your state we have FBI, poss DoE and one of the CBP agencies. - All on the same Freq, but different NACs


That looks like one of the Border Patrol frequencies down here in South Texas.
 
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