Uidentified Systems

[mike_s104]

as I was flying from Las Vegas to Dulles, I was searching in-flight (don't want to hear about if I should have been doing this or not since this is not the reason for posting here) and ran across SysID CA0D on 409.4125MHz. I have no idea where exactly I was (other then about 30,000'). only thing I have to go on for location is before I saw this show up, I saw SysID 5D13 which is Springfield MO (http://www.radioreference.com/modules.php?name=RR&action=sysid&sysid=5D13). right after the 5D13, I saw "Community SMR" display with a CC of 406.1625 and 406.3625.

I did a search for all three freqs in the database. for SysID CA0D on 409.4125MHz, I found nothing for that SysID. 409.4125MHz shows up mostly as Federal Prisons throughout the country.

as for 406.1625 and 406.3625, only Tyndall Air Force Base (http://www.radioreference.com/modules.php?name=RR&sid=3439) and Bluegrass Army Depot System (http://www.radioreference.com/modules.php?name=RR&sid=1402) are the only trunked systems showing up using both of those freqs. neither have "Community SMR" listed as the System Name. the only systems listed with that name are in CA. that would maybe correspond with the "CA" in the first part of the SysID. being that I was in-flight, I guess it would not be out of the question to receive a system far from where I was.

anyone else ran across these?

 

[Gilligan]

I don't think the system ID prefix has anything to do with states. As far as I know, it's just a hex number. Speaking of which, does Motorola issue your system ID when you buy a Motorola trunked system?

 

[Gilligan]

as I was flying from Las Vegas to Dulles....

Were you able to pick up very many systems? How was reception?

 

[cristisphoto]

Posibly Air MArshalls
OR the FAA
Defnitly Government LOL
I think we all know that much LOL

But if you were in the air the Defintly one of the two or Someone in the Governemt related to Air Operations
mAy be AirForce
Thought the IDea of Receiveing ANYTHING from the Ground other than Sattelite or AM type
Frequs
WOuld Strike me as odd
I dunno
Crista

 

[Gilligan]

Posibly Air MArshalls OR the FAA
Thought the IDea of Receiveing ANYTHING from the Ground other than Sattelite or AM type
Frequs WOuld Strike me as odd

He was definately picking up a trunked system on the ground as he had to have found the control channel in order to ID the system. Besides this, I'm pretty sure that from that high up you can actually hear quite a bit more because of your perspective. Remember, planes can be heard for hundres of miles away because of their locations. So it should work the other way around from in the air.

 

[mike_s104]

Were you able to pick up very many systems? How was reception?

I never really heard anyone on them. I don't remember what the signal strength was.

 

[JHaislet]

If you know precisely what time the transmission(s) occurred, you can get your precise GPS location from http://www.flightaware.com

You simply input your flight carrier & flight number, and pull up the log for that flight. It will then display the coordinates for every couple of minutes of the flight.

 

[mburdette]

Hi Mike _s104. I hardly ever look at this section of RR, but for some reason I did this evening. I hope you still check for answers here on your question.

I live about 17 miles north of Springfield, Mo, and checked 409.4125. I do hear a faint control channel signal! But, after trying different receive modes, I could get no system ID code. ( Pro-97) I believe it might be the Federal Medical Center for Prisoners in Springfield. ( First guess!!) It may be a week or two before I get up to SGF, but I will check it for you.

 

[JHaislet]

MBurdette, Have you tried it as a Motorola Type II P25 system? The Yankton Federal Prison here in SD uses 409.4125 as well as 4 other 4xx frequencies.

They also have a rolling control channel that changes about every 24hrs.

http://www.radioreference.com/modules.php?name=RR&sid=4925

 

[mike_s104]

If you know precisely what time the transmission(s) occurred, you can get your precise GPS location from http://www.flightaware.com

You simply input your flight carrier & flight number, and pull up the log for that flight. It will then display the coordinates for every couple of minutes of the flight.

not sure about the time. I don't even know what time zone I was in. I'm pretty sure it wasn't aircraft.

Hi Mike _s104. I hardly ever look at this section of RR, but for some reason I did this evening. I hope you still check for answers here on your question.

I live about 17 miles north of Springfield, Mo, and checked 409.4125. I do hear a faint control channel signal! But, after trying different receive modes, I could get no system ID code. ( Pro-97) I believe it might be the Federal Medical Center for Prisoners in Springfield. ( First guess!!) It may be a week or two before I get up to SGF, but I will check it for you.

thanks. not a big deal. I posted more as info for people in the area (large area) to look for. I know where I am there are a lot of unidentified federal P25 systems.

Have you tried it as a Motorola Type II P25 system? The Yankton Federal Prison here in SD uses 409.4125 as well as 4 other 4xx frequencies.

They also have a rolling control channel that changes about every 24hrs.

http://www.radioreference.com/modules.php?name=RR&sid=4925

I cannot try it now since I'm home.

 

[mburdette]

MBurdette, Have you tried it as a Motorola Type II P25 system?

Sorry, the Pro-97 doesn't do P25. But, I wonder if an ID would show up anyway.

 

[mburdette]

thanks. not a big deal.

Yes, but now you've got me curious!

 

[JHaislet]

Sorry, the Pro-97 doesn't do P25. But, I wonder if an ID would show up anyway.

That's right, I got the 97 confused with the Pro-96 which I think does digital (I only have experience with the Uniden line).

In P-25 systems, the system/site ID is part of the control channel data which is a purely digital stream.

 

[mike_s104]

Yes, but now you've got me curious!

good!! that's what I wanted to happen.

 

[mburdette]

This is interesting! Just a short while ago, I ran into a guy I know who retired from the Federal Medical Center for Prisoners in Springfield, Mo about a year ago. I asked him about the radios they used and although he didn't know much about them (digital or analog), he said that sometimes in the control room they could hear the radio traffic at the Leavenworth, KS prison! That's roughly 175 miles. Just thought that was quite fascinating!

 

[JHaislet]

That's not uncommon, especially if both sites were part of the same system and shared the primary controller & switch for the radio system. Given the way trunked systems are programed, their radio's probably had the Ft. Leavenworth TGID's in them as well (lazy programming).

 

[mburdette]

That's not uncommon, especially if both sites were part of the same system and shared the primary controller & switch for the radio system. Given the way trunked systems are programed, their radio's probably had the Ft. Leavenworth TGID's in them as well (lazy programming).

Yes, I'm sure you are correct. Many people using radios in connection with their work have no idea how it works, as long as it does work. But, that's what makes it fun for us who are into scanners and such.

Slightly OT example: A local busines uses some Motorola radios for in-store comms. Their radios use a PL tone and I've heard another user on the same freq ( they are in dumptrucks, but I've not figured out the company) that doesn't use the tone. So, they hear the store but the store doesn't hear them. I hear the trucks coming into town one morning and they are talking about how every time they hear a lady on their radios who is "telling everybody what to do" and immediately I knew who they were talking about, as I do business with this store. The next time I went to that store, I told the lady at the front counter about this ( she is the one they were referring to) and now it is a running joke!!!

 

[EFjohnsonVHF]

This term was mentioned in an above reply, So can someone tell me what a "Rolling Control Channel" is, and what the point of it is?

 

[JHaislet]

A rolling control channel is simply a setup where the site controller (which assigns frequencies each time PTT (push-to talk) is keyed up) changes the control channel between different frequencies assigned to that site on a predetermined basis (e.g. hourly, daily, weekly, whenever).

I personally see no reason for it, but the local Federal Prison which uses 5 channels in the lower 400mhz range, changes to a different control channel approximately every 24hrs (between those 5 frequencies).

Obviously anyone with a scanner or access to the FCC database could easily determine where to listen for the CC.

I guess it gives the bean counters "comfort" as it's "sold" as a quasi-security feature...

 

[edweirdFL]

I thought the rolling CC feature was designed to even out the total duty cycle (transmit times) over the life of the system's base transmitter(s).