Traffic Monitors (I-35 construction)

[mam1081]

Anyone stumbled on the trailer's frequency. I was travelling up I-35 from TX this weekend, and found a 464.50 in the construction site near the border (Love County). It seemed to be a tone, then a really short data burst. I'm guessing this was the traffic trailers. They seemed to monitor the traffic flow and speed to change the warning signs.

Closer to the metro (OKC), in Moore, I got a CloseCall hit on something like 451.4375 (I think that's what it was). It sounded vaguely like APRS (Ham stuff, for those not in the know. Search for it online). I was curous, so tuned my Kenwood D700A (decodes and encodes APRS packets) to that freq at 1200 baud, and voila! I could read packets. The "station" was MOORE, and there were some characters that the radio couldn't decypher, but for the most part it worked (lots of numbers and such - we could probably figure out the protocol). Are these trailers transmitting in AX.25 (type of packet) just like the hams?

Can anyone find what the trailers (I assume there are some) on the 63rd and Broadway (I-235) construction are operating on? Maybe I'll make a drive up that way today to try to find them. For comparison, the national APRS frequency is 144.39. Compare what you hear on there with the traffic monitors (if you can find them!).

 

[freqscout]

Traffic Monitors

What are the traffic monitors? Are you referring to the roadside signs or some other device? Is this the device that causes the roadside signs on I-240 to give a time as to the length of traffic delay that it displays? Is it a radar based item?

 

[mam1081]

Yes, the traffic trailers that have text displays.

I do think it's tied in with radar somehow. They seem to have some IR (maybe?) monitoring device (like on automatic doors) that can detect traffic. I don't remember my radar detector going off in the construction in Moore - it did in the southern construction zone (near the border), but they had a radar tied into that one.

 

[freqscout]

Was the data streaming constantly? Did you do a search to make sure that you didnt stumble on another service in that area not related to the construction?

 

[mam1081]

Negative - I was just playing and found that.

I just looked on the FCC site, and see that Moore does have a license for that frequency. It comes back to the utilities department. I picked up a similar transmission near the border on 464.5, which is probably impossible to figure out who that was.

It was not a constant transmission. It was in short bursts, a few seconds apart.

Also, Moore's license is for 100 transmitters, with a max of 2W each - maybe it is some kind of meter reading for the city. The DB does not seem to list is as identified.