Strange signal 851.5875 in Wichita Falls

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nd5y

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I'm hearing a base station (or repeater?) on 851.5875 DPL 073 here in Wichita Falls.
Every 10 minutes or so it sends what sounds almost like a telephone 440/480 Hz ring signal for about 3 seconds.
There are no current or recently expired FCC licenses for 851.5875 anywhere around here and this area has been rebanded so it should be a public safety-only frequency.
 
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Alliance01TX

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Tom

Perhaps a portable DPS repeater or DoD at Sheppard?

Or the old Space Fence site?

Would be interesting to get a azimuth on that one..

Bill
 

nd5y

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It doesn't transmit long or often enough tell what direction it is coming from. It's about the same signal strength as the commercial 800 MHz LTR across town.

It's way too strong to be from the SPASUR site in Archer County, and way back when I worked there they had a VHF repeater and no other RF control or monitoring stuff.

I don't think the federal government can use 800 MHz except when they are subscribers on state and local systems.

When you look at it on a scope it looks like the tone has 180 degree phase shifts so I think it is some type of PSK data signal. Probably some kind of SCADA.
 

nd5y

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This time I saved it as a .mp3. Now it's small enough to make vBulletin happy.
The signal is transmitted every 15 minutes.
 
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Alliance01TX

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Tom

Nice Audio Clip...

Perhaps a 'cross-patched' channel/circuit to a "ring-down" or "order-wire" as one-of-many options...?

Does this repeat with a typical measured (in seconds) gap between the duty cycles?

We used "Ring Generators" in some comms work (long ago) in the USAF Comm stations and also 400Hz was heavy used in Tactical (old TAC) and the Aircraft areas used too...no idea...

Let me know if still hearing and will tune it up..

Bill
 

nd5y

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Does this repeat with a typical measured (in seconds) gap between the duty cycles?
It only "rings" one time every 15 minutes. It's still on the air today.

In the past year or so since I moved back here I have been doing a lot of 851-866 MHz band searching. I don't know if this is something new or I just happened to always miss it.
 
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