Trying to identify an 800mhz frequency in Ingham County

knockoffham

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Hello. I am doing some scanning in East Lansing, MI, and have come across a frequency: 851.475 to 851.4875 MHz. It is not always 100% duty cycle, and sounds like some sort of digital audio format, but not one that is familiar to me. It is a strong signal like a repeater output. Additionally, neither of those frequencies show up in FCC licenses throughout the county as far as I can tell. They do show up in a license for what I presume was a Motorola Type II trunking system owned by the city of Lansing (WPVC909) for a very short time (under a year) and terminated in 2003, as well as what looks like another type II trunking license that was canceled in 2014 (WQPY812). It seems to be a 20 kHz signal. All I have here to listen to it is some analog radios that happen to be able to pick up ~750 to 950 MHz. So if there is anyone in the area with a proper trunktracking or digital voice scanner or knowledge on what more digital formats sound like in FM, please try and help- I'm just very curious. The only 800+ MHz trunking systems I know of around here is the General Motors one and Lansing Public Services which are both DMR- this definitely isn't, and MPSCS, which this also isn't. I really do not know...

Edit: now that I am trying to hear more I am experiencing some sort of broadband interference across the entire 800 MHZ bands coming from across the parking lot :(

Edit 2: I have got the signal again and it sounds like it is something with TDMA
 
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dave3825

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Which freq? 851.475 or 851.4875? Either way, both are in use on Michigan's Public Safety Communications System (MPSCS)

475 is used on 9 different sites and 4875 is used on 10 sites

Go to the link and after the page loads, use your browser's find feature and search 851.475 and 851.4875 and see if any of the sites are near you.

Is it a constant sound or comes and goes? .
 

knockoffham

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Ingham County, MI, USA
Which freq? 851.475 or 851.4875? Either way, both are in use on Michigan's Public Safety Communications System (MPSCS)

475 is used on 9 different sites and 4875 is used on 10 sites

Go to the link and after the page loads, use your browser's find feature and search 851.475 and 851.4875 and see if any of the sites are near you.

Is it a constant sound or comes and goes? .
Both at the same time, so it seems like it might be 20/25 kHz wide. I looked at MSPCS and none of the sites using those are anywhere near me. It’s almost a full S-meter and that’s with an antenna tuned to a different band sitting on a window sill.

It comes and goes, but is very active. It sounds like a repeater output. Maybe it’s a telemetry signal, like a utility water meter or something?
 

knockoffham

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I took a couple videos if anyone knows what this is by ear. Some other ideas are maybe it’s a conventional P25 repeater on wheels being used for some reason? There are several businesses around here who operate on expired or no licenses but I feel that wouldn’t be the case for what sounds like a public safety system, especially because they’re all on MPSCS as of a couple years ago.


 

knockoffham

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If it's definitely P25, a 30 dollar sdr with dsdplus should give the details as well.
Ok. I will do that. However I’m moving a few miles away as of today (moving out of a college dorm) so hopefully I’m still in range. The only digital radio signal I can really identify by ear is DMR and that’s not it. Thanks
 

knockoffham

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Back in Williamston (about 10 miles away) I am still hearing it with like S7 signal strength, for probably about 10 seconds out of every minute with a crappy amateur radio and a mag mount antenna inside a bedroom on the floor. Still cannot find any nearby active licenses for the frequency
 
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