Need help indentifying/locating interference

[jeatock]

Need some help; I am chasing a source of interference on a Pike County Illinois Public Safety system frequency (151.130), and two adjacent frequencies.

Somewhere in NW Pike County, SE Adams or SW Brown (or points north) are fairly strong ‘rogue’ transmitters sending data bursts. Could be GPS position reporting or correction, or SCADA control data. Too short and regular for voice. One short second of “diesel engine noise”, sometimes repeating at random intervals, sometimes not at all. Seems to be more in the morning and early afternoon, and less as the day goes on. Sounds digital, but doesn’t decode as P25 or NXDN.

Omni-directional spectrum analysis shows three nice clean narrowband transmitters on 151.100, 151.115 and 151.130 at more or less the same time, not one wandering signal. Because of the brief and intermittent nature of the bursts, triangulation tracking has been tantalizing but fruitless.

The frequency range is allocated to PW-Highway. I have checked the FCC ULS database out to 200km. There are individual licensees on one of the three channels, but nobody authorized on all three. None of the licensed users that I don’t personally maintain have any idea. I have eliminated the regional water systems SCADA.

Anyone else run into this?

Any listeners that can help me out by reporting signals?

 

[gunmasternd]

I think your getting some kind of band opening.

 

[Starcom21]

Pike

I'll check my notes from a few weeks ago when I was in the area.

When I'm back in the area servicing Casey's stores in another couple weeks, I'll put those frequencies in and monitor those frequencies in the whole area I am in. I frequent the Casey's in Griggsville, Camp Point, Meredosia, and most to the East, North and South.

Just a quick think about those frequencies, they almost seem like MODOT possibilities.

 

[Starcom21]

OK, after a few months of scanning while working (traveling to Casey's in Pike/Cass/Brown/Adams/Morgan and many other Counties)

I have noted multiple NXDN transmissions, assumed bleedover, from Cass County's system. I have notes, I'll have to go though my whole notebook for the last 3 months, but will have to get it put together.

Some of the interference I got was just the scanner (or both scanners) just stopping on what seemed like a very narrow signal, that was often silent.

I have never heard anything for an extended period of time, except when literally in Cass County getting blasted by the signals.

I will update this more in the next few weeks, hopefully.

151.0075 Interference - Philadelphia (late July)
151.0025 Interference - Ashland (late june) [also heard on 155.0325, 152.6725]

(currently missing a month or more of notes)

So, in all reality, I don't think I found anything scanning on the road, or while in hotel at night. Just got some interference and some NXDN.

Terry

Need some help; I am chasing a source of interference on a Pike County Illinois Public Safety system frequency (151.130), and two adjacent frequencies.

Somewhere in NW Pike County, SE Adams or SW Brown (or points north) are fairly strong ‘rogue’ transmitters sending data bursts. Could be GPS position reporting or correction, or SCADA control data. Too short and regular for voice. One short second of “diesel engine noise”, sometimes repeating at random intervals, sometimes not at all. Seems to be more in the morning and early afternoon, and less as the day goes on. Sounds digital, but doesn’t decode as P25 or NXDN.

Omni-directional spectrum analysis shows three nice clean narrowband transmitters on 151.100, 151.115 and 151.130 at more or less the same time, not one wandering signal. Because of the brief and intermittent nature of the bursts, triangulation tracking has been tantalizing but fruitless.

 

[scanman1958]

I wonder if what you are hearing IS databurst info that could be related to water districts. I think there are a lot of them that send info over radiowaves with yagi's on all their pumping stations or water storage tanks. Just a theory.