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?
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?