teufler
Member
Got a request to check out some interence a local hospital is getting on their paging network.
Theirs is a two part system. They transmit a signal on 75.5 mhz and this is relayed on 152.24 mhz. The problem is they are getting another signal on 75.5 mhz that creates garbled pages.
I listen to 75.5 mhz and I can get a signal from 97.1 fm talk radio. I have logged and recorded interference from about 75.35 to 75.650. Using Freescan, log indicates RSSI 568 till it drops off to nothing. This is a 2-3 bar signal on the scanner.. 97.1 I get a high 8+ reading, 5 bars on a 396xt scanner. Now when the mode was nbfm, the interference was just "burps, chirps, scatchy audio. I then tried fm, and wbfm and finally bfm. By the time I get to broadcast fm, the audio is perfectly readible . Since the interference was 21.6 mhz lower than the 97.1 main transmission, I checked 97.1 + 21.6 and got nothing. I checked some other stations in the area , 21.6 lower than the main transmitter and got nothing. I df'ed with a beam, made for 145.00 but it still indicated a direction that indicated the signal direction. When compared with Google earth maps, and the FCC lat long of 97.1, , I had indications of the approximate direction..
Could others in the St. Louis area check , from their locations, are they getting audio on 75.5 fmb mode and post what kind of readings they get.
Theirs is a two part system. They transmit a signal on 75.5 mhz and this is relayed on 152.24 mhz. The problem is they are getting another signal on 75.5 mhz that creates garbled pages.
I listen to 75.5 mhz and I can get a signal from 97.1 fm talk radio. I have logged and recorded interference from about 75.35 to 75.650. Using Freescan, log indicates RSSI 568 till it drops off to nothing. This is a 2-3 bar signal on the scanner.. 97.1 I get a high 8+ reading, 5 bars on a 396xt scanner. Now when the mode was nbfm, the interference was just "burps, chirps, scatchy audio. I then tried fm, and wbfm and finally bfm. By the time I get to broadcast fm, the audio is perfectly readible . Since the interference was 21.6 mhz lower than the 97.1 main transmission, I checked 97.1 + 21.6 and got nothing. I checked some other stations in the area , 21.6 lower than the main transmitter and got nothing. I df'ed with a beam, made for 145.00 but it still indicated a direction that indicated the signal direction. When compared with Google earth maps, and the FCC lat long of 97.1, , I had indications of the approximate direction..
Could others in the St. Louis area check , from their locations, are they getting audio on 75.5 fmb mode and post what kind of readings they get.