- Joined
- Aug 19, 2004
- Messages
- 133
For the past few weeks while scanning the UofA PD primary dispatch frequency on 460.375 MHz, my PRO-97 has been latching onto a pulsing signal that's about 1/2 second in length, every 3 seconds.
Using a better receiver that is all mode (AM/USB/LSB/FM), I have found that the actual pulsing signal is about 460.390 MHz. (The PRO-97 is kind of broad, so that would make sense...)
I started tuning the 460 MHz band by hand using USB, and I find the signal repeats itself (sort of--more on that later) at the following frequencies. (The FM frequency is where it is strongest on FM, the USB frequency is where it "sounds right" for a single-sideband signal).
FM............................USB
460.410...................460.411
460.390...................460.386
460.335...................460.336
460.310...................460.311
460.260...................460.261
I find, though, that by tuning two receivers to two of the different frequencies, that the frequencies pulse ("light up") at slightly different times, so it's not as though the frequencies are all related to a single fundamental frequency and its images.
I do not recall hearing this weeks ago, but it has been solid ever since.
In FM, it sounds like a carrier pulse, but in SSB, it sounds more like a packet (AX.25) burst. And once last night, while driving around Fayetteville looking for it, one of the bursts was of longer duration, and it was clearly sending some intelligence.
I tried driving around an DF'ing it with a 10-element 70cm yagi, but I think being 10+ MHz off resonance made it a tough act. I _think_ I isolated it to the Garland and North Street area, but I'm far from sure, and got a good signal on North just west of College, too. I went up on Mt Sequoyah, and results there suggested very much it was in that Garland/North streets region.
Can anyone else hear it? Any thoughts?
Thanks.
Bernie
Elkins
Using a better receiver that is all mode (AM/USB/LSB/FM), I have found that the actual pulsing signal is about 460.390 MHz. (The PRO-97 is kind of broad, so that would make sense...)
I started tuning the 460 MHz band by hand using USB, and I find the signal repeats itself (sort of--more on that later) at the following frequencies. (The FM frequency is where it is strongest on FM, the USB frequency is where it "sounds right" for a single-sideband signal).
FM............................USB
460.410...................460.411
460.390...................460.386
460.335...................460.336
460.310...................460.311
460.260...................460.261
I find, though, that by tuning two receivers to two of the different frequencies, that the frequencies pulse ("light up") at slightly different times, so it's not as though the frequencies are all related to a single fundamental frequency and its images.
I do not recall hearing this weeks ago, but it has been solid ever since.
In FM, it sounds like a carrier pulse, but in SSB, it sounds more like a packet (AX.25) burst. And once last night, while driving around Fayetteville looking for it, one of the bursts was of longer duration, and it was clearly sending some intelligence.
I tried driving around an DF'ing it with a 10-element 70cm yagi, but I think being 10+ MHz off resonance made it a tough act. I _think_ I isolated it to the Garland and North Street area, but I'm far from sure, and got a good signal on North just west of College, too. I went up on Mt Sequoyah, and results there suggested very much it was in that Garland/North streets region.
Can anyone else hear it? Any thoughts?
Thanks.
Bernie
Elkins
) and the interference is crippling. Not only is it causing broadband RFI in the 460 range, but it is desensing my scanners when it pulses on, such that the Fayetteville 800 MHz system gets wiped out in my 396 when the noise pulses.
