- Sep 18, 2004
Same here. show us the recordings/pictures. Throw us a bone.
I agree entirely. To quote a famous detective: “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” - Sherlock Homes”Taking a very quick look I see the tower frequency shows full strength noise on your S-meter when no-one is transmitting. You'll have to find the reason for that as the radio looks like it's swamped with RF in that part of the band. Switch the radio to different modes - FM, WFM etc and see if there's any intelligence in that noise, music, voices, data and go on and search from there.
Second, the ATC transmitters may not be at the airport for the approach/departure frequencies. They may be at a remote radio site much higher up and/or closer to you. This would make sense if the same ATC frequencies are used for multiple airport terminal control activity. There are even mutiple sites at the SAME airport in many cases. We do that to separate main and standby radio from being affected by power or landline failures. Tower and ground frequencies may be running at lower RF power than IFR frequencies as well, but I can't say that's the case there obviously. Of course that would have no impact on how you hear the aircraft, that's strictly a distance, terrain, altitude and noise background related. 25km is quite a stretch for ground to ground reception with that terrain but it is possible - I have a similar situation here and can pretty much hear things at an airport about 25km south of me with a 120m rise in terrain not 4km away from me. The airport sits in a bit of a depression in the terrain atop that hill and is certainly not line of site for me in any way.
Your first task is to slowly (manually) run through the air band (and both sides of it) and watch the signal meter on the radio when there are no transmissions. If you have broadband noise that covers most of the band, especially the low end, then continue down the dial, as far as you can go, and see if there are and real hot spots in signal level. Do this WITHOUT any filters or preamps or other devices between the antenna and radio. You don't want that stuff influencing the result initially. If you see something curious it may be time to start powering off devices in your home (LED/CLF lights, dimmers, wireless devices of ANY type and anything that has a CPU of any type in it including telephones, routers, TV sets, cable/satellite boxes and so forth to start with). If you could a great starting point would be to power you radio from 12V DC battery and kill the power to your entire house. Then, if that changes nothing, take the radio mobile and scouring the area of a source. It could be very local to you and relatively low power, it could be industrial or even broadcast related. I've been involved with similar situations at work where factory machinery that uses RF energy loses it's shielding in a factory miles away which results in lumps of RF energy at differenet places in the spectrum. It doesn't take much, these radios are VERY sensitive. Once that's sorted the noise floor drops.
Keep me updated! My entire career was centered in part to almost exactly what you're chasing.