ACARS sound in background

[KevinC]

I have been scanning airplanes for 60 years and never had the problem and I can hear both the controllers and the planes at the Lexington airport which has tower (119.1), ground (121.9) and approach/departure (120.15 and 120.75), so one quick question, have you tried going to different locations with your ICOM R30 to see if the problem follows you? In other words, if you are 4 miles east of the airport, do you have the problem 4 miles west of the airport, or 8 miles south of the airport?

And yes, I have just about every kind of scanner and receiver (R30, R15, AOR8200/8600, Uniden, crystal scanners, etc).

That's a good suggestion, but unfortunately due to health issues with my wife I'm unable to go very far from the house, plus I can go hours without hearing it so it would be difficult to tell if it just wasn't happening or changing locations resolved it. Thanks for the suggestion though!

 

[DudleyG]

Another thought - There is a VOR Locator Beacon about 1/3 of a mile from my house, it transmits constant "beep - beep" signals on a frequency of 112.6, but that doesn't cause me any problems. Is there by any chance a VOR Locator Beacon within a mile or so of your house? Many of the beacons are located near airports to help planes find the airport, especially if the plane is not equipped with GPS capability. It might be on a harmonic frequency that by adding 10.7 gets you to the frequency of the tower or ground. If the beacon signal is weak at your house, it wouldn't break the squelch until a real transmission from the tower or airplane was active.

The VOR Locator Beacon frequencies are 108.00 thru 117.90.

 

[AirScan]

For all it's worth before I retired from flying the B737 I would hear this occasionally on the aircraft while monitoring ATC frequencies. It usually happened on the ground when near the terminal so I just asssumed it was bleed over interference from being so close to the ACARS transmitters. I have also heard it on some LiveATC feeds from radios that are located at an airport.

As mentioned above I suspect it's related to your relatively close proximity to the airport. Any chance you can name the airport and we can check the ACARS frequency specs on the FCC website. Maybe it's from an ACARS transmitter off airport closer to your location ? If you monitor an actual ACARS frequency (try 131.550) how loud/strong are you hearing the transmissions ? Or better yet try decoding ACARS and see if you are able to receive the ground station.

 

[KevinC]

Another thought - There is a VOR Locator Beacon about 1/3 of a mile from my house, it transmits constant "beep - beep" signals on a frequency of 112.6, but that doesn't cause me any problems. Is there by any chance a VOR Locator Beacon within a mile or so of your house? Many of the beacons are located near airports to help planes find the airport, especially if the plane is not equipped with GPS capability. It might be on a harmonic frequency that by adding 10.7 gets you to the frequency of the tower or ground. If the beacon signal is weak at your house, it wouldn't break the squelch until a real transmission from the tower or airplane was active.

The VOR Locator Beacon frequencies are 108.00 thru 117.90.

The 10.7 idea would work if anything I was using is dual-conversion, but everything is triple. And no VOR anywhere near me, the closest is around 30 miles away.

 

[eorange]

Another thought - There is a VOR Locator Beacon about 1/3 of a mile from my house, it transmits constant "beep - beep" signals on a frequency of 112.6, but that doesn't cause me any problems. Is there by any chance a VOR Locator Beacon within a mile or so of your house? Many of the beacons are located near airports to help planes find the airport, especially if the plane is not equipped with GPS capability. It might be on a harmonic frequency that by adding 10.7 gets you to the frequency of the tower or ground. If the beacon signal is weak at your house, it wouldn't break the squelch until a real transmission from the tower or airplane was active.

The VOR Locator Beacon frequencies are 108.00 thru 117.90.

Purely FYI: I can hear a local VOR locator beacon on 111.1 and I occasionally listen to ACARS (because I built a rPi solution that decodes and displays ACARS messages) and I also listen to that local airport's airplane and tower comms. None of these transmissions have ever mixed in my listening.

I'm not shooting down your suggestion by any means; just relaying my experiences with a non typical trifecta of airband transmissions lol.

 

[KevinC]

I think I'm going mark this as one of the mysteries of the universe for now. If I could get oot and aboot I'd confirm if I hear it at other locations, but unfortunately I can't.

I'll do some research to see if an ACARS transmitter is at that airport, but even if it is the tallest structure there is less than 100' AGL and I'd imagine ACARS would use a zero gain antenna, so at a little over 4 miles away I can't see it causing an issue internal to me.

Thanks for all the suggestions and opinions!

 

[kc2asb]

I think I'm going mark this as one of the mysteries of the universe for now. If I could get oot and aboot I'd confirm if I hear it at other locations, but unfortunately I can't.

I'll do some research to see if an ACARS transmitter is at that airport, but even if it is the tallest structure there is less than 100' AGL and I'd imagine ACARS would use a zero gain antenna, so at a little over 4 miles away I can't see it causing an issue internal to me.

Thanks for all the suggestions and opinions!

I doubt it's an internal issue to you.

I'm 2 miles away as the crow flies from Newark Inter'l Airport and have been listening to aviation as long as I've been in the hobby, almost 40 years. I've never heard ACARS on the aircraft or tower side of a transmission. I've used a wide variety of receivers over the years, and currently, a BCT-15X, BC-780XLT, 996T, and 996P2 and have never experienced issues with overload/mixing on aviation freqs.

 

[eorange]

I think I'm going mark this as one of the mysteries of the universe for now. If I could get oot and aboot I'd confirm if I hear it at other locations, but unfortunately I can't.

I'll do some research to see if an ACARS transmitter is at that airport, but even if it is the tallest structure there is less than 100' AGL and I'd imagine ACARS would use a zero gain antenna, so at a little over 4 miles away I can't see it causing an issue internal to me.

Thanks for all the suggestions and opinions!

Can you go buy the Alinco DJ-X100 and see if you can decode the ACARS signal, not for your benefit but really for us to satisfy our curiosity?😀

 

[KevinC]

Can you go buy the Alinco DJ-X100 and see if you can decode the ACARS signal, not for your benefit but really for us to satisfy our curiosity?😀

Sure! Shoot me the funds and I'll do almost anything...almost.

 

[Ubbe]

lots of times a hear a "digital" noise in with both the tower and ground transmissions.

Then it has to be a local RF issue happening to you, as that would be unacceptable and airline pilots would be complaining if critical communications from the tower are compromised.

/Ubbe

 

[Ubbe]

I checked my SDS100 using 131.525MHz from a signal generator, one of the ACARS ones, at -70dBm. It received the signal at 8 different frequencies from 131.075 up to 136.325 and half of them didn't change when applying IFX to them. I couldn't detect any interference when listening at lower frequencies.

AM modulation allows two signals to be heard as the signals just add to each other and are the reason why they use AM as the tower will still be able to hear a transmission even if another aircraft transmits at the same time. So any ACARS signal that can be heard at another frequency where there are voice communication will simply be mixed together and not as it is with FM that you only hear one transmission at best but usually only a squealing interference tone will be heard.

/Ubbe