Buzzing but no AM signal

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Daniil
Posts: 2
Joined: Sat Feb 09, 2019 2:16 pm

Buzzing but no AM signal

Post by Daniil » Sat Feb 09, 2019 2:36 pm

Hello!

I'm trying to listen voice air band. I bought an RTL dongle, connect to it an antenna from old FM radio, and use an SDR#. SDR# installed as in instruction on site, drivers are installed successfully.
I can hear commercial FM stations, and audio track from UHF television channels, but when I try to listen air band (for example, 127.3MHz - ULLI (Pulkovo airport) ATIS, 10 kilometers from me) after I switching modulation to AM, I can see the signals, but can hear only buzzing. Same thing with 433 MHz diapazone - I can see the peaks of signal, but only buzzing are in headphones.

What's going on, how can I fix this? I can't even calibrate a dongle - I can't understand what station emits selected signal.
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SDR trouble 1.png
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jamesbond
Posts: 7
Joined: Sat Feb 09, 2019 2:10 am

Re: Buzzing but no AM signal

Post by jamesbond » Sun Feb 10, 2019 1:54 am

i find most of those spikes are interference from televisions or computer monitors, try leaving SDR running but turning your pc monitor off to see if there's a gap in the waterfall

rtlsdrblog
Site Admin
Posts: 2913
Joined: Mon Nov 19, 2012 11:54 pm

Re: Buzzing but no AM signal

Post by rtlsdrblog » Sun Feb 10, 2019 4:49 am

I'd recommend turning off RTL AGC first.

Those spikes are most likely noise from nearby electronics, those aren't actually airband signals.

If you haven't already, get your antenna outside, and with a good video towards the airport. That should help.

JEL
Posts: 186
Joined: Wed Feb 07, 2018 2:08 am

Re: Buzzing but no AM signal

Post by JEL » Sun Feb 10, 2019 6:33 am

Looks like noise to me too.

And your noise-floor at -30 dB seems very high, so a lot of the air-signals may be under that.

You should be able to get the noise-floor down to at least -60 dB.

Daniil
Posts: 2
Joined: Sat Feb 09, 2019 2:16 pm

Re: Buzzing but no AM signal

Post by Daniil » Sun Feb 17, 2019 9:13 am

Yes, that was noise from my secondary (old) monitor. I turned off monitor, use a good coaxial cable as antenna cable, and bring antenna far from PC to windowsill.
Now it's working fine. Thank you very much!

WIking030303
Posts: 1
Joined: Fri Apr 23, 2021 12:49 pm
Location: Sweden - southern part
Contact:

Re: Buzzing but no AM signal

Post by WIking030303 » Fri Apr 23, 2021 1:17 pm

Hi all, I'm new here and an amateur on sdr-radio. As an old private pilot (retired) I'd very much like to listen to the airbands.
I've got and installed the RTL-SDR.COM dongle with appropiate sowftware and can listen to commercial fm-radios bur when commin up to airband-voice no voice!!??
Please see enclosed screenshots and pse telle me what's wrong.

Best regards from the land of bears and mosse = Sweden
rtl-sdr.com-1.png
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rtl-sdr.com-2.png
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rtlsdrblog
Site Admin
Posts: 2913
Joined: Mon Nov 19, 2012 11:54 pm

Re: Buzzing but no AM signal

Post by rtlsdrblog » Mon May 10, 2021 2:25 am

WIking030303 wrote:
Fri Apr 23, 2021 1:17 pm
Hi all, I'm new here and an amateur on sdr-radio. As an old private pilot (retired) I'd very much like to listen to the airbands.
I've got and installed the RTL-SDR.COM dongle with appropiate sowftware and can listen to commercial fm-radios bur when commin up to airband-voice no voice!!??
Please see enclosed screenshots and pse telle me what's wrong.

Best regards from the land of bears and mosse = Swedenrtl-sdr.com-1.pngrtl-sdr.com-2.png
Gain increased, and appropriate outdoor antenna being used?

radiolistener
Posts: 84
Joined: Thu Jan 25, 2018 10:48 pm

Re: Buzzing but no AM signal

Post by radiolistener » Sat May 15, 2021 8:34 pm

WIking030303 wrote:
Fri Apr 23, 2021 1:17 pm
As an old private pilot (retired) I'd very much like to listen to the airbands.
I've got and installed the RTL-SDR.COM dongle with appropiate sowftware and can listen to commercial fm-radios bur when commin up to airband-voice no voice!!??
First, air band radio works with AM modulation, but you're using WFM. You cannot receive it with WFM.

The second, air band transmitters not so powerful like FM stations. So it may needs good antenna, preselector bandpass filter and LNA. But you can experiment by change gain manually.

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