Pulsing DTMF tones all over the spectrum?

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Joined: Fri Oct 16, 2020 2:05 pm

Pulsing DTMF tones all over the spectrum?

Post by Divarin » Fri Oct 16, 2020 2:26 pm

Hi. so I'd like to start off by saying I'm a newbie. I had two NooElec SDR units that came with a kit that I used when flying a cession 150 on a budget as a way to pick up ADSB signals and view them on an old android phone overlayed on a moving sectional map. As of a couple of years ago life happened and I no longer fly so I decided to plug in one of these units to my PC and play around with SDR.

One of the first things I noticed is that all over the spectrum I see these pulsing signals all pulsing at the same time and each pulse lasting for about 1.5 - 2 seconds:
tones.jpg (747.34 KiB) Viewed 1649 times
I tuned into some of them and they all sound like DTMF (like telephone touch tones, multiple tones.
tones2.jpg (761.49 KiB) Viewed 1649 times
I tried some googling and looking around on this forum and didn't see anyone else asking about this so I'm thinking it might be interference from something near my PC (or the PC itself) since my setup currently is kind of ... bad with just a little 5 inch telescoping antenna only a few feet away from the PC but it's strange that it's all over the spectrum no matter where I look.

Posts: 613
Joined: Sun Oct 09, 2016 7:27 am

Re: Pulsing DTMF tones all over the spectrum?

Post by Username » Tue Nov 10, 2020 9:26 pm

Where is the Antenna? Did you use a HW Amp?
Can you make a Picture of your setup?
Let me say it so to get a SDR Dongle to run good is need much €€€ to going into.

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