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Noob question: RTL-SDR as noise source

Noob question: RTL-SDR as noise source submitted by /u/EmirMore
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Troubleshooting Help • FM broadcast mirrored to different bands — fault?

Hi everyone!
I'm new to SDR and the RTL-SDR particularly. I've just received my RTV-SDR v3 dongle and started playing with it.
The first thing I noticed is the strange behavior at different bands when strong signals appear to be mirrored to different frequencies. But when I change tuning of the receiver by shifting the whole spectrum in SDR# these mirrored signals move to different frequencies.
I noticed this behavior in CB, HAM, 800 MHz, 900 MHz, 2400MHz band etc.

For example,
I can see FM broadcast stations by tuning to about 27MZh (see the attached Screenshot 1). I'm able to listen to the FM stations by moving the cursor to the corresponding frequencies and selecting WFM.
The really strange thing happens when I change tuning of the receiver by moving the whole spectrum to the left or to the right. The mirrored ghost FM broadcast stations move to different frequencies (see Screenshot 3 and Screenshot 4).

The same thing happens in different bands mentioned above. I get ghost signals (not from FM stations but from digital stuff in the higher bands) that change frequencies corresponding to tuning of the receiver.

Is that faulty hardware or is it that the expected behavior?
Can it be something wrong with the mixer,filters etc?
1_c.png

3_c.png

4_c.png

Statistics: Posted by Na svyazi — Sun Nov 11, 2018 10:23 pm


Comment on AERO C-Channel Voice Audio Now Decodable with JAERO by Joe Blasco

the RF power drops on the channel after initial contact to save power to the satellite. As for the channel overlapping you need a better antenna like a dish with a feed, in that way one signal (the beam that is geographically nearer to you) will be inevitably stronger thus more distinguishable from the other.

Comment on AERO C-Channel Voice Audio Now Decodable with JAERO by CE3SNA

Yes, I don’t get a 100% decode here. I noticed all the features mentioned by Jontio: sporadic transmissions in a number of adjacent channels, with variable power, sometimes the transmission seem to overlap preventing JAERO from getting a lock or decode. However, when I lock on an isolated high-power tx, I get audio decoded. Perhaps a better antenna or orientation could help.

Comment on Buy RTL-SDR Dongles (RTL2832U) by Andy

Hi,
I am looking for a directional antenna I can use and carry with me. I want to chase RFI, EMI in and around my house so I can figure out what it is and eliminate it. I want to do this with laptop, small USB SDR. But need some directivity. Would the dipole that comes with the dongle work reasonably well to get some directivity? I would think, but wnated to check with others…

Comment on AERO C-Channel Voice Audio Now Decodable with JAERO by Ronald van der Meer

Very good indeed ,thank you

Comment on AERO C-Channel Voice Audio Now Decodable with JAERO by @freemonotoring

Yes, audio ok for me with patch antenna on lband. Not easy because very short audio log.

Всем доброго времени суток! Подскажите, какие спутники ДЗЗ в 2м и 70см…

Всем доброго времени суток! Подскажите, какие спутники ДЗЗ в 2м и 70см диапазонах можно принять, используя обычный SDR свисток с китайским усилителем, и декодировать?

Beginner questions about sat list and tracks

I'm very new to this, I have a good understanding of Satellite theory and comms, but receiving a NOAA or GOES image seems to have a steep learning curve.
Therefore I have a few questions.

  1. Where can I find a tracks or a list of weather sats and there freqs that cover Western Australia or what there foot prints are.
  2. I have a RTL-SDR and am using Windows with Airspy (sdrsharp), and have looked at a few antenna guides so I guess is it best to cut you antenna to the perfect length for the frequency or is the dongle smart enough to filter out the others?
  3. Once I get receive signal from the sat how to I move that traffic to a decoder to turning into images, is it an app or a python script that does the decoding?

Thank you in advance, and forgive me if I asked so pearlers.

submitted by /u/for3stau
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Periodic signal at ~156.0 MHz — what might it be?

Periodic signal at ~156.0 MHz - what might it be? submitted by /u/MartyMacGyver
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