I have an airspy R2 that is recieving a ton of garbage that none of my other SDRs can see with the same antenna. It looks like an actual signal based on its consistency, but i cannot see it on any other sdr. Ive also never seen anything like it in that frequency range. The unknown signal is sitting right below my counties P25 Simulcast frequencies in the 770MHz range.
Airspy R2 noise issue / interference
- Thread starter hruskacha
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wgbecks
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A quick glance at your waterfall suggests its DTV. I am guessing that your R2 is set to 10 MSPS and you may have to reduce the sampling rate if these signals are overloading the SDR and causing decoding issues with your P25 system.
However, if this is causing decoding issues, then I would first try to run the R2 in Free or Custom Gain Mode if your SDR Software allows this configuration. Doing so will enable you to disable the AGC gain functions and be able to LNA, MIXER and IF gains independently that may be enough to abate the interference while still being able to decode the P25 system. Otherwise, if this doesn't work, they you'll have to reduce the sampling rate to get rid of it.
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Nope. This is one of the bands used for phones (Verizon LTE4 is one user here). It looks just like that here as it should. All my receivers see similar--this includes Airspy. HackRF1, Icom R8600, and Icom R9500. The questions is why do his other receivers not see it.
Note also that digital TV will have a pilot carrier looking like spike in the spectrum 1.25 MHz above the lower end of its spectrum.
wgbecks
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The OP didn't list what his other SDR's are. SO, it's all dependent upon the sampling (bandwidth) rate of the SDR and the software applications ability to process the available spectrum. He's not going to see the Verizon stuff or whatever is operating below the 700 MHz public safety
band with an RTL SDR tuned up spectrum.
Often times narrower bandwidth is desirable if your application tunes the SDR to a specific frequency in following conversations on a trunked radio system. However, if you're running a program like SDRTrunk, then you need wideband devices or a couple of narrower banded devices to be able to ingest the required spectrum in use by any given system.
band with an RTL SDR tuned up spectrum.
Often times narrower bandwidth is desirable if your application tunes the SDR to a specific frequency in following conversations on a trunked radio system. However, if you're running a program like SDRTrunk, then you need wideband devices or a couple of narrower banded devices to be able to ingest the required spectrum in use by any given system.
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I agree he may not see it with an SDR tuned too narrow looking at the same range but assume that he did not do that and did look at the correct spectrum range with them--may be not. That was the reason for that part of my post, for him to resolve why he did not.
You are correct. I did not see the signal with my other SDR's because their bandwidth is ~1.92MHz and the Airspy R2 is 10MHz, so I simply didnt notice it. The signal is actually a signal too, not sure for what, but its next to my counties P25 frequencies and I simply didn't ever notice. The waterfall on SDRTrunk made the signal look really funky, that why I suspected noise and interference.
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As I noted, it is one of the phone call services. At my location, Verizon is a user in that spectrum and I get a similar waterfall here. That is how the waterfall looks for them, Yes, they are near 700 MHz P25 frequencies as are 800 MHz P25 near 800 MHz phone frequencies. Phone services use spectrum various ranges including that one in the U.S. Of course phone services also are up in the GHz range which a scanner will not cover (your SDR may see them in the 1.7 GHz range).
Here is one place to see frequencies
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