Topics

Airspy R2, Raspberry Pi3 2.500 MSPS #hardware #sdrsharp #spyserver #raspberrypi

adriaan_schep@...
 

Hello Airspy team,

i'm having a big "noise" problem on the Airspy R2:



This is every few seconds, and then it falls back to make some sort of WFM signal (see the waterfall) for a few seconds, and then all the small noise comes back. This is throughout ~110 up to 1000mhz as far as i've tested (not realy interested in >500mhz)

The airspy was a change from a RTL-SDR stick which worked wonderfully. Its connected to a Diamond N130 discone with Aircell 7 cable, and N connectors (sma>Nfemale from RTL-SDR.com connector kit). The strange thing is, if i connect the rtl-sdr stick no noise visible this big (altough some well known birdies from the internal clock generator).

 

The Airspy is connected to a Raspberry pi 3 running latest Airspy software (had problems getting it to work so reinstalled all, figured out just a simple "re insert" when pi was running fixed it for some reason) But now i'm seeing this noise throughout the whole RX band i've tested...

 

Can anybody help me figure out how to fix this? I thought the 12bit would mean better Signal/Noise. But it seems like its worse then a simple RTL-SDR stick....

prog
 

On Fri, Mar 9, 2018 at 08:22 am, <adriaan_schep@...> wrote:

Hello Airspy team,

i'm having a big "noise" problem on the Airspy R2:

[Image removed]

This is every few seconds, and then it falls back to make some sort of WFM signal (see the waterfall) for a few seconds, and then all the small noise comes back. This is throughout ~110 up to 1000mhz as far as i've tested (not realy interested in >500mhz)

The airspy was a change from a RTL-SDR stick which worked wonderfully. Its connected to a Diamond N130 discone with Aircell 7 cable, and N connectors (sma>Nfemale from RTL-SDR.com connector kit). The strange thing is, if i connect the rtl-sdr stick no noise visible this big (altough some well known birdies from the internal clock generator).

 

The Airspy is connected to a Raspberry pi 3 running latest Airspy software (had problems getting it to work so reinstalled all, figured out just a simple "re insert" when pi was running fixed it for some reason) But now i'm seeing this noise throughout the whole RX band i've tested...

 

Can anybody help me figure out how to fix this? I thought the 12bit would mean better Signal/Noise. But it seems like its worse then a simple RTL-SDR stick....

The 8 bit dongles have higher quantization noise (and IF noise figure) than the 12bit ones, so they don't "see" the problems you have in the RPi. You can observe that that the spurs are all below 60 dBFS which is the average SFDR of 8bit dongles. Also, the PSU noise can leak through the coax to the RF input, or travel to the antenna. In this case, a better RF hygiene will help a lot.
Possible solutions:
  • Cleaner PSU (Linear PSU's are the best)
  • Better USB cable with lots of ferrite chokes
  • Better coax with lots of ferrite chokes
  • Keep the antenna away from the sources of interference
  • All the above.