USB cable quality and QRM in a spyserver setup with an Airspy Hf+ and Raspberry PI3. 6 microUSB cable test. #airspyhfplus #bestpractice #raspberrypi

ea5ehs@...
 

Last February I got surprised for the QRM emitted from USB cables at the remote RX site when performing the initial setup of the SDR.

In the remote RX site, I replaced the nice working Red Pitaya SDR (Soft from Pavel Demin) with the Airspy HF3 + Raspberry PI 3B configured as a spyserver.

I soon discovered a really bad noise floor and began checking with my Swiss army tool "Tecsun PL600".
RF emission in VHF/HF from the RPi3, SDR, and cables was unacceptable. The culprit was traced to the USB cable connecting between the Rpi3 and the Airspy HF+. 
Using all the USB cables available on the site and my car, I improvised a USB cable comparison test in HF and VHF whose results can be found attached to this post ( 3.2MB pdf file, I have never published before). 

This is an unscientific test because it was improvised, please don't blame me for any inconsistency in the results. I had to quit testing after 2 hours because I couldn't cope with the cold and windy conditions (QTH is 950m ASL).
Conclusion: Good quality USB cables are a must in RX QTH.

I wish this can be useful and/or inspiration to others.

My best 73 all
from Niceto
EA5ZL

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