Why USB cable quality matters

Several RTL SDR dongles, accessories and most higher-class SDRs use an USB cable to connect receiver to computer.
Every cable is the same, right? No.
Click or tap images for full-screen view, differences will not be apparent on a small display.
Subscribe on Twitter @rtlsdr4everyone or by clicking on blue button (top left) to get the latest updates.

Two cables with same RTL-SDR dongle, waterfall changes:

Only RTL-SDR dongles? No, SDRplay RSP2, only cables swapped:

Receiver in same location during testing, 1 metres away, but I had to move laptop closer to be able to use the 0.3m cable.

USB hubs, ferrites, chanting medieval prayers

Did several tests, and adding ferrites to USB cable did not hurt. USB hubs were temperamental, had 0.3 dB better performance with one, worse performance with other, then roles and figures changed in a different location, so it's not a clear-cut case of this or that is better.
Listening to medieval music helps a lot, primarily to lower your blood pressure level and to relieve frustration.
Final advice is: see a compatible cable, buy it. Impossible to know, or recommend one, get as may cables as you can, then test actual reception performance.
Length, diameter, ferrites, make or model will not guarantee excellence.


  1. I found the most important aspect of a USB cable was length. I was picking up a LOT of noise from my laptop, and just putting a 15m USB cable on it to get the RTL-SDR away helped tremendously. My noise floor dropped -30dB compared to a short 18 inch USB cable, and even more compared to plugging the RTL-SDR directly into my laptop.

  2. No he could be corect. I tryed it with a 50 foot 15.24 meters amplified USB CABLE and on my chep dongle it works better less QRM.