Noise from USB cable?

FlightAware ADS-B Flight Tracking
1

In an attempt to add dump978, I placed a USB extension cable between my Pro Stick Plus and Pi3 as the width of the Pro Stick Plus blocks the other USB ports on the Pi. A day later I noticed a dramatic drop in messages received, from 409k down to 265k (messages per second dropped from ~350 to sub 200). Looking at the Signal Level graph I can see the noise change from -18 to -13 at the same time frame.
Is this to be expected with USB extension cables, or did I just get a bad cable? Any recommendations on a good cable? Would love to add 978 as there is a parachute school close by, plus some small airports.

PS Having a lot of fun with this, even with the FA antenna just in the loft I see ~1400 planes per day. The kids enjoy seeing the planes as the approach us on the map, and then hear them fly over head. And we’ve picked up the occasional helicopter (medivac and news), and military transport plane bound for Europe.

edit My setup is: 26"FA antenna, N-Male to SMA-Male Wi-Fi Adapter, Pro Stick Plus, directly plugged in a Pi3 running the adsbreceiver.net 2.5 release (gain at default of -10), all hanging from a string in my loft/attic.

2

What length of extension cable and is it wood quality?

The more usual problem would be one of getting sufficient power to the pro Plus stick.

3

Morning Peter,
It is a 3.3ft / 1m made for Amazon - so not pushing the limits of USB for signal length or power delivery.
Thx

4

You could try putting some ferrites on the USB cable and see if it changes anything. en.wikipedia.org/wiki/Ferrite_bead

5

I’m using a 9.8 ft Amazon USB 3 extension cable coiled next to the RPi right now with no issues. However, I had it mounted in vertical line on my tower and I had a similar experience. The other variable was a cable adapter at my antenna. I have not run more tests yet but the USB cable works fine coiled on the floor of my storeroom.

6

Thanks obj, I’ll look into them.

Thanks for the data point zeek70706 - maybe the USB3 cables have better sheilding.

7

I actually tried place beads on both ends of a 10 foot USB cable and noticed no difference. I also placed a bead on the low voltage side of the power supply.

I’ll try removing the USB cable and see if it improves things.

8

I use decent quality USB3 cables, only 6", (hoping it would be better shielded) with ferrites and have a metal case on the RPI (again to try to reduce noise). I also put the dongle itself in a metal case from rtl-sdr.com.

9

Did the metal case on the Pi and dongle help? Also, what decent quality USB3 cable did you use? I’m not seeing many 6" ones, and I’m not seeing any brand-names I recognize. Thx

10

I just used these USB 3.0 cables. They got reasonable ratings on Amazon.
amazon.com/gp/product/B00S2 … UTF8&psc=1

I am not sure how well the metal cases worked. I have heard of fitting issues with the plastic cases being a little to long and not fully fitting into the USB port.
You can cut them down with an razor or sharp knife.

11

Thanks jonhawkes2030, I’ll add one of those short cables to my cart.