cable related issues for AIS reception?

[bjo81]

Hi,
I'm running a Pi 3B (https://aiscatcher.org/station/2421) with 2 Nooelec NESDR SMArt v5 dongles. The dongles are directly connected to the Pi, but somehow the connections are loose. But when it runs, I'll get 0.7msg/s to 1.5msg/s in ais-catcher. For some improvement, I got 2 30cm USB3 cables and attached them between the dongles and the Pi. While one dongle runs fine for ADSB, the dongle used for AIS dropped to 0.1msg/s / 0.2msg/s. Somebody told me the issue could be power related, but also when I attach the AIS-dongle directly into the Pi and the ADSB-dongle is connected via cable nearby, the issue persists. Does somebody has a clue why this happens? Does the cable disturb the AIS reception? (The cables are from a german shop in ebay, no AliExpress-stuff).

[jvde-github]

Hi, good systematic testing. So poor performance with 30cm for AIS only and two dongles with ADSB on 30cm and AIS directly connected.
So, the issue does not occur if both USB sticks are directly connected (and it is not loose)?

Not an expert in this area. But your cables are might be causing interference. The 30cm cable might be close to a fraction of the wavelength (30 cm is approximately 300/162 / 6 or 1/6th of the wavelength). Perhaps a shorter cable would help. I would check if it makes a difference if you are not using the USB 3 ports. Another possible solution might be to add ferrite beads to the cables?

Perhaps other folks have a suggestion.

ps I am glad I am not the only one with issues with these loose connections.

[bjo81]

Yes, the issue doesn't appear when directly connected. I tried also 2 USB2.0 20cm cables, but the issue also existed, and I read that USB 3.0 cables would be better shielded. I've ordered now some ferrite beads and hope they will improve the situation.