FlightAware Discussions

Reception impacted by wifi and usb on raspberry pi

I have a setup with a raspberry pi and a flightaware pro stick plus v1.0. I make recordings of the output available on localhost:30005 (beast output). The antenna is indoor in front of a window, so the number of aircraft seen is not very high. Over the last months, I noticed that the number of messages received is heavily impacted by at least two things:

  1. On my raspberry pi 3B, I originally wrote the data to an external hard disk (with its own power supply) connected to the raspberry pi. Later, I changed this to writing the data to the internal sd-card. The number of received messages increased dramatically.
  2. I changed the raspberry pi 3B to a 3B+. The rest of the setup remained the same (same dongle, antenna, etc). When I use wifi on the raspberry pi, the number of received messages is again much lower than when I disable wifi and only use cabled network.

I have no idea where the differences are coming from. It could be an EMC shielding problem, a data bus inside the raspberry pi suffering from saturation, or something else…

Are such differences normal? Can they be avoided?

A filter might help. Moving the antenna further away from switched mode power supplies and WiFi sources will also help.

in the case of a memory card, it seems to me that needed connect this RTLSDR receiver to a hub with external power.

The dongle used in the setup has a built-in filter. I’ll see if increasing the distance helps…

Placing the RPi lower than the antenna is not a bad idea. That way the pi is not in the main reception area of the antenna.

What type of antenna are you using? Cutting the small DVB-T whip antennas to size and adding a ground plane might also help with reducing interference.

Also if you are using the blue dongle, the LNA which is in front of the filter can also be overloaded by a strong wifi signal (RPi right next to it)

Thanks for this feedback. The antenna is the flightaware ads-b antenna.
Concerning your last remark, would it be better to connect the dongle via a usb cable, so that I can place it further away? (I have seen some websites claiming that a usb cable is also not ideal.)

Obviously leave the FA antenna as is :slight_smile: (i should have added that to the last post, only the small crappy antennas profit form such shenanigans)

How long is your coax cable?

As long as the antenna is oriented vertically and the RPi is a meter below it shouldn’t be a problem.
You can also place aluminium foil between the RPi and the antenna. Not too close to the antenna though. And don’t short anything on your Pi :wink:
You could cover a shoe box on 3 sides with aluminium foil and make a hole for the cable.
That way the Pi can’t interfere with the antenna and you should still get WiFi reception.

You can also check the connection of the FA antenna to the dongle. Sometimes happens the N connector of the cable has a wrong pin size to mate up with the antenna.
Also antenna position especially in a window can make big differences and it is not necessarily clear what position is best. (If the antenna is mounted at a high point with plenty of free space around the performance is easier to anticipate)

As a last point: The amount of traffic seen changes with the seasons and different days of the week, right now over christmas the traffic is down significantly.