FlightAware Discussions

Not sure if I have a dead antenna

So I upgraded my piaware today to v5 then while checking if all was ok, I noticed it was not picking up any aircraft around me, while my other PI was.

Is there a way to check if an antenna has died?

If it matters I have a flightaware antenna and it lived indoors all of its life.

Looking at the graphs for my feeders it looks like something may have happened on the 20th of February.


An antenna is unlikely to have issues as it’s a passive device, no active electronics.
There can be water ingress into the coax or the antenna but not indoors.

It’s likely that either the SDR is going bad or that the power supply is bad.

If you get no output for this command the power supply is likely not the issue:

sudo dmesg --ctime | grep voltage

So … most likely is that the SDR isn’t working properly anymore.

He has a couple of feeds that have become sick at the same time.
https://uk.flightaware.com/adsb/stats/user/gaz492

Other sites in the area didn’t show the same drop in traffic.

I don’t know if it a shared antenna, but he must be using two SDR dongles.

Water in the coax or connector? Did a storm go through around the time of the downturn? Also, same have had water in the FA antenna.

It could also be noise. I have a setup in a bedroom that drops about 25% when the TV is on. Any new cell towers close by?

Yea, no messages came back from running that command.

I’ll swap the receivers around tomorrow and see if the results are the same.
I don’t think I changed any settings on either of them on the 20th either.

Try running only one of the receivers without a splitter.

It’s not impossible that one bad SDR would send noise to the other via the splitter.
Unless it’s a really good splitter.

And yeah it could be a new interference source, you don’t happen to have a filter handy?

Indoor? Pretty unlikely

Any 5G upgrades next to you, new installations? I suffer bad from one at 1100mhz, all though that’s been there all the time for me.

LED lamps and HDMI have been discussed recently regarding wide-band noise.

The dongle can receive RF signals (and noise) in the range of about 24 MHz ~ 1800 Mhz.

To check noise picked by antenna in this range, unplug your dongle from RPi, plug into a Windows computer (with antenna connected to dongle) and run following scan:

Spektrum - How-to Speedily Scan RF Noise in band 24MHz ~ 1800MHz

 

Below are scans at my urban location with lot of Cell/mobile antennas on top of my building and adjuscent buildings, as well as many strong TV & FM stations.

Scan 1 of 3 - FA Antenna + Generic DVB-T (no internal or external filter)

Thumb-Generic DVB-T
CLICK ON IMAGE TO SEE LARGER SIZE

Scan 2 of 3 - FA Antenna + ProStick Plus (Only Internal filter of ProStick Plus. No External filter)

image
CLICK ON IMAGE TO SEE LARGER SIZE

Scan 3 of 3 - FA Antenna + ProStick Plus (with internal filter) + External Filter (FA Light Blue)

imageimage
CLICK ON IMAGE TO SEE LARGER SIZE

 

sorry, was just thinking outside the box…

Just to give an update, its indeed not the antenna but possibly noise from something near by.
Here are 2 scans I did the top one with out an FA filter and the bottom with the FA filter.

The filter did help a little bit, I also went over the logs I keep and I did run the update and restart Piaware command from the FA website on that day but I don’t have any detailed info if the drop was before or after I ran the update as I did not have any graphs setup.

Anyway, I’m slowly tuneing the gain back to where its optimal again and will eventually move the antenna to a shed outside (waiting on a solar panel kit and some batteries to arrive)

An extra update, I ended up replacing the USB hub I used to power the PI and the PI itself and this resolved the rest of the issues I was having.
Based off the USB power meter I used, the power supply was very inconsistent and this is just a guess was also being a little noisy.

Time to buy a some spare PIs incase this happens again :stuck_out_tongue:

Ripple … hard to detect with a voltmeter but the pi still doesn’t like it.