FlightAware Discussions

Sudden Loss Of Reception Range

Over the last day i have suffered a sudden loss of receiver range, going from around 190+ miles to only receiving signals that are almost line of sight.

I have tried a reboot then ran sudo bash -c "$(wget -nv -O - https://raw.githubusercontent.com/wiedehopf/adsb-scripts/master/rtl_test.sh)"
and this was the output;

Found 1 device(s):
0: Realtek, RTL2832U, SN: 00001000

Using device 0: Generic RTL2832U
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
[R82XX] PLL not locked!
Sampling at 2400000 S/s.

Info: This tool will continuously read from the device, and report if
samples get lost. If you observe no further output, everything is fine.

Reading samples in async mode…
Allocating 15 zero-copy buffers
lost at least 4 bytes
Signal caught, exiting!

User cancel, exiting…
Samples per million lost (minimum): 0

Test finished!
More than 2 lost samples per million or other errors probably mean the receiver isn’t working correctly.
Try another power supply before condemning the receiver though!


No undervoltage detected, looking fine!
If the dongle is not directly plugged into the Raspberry Pi, lack of power/voltage could still be an issue.
Even without detected undervoltage a better power supply can often improve reception!
For optimum performance i would recommend the Official Raspberry Pi power supply.

I then ran sudo systemctl status dump-fa -I

sudo systemctl status dump1090-fa -l
● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2020-05-13 15:42:08 BST; 7min ago
Docs: https://flightaware.com/adsb/piaware/
Main PID: 5297 (dump1090-fa)
Tasks: 3 (limit: 2200)
Memory: 4.3M
CGroup: /system.slice/dump1090-fa.service
└─5297 /usr/bin/dump1090-fa --device-index 0 --gain -10 --ppm 0 --lat 56.61 --lon -2.81 --max-range 360 --net --net-heartbeat 60 --net-ro-size 1300 --net-ro-

May 13 15:42:08 raspberrypi systemd[1]: Started dump1090 ADS-B receiver (FlightAware customization).
May 13 15:42:08 raspberrypi dump1090-fa[5297]: Wed May 13 15:42:08 2020 BST dump1090-fa 3.8.1 starting up.
May 13 15:42:08 raspberrypi dump1090-fa[5297]: rtlsdr: using device #0: Generic RTL2832U (Realtek, RTL2832U, SN 00001000)
May 13 15:42:08 raspberrypi dump1090-fa[5297]: Found Rafael Micro R820T tuner
May 13 15:42:08 raspberrypi dump1090-fa[5297]: rtlsdr: enabling tuner AGC
May 13 15:42:08 raspberrypi dump1090-fa[5297]: Allocating 4 zero-copy buffers

I have attached screenshot of signal output from Graphs1090 (I amy only allowed to upload one image) and my gut feeling is there is perhaps a hardware issue?

Traffic volumes have certainly dropped, but it appears the receiver range has dropped to line of sight.

The hardware is around 5 years old and whilst it’s not run 24/7, it’s on a lot. The small FlightAware amber light on the dongle no longer works etc.

RSSI ratings are rarely below -15, where they would often within single figures, close to 0.

And advice wold be greatly appreciated! image_10618

image_10617
A copy of the receiver range graph around the reduction in range.

If you may, please tell us more about the antenna and its placement, the coax cable running to it, and what waterproofing material was used on the exposed coax connections.

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The system is housed indoors. The antenna is a 1090Mhz ADS-B antenna 66cm from FlightAware with a N Male to SMA Male Straight Plug 5M/https://www.amazon.co.uk/dp/B077ZSKL74/ref=cm_sw_r_em_apa_i_UweVEbZ791FFQ

Well get a new SDR.

Not much else you can do.
You’ll then know if it’s something else :wink:

Haha… I decided to order a new FlightAware Pro Stick Plus stick and a new coax cable. The cable should be here tomorrow but the ProStick won’t be here until next week so I guess I can check the new cable against the old SDR first to see if it makes any difference and potentially isolate the issue to one or the other.

Out of interest; how easy is it to replace the standard FlightAware stick (orange one) with the new blue ProStick? Is it simply ‘plug and play’?

All the same hardware in the eyes of the computer.

Pretty much all the rtl-sdr compatible SDRs behave very similarly.

And from experience, you can unplug the old receiver from the usb / antenna and swap in the new receiver. Dump1090 recognizes the loss of the old one and replacement with the new one. Dump1090 will initialize the receiver and continue operating just as before. No need to power down and reboot at all.

Ah ok, I didn’t think you would be able to remove the old one and replace it with a new one whilst the PI was on. I was planning a ‘shutdown - h’ and then switching it back on again.

New coaxial cable and new blue FlightAware stick seems to have solved the issue. :slight_smile:

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