Inconsistent WiFi scanning and "Ghost" ESSID's

Autonomous Machines Jetson & Embedded Systems Jetson TX1
1

On a Jetson TX-1 we are seeing very inconsistent WiFi performance. To troubleshoot I ran this small script to repeatedly show signal strength for nearby AP’s:

while true; do sudo iwlist wlan0 scan | egrep 'Cell |Encryption|Quality|Last beacon|ESSID|Frequency' >> wifiscan; sleep 3; echo "-----" >> wifiscan; done

In the output below there are a few issues I am trying to understand:

  1. Several entries have ESSID:“”. I don’t see these empty SSID’s with any of several WiFi analyzer tools running on co-located (same desk) Android, iOS and Linux machines.

  2. The empty ESSID’s sometimes share a MAC address, or are very close to other MAC addresses (for example lines 5/6, 50/51) below.

  3. The signal level is sometimes shown as 0dBm and Quality 70/70 (lines 10/11, 18, 50/51) for both valid and empty SSID’s. At other times a different (and likely more legitimate) signal level is shown.

This occurs on a stock TX-1 Devkit with the stock antennas and has been verified on two different TX-1’s, both with the -400 serial number suffix. Are these normal occurrences?

Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=58/70  Signal level=-52 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 100ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=25/70  Signal level=-85 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 100ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=65/70  Signal level=-45 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 100ms ago
Cell 04 - Address: B2:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 14380ms ago
Cell 05 - Address: 00:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=21/70  Signal level=-89 dBm  Encryption key:on ESSID:"Stefano" Extra: Last beacon: 4840ms ago
Cell 06 - Address: 02:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=18/70  Signal level=-92 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 14380ms ago
Cell 07 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 100ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=58/70  Signal level=-52 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 90ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 90ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 90ms ago
Cell 04 - Address: 00:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=21/70  Signal level=-89 dBm  Encryption key:on ESSID:"Stefano" Extra: Last beacon: 9580ms ago
Cell 05 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 4840ms ago
Cell 06 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 90ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=58/70  Signal level=-52 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 90ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=26/70  Signal level=-84 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 90ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 90ms ago
Cell 04 - Address: 00:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=21/70  Signal level=-89 dBm  Encryption key:on ESSID:"Stefano" Extra: Last beacon: 14300ms ago
Cell 05 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 9560ms ago
Cell 06 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 4810ms ago
Cell 07 - Address: BE:34:26:53:51:EE Frequency:2.437 GHz (Channel 6) Quality=22/70  Signal level=-88 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 90ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=57/70  Signal level=-53 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 90ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=25/70  Signal level=-85 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 90ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 90ms ago
Cell 04 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=18/70  Signal level=-92 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 90ms ago
Cell 05 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 9640ms ago
Cell 06 - Address: BE:34:26:53:51:EE Frequency:2.437 GHz (Channel 6) Quality=22/70  Signal level=-88 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 4920ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=57/70  Signal level=-53 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 100ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=22/70  Signal level=-88 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 100ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 100ms ago
Cell 04 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=18/70  Signal level=-92 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 4820ms ago
Cell 05 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=20/70  Signal level=-90 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 14370ms ago
Cell 06 - Address: BE:34:26:53:51:EE Frequency:2.437 GHz (Channel 6) Quality=22/70  Signal level=-88 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 9650ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=57/70  Signal level=-53 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 100ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 100ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 100ms ago
Cell 04 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=18/70  Signal level=-92 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 9550ms ago
Cell 05 - Address: BE:34:26:53:51:EE Frequency:2.437 GHz (Channel 6) Quality=22/70  Signal level=-88 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 14380ms ago
Cell 06 - Address: 84:00:2D:57:E2:5B Frequency:2.437 GHz (Channel 6) Quality=20/70  Signal level=-90 dBm  Encryption key:off ESSID:"" Extra: Last beacon: 100ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=57/70  Signal level=-53 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 90ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 4870ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 90ms ago
Cell 04 - Address: DC:EF:09:3C:ED:91 Frequency:2.412 GHz (Channel 1) Quality=18/70  Signal level=-92 dBm  Encryption key:on ESSID:"NETGEAR61_EXT" Extra: Last beacon: 14320ms ago
Cell 05 - Address: 84:00:2D:57:E2:5B Frequency:2.437 GHz (Channel 6) Quality=20/70  Signal level=-90 dBm  Encryption key:off ESSID:"" Extra: Last beacon: 4870ms ago
Cell 06 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 90ms ago
Cell 07 - Address: B2:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 90ms ago
Cell 08 - Address: 02:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=21/70  Signal level=-89 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 90ms ago
-----
Cell 01 - Address: 78:24:AF:7A:F1:04 Frequency:5.2 GHz (Channel 40) Quality=58/70  Signal level=-52 dBm  Encryption key:on ESSID:"ASUS_5G" Extra: Last beacon: 100ms ago
Cell 02 - Address: 08:86:3B:22:8F:4C Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"LifeIsGood" Extra: Last beacon: 9680ms ago
Cell 03 - Address: 78:24:AF:7A:F1:00 Frequency:2.442 GHz (Channel 7) Quality=64/70  Signal level=-46 dBm  Encryption key:on ESSID:"ASUS-24" Extra: Last beacon: 100ms ago
Cell 04 - Address: 84:00:2D:57:E2:5B Frequency:2.437 GHz (Channel 6) Quality=20/70  Signal level=-90 dBm  Encryption key:off ESSID:"" Extra: Last beacon: 9680ms ago
Cell 05 - Address: BC:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"HOME-3A02" Extra: Last beacon: 4900ms ago
Cell 06 - Address: B2:CA:B5:AA:3A:00 Frequency:2.412 GHz (Channel 1) Quality=70/70  Signal level=0 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 4900ms ago
Cell 07 - Address: 02:1D:D5:8B:AC:50 Frequency:2.412 GHz (Channel 1) Quality=21/70  Signal level=-89 dBm  Encryption key:on ESSID:"" Extra: Last beacon: 4900ms ago
2

I couldn’t answer your question, but I’m curious about whether you are using anything PCIe? I’m curious about whether there is a noise relationship. If there is anything PCIe, it might be of interest to see if you have the same issues with the PCIe device removed.

3

nope. No PCIe devices. The issue occurs both in the lab and in the field with completely different RF environments. The TX-1 can be mounted on a stock dev kit or on our Leopard Imaging carrier cards with multiple sensors and the same issue occurs.

4

Hi sperok,

I just tried the scripts on my device. However, I cannot see duplicate ghost SSID…

5

Found the problem - Chromecast devices with Guest Accesss enabled generate these bogus SSID’s.