SNR archive plots go full scale (0 dBm) instead of down to noise floor?

It would not be related to auto distance, rather directly related to how the chart logic interprets the RSSI value.   This is a  value defined in the 802.11n specification between 0 and 255.  It is a relative value, not an absolute measure of power.   The process in openwrt ath9k driver is to measure the ambient noise background, a "Clear Channel Assessment" (CCA), then whatever this measured value is, call it -95dBm @ 20Mhz channel, the theoretical noise.   Cisco is known to only use this range to be between 0 to -100, Atheros 0 to -127.  The usage of this value range is different between chip manufactures.  This is then interpreted as 0dBm (1 mW) down to -127 dBm below the hardware noise levels. 

The spikes to 1 mW in the chart would have to be because a value of '0' is in the data, or close to '0' for some reason.  There is a data file in /tmp for snrlog that you can inspect to confirm and see this data.  The code needs reviewed to handle the logic of what to do when this 0 value is encountered.    A '0' is not believable in normal operating use and IMO should be considered bogus.   Although, on the bench, one could probably achieve this signal strength between devices.   Possibly, the data shows a new range of values between 1 and 10, also not generally believable and if so, in this case bogus.  I thought the chart code handled '0's before, but maybe this is a new data range we weren't seeing before.

Joe AE6XE

in the folder /tmp/snrlog, look for a filename for each neighbor.   tar, zip, etc. this file for one of these interesting charts and upload here.

Joe AE6XE

NM7B, assuming windows 10, start up a windows "PowerShell".  Here is an example below.

caution:
1) linux is case-senstive on file/host names
2) the filename in linux is not allowed in windows, so this command renames it.  be sure the wildcard, in this example, "*W6LY*" does not match more than one filename.