We have seen this on several nodes, and know it is not a real signal, but I wonder if it could an effect on the AGC, or other software tweaks that the node will do? Typically I have seen this on Nanostations M2 or M5, where the node is receiving a signal hovering right around the noise floor. This is not presenting any problems, but I just wanted to mention it in case it could affect the node operation.
73,
Glenn WA3LAB
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95 SNR?
Thu, 04/01/2021 - 15:14
#1
95 SNR?
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Check on this, but I don't think these devices have AGC.
I have many devices on adjacent channels that show no change in SNR or LQ/NLQ or TxMbps with/without neighbors
on adjacent channels.
Chuck
It's an anomaly that has existed for years. If there is zero signal, it will show zero instead of at the noise floor as it should be. Just confirmed on one of my nodes that is not talking to anything.
This is most likely a bug. I'm trying to recall, but sometimes when the call to collect this data returns a "0", it should be interpreted as "no value", instead of 0dBm. The dilemma is to determine what to do where there is no value, make it 95dBm at the noise floor? make it the same as the prior reading? show it as no signal and a gap on the chart...
Joe AE6XE
I'd suggest that if the data returned is truly a "0" then "no value" should be considered NO DATA and left as a gap on the chart. Anything else would be artificial IMO.
Just an opinion,
- Don - AA7AU
I vote for -95 dBm...
Orv W6BI
At the noise floor - which is not always -95.
.
I assumed it was some type of bug. I would vote for no signal to at the noise floor as well. Thanks for all the answers.
73,
Glenn WA3LAB
Glenn, there is a fix for this issue in the latest Nightly Build (#257 or newer). http://downloads.arednmesh.org/snapshots/trunk/CHANGELOG.md Here is what it looks like.
Before the fix:
After the fix:
I like it. Upgraded a few of my nodes, and saw something quite unexpected on one. The two nodes that truly have nothing to talk to showed a flat line (as expected) Here is a S/N chart from a Rocket M3 while I updated the other end of the link. I was expecting the signal to drop to the noise floor while the far end node was rebooting. This is what I saw:
The Rocket that this screen capture came from is about two feet from the far end of the link, and is operating with dummy loads for antennas on the near end. The far end has the feed only for a Rocketdish antenna. Both radios are operating at low power settings.
For those that are running Google Chrome and could not see the graphic is the above post here is a link to it: http://extraphotos.info/Chart.jpeg
Yes, it's a Google Chrome induced issue.