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A question about S/N on the WiFi Signal Graph

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kf6iiu
A question about S/N on the WiFi Signal Graph
I've switched to a CPE710, which has a dish, and is thus picky about aim. I am noticing on the WiFi signal graph that the upper line and the textual readout of the signal agree (about -77 dBm) , but the lower red line, which I assume is the noise level, and SNR don't add up. I see the red line (which I assume is the noise level) steady at about -96 but my SNR textual readout shows 38.

The SNR for my CPE510's does add up, the signal when connecting to the same node as the CPE710 shows -77 as well, but the SNR runs about 20.
 
Is the SNR reported by the node itself or is it calculated from the signal level and noise level? I remember hearing some where that the TPLinks report a bogus noise level reading. That would explain the red line being in the -96 range for all of my TPLink devices, and never moving up or down. 
 

 
w6bi
w6bi's picture
SNRs and signals
All 802.11n devices report -96 as their noise level; it's not really measured.   802.11ac devices on the other hand, do report real noise levels.

More info is at https://docs.arednmesh.org/en/latest/arednGettingStarted/node_admin.html...

Hope this helps.

Orv W6BI
kf6iiu
CPE710 is ac capable.....
Thanks for jogging my memory. The CPE710 is ac capable. But I do notice that the 3.25.5 sysupgrade binary is over twice as big as the CPE510 sysupgrade binary, so maybe the latest upgrade took aim at this. 

The CPE710, though it has higher gain, does not offer as reliable a connection to my nearby mountaintop node as the CPE510. There is a tree blocking a substantial part of the fresnel zone in the path, and the wider beam of the CPE510 seems somehow better able to deal with that. Although the link is slower, LQ and NLQ are 90+%. That's microwaves for you. The CPE710 is hard to aim since it doesn't come with any sighting aids like some of the Ubiquitis. I'll probably sell it off to someone with clearer paths.
w6bi
w6bi's picture
Sighting aids
There are both visual and audible sighting aids in the AREDN software.  Look at WiFI Signal in the Tools area (lower LH corner).

Orv W6BI

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