About the Signal Quality given by mmcli

[Aleksander Morgado]

On Sat, May 14, 2016 at 10:23 PM, Nizar BEN NEJI <nizarbenneji at gmail.com> wrote:
> I'm using mmcli with Huawei (E3372H) modem and I would like to evaluate the
> signal quality. The only value I can get with mmcli -m 3 is:
> ...
> access tech: 'umts'
> signal quality: '32' (recent)
> ...
>
> What does 32 means? How can I deduce if it is weak, fair, good or excellent?
> I am a little bit confused, is this value ASU (Arbitrary Strength Unit) or
> RSR, RSRQ, RSSI or SNR?

That value is the quality given as a percentage, usually computed from
RSSI. E.g. if +CSQ can be used, the signal quality is computed as:

                quality = CLAMP (csq_value, 0, 31) * 100 / 31;

Where csq_value:
  0 Equal to or less than -113 dBm
  1 -111 dBm
  2...30
  -109... -53 dBm
  31 Equal to or higher than -51 dBm

For the additional possible signal quality measurements (e.g. RSSI in
dBm, RSRQ, RSRP, SNR...), we'd need to implement the "Signal"
interface for AT-based modems (likely a per-plugin implementation).
This is likely not a very complex task, so ideal for newcomers if
anyone interested :)

-- 
Aleksander
https://aleksander.es