Using mm_modem_signal_setup_sync() to set rate

[Aleksander Morgado]

Hey Tom,

>
> I want to be able to read the RSSI from my modem. I can do this by
> calling mm_modem_signal_setup_sync() to set the rate then later
> calling mm_modem_signal_get_lte() and mm_signal_get_rssi(). But is
> there any guidance on what rate I should set? Will a short rate
> degrade modem performance or increase power usage? Or can I just set
> it to anything I want?
>

If you enable signal polling by configuring a rate in the
Signal.Setup() method, the host will send a request to the modem with
the configured period, and the relevant properties will be updated
whenever the signal quality values are refreshed. I don't think this
degrades performance, but it will definitely consume more power. If
you're using a battery powered device, please don't use this.

If you have a new enough MM you can also use Signal.SetupThresholds(),
see https://www.freedesktop.org/software/ModemManager/doc/latest/ModemManager/gdbus-org.freedesktop.ModemManager1.Modem.Signal.html#gdbus-method-org-freedesktop-ModemManager1-Modem-Signal.SetupThresholds,
where you can configure a RSSI delta so that the modem will emit
signal notification updates whenever the RSSI changes more than the
delta. This setup is quite new, and obviously depends on the modem
supporting these threshold configurations. This type of configuration
is preferred on battery powered devices, as it is up to the modem the
signal quality update reports whenever they change substantially.

-- 
Aleksander