Unknown behaviour when signal quality is poor

[Alejandro Vega]

Hello again,

I am finding a unexpected behaviour and I would like to know how does the
ModemManager work in situations like this one, when the modem has no signal
at all or the signal is quite poor:

<debug> [1607682864.814360] Received notification (service 'basic-connect',
command 'signal-state')
<debug> [1607682864.814379] Signal state indication: 6 --> 19%
<debug> [1607682864.814532] Modem /org/freedesktop/ModemManager1/Modem/0:
signal quality updated (19)
<debug> [1607682866.172436] (ttyACM1): --> 7e 00 78 f0 7e
<debug> [1607682866.172535] (ttyACM0): --> 7e 00 78 f0 7e
[/dev/cdc-wdm0] Received message...
>>>>>> RAW:
>>>>>>   length = 64
>>>>>>   data   =
07:00:00:80:40:00:00:00:00:00:00:00:01:00:00:00:00:00:00:00:A2:89:CC:33:BC:BB:8B:4F:B6:B0:13:3E:C2:AA:E6:DF:0B:00:00:00:14:00:00:00:00:00:00:00:63:00:00:00:05:00:00:00:02:00:00:00:FF:FF:FF:FF
[/dev/cdc-wdm0] Received message (translated)...
>>>>>> Header:
>>>>>>   length      = 64
>>>>>>   type        = indicate-status (0x80000007)
>>>>>>   transaction = 0
>>>>>> Fragment header:
>>>>>>   total   = 1
>>>>>>   current = 0
>>>>>> Contents:
>>>>>>   service = 'basic-connect' (a289cc33-bcbb-8b4f-b6b0-133ec2aae6df)
>>>>>>   cid     = 'signal-state' (0x0000000b)
>>>>>> Fields:
>>>>>>   Rssi = '0'
>>>>>>   ErrorRate = '99'
>>>>>>   SignalStrengthInterval = '5'
>>>>>>   RssiThreshold = '2'
>>>>>>   ErrorRateThreshold = '4294967295'
<debug> [1607682867.822380] Received notification (service 'basic-connect',
command 'signal-state')
<debug> [1607682867.822400] Signal state indication: 0 --> 0%
<debug> [1607682867.822557] Modem /org/freedesktop/ModemManager1/Modem/0:
signal quality updated (0)


- The modem does not seem to transition from the "*connected*" state to the
"*registered*"  state , or at least I cannot see it in the logs (attached
in a previous mail). It remains as  *state: connected.*
What is the expected behaviour here?
*- *What does the ModemManager do in these cases where the modem is
connected to the ISP but has really really low signal (i.e.  signal state
0) ? When does the Modem Manager consider the modem disconnected ?

Regards,
Alejandro


El lun, 14 dic 2020 a las 15:31, Alejandro Vega (<alexvega48 at gmail.com>)
escribió:

> Attached logs of the found behaviour and status of the modem before the
> signal loss.
>
> Kind regards,
> Alejandro
>
> El lun, 14 dic 2020 a las 10:07, Alejandro Vega (<alexvega48 at gmail.com>)
> escribió:
>
>> Attached logs
>>
>>
>> El lun, 14 dic 2020 a las 10:05, Alejandro Vega (<alexvega48 at gmail.com>)
>> escribió:
>>
>>> Hello !
>>>
>>> First of all, thanks in advance for your time and dedication. I am
>>> developing an application making use of libmm-glib high level API and
>>> running under *ModemManager version 1.10.6*.
>>> I am currently experiencing some trouble and I would like to know if the
>>> behaviour of the Modem + ModemManager system is the expected one or there
>>> is some kind of malfunction somewhere.
>>>
>>> The problem is that we are experiencing some signal problems around an
>>> specific area (particularly, every time that a bus passes by an area where
>>> the signal strength is poor). I *attach *the *ModemManager debug logs*
>>> of the outward and return journey only when the bus is passing by this
>>> area.
>>>
>>> Regarding this, we have the following doubts:
>>>
>>>    - Is the behaviour of the ModemManager the expected one ? Our
>>>    application queries the ModemManager to scan for devices periodically, can
>>>    this cause an unexpected behaviour ?
>>>    - We are using a "global" M2M card which should be able to use
>>>    different network operators. Is the ModemManager able to switch between
>>>    operators in order to achieve better signal strengths ? If this is not the
>>>    case, in order to achieve this, how would we need to proceed?
>>>
>>> Once again,thank you very much.
>>>
>>>
>>> Kind regards,
>>>
>>> Alejandro Vega
>>>
>>
>>
>> --
>> Un saludo.
>>
>> Alejandro Vega
>>
>
>
> --
> Un saludo.
>
> Alejandro Vega
>


-- 
Un saludo.

Alejandro Vega
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