[Ovmsdev] 3G / 2G fallback on SIM5360 Europe?

Chris van der Meijden chris at arachnon.de
Mon Aug 3 17:33:06 HKT 2020


I did some more reading on the SIM5360 and also digged a bit through
the simcom source. Found loads of AT-commands there :-)
I could not find an AT command to restrict the selection to 2g. Perhaps
I did not look deep enough, but if someone knows the command ...
I'm still thinking why the automatic fallback to 2g does not happen. 
- The transmitter offers only 2g (GSM 900 mHz) and LTE (800 or 1800).
No 3g.- I have a signal strength of -110 to -100 dBm- AT+COPS? gives me
an empty response.
Could it be possible, that somewhere in the code something like
- I don't have 3g- I do have LTE- Lets try LTE- I see LTE- I have no
hardware for LTE- OK, don't do anything
happens? So somehow fallback to 2g never happens?
Just guessing around ...
Regards
Chris 
Am Montag, den 03.08.2020, 10:10 +0800 schrieb Mark Webb-Johnson:
> The SIM5360E should auto-switch between 2G and 3G. It supports the
> following frequency bands:
> GSM/GPRS/EDGE 850/900/1800/1900MHz;
> UMTS/HSPA+ 900/2100MHz
> There are SIMCOM options/commands to restrict the selection, but the
> default is automatic.
> 
> Regards, Mark
> > On 2 Aug 2020, at 6:40 PM, Chris van der Meijden <chris at arachnon.de
> > > wrote:
> > 
> > 
> >     
> >   
> >   Hey Michael
> > Thanx for the help :-)
> > The AT commands are working now, but as expected no connection at
> > all. So also no fallback to 2g. Or no GPRS offered on 2g ...
> > Here some (German) information on the "site lite" transmitters:
> > https://www.telekom.com/de/blog/netz/artikel/standort-light-pilotpr
> > ojekt-552152
> > I also did not find any AT command for the SIM5360 to force 2g. I
> > will play a bit around with the modem in the next days. Will also
> > try congstar, I do have a congstar SIM laying around here ...
> > Greetinx
> > Chris
> > 
> > Am Sonntag, den 02.08.2020, 10:59 +0200 schrieb Michael Balzer:
> > >     Chris,
> > > 
> > >     
> > > 
> > >     how to send modem commands and read the responses:
> > > 
> > >     
> > > 
> > >     OVMS# log level debug simcom
> > > 
> > >     Logging level for simcom set to debug
> > > 
> > >     OVMS# simcom cmd AT+COPS?
> > > 
> > >     SIMCOM command has been sent.
> > > 
> > >     D (164488782) simcom: tx mcmd ch=4 len=10  : AT+COPS?
> > > 
> > >     D (164488792) simcom: rx line ch=4 len=23  : +COPS:
> > >       0,0,"congstar",2
> > > 
> > >     D (164488802) simcom: rx line ch=4 len=2   : OK
> > > 
> > >     
> > > 
> > >     Now let's see if we have 3G:
> > > 
> > >     
> > > 
> > >     OVMS# simcom cmd AT+CPSI?
> > > 
> > >     SIMCOM command has been sent.
> > > 
> > >     D (164693462) simcom: tx mcmd ch=4 len=10  : AT+CPSI?
> > > 
> > >     D (164693482) simcom: rx line ch=4 len=85  : +CPSI:
> > >       WCDMA,Online,262-01,0x16C3,7824927,WCDMA IMT
> > >       2000,454,10836,0,7.5,104,18,8,500
> > > 
> > >     D (164693482) simcom: rx line ch=4 len=2   : OK
> > > 
> > >     
> > > 
> > >     Yes. Well, no surprise, Telekom network :-).
> > > 
> > >     
> > > 
> > >     The SIM5360 is supposed to automatically fall back to 2G if
> > > 3G isn't
> > >     available. On a quick browse through the manual, I didn't
> > > find a
> > >     command to force 2G, just one to lock to a specific 2G cell…
> > > you
> > >     could do that depending on your location, but maybe you
> > > should first
> > >     inspect your modem status now.
> > > 
> > >     
> > > 
> > >     Regards,
> > > 
> > >     Michael
> > > 
> > >     
> > > 
> > >     
> > > 
> > >     Am 02.08.20 um 09:39 schrieb Chris van
> > >       der Meijden:
> > > 
> > >     
> > > 
> > >     
> > > >       
> > > >       Hi all
> > > >       
> > > > 
> > > >       
> > > >       I'm trying to understand some principals of the SIM
> > > >         connection methods of OVMS.
> > > >       
> > > > 
> > > >       
> > > >       Reason is that I recently moved from "the big city"
> > > > Munich to
> > > >         the very much rural village Thalham. In Thalham we have
> > > > so
> > > >         called "lite" mobile transmitters. These transmitters
> > > > are
> > > >         installed, as far as I understood, to safe money and to
> > > > prepare
> > > >         the transition of the providers to 4g / 5g. They are
> > > > forcing the
> > > >         frequencies towards the 4g band with those.
> > > >       
> > > > 
> > > >       
> > > >       So these transmitters seem to offer only 2g and 4g, but
> > > > no
> > > >         more 3g (really ???).
> > > >       
> > > > 
> > > >       
> > > >       I don't have any network connection with the SIM in my
> > > > OVMS
> > > >         here in Thalham. In the next village Zolling I have
> > > > connection.
> > > >         In Zolling they don't have the "lite" transmitters, but
> > > > still
> > > >         have full 3g support. The antenna of my OVMS is working
> > > > well
> > > >         (-100 dBm to -70 dBm).
> > > >       
> > > > 
> > > >       
> > > >       Now my questions ...
> > > >       
> > > > 
> > > >       
> > > >       Does OVMS have a fallback on SIM5360 Europe to 2g (EDGE)
> > > > if
> > > >         3g is not available?
> > > >       
> > > > 
> > > >       
> > > >       I also did some reading in the modem documentation and
> > > > tried
> > > >         to send some AT commands. Goal is to try to force the
> > > > SIM into
> > > >         2g mode. I tried i.e.
> > > >       
> > > > 
> > > >       
> > > >       simcom muxtx 2 AT+COPS?
> > > >       
> > > > 
> > > >       
> > > >       to get some information from the SIM, but I don't get an
> > > >         answer on that command at all. No matter what channel I
> > > > try. Am
> > > >         I missing something there?
> > > >       
> > > > 
> > > >       
> > > >       Thanx for input.
> > > >       
> > > > 
> > > >       
> > > >       Regards
> > > >       
> > > > 
> > > >       
> > > >       Chris
> > > >       
> > > > 
> > > >       
> > > >       _______________________________________________
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> > > > 
> > > >     
> > > 
> > >     
> > > 
> > >     
> > >   
> > > 
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