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

Michael Balzer dexter at expeedo.de
Wed Aug 5 14:01:19 HKT 2020


Chris,

two additional thoughts:

- maybe the VW antenna contains a GSM and a GPS antenna (?), and you
connected the wrong one?

- maybe the VW antenna is an active one and needs a supply voltage which
is currently missing?

Regards,
Michael


Am 05.08.20 um 07:24 schrieb Mark Webb-Johnson:
> Maybe,
>
> Or the VW antenna is way off on specification.
>
> Regards, Mark.
>
>> On 5 Aug 2020, at 1:17 PM, Chris van der Meijden <chris at arachnon.de
>> <mailto:chris at arachnon.de>> wrote:
>>
>> Thank you for your response.
>>
>> That leaves me with a poor home made SMA to Fakra adapter cable, I
>> guess ...
>>
>> Regards
>>
>> Chris
>>
>> Am Mittwoch, den 05.08.2020, 09:27 +0800 schrieb Mark Webb-Johnson:
>>> The antenna surely helps, but in some locations you can receive a
>>> signal with a piece of wet string resting on the antenna connection.
>>> Seriously. At my office desktop, I still get 3G without an antenna
>>> connected (but I don’t recommend it due to possible feedback in the
>>> modem module).
>>>
>>> These are not binary on/off situations. An antenna rated to
>>> 1710-1990 will still work at 1991, or even 2100, but just not
>>> optimally with the best reception or transmission.
>>>
>>> The original Fasttech antennas were designed for 2G (OVMS v2), but
>>> should still cover some 3G ranges optimally. The newer ones (from
>>> Medlock in USA and OpenEnergyMonitor in UK) should cover all ranges
>>> (up to and including 4G LTE) - and we used these for radio
>>> certification so have been very thoroughly tested at all the
>>> supported 2G and 3G frequency ranges.
>>>
>>> Regards, Mark.
>>>
>>>> On 5 Aug 2020, at 12:21 AM, Chris van der Meijden
>>>> <chris at arachnon.de <mailto:chris at arachnon.de>> wrote:
>>>>
>>>> Still digging on the subject ...
>>>>
>>>> Today I took my original Fasttech OVMS v2 antenna out of my Nissan
>>>> Leaf and connected it to the OVMS v3 in our VW e-Up. And surprise,
>>>> surprise I got direct connection over the SIM to the network.
>>>>
>>>> The VW antenna gives me -101 dBm, the Fasttech antenna gives me -91
>>>> dBm.
>>>>
>>>> So I took a look at the frequencies ...
>>>>
>>>> The old fasttech antenna has a frequency range of 824-960 / 1710-1990.
>>>>
>>>> o2 (my SIM card provider) uses GSM 900 and GSM+LTE 1800 for 2g (4g
>>>> LTE cannot be used on the SIM5360) and uses UMTS 2100 for 3g.
>>>>
>>>> Now I have two theories on what make things go wrong with the VW
>>>> antenna, but work with the fasttech antenna:
>>>>
>>>> 1. My home made sma / fakra adapter cable to the VW antenna is bad
>>>> (could be, but in the city it connects)
>>>>
>>>> 2. Because 3g on 2100 mHz is not available through the fasttech
>>>> antenna, OVMS v3 is forced to 2g and everything runs fine.
>>>>
>>>> Any corrections on the second theory are welcome. I'm guessing ...
>>>>
>>>> I will buy an other sma 2g/3g antenna just to get rid of the
>>>> problem, but will also continue thinking on this one.
>>>>
>>>> Greetinx
>>>>
>>>> Chris
>>>>
>>>>
>>>>
>>>> Am Montag, den 03.08.2020, 12:31 +0200 schrieb Chris van der Meijden:
>>>>> Hi Michael
>>>>>
>>>>> yeah, economical visionaries are always a lot of fun :-))
>>>>>
>>>>> I read that "GSM voices services" line too and checked on that
>>>>> with my mobile phone. I restricted the connection of the phone
>>>>> with *#*#4636#*#* to "GSM auto (PRL)" and it connects to EDGE. So
>>>>> data over GSM is available ...
>>>>>
>>>>> Still mysterious. Will dig some more ...
>>>>>
>>>>> Greetinx
>>>>>
>>>>> Chris
>>>>>
>>>>> Am Montag, den 03.08.2020, 12:21 +0200 schrieb Michael Balzer:
>>>>>> Chris,
>>>>>>
>>>>>> we don't tell the modem to restrict itself in any way. Bugs in
>>>>>> the modem firmware are likely, but I think a serious bug like
>>>>>> this would have been solved early.
>>>>>>
>>>>>> I've read the pilot description now, and you need to pay
>>>>>> attention to this section:
>>>>>>
>>>>>>> statt der üblichen drei Dienste LTE, UMTS und GSM kommen in
>>>>>>> Kirchfarrnbach "nur" LTE 800 und LTE 900 für die Datenversorgung
>>>>>>> sowie GSM für Sprachdienste und SMS zum Einsatz. Auf UMTS haben
>>>>>>> die Funknetzplaner hier verzichtet, weil bereits LTE und GSM
>>>>>>> alle Anforderungen der Bevölkerung erfüllen.
>>>>>>
>>>>>> …translated…
>>>>>>> Instead of the usual three services LTE, UMTS and GSM, "only"
>>>>>>> LTE 800 and LTE 900 are used in Kirchfarrnbach for data supply
>>>>>>> as well as GSM for voice services and SMS. The radio network
>>>>>>> planners have dispensed with UMTS here because LTE and GSM
>>>>>>> already meet all the requirements of the population.
>>>>>>
>>>>>> So you have neither UMTS nor EDGE. GSM is only available for
>>>>>> voice streams and SMS. Data is only available via LTE.
>>>>>>
>>>>>> Your only option is to tell them they're a bunch of … outstanding
>>>>>> economical visionaries, who could possibly consider rethinking
>>>>>> their IoT compatibility ;-)
>>>>>>
>>>>>> Regards,
>>>>>> Michael
>>>>>>
>>>>>>
>>>>>> Am 03.08.20 um 11:33 schrieb Chris van der Meijden:
>>>>>>> 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 <mailto: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-pilotprojekt-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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-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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