[Ovmsdev] 3G / 2G fallback on SIM5360 Europe?
Mark Webb-Johnson
mark at webb-johnson.net
Wed Aug 5 13:24:02 HKT 2020
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> 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 <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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