Hello. I hope somebody can help me to find out the reason for this unbelievable situation I experience, I am meanwhile running out of ideas.
What I experience since I got my testing SIM cards Jan 25, 2024) is not very satisfying:
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On first days, both BC660K registered within a few seconds. Meanwhile this changed to a condition where I can be happy when the BC660K registers at all after every power cycle. The modem stucks in +CEREG: 2 for hours, often the whole day long. Often it has reached +CEREG: 5 over night, but even then it is impossible to open a TCP/IP connection to a host.
When trying “at+qping=0,"dns.google",2,3” I see now “+QPING: 569” and sometimes pings are answered, often not.
Trying anat+qiopen=0,0,"TCP","fqhn",<correct port num>,<correct port num>alm ost always ends with this:
OK
+QIOPEN: 0,566 -
In the seldom case that I see +QIOPEN: 0,0 it is also very often the case that absolutely nothing arrives at the host, and also no responses from there come back-
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Then there are days (very seldom in last days) where it surprisingly works for some time. I can see round-trip times od 2-3 seconds (this is wonderful), and after some packaged it stucks again. Sometimes the round trip time is then 30+ seconds (= useless), sometimes the connection is simply completely “clogged”. BC660K tells me “SEND OK”, bu nothing arrives on host side, and vice versa.
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To verify if the fault is on my hardware, I swapped the SIM cards between my two BC660K modems. As result, I had to wait literally 1 day to get the one on my desk registered with the other SIM. Then the same situation as before, see above.
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At the moment I have a pending ticket at T-MOBILE support, but I doubt I will receive an useful answer during this week.
Is it possible that this crazy behavior is a side effect of stopping the 3G network in Austria?
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So I decided last week to build a new modem PCB.
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This board is based on BG950A-GL, so a different and more powerful technology. Meanwhile PCBs and modules are ordered, but it will need some time (don’t have them ready earlier than 2 weeks, I assume).
Some questions on this module (because the PDFs I found are a bit unclear:
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BG950A-GL is based on LTE (so it is 4G) and does support LTE-M and also NB1. But it does not support 3G and also has no GPRS fallback. Is this correct?
If so, it should be in harmony with the current 4G LTE networks? -
My SIM cards are open for LTE-M, NB-IoT, GPRS. So this cards should be useful with BG950A-GL, too. Correct?
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Does the BG950A-GL allow moving between radio cells? I have the need for transmitting data from moving locations (from cars). Data quantity is low (~1200 Byte every 10 minutes), but it has to be done so fast that data don’t pile up in the moving devices because of extremely long round trip times or long times of not accessible host (caused by delayed registration and/or other issues).
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To save cost, I would like to use BG950A-GL simultaneously for TCP/IP communication to the host, and also as GPS receiver. What I read in some PDFs, is not very clear. It seems WWAN and GNSS cannot run at same time. Is WWAN the radio network of BG950A-GL, or is this something different?
If this doesn’t work, I will have to continue using a completely independent GPS module (as I currently do with BC660K), then it will be more expensive.
I designed the PCB to have the MAIN_UART and CLI_UART connected to the microcontroller. I would like to continuously receive NMEA sentences from GPS, also when exchanging data through MAIN_UART.
Sadly the documentation of GNSS I could find is extremely thin, so I ask here.
Does the BG950A-GL continue to report time and date in NMEA sentences, even when there is no satellite in sight? I currently use ublocks based GPS receivers “NEO M8N”. They do this, and this is important to me because every data record must have a precise time stamp. Transmission may happen delayed, but recording will proceed locally.