at!gpscoldstart

IoT Modules MC/EM Series
1

Hi!

I evaluate the GNSS receiver of MC7455 using a GNSS constellation simulator. There are several scenarios for testing, with different dates. It seems to me that MC7455 somehow remembers the latest date. I mean, if the GPS week number is below what is has been, the modem thinks that the GPS week has rolled over, and adds 1024 weeks to calculate the new date.

So if I for example run a scenario with date somewhere in year 2016, MC7455 outputs a date in year 2035.

SIM card is not installed, so that does not disturb testing.

This is what I do to cold start:

at!entercnd=“A710”
OK
at!gpsclrassist=1,1,1,1,1
OK
at!gpscoldstart
OK

Anything else needed?
Br, Karppa

2

Hi Karppa,

Can you please issue this command at!gpsend=0,255 prior to End all active gps sessions before executing at!gpsclrassist=1,1,1,1,1 command.
Let us know your feedback on this.

Thanks and Regards,
Rex

3

Hi Rex,

at!gpsend=0,255 did not help.

I managed to run a couple of Galileo-only scenarios, with date in past, and MC7455 outputting correct date.

Scenarios including GPS+GAL, with date in past, lead to wrong date, and rejected Galileo satellites, probably because the receiver thinks that there is discrepancy between GPS week and GAL week.

GPS-only scenarios lead to wrong date. That is, if the simulated date is in the past. So somehow the problem is that the modem remembers the GPS week, even after power off-on cycle.

Is MC7455 suitable for applications requiring eCall capability?

Br, Karppa