Cold Start / Warm Start / Hot Start

botletics / SIM7000-LTE-Shield

Botletics SIM7000 LTE CAT-M1/NB-IoT Shield for Arduino

https://www.botletics.com/products/sim7000-shield

GNU General Public License v3.0

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Cold Start / Warm Start / Hot Start #100

Closed ttorkar closed 5 years ago

ttorkar commented 5 years ago

Hi Tim,

I was wondering if you had any further information about Cold Start / Warm Start / Hot Start and how they operate? Is it simply a matter of AT+CGNSHOT or is there something more? Is everything handled by the SIM7000?

Or does it require the XTRA file as per.

SIM7000 Series_GNSS_Application Note_V1.01

It provides enhanced standalone performance, and eliminates the need to demodulate the GPS signal for ephemeris, almanac, iono, UTC, or health. Normally requires -144 dBm or stronger for all SVs in view. TTF can be reduced by 18 to 30 sec (or more in harsh signal environments)

Thanks in Advance

botletics commented 5 years ago

Sorry, besides what in the app notes I'm really not sure.

ttorkar commented 5 years ago

Ok thanks, I'll let you know if I find anything out

robbiet480 commented 4 years ago

Sorry to bump an old issue, but just wanted to point out that there are example commands in the GNSS app note to enable XTRA.

AT+SAPBR=3,1,"APN","hologram"
AT+SAPBR=1,1
AT+CNTPCID=1
AT+CNTP="pool.ntp.org",-28,1,2
AT+CNTP

AT+CNACT=1,"hologram"
AT+HTTPTOFS="http://xtrapath1.izatcloud.net/xtra3grc.bin","/customer/xtra3grc.bin"
AT+CGNSCPY
AT+CGNSXTRA=1
AT+CGNSCOLD

However, even after following the instructions, I get a URC +CGNSXTRA: 2 which according to the AT commands manual means XTRA file is not effective. Unsure why.

robbiet480 commented 4 years ago

Turns out, you need to have a very good GPS signal for the XTRA file to work. Once I went outside and had clear view of the entire sky it instantly worked.