Question for the programmers working on GNSS.
I run a few nodes as trackers that need battery life of +180days. The big bulk of power goes ofcoruse to aquiring a GNSS/GPS position, and naturally the faster it gets a position, the faster it can go back to sleep.
1: Does the MT firmware keep the hardware RTCs that for example Esp32 have active in sleep mode to keep the time?
2: If so, Does MT firmware give this time to the GNSS module for a faster position lock when waking up?
3: If no to either, Can we implement this in an future update?
Reducing each position lock time by only a few seconds can give a massive increase in battery life for tracker units.
Indeed.
Cannot see how you can ‘set’ the GPSs internal clock in the first place, or why that would improve the position lock time.
Do you have any details or examples of how this actually works or anyone who has done it ?
A lot of the aquire time for a gps module is just listening to the satelite signals to figure out the coordinated gps system time, especially if it has been turned off/sleept for a while(cold start). It then uses the time to know what sattelites to expect to hear from the downloaded sattelite position Almanac. This is why it takes longer to get a position fix the longer the time is between fixes. With faster update frequency there is less movement of the sattelites and less prosessing and searching to do before calculating the fix.
If you can give the gnss a correct time as it starts up without it having to listen to the signal first you significantly reduce the aquire time because it doesnt have to listen for X seconds to recieve decode and sync to the clock signal thereby reducing power usage and giving a lot faster position fix. Your phone does this all day by using the set time in the phone.
The gnss modules can be given the correct time over the serial connection. I believe the Ublox protocol can do this, not sure about NMEA
The U-Blox gps company is even moving the time signal to the Cloud with their new modules, and is having the gnss module go online for the correct time, Almanac and signal processing instead of waiting for the signal from the sattelites. Makes it possible to get insanely short fix times even with a cold start.
Well GPSs in mobile phones are a separate issue since they can use various forms of internet assist to tell the GPS which are the satellites should be in view, no need to search for them.
So assuming you don’t have an internet connection, are there any known working examples you can point out of pushing a time from an local RTC into a GPS to improve hot fix time ?