Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Fri, 20 Jan 2023 09:27:56 GMT

[quote user="Marshall"]It worked but was a bit aggressive, as Asset Tracker 2 then requested all the data again when the modem came back online[/quote]

How often do you search for a fix?

Great if this solution works. Is there anything particular about it you would like to discuss?

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

Marshall — Fri, 13 Jan 2023 02:08:15 GMT

Thanks Helsing,

I had a look at that example, and gave it a go using,

err = lte_lc_func_mode_set(LTE_LC_FUNC_MODE_DEACTIVATE_LTE);

It worked but was a bit aggressive, as Asset Tracker 2 then requested all the data again when the modem came back online, and I ended up getting in a loop of shutting down, to request the location data, turning LTE back on, after getting the data, and then having to repeat.

So in the end I did the following:

prj.conf 
CONFIG_MODEM_AUTO_REQUEST_POWER_SAVING_FEATURES=n


location_module.c -

search start() {

//check for time of day if not correct just send an event and return.
    if (!allowed_to_search){
        SEND_EVENT(location, LOCATION_MODULE_EVT_DATA_NOT_READY);
        LOG_DBG("NOT middle of the night so not checking location");
        return;
  }

//add this line which asks for power savings, the location module sees the PSM event and gets location. 
     err = lte_lc_psm_req(1);

//rest of the search_start function. 
}




inactive_send(){
//on time out or success this function is called. 
//turn off power savings so we are back online all the time.
     err = lte_lc_psm_req(0);
}

Regards

Marshall

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Thu, 12 Jan 2023 20:07:08 GMT

[quote user="Marshall"]no power savings during business hours so that we can obtain <10sec response time[/quote]

The multi or single cell location service could be an option depending on your application.

[quote user="Marshall"]2:00am location update - update speed is not an issue, [/quote]

As you know, you will have ave to shutdown the LTE connection in order to use GNSS service. See the sample nRF91 simple tracker solution – Nordic Developer Academy to learn how this works.

[quote user="Marshall"]the rest of the time it can do the default Asset tracker stuff.[/quote]

Check out the Date-Time library that can be used to trigger GNSS searching task.

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Tue, 10 Jan 2023 15:21:25 GMT

Sorry for the delay. Yes, this should be possible. I will get back to you with more details.

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

Marshall — Sun, 08 Jan 2023 22:05:58 GMT

Thanks for the response. and apologies for not providing enough information.

I would like a quick response time - during business hours.

The user will be operating/testing the device from the cloud on occasion. during these operations I would like a quick response say <10sec.

The unit is largely static and might move once a week. so I was thinking that a daily location update would be fine.

So the ideal would be.

no power savings during business hours so that we can obtain <10sec response time
2:00am location update - update speed is not an issue,
the rest of the time it can do the default Asset tracker stuff.

Regards

Marshall

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Fri, 06 Jan 2023 21:51:54 GMT

Thank you for rephrasing.

[quote user=""]I would like a quick response time[/quote]

How quick does the response time need to be?

If your modem has a fresh fix it could produce more fixes in RRC Idle for a limited time. However, you would need to accept longer response times every now and then to get a fix from scratch. RRC Idle is usually not enough without either eDRX or PSM in use in order to prolong the sleep interval of the LTE stack.

If your application requires the device only to be mostly on, then eDRX could be part of the solution. You could experiment with different values to find a suiting compromise between latency for LTE and how long time it takes to get a fix.

In any case, consider A-GPS as it is much faster and because it will make it less difficult to get a fix.

An alternative is to use an external GNSS module, and then use nRF9160 for LTE only. However, it might still be challenging to get a fix, considering the potential RF-interference from LTE. Please let me know if this is something you consider, and I could try to get some of my other team members who have more expertise in this area to comment on the topic.

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

Marshall — Thu, 05 Jan 2023 21:22:59 GMT

Thanks, let me rephrase the question.

If the device never enters PSM then the GNSS will never work.

What is the suggested method to get a GNSS fix when no power saving mode is implemented.?

Regards

Marshall

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Thu, 05 Jan 2023 15:27:50 GMT

[quote user=""]

However I would like to update the GNSS location every now and then to see if the unit has moved.

How would I best achieve this?

[/quote]

Check out the section on Real-time configurations. You may alter the Location timeout in order to retrieve the location more often. The default value is 300 seconds.

Do you keep your device in Active mode or Passive mode? If the device is in Passive mode, then the Passive Movement timeout is also relevant. If the no movement is detected, there will be an update after 3600 seconds, by default.

RE: Disable power saving and still get GNSS periodically (weekly) in Asset Tracker 2

helsing — Thu, 05 Jan 2023 09:48:55 GMT

Hi Marshall,

Just letting you know I have started looking into this.