nrf9160 gnss power saving mode

RE: nrf9160 gnss power saving mode

Michal — Wed, 30 Oct 2024 09:23:39 GMT

I can now confirm that yes, functionality like that requires development on your side. In power saving mode the GNSS only enters duty cycling, when it has a good enough fix.

Best regards,

Michal

RE: nrf9160 gnss power saving mode

Michal — Thu, 24 Oct 2024 21:56:33 GMT

Thank you for the answers Vasil.

I will have to look more into it and check how exactly it is implemented. Worst case there may be some development needed.

Best regards,

Michal

RE: nrf9160 gnss power saving mode

ncvasil — Wed, 23 Oct 2024 08:01:18 GMT

[quote userid="114944" url="~/f/nordic-q-a/115402/nrf9160-gnss-power-saving-mode/507431"]

So the desired result is for the duty-cycling to timeout after the first fix, right?

[/quote]

Yes

[quote userid="114944" url="~/f/nordic-q-a/115402/nrf9160-gnss-power-saving-mode/507431"]But then, should it always timeout if it cannot get the fix in time (and risk potentially never getting a fix), or maybe every nth try it should still try for longer time?[/quote]

The second approach sounds like a better trade-off: we accept getting a fix less frequently and have lower power consumption.

If that frequency of getting a fix gets too low (like you said - after nth try we fail) - then it is ok to go back to normal continuous mode with higher power consumption.

That was my understanding while I read this:

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/nrf_modem/doc/gnss_interface.html#power_saving_mode

I could be wrong.

It would fit very well in my application. because in case there are no healthy satellites (even on cold start, before first fix) for a certain period of time - I will stop the gnss for a while and not waste any energy while the conditions for a fix are not good.

Hope there is some approach I can use constant (forced) duty-cycling after first fix. Thanks.

Best regards,

Vasil

RE: nrf9160 gnss power saving mode

Michal — Tue, 22 Oct 2024 16:42:44 GMT

[quote user="ncvasil"]My question is: is there a way to constantly force the duty-cycling that will give me ~10 mA (after firs fix)? That will probably come at a cost - lowered accuracy I guess, but still it would be acceptable in my case.[/quote]

So the desired result is for the duty-cycling to timeout after the first fix, right?

But then, should it always timeout if it cannot get the fix in time (and risk potentially never getting a fix), or maybe every nth try it should still try for longer time?

RE: nrf9160 gnss power saving mode

ncvasil — Mon, 21 Oct 2024 13:06:48 GMT

Hi, Michal,

[quote userid="114944" url="~/f/nordic-q-a/115402/nrf9160-gnss-power-saving-mode/506765"]I assume that you are only testing this inside? What happens if you would for example put the device outside (for example outside the window)?[/quote]

The nRF9160dk is indoors, but right by the window.

After the application "cellular/gnss" boots up (continuous mode and power saving enabled as described above) the average consumption hovers around 40mA - I guess it is due to the constant listening and downloading the necessary data from the satellites.

Since the dk board is close to a window - it has little trouble getting first fix - a few seconds to a minute.

Observing the uart output I get a fix every second from this moment on (still indoors, close to window) and the current consumption is 40mA on average, and very rarely dropping down to 1-2 mA (when this happens, the uart log also displays "Sleep period(s) between PVT notifications" as expected)

However, if I handle the dk board and move it no more than 1 meter, slightly outside the window - then it gets the best 'view' of the satellites and the consumption drops as expected (5-6 seconds it is 1-2 mA, 1-2 seconds it goes back to 40 mA, around 10 mA on average) which is great.

In both cases I get a fix. And only when the conditions are perfect - I also get the desired ~10 mA consumption.

My question is: is there a way to constantly force the duty-cycling that will give me ~10 mA (after firs fix)? That will probably come at a cost - lowered accuracy I guess, but still it would be acceptable in my case.

NOTE: I also tried to use "A-GNSS" in order to minimize the satellite communication but the result was the same.

[quote userid="114944" url="~/f/nordic-q-a/115402/nrf9160-gnss-power-saving-mode/506765"]I wonder if it's behaving like this, because it takes so long to get a GNSS fix while inside.[/quote]

After the device obtains first fix - the consumption remains high ~40 mA - I get a fix every second, but the consumption is ~40 mA. Only in perfect conditions the consumption drops down - but I am ok to have 'close to perfect' conditions and get a lower accuracy fix, as long as the current consumption is low.

Best regards,

Vasil

RE: nrf9160 gnss power saving mode

Michal — Thu, 17 Oct 2024 15:34:51 GMT

Hello Vasil,

I took over the case from my colleague Simon.

I assume that you are only testing this inside? What happens if you would for example put the device outside (for example outside the window)?

I wonder if it's behaving like this, because it takes so long to get a GNSS fix while inside.

Best regards,

Michal

RE: nrf9160 gnss power saving mode

ncvasil — Fri, 11 Oct 2024 13:03:12 GMT

Hi, Simon,

Yes, I made sure that the changes from the Kconfig are saved to prj.conf and then rebuild. The

nrf_modem_gnss_power_mode_set(...) gets called with parameter

NRF_MODEM_GNSS_PSM_DUTY_CYCLING_POWER.

I tried that on nRF Connect SDK v2.5.0 and v2.6.2 - same result: current consumption is around 40mA before first fix and remains the same after the first fix - no change. I left it like that for a few minutes - no change (while it keeps getting more fixes from satellites).

The LTE is not used, only GNSS, so I can't see what else can draw current.

EDIT: After leaving it on for a while, I noticed that very rarely the consumption drops to 1-2 mA and in the serial terminal I see the message "Sleep period(s) between PVT notifications" which means that indeed the duty-cycling is engaged, but it happens very rarely. For example the consumption stays around 40 mA for 20-30 seconds, then drops below 10mA for 3-4 seconds and so on. But definitely the average consumption for the whole period is closer to 40mA.

Best regards,

Vasil

RE: nrf9160 gnss power saving mode

Simonr — Fri, 11 Oct 2024 11:11:30 GMT

Did you make sure to do a pristine build after enabling the power saving mode? Also, what nRF Connect SDK version are you using here, so I can do a test on my end? Is the initial fix completed or do you just measure the current consumption initially? As i think the current consumption here refers to the tracking after an initial fix has been established.

Best regards,

Simon