nRF9160 GPS IGPS_CONTINUOUS_PSM - can you please explain the basic functionality when the GPS runs in power save mode (to reach 9,8 mA). I cannot find information in the data sheet.

[Anders Larsson]

nRF9160 GPS IGPS_CONTINUOUS_PSM - can you please explain the basic functionality when the GPS runs in power save mode (to reach 9,8 mA). I cannot find information in the data sheet.

[Martin Lesund]

Hi Anders,
Source:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.5.1/nrfxlib/nrf_modem/doc/gnss_extension.html

"Continuous navigation mode is engaged by setting the fix interval to 1. In this mode, the GNSS receiver continues to produce fixes at 1 Hz rate without any time limit"

[Anders Larsson]

Hi Martin!

Thanks for the answer but I am interested in the Powe Save Mode (PSM). What duty cycle should be set to reach 9,8 mA current consumption? What will be the performance degradations in this case? What limitations will the PSM mode introduce?

BR Anders

[Martin Lesund]

Hi Anders,
DId you check the "Power Save Mode" section longer the page?

"The GNSS receiver may track signals (i.e. run) either continuously or in duty cycles.

In duty-cycled tracking (what it does in power save mode), the GNSS receiver operates in on-and-off cycles consisting of tracking and sleeping. The received GNSS signal has therefore short gaps during the sleep periods. This type of tracking reduces the power consumption at the expense of performance.

A duty cycle denotes the fraction of one cycle in which the GNSS receiver is tracking. In duty-cycled tracking the tracking period is fixed to 100 ms, and the sleeping period is fixed to 400 ms. Consequently, the total time needed to complete an on-and-off cycle is 500 ms. These values give 20% duty cycle. Since the GPS data bit length is 20 ms, and the smallest meaningful data primitive is 30-bit word (i.e. 600 ms), it is impossible to decode any data during duty-cycled tracking. This has significant impact on the performance. It means that any new GNSS signal cannot be utilized before any of the following conditions occur:

Continuous tracking is resumed to enable the decoding of the navigation data

A-GPS is used to provide relevant navigation data

The available power modes determine whether duty-cycled tracking is allowed. If it is allowed, the target performance is determined.

In the low power duty-cycled power mode (Power saving mode), duty-cycled tracking is engaged and run whenever it is possible with acceptable performance degradation.

The GNSS receiver continues to produce PVT estimates at the configured rate regardless of whether the tracking is continuous or in duty cycles. However, a failure to produce a valid PVT estimate during duty-cycled tracking may cause the GNSS receiver to resume continuous tracking."

[Anders Larsson]

Thanks Martin!

If the GNSS receiver is in PSM mode and resume continous tracking due to a non valid PVT estimate - will it go back to PSM mode automatically when valid PVT estimate has been produced?

BR Anders