How is the periodic mode working for L76?

IoT Modules GNSS Module
1

What does Second run time mean?

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Is there any timing diagram available for explaining the GNSS module working/sleeping time after entering periodic mode?

2

Hi Hanqi,

When the modules fail to fix the position in Run time, the modules will switch to Second run time and Second sleep time automatically. As long as the modules fix the position again, the modules will return to Run time and Sleep time.

Please note that the second run time should be longer than the first run time when the first run time is a non-zero value.
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Could you tell me which module you are using? I will send you related document via message.

Best regards.

3

Hi, I’ve downloaded the hardware spec of L76(L) and the explanation is like you said. But during the lab test, I found the module keeps trying to fix the position regardless of what parameters were given to ‘Second RunTime’.
Another thing I found during the test is that even though in Figure 8 above it shows that the module should enter ‘Sleep time’ after entering periodic mode, but it actually it always enter ‘Run time’ first.
Lastly, as I need the module generating PPS signal, and it should be disabled during standby mode. Do you know the start up delay for outputting PPS signal again after leaving standby mode?
Thanks for your support.

4

Hi Hanqi,

We don’t have records about the PPS delay after leaving standby mode. The default setting for PPS is outputting 1PPS signal after 3D fix. From the first 3D fix, the accuracy of 1PPS could be hundreds of nano seconds. But it will get preciser after signal become stabler. You can change the setting by sending $PQ1PPS,W command($PQ configurations are saved in flash memory automatically).
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Best regards.

5

Thanks for your explanation, it’s really helpful. Is the PPS signal going to have different accuracy of changed from 3D fix to others? If so, how much will be the difference?

6

Hi Hanqi,

Our data for 1PPS accuracy is tested in open sky scenario, and the valid fix is always 3D fix.

Generally, the module go through non-fix → 2D fix → 3D fix. 2D fix will last for very short time, and module will finally reach 3D fix.

Best regards.