www.st.com

[Francesco Virlinzi]

Hi all

Have a look @

https://www.st.com/resource/en/application_presentation/teseo-3-quick-testing-guide.pdf

it's an easy way to test the connection to the Teseo III server based Assisted GNSS without special equipment and/or tool.

[EHuse]

So comparing the "predictive data" vs the real time data? Is one better than the other?

If I use just program the Real Time ephemeris and almanac data, that should be enough to get a very fast fix, right?

[EHuse]

Okay, it is possible that my testing setup is causing issues. My problem now is that I cannot find a good test environment. It seems that time of day has far more impact on my time to fix than anything else.

Right now I have a good view of the sky and TTF is usually less than 3 minutes from a complete cold boot that deletes both ephemeris and almanac data. Which if this were true for our device all the time then I would not even need the assisted GPS.

Could the predictive ephemeris data be speeding up time to fix, even if all of the RT ephemeris and Almanac data are erased?

Why are there 2 methods on the chip for AGPS? Is there a reason to choose one method over the other?

[Francesco Virlinzi]

Ciao

Mike will be in contact with you to understand where the issue is.

>Why are there 2 methods on the chip for AGPS? >

> Is there a reason to choose one method over the other?

There isn't a method better that an other. Which method you select depends on the final application capability.

• RT-AGNSS has a better TTFF but it needs continuously internet connection;
• P-AGNSS has ah higher TTFF but it needs just ~8K each 2 weeks...

therefore "better" depends on the final application.

Regards

Francesco

[EHuse]

Thanks much for the information. A more specific question.

When I do a "$PSTMCOLD", I know it clears the RT Ephemeris data. But does "$PSTMCOLD" clear any of the data used for P-AGNSS?

If P-AGNSS is active (ST-AGPS right?), and I do a cold start, how does this affect time to first fix? I mean I've cleared the RT ephemeris data with a cold start but if the P-AGNSS data is still active then it will speed up the time to first fix, even without and RT data?

Does the gps attempt to use both ways if they are active?