[SOLVED] What are the conditions to have a FIX on the TESEO III chip ?

[rivieran]

Hi,

I have a CLOE board, I detect an average of 7 satellites with a SNR between 25 and 45 during the cold start but I can't have a fix. The CLOE board is running with a TESEO III chip.

Does anyone know the conditions to have a fix ?

Moreover, I have an EVB-LIV3F, also based on a TESEO III chip and I can have a fix in 3 min 30 s with the cold start.

[Francesco Virlinzi]

Hi Anthony

On the CLOE board you should ask to Sequans (www.sequans.com) as they are the platform's owner.

Generally speaking to get a FIX you needs 4 satellites... but they should be 'good' satellites. (with good signal)

In the Teseo platform we can configure the lowest CN0-threshold to involve or not a satellites in the position evaluation.

In details:

CDB-ID 132 – GNSS Positioning CN0 threshold --- default (ST) value is 15

therefore it seems your satellites are good.

Why you don't have a FIX on CLOE ... I don't know.. you could check if CDB-ID-132 has been changed.

While on EVB-LIV3F:

• '3 min 30 s'

It's really a lot and really strange...

I just took a FIX from COLD in 34 seconds! (NOT minutes) on a EVB-LIV3F... and my antenna is not well placed.

Is the antenna well placed out-side?

Regards

Francesco

[rivieran]

Thank you for answering so quickly,

Sequans tells me to ask my questions here. And as the software, the documentaion and the GNSS chip we're using is comming from ST, it seems a good idea.

The 3 min 30 s to fix a satellite comes from the test's conditions. We were testing a cold start with the same SNR as the one we were getting from the CLOE Board ( approximately 25 to 45).

So, for the EVB, the antenna was not well placed, but it's voluntary.

And for the CLOE board, we have made test outside without obstacles, and we obtain the same result.

Do you have an idea about how testing this plateform ?

[Francesco Virlinzi]

Hi

I have similar numbers (approximately 25 to 45) but I have a FIX from COLD in 34 seconds.

You should have the same with your EVB-LIV3F + Antenna provided in the kit

> The 3 min 30 s to fix a satellite comes from the test's conditions

Which is your test condition?

Which antenna are you using?

> Do you have an idea about how testing this platform ?

Generally for real test you should use a GNSS simulator to perform accurate test with always the same scenario.

Regards

Francesco

[rivieran]

Hi,

I'm using the antenna provided in the kit, but I hide it to obtain the same reception level of the CLOE's board signal.

I think our problem doesn't come from the antenna.

Is it possible that the ARM of the TESEO III is functional but the GNSS part is down ?

[Francesco Virlinzi]

Hi Anthony

> Is it possible that the ARM of the TESEO III is functional but the GNSS part is down ?

The standard TeseoIII firmware has several power mode functionality but all the functionality have a common starting point which is:

• FIX done
• ephemeris downloaded.
• almanac available

this means in case of COLD boot the power functionalities don't impact the TTFF.

But I'm describing the the TeseoIII.

You should ask to Sequance how are they managing the internal power mode in CLOE.

Hope this helps.

Regards

Francesco

[rivieran]

Hi,

Thanks you for all your answers. It helps me a lot.

Bye.

[rivieran]

All CLOE boards are supposed to use 4MB parts but in some cases Sequans provide a board that have a 2MB part by mistake. This prevented the GNSS to achieve a fix.

In order to solve this, all you need to do is recompile your binary removing the following line from the file called “fwcfg.txt�? within the project you are compiling:

250 -> 15

This line needs to be present only in case of 4MB.

(Thanks to mbotija).