STA8089 GA - Cannot activate IF pins to verify front-end functionality

[Armin Choopani]

I hope you have a great day

I’m Armin Choopani, Studying Electrical Engineering. I’ve been assigned a project which is setting up GNSS module. I decided to use the STA8089 GA IC. I’ve designed a matching circuit for its LNA pin. But Unfortunately I cannot verify its functionality (Front-end gain and NF), because I cannot find appropriate command to activate IF pins. I’ve read all NMEA file. But there wasn’t any command related to IF pins. I was wondering if you could help me to find this command. This problem halted my whole project, because I cannot verify anything.

Thank you all

[Armin Choopani]

Hi Francesco

Thank God you are back again =)

Yes, I have satellites issue again. Sometimes IC detects a satellite and sometimes no (But it just detect a satellite, not more. I have a Teseo module which detects lots of satellites with the same antenna and at the same place). Also when my IC detects a satellite, the CN0 fluctuates enormously (from 20 to 35).

Another point about hardware mask or signature string (which I don't know what they are exactly). On my IC it is written "BB" but when I use "$PSTMGETSWVER,255", it says that the IC mask is BD. Does this make any problem?

Best Regards

Armin

[Francesco Virlinzi]

Ciao Armin

> it says that the IC mask is BD

This is not an issue.

Your wafer-die is newer then DD, at the end it's a good chip.

> But it just detect a satellite, not more

It's very strange, it sees only one satellite.

> Also when my IC detects a satellite, the CN0 fluctuates enormously (from 20 to 35).

It could be an issue related the TCXO.

If not covered with a shield (or similar) it can introduce fluctuations in the RF part.

You could try to cover the TCXO and generally check if some-one is introducing noice in your platform

Ciao

Francesco

[Armin Choopani]

Dear Francesco

Again nothing interesting. I have tried different shieldings, but it just detects one satellite (satellite number 31 with CN0=34) while My Teseo III detects satellite number 31 with CN0=39. Even when the CN0 of two different satellites are same (based on Teseo III output), my IC just detects one of the satellites.

I don't know where I should search for the problem or problems! Digital section or RF section or both.

Best Regards

Armin

[Francesco Virlinzi]

Ciao

> I don't know where I should search for the problem or problems! Digital section or RF section or both.

I'm sorry to say you should check both.

It could be an issue in the power supply or something wrong in the pcb.

Regards

Francesco

[Armin Choopani]

Ciao Francesco

I check and see what I can do. By the way, thanks for your informative responses. I learned a lot from them.

Best Regards

Armin