Teseo-LIV3F, no satellite position

[Miche03]

Hello,

 

I m working in my design with the Teseo-LIV3F chip, I copied the schematic and routing of the eval board of the Teseo-LIV3F. the amplification stage is also the same that the eval board but I received no GPS or no satellite position.

 

I read many similar posts on this subject, and the issue is often due to RF section (wrong value of passive component for decoupling capacitor) or antennas. I need a MMCX antenna to connect to my PCB and I think maybe the choice of my antenna is not good.

I attached my schematic and theses are the caracteristics of the antenna and amplification 

 

Caractéristiques de l'antenne:
Amplifier Gain without cable: 27 dB Typical
Noise Figure: 1.5 dB Typical
Filtering: -25 dB (+ 100MHz)
Output VSWR: 2.0 Max.
Alimentation: 3 à 5.0 Vcc
Consommation: 22 mA Max. @ 5 Vcc

Caractéristiques module amplification:
Frequency: 1575.42+2 MHz
VSWR: 1.5 Max.
Bandwidth: 10 MHz Min. 
Axial Ratio: 3 dB Typical
Impedance: 50 ohms
Peak Gain: 4 dBic Min.
Gain Coverage: > -4dBic at -90 ~ 90 (over 75% volume)
Power Handling: 1 watt
Polarization: RHCP

 

 

[Andrew Neil]

Are you testing in a location with a good, clear view of the sky? Can a devboard get a fix in that same position?

 

With RF design, it's not just about schematics - layout is also critical.

And with capacitors it's more than just the nominal capacitance value ...

[Miche03]

I dont know if my antenna is a good choice, do I need to choose a passive or active antenna? Do you have some choices with MMCX terminaison to suggest ?

 

Thank you

[Miche03]

Yes i tested in a good location, outside of the building on the parking but no difference with inside. 

I have not devboard but i will maybe buy it.

For the layout we respect the guidelines on the application note. 

I suggested capacitors because this topic seems to have the same issue that me.

https://community.st.com/t5/gnss-positioning/teseo-liv3f-no-signal/td-p/773998