Hi , as I said in the previous question, I have designed a GNSS module with STA8089GA IC which works properly. It easily determines the 3D position, under two minutes, when I use an active antenna. Also, I use a GNSS simulator to demonstrate its functionality. By setting the simulator on satellite ID 10 with -80 dBm power and 42.5 dB/Hz CN0 and performing @PSTMRFTESTON,10 command on the IC, the CN0 is 43 dB/Hz based on the Teseo-Suite Pro software. The IC I use has two IF (Intermediate Frequency) pins to determines its RF front-end functionality which I want to use them to determines NF (Noise Figure). In the application notes of the IC, it is mentioned that to activate these pins you need to perform a NMEA command. But I cannot find the NMEA command. Does anybody know what is the command to activate these pins?
Also, because the IF pins are differential, a differential to single ampilfer is needed. The amplifier I used is shown in the picture. I want to know, does input impedance of the amplifier can load the IF pins and degrade the overall IC functionality? Should I increase its input impedance?
Any advice or help is appreciated.
Armin
