Front-end Gain calibration Procedure

Objective

Measure the total system gain at the output of the RSSI and equalize it.

Turn on equipment
- Spectrum analizer
- Power supply
Configure to desired parameters
- Spectrum analizer
  - Set center frequency in the middle of VCO output band (6250MHz)
  - Set span to match the VCO output band (1400MHz)
  - Set RBW and VBW to an adecuate level
- Power supply
  - Set Voltage to 3.3V
  - Set current limit to 0.3A
Set up nucleo board and PC
- Make sure the proper code is loaded into the nucleo board
- Connect the power supply to the payload:
  - Vcc to PoL (RED)
  - GND to GND (BLACK)
- Connect the DAC output to the DAC_In (GREEN)
- Connect the ADC input to the ADC_Out
- Load the IF Input with a 50 Ohm perfectly matched load.
- Connect the spectrum analizer to the switched measuring pin (PURPLE)
  Make connections
- Connect PC to ground (plug in the charger)
- Connect necleo board to computer by USB
Power on power supply
Begin the measurements procedure
- Run the flashed program in Debug mode
- Once the program stops at the breakpoint, collect the calculated mean and plot it in a data processing software like Matlab.
Realize the calibration
- Calculate the mean of the collected data and substract it from each frequency bin mean. This will be the deviation.
- Extract the trend line from the deviation.
- Subtract trend line function from the received RSSI value. This will be the calibrated measurement.
Reboot the program and check if the equalization is now correct. If it’s not correct repeat the previous step