Front-end Gain calibration Procedure

Objective

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

Steps to follow

• 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