Birth of the 32bit RS232 spectrum analyser

It is time to revisit the RS232 spectrum analyser. Below is an image of some prototyping on a breadboard followed by a soldered working version including a SMA connection. The problem with the previous spectrum analyser was mainly in the computation of the frequency set registers which involved large 9 digit values, a hard feat for a 8 bit micro controller. This time around a 32 bit micro controller, the PIC32MX220B032, will be used. This will allow for a maximum clock frequency of 50MHz leaving the radios internal frequency settling time as the only limiting factor to the spectrum analyzer sweep time. The proposed specification for this spectrum analyzer are as follows:

  • Bandwidth 260MHz – 960MHz (Realisticly about 150MHz according to the input filter of the RFM22B model used)
  • 2ms per sample
  • Sweep and Discrete measurement modes
  • Calibration mode (Calibrates the device with the help of a sweeping signal generator)
  • Wireless trace measurement (Two devices needed, one as a base station)
  • SD card for onboard storage and buffering
  • Connecivity – FTDI cable and rasberrypi GPIO connector header
  • Form factor: 1 square inch
    Soldered working version without SD card

    Soldered working version without SD card

    Breadboard prototyping of the 32bit spectrum analyser

    Breadboard prototyping of the 32bit spectrum analyser

Posted in Projects, RFM22B Spectrum Analyzer.

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