KB: How to enable PSK modulation and control phase transitions on AX5043

The AX5043 transceivers natively support PSK modulation.
We suggest to use AX-RadioLab to automatically generate the optimal radio register settings for a given application. PSK modulation can be selected among the available modulation schemes via the PHY panel.
More information on how to use the GUI for setting up the radio can be found in the AX-RadioLab User Manual.

In case an external microcontroller is used to drive our AX5043, here the steps that needs to be followed to enable PSK modulation:

  1. Program the PLLLOOP and PLLVCODIV registers;
  2. Program the frequency registers {FREQA0, FREQA1, FREQA2, FREQA3};
  3. Program the MODCFGA and MODCFGP registers (MODCFGP takes care of PSK settings, see picture below);
  4. Program the TXPWRCOEFFB0, TXPWRCOEFFB1 for the desired power (use A/C/D register if predistortion is required);
  5. Program the IFFREQ0, IFFREQ1;
  6. Program the MODULATION register (setting MODULATION = 0x04 for PSK);
  7. Program the tracking loop dynamics registers PHASEGAIN, FREQGAIN, and AMPLGAIN;
  8. Program the AGC dynamics registers AGCGAIN;
  9. Program the ENCODING register;
  10. Program the FRAMING register;
  11. Program the PINFUNCSYSCLK, PINFUNCDCLK, PINFUNCDATA, PINFUNCIRQ, PINFUN- CANTSEL, PINFUNCPWRAMP according to the desired pin usage.

In PSK mode, the phase transition will always be in 180 degrees jumps, and what can further configured is the direction of the phase transition. As shown below on a spectrum analyzer set into FM demodulation, the direction of the phase transition, displayed as instantaneous frequency variation, changes depending on the programmed PSKPULSECFG value.

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