I am trying to envision the circuit which will allow me to get PR-ASK modulation. Fundamentally there are two ways to produce the PR-ASK;

  1. Toggling digital data between +- V and mixing it with CW at Mixer stage, OR
  2. managing to introduce a phase shift of 180 degrees at each transition of digital data.

Now my questions how do I realize this in real life? I am using MCU to generate digital data (data rate 100 kbps) and feed it to Transceiver IC (S2LP) via GPIO and then mix it with CW (866 MHz) generated from S2LP at the mixer stage. My MCU is capable of toggling digital data between + V and 0 V.

IS there any other way by which I can achieve PR-ASK using S2LP? Like using some of the values of the registers which are generating ASK modulation and other modulation types (FSK, 2-FSK, 4-FSK)?

  • \$\begingroup\$ Numbers are needed. What is the carrier wave frequency and what is the data rate. Those numbers can determine a likely solution. \$\endgroup\$
    – Andy aka
    Commented Apr 14, 2021 at 11:34
  • \$\begingroup\$ I have added the numbers, the CW would be 866 MHz and a datarate of 100 kbps. \$\endgroup\$ Commented Apr 14, 2021 at 11:41
  • \$\begingroup\$ I'd use a mixer module - try mini-circuits. \$\endgroup\$
    – Andy aka
    Commented Apr 14, 2021 at 11:44

1 Answer 1


I don't think you will be able to do what you got in mind.

But, anyway, try this:

use the S2LP internal ASK/OOK modulation an then modify the FIR filter in order to shape the carrier according to your needs.

After that, have the S2LP transceiver handle packets transmissions and receptions.

  • \$\begingroup\$ I was thinking on this line too. Using the FIR filter, I can certainly tune/shape the bandwidth. But I am sure this wont allow me to see the phase reversal at the data boundary in the time domain. BTW, is it possible to use CONST_MAPregister in S2LP to achieve phase shift with ASK modulation? Or this facility is only for FSK modulation? \$\endgroup\$ Commented Apr 15, 2021 at 4:47
  • \$\begingroup\$ I don't know. Try posting the question on the ST wireless forum or contact your local FAE. I strongly though that the S2LP transceiver is that flexible. \$\endgroup\$ Commented Apr 15, 2021 at 5:52

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