I am currently trying to realize this block diagram in Gnu Radio Companion:

OQPSK modulation and demodulation

Before using a file source block with the binary I want to send, I plan on just using a vector with an alternating 1,0 pattern (e.g., [1,0,1,0....])

From there for the Serial to Parallel piece which block would I use? Does such a block exist; if so I am not able to find it. The way I picture this is that the first bit would go to the I multiply portion and the next bit to the Q.

[1,0,1,0] [1 -> I] [0 -> Q] [1 -> I] [0 -> Q]

Is that the right understanding?

Or would it be that, let's say 8 bits were transmitted at the same time to I and Q simultaneously and the Q branch would be on a delay?

Edit: I think that I don't need to do that serial to parallel at all.

Current setup: enter image description here

enter image description here

Something might be a little off though

enter image description here

  • $\begingroup$ I believe that with Offset QPSK, that the T/2 delay is naturally implemented by picking out the even-indexed bits and routing those to the in-phase (I) component and routing the odd-indexed bits (which are delayed by T/2, compared to the even bits) to the quadrature (Q) component. so it's a demultiplexing operation, no need to do "serial-to-parallel" and then apply T/2. I think your understanding is right. $\endgroup$ Commented Sep 10, 2021 at 18:49
  • $\begingroup$ I edited the comment above. I think it is possible just to multiplex but I still think I have something slightly off. $\endgroup$
    – dee_es_pee
    Commented Sep 12, 2021 at 1:56
  • $\begingroup$ I am no QPSK expert, but i have recently been thinking out loud about Offset QPSK, which I think is elegant . another and another. $\endgroup$ Commented Sep 12, 2021 at 4:22


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