[Discuss-gnuradio] Complex square wave source

[Nick Foster]

This is probably a Tom question, but I'm of course open to suggestions from anyone.

This is a restatement of Mario Ruz's question on 6/8 after additional conversation on the IRC channel. I think it didn't get much response due to the way it was phrased.

I'm not much of a DSP fundamentals guy, so take this with a grain of salt. Currently, the complex square source outputs a 90-degree-delayed square wave on the imaginary output, rather than an actual analytic square wave, which can be approximated by passing a float square source through a Hilbert filter. The imaginary component in that case is (2/pi)*ln(tan(t/2)); when used with complex input I believe the imaginary part of the result will actually be the real square wave component, since it's a Hilbert transform and so it's reciprocal.

The same general comment applies to the sawtooth and triangle wave sources although their analytic representations are different.

So, I don't actually care what the square wave source emits if there's a reason for it, but was there a reason it was implemented as a delayed square wave rather than the analytic representation? Is there actually a use for complex square/saw/triangle wave sources? Am I just causing trouble and it's way too late to be changing the behavior of this block?

--n