Hi Gilad, find something that actually produces a singing sine attached. Notice that the waterfall sink display isn't "perfect" by means of being a constant-height zig-zag line. But that was never to be expected – the DFT simply produces higher amplitudes at frequencies that are actually exactly "hit" by the signal, and since the signal frequency changes continously, this can't be always the case.
I don't think I can salvage the example – it's really an illustration of what not to do with a signal probe; if you want one signal to somehow modulate the other, you'd always (and that's the whole idea behind GR) combine the two sample streams, and not employ some inaccurate, hackish python-function-probing mechanism. So please don't take the example from the wiki as guideline for building modulators! Best regards, Marcus On 14.11.2016 13:23, Marcus Müller wrote: > > Hi Gilad, > > yes, that's now my new not-favourite example, because it uses a signal > probe where it shouldn't be using a signal probe. You're right, this > *cannot* work reliably. (to explain: GNU Radio blocks always run as > fast as possible. For example, the the signal probe just drops the > signal as fast as possible, but "writes down" the last value every > iteration; thus, the triangle-generating signal source runs as fast as > it can, and probably produces 10s of millions of samples per second. > Thus, the value seen by the function probe every roughly so and so > many milliseconds is absolutely random. I wonder under which > conditions this flowgraph used to work; in theory, we've tested them > all :) ooops) > > I'll fix the example and let you know as soon as I have something > better for you :) > > Best regards, > > Marcus > > On 14.11.2016 06:03, Gilad Beeri (ApolloShield) wrote: >> Hi, >> Going over tutorial >> 2 http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_GRC, >> trying the last example (a triangle wave, prove signal and a sine >> wave), which based on common sense and the image in the tutorial, >> should result in a periodic triangle shape in the waterfall scope. >> >> I get a completely different result, see image attached. >> My flowgraph seems to be accurate, also when running >> tutorial_two_7.grc from the examples I get the same result. >> >> GNU Radio 3.7.10.1, mac OS 10.12.1. >> >> Do you have an idea why I don't get the expected shape? >> >> This is the image from the >> tutorial: >> https://raw.githubusercontent.com/gnuradio/gr-tutorial/master/examples/tutorial2/images/singing_waterfall.png >> >> This is what I get (when running the example, not my own flowgraph): >> pasted1 >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
singing sine.grc
Description: application/gnuradio-grc
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