Thank you all for your responses. I will look into the suggested libraries and blocks to see if they can work for me.
My goal right now is to simulate a dynamic frequency offset on higher frequency (2.4GHz and above) and wideband signals (1 MSps and above) for say a LEO satellite. This scenario would assume I should simulate some type of expansion and contraction on the signal bandwidth. I will try the periodic callback suggestion from Mr Estevez and see if that works for my Doppler simulation at LEO. Thanks, Jose On Fri, Jul 28, 2023 at 8:58 AM Daniel Estévez <dan...@destevez.net> wrote: > Hi all, > > Whether a resample (i.e., group delay change) is needed depends on the > intended application. The question you need to ask yourself is: is the > fact that in real life the Doppler at each frequency in your passband is > slightly different because they are all different carrier frequencies > relevant, or is it not and can we just take the Doppler for the centre > frequency as Doppler for all frequencies? > > If a resample is needed, then it is easy to do a constant resampler rate > (corresponding to constant Doppler) by using the Polyphase Arbitrary > Resampler (or the Channel Model block, which contains a Polyphase > Arbitrary Resampler). Currently there isn't a simple way to make the > resample rate change over time (corresponding to Doppler change over > time). Perhaps a simple solution is to periodically call the callback to > update the resample rate, according to the required Doppler curve. > > Best, > Daniel. > > On 27/07/2023 22:54, Tim Meehan wrote: > > Hi Jose, > > > > I would take a look at gr_sattelite. The work described here > > > https://destevez.net/2022/07/real-time-doppler-correction-with-gnu-radio/ > > was integrated. A true doppler correction would need to also > > resample, but the time varying frequency correction may be enough for > > your use case. > > > > Tim > > > > On Thu, Jul 27, 2023 at 1:19 PM Jose Ruvalcaba <joruv...@gmail.com> > wrote: > >> > >> Hello, > >> > >> I am trying to simulate an accurate representation of Doppler Shift in > a channel and I was told that to do this I would have to multiply a complex > signal with a cosine and implement a resampler block to simulate the signal > samples that are coming closer or farther away from each other. > >> > >> My question is this, can I use either the rational resampler or > fractional resampler block in GNU Radio to dynamically simulate samples > moving closer or farther than each other? Or would I need to make my own > OOT block to do this? > >> > >> I tried using a QT GUI Range block to change the resampling ratio of a > fractional resampler but my flowgraph froze. > >> > >> Any suggestions? > >> > >> Thanks, > >> Jose > > > >
