# How to use SDR equipment and Gnuraio record time domain data?

A comment has pointed out that one could think of the saved data as in the time domain under some circumstances because it is literally series of 32-bit values written as fast as possible in time order. I think this is a conceptual mistake

As gnuradio sink data byte by byte,not second by second,Can I suppose time scale of data is uniform distribution? If not,can I process data with fft(data)?

• hi! Your link to an answer is sadly broken! Could you fix it? I think the context of the answer might really help here! Apr 5 at 11:41
• Ah found it, fixed it. The literal next sentence after the sentence you've copied seems to answer your question. Apr 5 at 11:45
• In my Answer I link to the GNU Radio tutorial that shows how you can simulate a frequency sink using an FFT and other blocks, which shows how this works. Of course, the FFT block also works in reverse, which you could experiment with. Apr 5 at 12:44
• @jdv,FFT block in gnuradio is multiply with window.Is there pure FFT block in gnuradio? Apr 6 at 20:31
• @kittygirl not sure. The window size is optional, I recall. Apr 6 at 21:10

It only really holds for data that you know is sensible values vs. time.

And a time-domain sampled signal is exactly that. As, by the way, two sentences later also already tell you:

So, yes. If you are capturing Complex data, it will be a series of real and imaginary parts in order that could be easily expressed as being in the time domain.

also:

can I process data with fft(data)

we already established you can, in other questions of yours. You do need to read back the data in its original format. Which complex numbers composed of interleaved 32 bit floats in your machine-native format.

• the fact that you're sampling at a sampling rate. The LO has absolutely nothing to do with it. I think it would be a very good idea if you took a big step back und made a drawing of your system, which involves everything from the receive antenna to the file sink, and clearly label what kind of signal (band pass or low pass and continuous-time or discrete time) you have at each point. Apr 6 at 20:53
• I'm just going to give this answer a down-vote because I think it's poorly written. Jun 21 at 14:10
• I meant "Can I suppose time scale of data is uniform distribution?" It seems to me that (as you say) the whole point of the sample rate is how fast we can stream the data to the file, but I don't think there is any promise of a range of this "time domain" data being put in the file uniformly across time. Jun 21 at 17:12
• Hey Jack, I don't think that's a good reason for downvoting an answer! Jun 22 at 15:55
• @Jack0220 "I don't like it" isn't a reasonable reason to downvote. Jun 22 at 20:41