Hi Avinash, that's pretty much a basic OFDM question:
You take the DFT of the input signal. Hence, the bins of the DFT are f_nyquist/l_fft spaced. Best regards, Marcus On 17.06.2016 17:57, avinash kalyanaraman wrote: > Thanks Marcus - that helps. > > Could you please let me know what's the bandwidth of each sub-carrier? > How can I calculate that and reconfigure the same? > > > On Sat, Jun 18, 2016 at 12:50 AM, Marcus Müller > <[email protected] <mailto:[email protected]>> wrote: > > Hi Avinash, > > On 06/16/2016 03:29 PM, avinash kalyanaraman wrote: >> i) These 64 complex values (a + ib) represent the 64 sub-carriers >> and I can get the amplitude and phase of each sub-carrier as >> sqrt( a^2 + b^2) and arctan(b/a) respectively ? > Yes. >> >> ii) I see that the CSI calculation is per tag. I understand from >> your link that the tag represents additional information/metadata >> attached to a specific item. However, in this case, I am unsure >> what a tag denotes? In other words, could you please tell me what >> a “tag” is being attached to here, on which a channel estimate is >> calculated? > If I remember correctly: > To the first sample of the "chunk" of samples that were used for > estimation, that is, on the first sample of the OFDM symbol. > > I do think that if you're into channel estimation, reading the > source code is very much worth your time, and you'll notice > variable and method names were chosen sensibly to make > understanding what's happening easier. Go for the get_chan_taps() > method in ofdm_chanest_vcvc_impl.cc; you'll find it in your GNU > Radio source tree; be sure to use a recent version of GNU Radio > (3.7.7 or later). >> >> iii) Please let me know what is the unit of rx_time ? Seconds? >> Offset: 76 Source: n/a Key: rx_time Value: {7 0.303} >> Offset: 77 Source: n/a Key: rx_time Value: {7 0.399} > http://gnuradio.org/doc/doxygen/page_uhd.html > > look for "timestamp" on that page. > > Best regards, > Marcus > > > > > -- > Avinash
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