On Wed, Feb 23, 2011 at 5:41 PM, Tuan (Johnny) Ta <ta.tu...@gmail.com>wrote:
> A lot of people seem to have problem with the OFDM receiver in gnuradio. > Since there's no confirmation of a working *2-way* communication using > OFDM yet, I've decided to dig into the OFDM receiver implementation. I want > to test the performance of the OFDM synchronization block. To do that, first > I want to isolate the ofdm_sync block and make sure the rest of the chain > works. > > I found that there is a test file for OFDM mod and demod, named > ofdm_mod_demod_test.py, without invoking OFDM synchronization, FFT, preamble > and cyclic. However, that code is outdated and not applicable for the > current implementation. > > I'm trying to generate similar test code for the current version of OFDM > mod and demod but there seems to be no straight-forward way. It used to be > that we can hook the ofdm_mapper straight into an ofdm_frame_sink. It's no > long the case as the frame_sink now requires a 2nd input, which is a stream > of bytes signaling the beginning of a symbol. This input is provided by > ofdm_frame_acquisition, which in turn requires the signaling from the > ofdm_sampler. The ofdm_sampler gets the signaling from the ofdm_sync x_x. > > Long story short, I haven't found a way to test the system while bypassing > the ofdm_sync block yet. Can anyone give me some suggestion? > > Thanks a lot, > > Johnny > Johnny, Try using the "fixed" version of the ofdm_sync block found on line 96 of ofdm_receiver.py. This takes information about what you expect the timing and frequency offset to be and does nothing but use that to trigger the follow-on components. It was made for doing exactly the kind of things you are looking at doing. Tom
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