I have converted atsc_field_sync_mux to type gr_block and added atsc_symbol_mapper and atsc_weaver_mod_head. The rest can be done using existing GR blocks; I don't frequency translate the signal away from complex baseband (see 3 below):
[atsc stuff] => [float_to_complex] => [fir_filter_ccf] => [pfb_arb_resampler_ccf] => [file sink] I have a couple more questions: 3) Is there a reason the weaver_mod_tail module was introduced as opposed to the output being complex baseband (-3 MHz to 3 MHz)? I could combine some of the other blocks with frequency translation to mimmic what was GrAtscWeaverModTail but im not sure that is the idea here. 4) What is the purpose of the atsci_x functions as opposed to atsc_x? Thanks, I'll get this cleaned up and documented and submit it. Jacob On Mon, Sep 26, 2011 at 8:56 AM, Tom Rondeau <trondeau1...@gmail.com> wrote: > On Sat, Sep 24, 2011 at 10:40 AM, Jay Jones <jg.g...@gmail.com> wrote: > >> Hi, >> >> I am relatively new to gnuradio block-level development and am working >> with the gr-atsc module. I am specifically interested in the transmit >> portion and have a few [likely elementary] questions: >> >> 1) From what I can see the transmit functionality is only implemented up >> to the atsc_field_sync_mux(), I don't see the symbol mapping or VSB >> modulation though I have read a few other posts that suggest it is there. >> The gnuradio 0.9 has GrAtscWeaverModHead and GrAtscWeaverModTail header >> files but maybe these did not get modified into gr 3.x. >> > > Well, the atsc receive functionality hasn't worked properly for some time. > It's been on my todo list for ages, but I haven't gotten there, yet, so if > you are working on it and can fix it up, that would be great! > > So having said that, no, I don't think all of the pieces to make an atsc > transmitter are there, either. So I don't think you are wasting your time or > far off track. > > >> 2) The atsc_field_sync_mux block is derived from gr_sync_block however it >> outputs more data fields than it consumes (by a factor of 313/312). Even >> though this seems to work, for my own benefit I re-did this as a gr_block >> but I am not sure if that is necessary; could someone shed some light on why >> gr_sync_block works (or appears to but doesn't)? >> >> Thanks for your time, JJ >> > > Yes, if the block is outputting 313 and consuming 312 items, then it's not > a sync block, so it sounds like you are doing the right thing. Being off by > that small amount will have an effect, but my guess is that it was minimal. > Maybe a blip or overwriting a value or two here and there. So it was > probably that the problem wasn't noticeable but present. > > Let us know how you're getting along with it. > > Tom > >
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