git.gag.com Git - debian/gnuradio/blob - gr-atsc/README.signal_flow

   1 This describes the signal flow through the gnuradio-0.9 ATSC Transmitter
   2 and Receiver programs.
   3
   4 ATSC Transmitter
   5 ================
   6
   7 module                  input                         output                       notes
   8 --------------------    ----------------              -------------------          --------
   9 VrFileSource            "MPEG transport stream"       atsc_mpeg_packet
  10 GrAtscRandomizer        atsc_mpeg_packet              atsc_mpeg_packet_no_sync     whiten data with LFSR
  11 GrAtscRSEncoder         atsc_mpeg_packet_no_sync      atsc_mpeg_packet_rs_encoded  Reed-Soloman encoder
  12 GrAtscInterleaver       atsc_mpeg_packet_rs_encoded   atsc_mpeg_packet_rs_encoded  convolutional interleaver
  13 GrAtscTrellisEncoder    atsc_mpeg_packet_rs_encoded   atsc_data_segment            trellis encoder
  14 GrAtscFieldSyncMux      atsc_data_segment             atsc_data_segment            add in field syncs
  15 GrAtscSymbolMapper      atsc_data_segment             float                        map [0,7] to +/- {1,3,5,7} and add pilot
  16 GrWeaverModHead         float                         float,float                  front half of Weaver VSB modulator
  17 GrFIRfilterFFF (2x)     float                         float                        low pass root raised cosine (matched filter)
  18 GrWeaverModTail         float,float                   short                        back half of Weaver VSB modulator
  19 VrFileSink              short                         "16-bit passband data"
  20
  21
  22 ATSC Receiver
  23 =============
  24
  25 module                    input                        output                       notes
  26 --------------------      ----------------             -------------------          -------
  27 VrFileSource              "16-bit passband data"       short
  28 GrConvertSF               short                        float                        convert short to float
  29 GrFIRfilterFFF            float                        float                        band pass root raised cosine centered at IF freq (matched filter)
  30 GrAtscFPLL                float                        float                        carrier tracking freq and phase lock loop with down converting mixer
  31 GrFIRfilterFFF            float                        float                        low pass to kill unwanted mixer image
  32 GrRemoveDcFFF             float                        float                        remove DC offset prior to symbol timing module
  33 GrAtscBitTimingLoop3      float                        float,syminfo                track symbol & segment timing and do fractional interpolation
  34 GrAtscFieldSyncChecker    float,syminfo                float,syminfo                look for field sync patterns
  35 GrAtscEqualizer           float,syminfo                float,syminfo                LMS equalizer
  36 GrAtscFieldSyncDemux      float,syminfo                atsc_soft_data_segment       remove field syncs and pack into data segments
  37 GrAtscViterbiDecoder      atsc_soft_data_segment       atsc_mpeg_packet_rs_encoded  Viterbi decoder (12 seg delay)
  38 GrAtscDeinterleaver       atsc_mpeg_packet_rs_encoded  atsc_mpeg_packet_rs_encoded  convolutional de-interleaver (52 seg delay)
  39 GrAtscRSDecoder           atsc_mpeg_packet_rs_encoded  atsc_mpeg_packet_no_sync     Reed-Solomon decoder
  40 GrAtscDerandomizer        atsc_mpeg_packet_no_sync     atsc_mpeg_packet             de-whiten with LFSR
  41 VrFileSink                atsc_mpeg_packet             "MPEG transport stream"