Re: [Discuss-gnuradio] partial atsc 2.x in use

[Matt Ettus]

You're making great progress!  Any idea what's wrong with the 2.0 bit
timing?

Once you get that done we can work on some serious optimization, since
the chain as constituted has a lot of redundancy.

Matt

On Mon, 2006-05-08 at 14:57 -0400, Charles Swiger wrote:
> It turns out to be not too awefully difficult (tho not officially
> approved ;)   to modify the gnuradio-0.9 atsc code to use a subset
> of blocks, specifically everything from bit-timing-loop to
> field-sync-demux (float in, soft-data-segments out).   So here's
> what I have working across 4 cpu's:
> 
> Start with 8Msps complex with signal centered on 0Hz
> using usrp_rx_cfile.py to collect data.
> 
> Then simultaneously running:
> 
> 1) One fully 2.x module upsamples to 20Msps and translates
> to 5.75Mhz center float, using 99% of one cpu - this is the
> bottleneck - piped to:
> 
> 2) A fully 2.x module with root-raised-cosine filter (taps
> calculated in python using the 0.9 filter method), the ported
> (formerly 0.9) FPLL, and remove-DC (iir), using about 60%
> of another cpu, piped to:
> 
> 3) the old 0.9 bit-timing thru fs-demux code, about 55% of
> another cpu, piped to
> 
> 4) The 2.x Viterbi, Deinterleaver, Reed-Soloman decoder
> and de-randomizer, about 20% of the 4th cpu.
> 
> 
> It took some hacking on packet padding and de-padding but
> the chain works, with some room for moving processes
> around and optimizing. For instance, the RF gets mixed
> and translated twice. A complex FPLL could handle that
> in one step using, say, a more convenient 16Msps (8->16,
> instead of 8->40->20)
> 
> Earlier the busiest cpu was only at 60% - switching from
> Samba to NFS (the rf datafiles are on another machine) 
> moved the bottleneck off the network disk sharing to the
> resampler module.
> 
> --Chuck
> 
> 
> 
> 
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-- 
Matt Ettus <address@hidden>