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

From: Matt Ettus
Subject: Re: [Discuss-gnuradio] partial atsc 2.x in use
Date: Tue, 09 May 2006 23:03:04 -0700

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

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


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>

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