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Removed failed ideas from TODO list.

This commit is contained in:
Joris van Rantwijk 2014-05-31 21:07:04 +02:00
parent 6a5ccbb818
commit c4c6c79765
2 changed files with 20 additions and 4 deletions
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20
NOTES.txt
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@ -207,6 +207,26 @@ Difference only clear in stereo mode.
Don't know what's going on here, maybe the DIY antenna is just not good. Don't know what's going on here, maybe the DIY antenna is just not good.
IF processing
-------------
Idea: Filter I/Q samples with 3rd order Butterworth filter
instead of 10th order FIR filter.
Implemented in branch "iirfilter".
Speed is unchanged.
Sound quality is not much changed for strong stations.
Sound quality is a bit worse for weak stations (at 1 MS/s).
Conclusion: not worthwhile.
Idea: Downsample I/Q samples to ~ 250 kS/s BEFORE quadrature detection
instead of immediately after detection. Would reduce amount of work in
I/Q filtering for same or higher FIR filter order.
Implemented in branch "filterif".
CPU time reduced by ~ 25%.
Sound quality very slightly worse.
Conclusion: not worthwhile.
Local radio stations Local radio stations
-------------------- --------------------

4
TODO.txt
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@ -1,6 +1,2 @@
* (speedup) maybe replace high-order FIR downsampling filter with 2nd order butterworth followed by lower order FIR filter * (speedup) maybe replace high-order FIR downsampling filter with 2nd order butterworth followed by lower order FIR filter
* (feature) implement RDS decoding * (feature) implement RDS decoding
* (quality) consider FM demodulation with PLL instead of phase discriminator
* (quality) consider pulse-counting discriminator
* (speedup) consider downsampling of IF signal before FM detection
(work in progress in branch "filterif")