Hi Pavel,
Thanks for the additional information. Your choices make good sense.
Do keep in mind that the sequential decoders in wsprd and wsprd_exp have
an easy-to-use tuning parameter, "maxcycles". In wsprd_exp.c it's
defined on line 628:
unsigned int maxcycles=10000; //Decoder timeout limit
You can probably speed up your decodes by nearly a factor of 2 by
changing the number to 5000. The cost will likely be less than 0.5 dB
in sensitivity, perhaps ~1% in number of decodes.
-- Joe, K1JT
On 3/30/2016 3:26 PM, Pavel Demin wrote:
> Hi Joe,
>
> Thank you for confirming that switching to floats should be relatively safe.
>
> I started to use wsprd_exp after reading the following threads on this
> mailing list:
> https://sourceforge.net/p/wsjt/mailman/message/34326507/
> https://sourceforge.net/p/wsjt/mailman/message/34334059/
>
> Looks like wsprd_exp already worked very well more than six months ago
> and wsprd_exp -J produced more decodes than wsprd.
>
> Since I'm running wpsrd_exp on a small embedded system (Red Pitaya) and
> decoding eight WSPR bands simultaneously, other factors like simple
> installation and high performance are also important for me.
>
> Out of the box, wpsrd_exp is more than 20% faster than wpsrd on my
> system and I can easily install wpsrd_exp (but can't wpsrd) with just
> two commands:
> svn co svn://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx/lib/wsprd
> make -C wsprd CFLAGS='...' wsprd_exp
>
> All in all, the experimental status of the wsprd_exp code fits very well
> the experimental status of my multiband WSPR receiver and I'm having a
> lot of fun with both :-)
>
> Best regards,
>
> Pavel
>
> Joe Taylor wrote:
>> Hi Pavel and all,
>>
>> Thanks for your effort on optimizations in wsprd. The change from
>> doubles to floats has been on our "To Do" list for many weeks. We
>> didn't get around to it because the potential gains (though desirable)
>> were not likely to be huge. Floats have enough precision for use in all
>> the long arrays.
>>
>> Is there a reason why you worked with wsprd_exp rather than wsprd? Our
>> "production code" is wsprd; wsprd_exp is an experimental version that
>> uses the "Jelinek" rather than "Fano" algorithm for sequential decoding
>> of the convolutional code.
>>
>> -- Joe, K1JT
>>
>
>
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