Re: LF: EbNaut and The Cat / Take 3

[Markus Vester <markusvester@aol.com>]

And any proper test will sometimes fail ;-) No success here on the 21:30 transmission, only a couple of bogus decodes with very high rank numbers. The signal is competely invisible now, and to make thnigs worse DCF39 has gone into another hyperactive period, splattering all over the band. Will keep trying...

 

73, Markus

 

-----Ursprüngliche Mitteilung----- 
Von: Paul Nicholson <vlf0403@abelian.org>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 24 Nov 2015 11:04 pm
Betreff: Re: LF: EbNaut and The Cat / Take 3

Domenico wrote: 
 
 > a little signal, but decoded also here 
 
Excellent result.   That's the sort of test I like to 
see, where Eb/N0 = 0.7 dB and the program will have 
had to search for the phase and it had to use some 
list decoding.   That's a proper weak signal test. 
I guess it should stand another dB weaker. 
 
The 21:30 just decoded here with Eb/N0 = -0.6 dB and 
the phase pattern was -30  -60  -30  -60, might be 
propagation or my timing system having a hiatus. 
 
The symbol timing of the 21:00 looked good.  I tried 
some time shifts both ways and it didn't improve. 
 
Markus wrote: 
 
 > It seems that non-existing symbols with null 
 > amplitude are not being counted as symbol 
 > errors, which severely biases the error rate. 
 
Yes it looks like you're right, the zero symbols are 
not counting as errors.  They contribute neither positive 
or negative to the accumulated log-likelihood of the 
path metric.  It's effectively an erasure code.  I'll 
alter the BER arithmetic tomorrow, it probably should 
consider only the non-zero symbols.  Might need some 
thought. 
 
Have to go out now but the rx continues recording. 
-- 
Paul Nicholson 
--