Andy and others,
re Jim's comments :
>
> I have been thinking along similar
> lines for somewhat different reasons. I don't claim to have
> expertise in this field, but suppose the data rate of Wolf was
> reduced by a factor of 10, ie, to 1 bit per second. What would be
> the effects?
>
I was not proposing just slowing Wolf down, I was arguing the merits of
using Uncoded BPSK for the same performance (a-la VE2IQ & Coherent) but
at 1 b/s - this would give a few extra dB capability immediately. With
Wolf coding as well, this could give 10 dB extra but at 16 minutes for a
15 character message.
I suggest that there are also middle options. At LF there are "lightning
pops" and some forms of QRM that are that are "bursty", and either could
thwart successful decoding of a few parts of a message, but inbetween noise
bursts the RF S/N conditions could be satisfactory for reception. So having
some redundancy is desirable, especially for a text messaging system. The
question is in the selection of the degree of coding overhead. I do not
have a suggestion as to where the optimum answer lies.
73, Bob ZL2CA
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