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  2. psk characters speed

Re: psk characters speed

David Westbrook
 

thanks steve!

If the rate is the same, and QPSK provides FEC (forward error correctrion)
for robust decodes, why isn't it used more?

Is is because of the latency? (from wiki) "To successfully decode an
input bit requires a large number of phase shift sequences to be received,
causing a 20 bit, 640 millisecond latency (delay) in the output of the
decoder"
Or because we just d_n't r_a_ly n__d 10_% cp_ to un_ers__d th_ m___age?
Or other (historical/etc) reasons?

--david
kj4izw

On Mon, Jan 7, 2013 at 10:00 AM, melachri <w3hf@...> wrote:

**



===> I'm looking for someone more knowledgeable than me about the inner
workings of the BPSK31 mode to verify the calculations...
I based it one the varicode length (from Wikipedia) plus '00' between
characters, and 32ms per bit.
I didn't check your lookup table, but the 00 delimiter and 32 ms per bit
parameters are correct.

And FWIW, it's the same for QPSK31. Although QPSK encodes two bits per
modulation symbol, the rate-1/2 convolutional code exactly compensates,
making the character rate identical.

Steve
W3HF
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