Re: psk or PSK


Steve W3HF
 

It takes a little bit longer for psk31 to send a CAPITAL LETTER,

To test my theory I typed the same macro in both upper and lower
cases...it is a
surprising difference in speed!

Duncan (and others) -

You are exactly correct. The actual speed of characters is dependent
on the distribution of letters in the text, but on average, capital
letters are 2-3 bits longer than lower-case in the Varicode used in
PSK31.

I think lower-case letters average about 5-6 bits each (averaged over
English text), and upper-case about 8-9. This has the two effects
Duncan mentioned:

1. At a rate of 31 bits per second, lower case will produce about 5
letters per second, versus 4 letters per second for upper case. This
means your message gets through faster.

2. You also only have to get 5 or 6 bits correct for the software to
decode a lower case letter, three less than for an upper case. For a
fixed bit error rate, this means the letter error rate will be lower
for lower case than for upper case.

Finally, there is the "email rule": capital letters are usually used
for emphasis (i.e., shouting), and are sometimes considered rude for
routine use.

Steve
W3HF

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