[UK-CONTEST] Data contests

[David G3YYD]

I agree, it is always up to the receiving station to ask for a repeat if 
there is any doubt about the received exchange being correct. Repeating 
the exchange back wastes time at the best and at the worst adds confusion.

N1MM software by deliberate design does not have a macro to allow the 
received exchange to be repeated back.

Same with RYs all that is needed is a space character before the first 
printable character is sent. This separates the wanted text from the 
previous garbage characters. Same goes for CRLF please do not do that as 
it means having to chase data as it scrolls up the screen. A space at 
the beginning  and at the end of a callsign helps callsign 
identification software to work and automatically grab the call cutting 
down operator fatigue. The same goes for the exchange bracketing each 
part of the exchange with space helps the software grab the correct data 
when clicked upon.

Also turn on UoS - Unshift on Space - for TX and RX this helps copy when 
figs/ltrs shifts become corrupted saving a repeat being asked for.

Also set the software to work with TX stop bit of 1.5 and RX of 1. This 
is selectable in MMTTY configuration menu. This setting gives more time 
for the RX to resynchronise if a corruption has caused the RX to respond 
to a false start bit.

On the sound card settings do not use 11025Hz sampling rate as modern 
sound cards will not provide an accurate rate. It is better to use 
12000Hz. Modern sound card sample at 48KHz or integer multiples of 
48KHz. The driver software then converts the 48KHz to the requested 
speed. As a result 12KHz is easy to do by sending every 4th sample to 
the decoding software. Generating 11025 from such a card will result in 
a compromise rate, which could be significantly different. This does 
result in TX/RX baud rate being incorrect along with the received tone. 
If using FSK this can mean you call people off frequency another reason 
for using AFSK rather than FSK.

The baud rate setting should be 45.45 and not 45.

73 David G3YYD

On 21/01/2011 20:11, Colin Chidgey wrote:
> I'm with Robin G3TKF on this one.
> Its plainly daft to send my report to you back to me!
> In poor conditions with broken reception I am likely to take
> a guess at the numbers coming back and the last number I need is
> mine repeated to me.
> Strings of RYRY are also silly.The RY sequence was used with mechanical
> teletype machines to exercise the cogs! My DSP/FFT software does not use
> cogs (I think).
> Colin G3YHV
>
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