[UK-CONTEST] Data contests

[David G3YYD]

PSK31 uses a character coding system called varicode. It uses different 
numbers of bits for each character which is related to the frequency of 
use of that character. This means that upper case characters being used 
less frequently than lower case characters have a higher bit count. QED 
if you want to communicate faster use lower case. Example g3yyd would be 
sent faster than G3YYD.  Or david will be slightly faster than David.

73 David G3YYD

On 22/01/2011 17:31, geoff plucknett wrote:
>
> Its interesting regarding lower case. I noticed on Thursday that some 
> people were sending their exchange in lower case. Some were mixed eg 
> most of the exchange in lower case but my call in upper case!
>
> I'm sure there is some science to it but I've never explored it.
>
> MixW 2.18 in use here so I might have a look.
>
> Geoff
>
> On 22 January 2011 15:21, ALEX LISTER <alexcom22 at btopenworld.com 
> <mailto:alexcom22 at btopenworld.com>> wrote:
>
>     Also if ur software has it turn off AFC particurly on BPSK
>     Also I understand the is some advantage to using lower case on BPSK
>     Obviously upper or lower on RTTY makes no difference..
>     I wish I could find how to i/p Letter shift and CR/LF on the TX
>     preamble on my MIXw2 package .
>     And force Letter shift on RX as per a real teleprinter
>     Alex
>
>     ------------------------------------------------------------------------
>     *From:* geoff plucknett <geoffg4fka at virginmedia.com
>     <mailto:geoffg4fka at virginmedia.com>>
>     *To:* David G3YYD <g3yyd at btinternet.com <mailto:g3yyd at btinternet.com>>
>     *Cc:* UK-Contest at contesting.com <mailto:UK-Contest at contesting.com>
>     *Sent:* Saturday, 22 January, 2011 12:40:44
>     *Subject:* Re: [UK-CONTEST] Data contests
>
>     Also agree with the general sentiment.
>
>     And to add to an earlier thread, turn off your speech compressors.
>     Some of
>     those PSK signals on Thursday looked like a 6 lane motorway!
>
>     Geoff G4FKA
>
>     On 22 January 2011 10:36, David G3YYD <g3yyd at btinternet.com
>     <mailto:g3yyd at btinternet.com>> wrote:
>
>     > 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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