Re: [wsjt-devel] 13 characters free text feature in FT8/MSK144 : a question

[Bill S. <g4...@cl...>]

On 27/12/2018 23:36, ON4KHG wrote:
> Dears,
>
>
>
> In WSJT-X, in FT8 or MSK144, I like the "13 characters free text" feature. This allows to send one's power/ant, name, etc and to extend the QSO to more than the minimum minimorum sometimes.
> I have one question on that subject : is the sensitivity of the decoder different for this kind of messages (the free text ones) than for the structured messages ?
>
> When at the end of a QSO I send the free text "73 XYZ TU" (XYZ = name), my QSO partner sometimes keeps on sending (eg) "ON4KHG F6ABC RRR" (or RR73) until I finally send "F6ABC ON4KHG 73".
> My question above in other words : does my QSO partner sees "73 XYZ TU" equally well as "F6ABC ON4KHG 73" ? I suppose yes but when he has the Auto Seq on, the auto sequencer waits for a structured msg like "F6ABC ON4KHG 73" to further proceed ? Is my assumption right ?
>
> Thanks in advance for your feed-back.
> 73 and Happy New Year 2019,
>
> Gaëtan, ON4KHG
> http://on4khg.be

Hi Gaëtan,

there are some potential sensitivity advantages to the standard messages 
if AP decoding is enabled. AP decoding of a standard 73 message from 
your QSO partner only needs to decode the 73 word and a valid checksum 
since it can assume both of the callsigns so their bits and some FEC 
parity bits can be lost in the QRM without impairing a successful decode.

Any message with the word 73 and your QSO partner's callsign should be 
taken by the auto-sequencer as equivalent to a 73 standard message. 
Messages without your QSO partners callsign cannot be considered by the 
auto-sequencer as it has no clear means to determine the message was 
actually for them. OTOH your QSO partner is supposed to be looking at 
the messages and reacting to them so a station that copies your "73 XYZ 
TU" message really ought to quit the QSO by pressing the "Halt Tx" or 
"Enable Tx" button.

73
Bill
G4WJS.