On 3 Jan 2019 at 12:16, Bill Somerville wrote: > On 03/01/2019 12:07, Martin Davies G0HDB wrote: > > Just out of interest, is there any particular technical reason why the > > extra 'word' for inclusion > > in a directional CQ message couldn't incorporate numeric characters as well > > as letters? It > > would add a bit more flexibility to directional CQ'ing, eg. the ability to > > call CQ to say W6 or > > UA0. > > Hi Martin, > > it is simply a size limitation, adding the possibility of one of ten > digits to each of 4 character positions increases the permutations from > > 27 x 27 x 27 x 27 = 531441 and requires 19 bits > > to > > 37 * 37 * 37 * 37 = 1874161 and requires 20 bits > > actually the value shares some bits with the possibility of a standard > callsign, QRZ, DE, or CQ and a 3 digit numeric values use for MS split > working from a calling frequency. > > Whatever way you look at it, there are not enough bits in a 77-bit > payload to represent both letters and digits for directional CW calls. > > 73 > Bill > G4WJS.
Hi again Bill, many thanks for the very informative reply - it's good to be able to understand the reasons why some things just aren't possible! I'll have to try to restrict my directional CQ qualifiers to letters only, although I suspect if someone saw a CQ call in the form <CQ_W6W7> G0HDB IO82 they might be able to work out which call areas I was looking for... :-) If someone saw a CQ in that format and double-clicked on my callsign would the normal QSO sequence start, or is a message in that format treated as free-text and therefore not clickable? -- 73, Martin G0HDB --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
