2023 Summer VHF UHF Field Day 14/15 January

[VK4ADC]

How many people read the WIA Summer VHF/UHF Field Day rules before the contest ??

I noted there were quite a few stations using FT8 on 6M (50.313) and all were using just 4-character grid exchanges. Now whether they planned to count these QSOs in the FD contest log, or not, I don't know BUT.. 

The rules quote :

"General Rules
There are no Divisions.
A Square refers to the Maidenhead Locator system definition, as denoted by the 4-character locator. This matters to Rovers, but no-one else.
All stations are required to exchange Sub-Square locations (i.e. the 6-character locator).
"

and then further down in Contest Exchanges  :
"For digital contacts, as RS or RST reports plus serial number make for a cumbersome exchange, it is sufficient to exchange callsigns and 6-character locators, plus two further digits that cannot be predicted by the other station.
"

The two values/chars that can't be predicted are typically going to be the relative signal level (eg -08dB, so the 0 and 8 are unique) but in contest mode, these exchanges are reflected in the "S" component of the RST part of the exchange.   There is a lookup table to convert signal levels down to -30dB to a relative S-unit value, and that all happens within WSJT-X (or equiv).

I should add at this point that the typical contest setup is by going into the Advanced tab from File/Settings and selecting "Special Operating Activity" and then the "EU VHF Contest". { Note that on the General tab, you may need to enable "VHF and sub-mode features" if the EU Contest mode is not available.}  This is the mode that uses 6-char grid exchanges so complies with the VHF Contest rules. Here is another BUT, but you need to set up the maidenhead grid value for your station as 6-char { beforehand ! } on the General tab.

What does it all mean ?  Theoretically, we can't use WSJT-X for digital modes (no two unpredictable chars option) or, if we do in practice, the rules say the QSOs are invalid.

A future option is to specify VHF EU Contest mode in the rules for digital modes like FT4, FT8, Q65 etc, at least until something better than WSJT-X comes along.  Alternatively, drop the two unique character requirement for these same modes but still require the 6-char grid.

I had reason to verify a couple of QSOs in my log so went back to the rules to confirm some details and that is when the above anomoly hit me..   We need to fix this ASAP.

I have yet to re-read the Australia Day Contest rules but I think those rules have bypassed the need for EU Contest mode.  

I'm almost ready to submit my log for last weekend's participation - are you ?

See you on the bands..
73 Doug