The Maidenhead Locator System, paired with the phonetic alphabet (or via CW) is extremely robust, but requires a relatively long string to get to 3m accuracy.

The Maidenhead Locator System, paired with the phonetic alphabet (or via CW) is extremely robust, but requires a relatively long string to get to 3m accuracy. https://en.wikipedia.org/wiki/Maidenhead_Locator_System https://en.wikipedia.org/wiki/Maidenhead_Locator_System What I would suggest to W3W or WFW is to have a alphanumeric "backup" similar to the gridsquare system that can be spoken over rough radio channels.