The specs I read say that FT8 has a 13-character limit for messages. Yet I see many that are longer such as "CQ DX WA4XXX EM55". Are the grid-locator characters not counted in the message limit? Spaces?

...doug, K6DRK

Hi,

well, the explanation is that the information in the message is encoded into 77 bits. So the message is not sent literally as what you see when it is displayed.

All information, although slightly technical :), is found in the following very good paper:

https://physics.princeton.edu/pulsar/k1jt/FT4_FT8_QEX.pdf

73

Thomas, SM0KBD

Den 2022-11-30 kl. 06:17, skrev Doug Kaye:

--
Thomas Nilsson, SM0KBD
sm0kbd@...
https://www.thuben.com/sm0kbd

There are compression shortcuts for many things so "known" message formats can have more then 13 chars.
Random text or non-standard messages are limited to 13 chars.
Mike W9MDB

On Nov 29, 2022, at 22:17, Doug Kaye <doug@...> wrote:

The specs I read say that FT8 has a 13-character limit for messages. Yet I see many that are longer such as "CQ DX WA4XXX EM55". Are the grid-locator characters not counted in the message limit? Spaces?

Dare I say it? RTFM. ;o)

Gary - AG0N

Yes, if I knew where to find the FM I would have R it. Thankfully, Thomas, SM0KBD was kind enough to post the URL.

…doug, K6DRK