	Temporary Supplement to WSJT User's Guide, version 7.1+
	-------------------------------------------------------

Version 7.1+ of WSJT is an experimental release designed to allow
testing of two new modes:

  JTMS_2  -- possible replacement for FSK441 (meteor scatter)
  ISCAT_2 -- possible replacement for JT6M (ionoscatter, weak Es, F2)

Despite the similarity in names, these modes are *not* the same as the
modes JTMS and ISCAT offered for testing in WSJT8.  The "_2" versions
use the same modulation methods but different coding.  They use
free-text rather than structured messages.

If JTMS_2 or ISCAT_2 remains part of a production release of WSJT, the
"_2" portion of the mode name will eventually be dropped.  In the
meantime, during the testing phase, the suffix should help to avoid
confusion.



The following table summarizes some parameters of the new modes in
WSJT 7.1 and the comparable older modes.

                      FSK441  JTMS_2            JT6M    ISCAT_2
------------------------------------------------------------------
T/R period (s)          30     30                30       30
Modulation type       4-FSK   MSK*             44-FSK    41-FSK
Keying rate (baud)     441   1378               21.5     43.1
Characters/s           147    197               14.3     32.3
Bandwidth (Hz)        1764   1378               947      1809

*MSK stands for "minimum shift keying", a technique that allows faster
keying while minimizing bandwidth.
