[SOC] MCW and Auto Alarm for MF distress

[D.J.J. Ring, Jr.]

The book is available here at no charge in electronic format.
https://archive.org/details/AdmiraltyHandbookOfWirelessTelegraphy1931

Autoalams responded to Spark, Arc, Interrupted CW (ICW), Modulated CW (MCW
or A2A), and Continuous Wave (A1A) which hams call CW.

They needed to because all of those modes were at one time on ships and
were still all legal in a SOS.

73
DR