[GreenKeys] That's not a RTTY station........

[Duncan Brown]

Bruce,

On 1/25/2020 08:03, Bruce Gentry via GreenKeys wrote:
>
>   When was commercial RTTY introduced? Was it FSK, AFSK, or something 
> else?
>
Morkrum did wireless TTY experiments, including with the US Navy, in the 
early 1920s. They initially used on-off keying.  The first patent using 
FSK for a "Radio Telegraph" was filed by Lawrence Schmitt of Morkrum in 
1924 and issued in 1929: #1,705,211. Probably the first commercial use 
of FSK RTTY  was by RCA on a San Francisco to Hawaii circuit in 1932.

Have fun,

Duncan
K2OEQ