[RTTY] RTTY WAS

[Kok Chen]

On Aug 1, 2005, at 7:58 AM, Bill Turner wrote:
> RTTY is commonly processed by a digital computer, but the Baudot  
> character
> set itself is purely analog.

At some level, all digital modes used over the airwaves are analog,  
unless you send baseband Walsh functions or Manchester codes over the  
air -- and if you do that, each bit of information will be spread in  
the Fourier spectrum (what hams usually call "spectrum") between DC  
and "daylight." :-)

At the demodulator level, RTTY is analog.  But after the slicer, RTTY  
is discrete.

If I send cards for Hellscriber QSOs in for DXCC, I am almost sure  
the ARRL would issue a "digital" certificate.  But there is  
absolutely nothing digital in that mode.

What the ARRL calls "digital" is probably better described as  
"keyboard" or "character" based modes.

73
Chen, W7AY