[RTTY] OOK Recieve Mode?

[Kok Chen]

On Feb 17, 2005, at 3:55 AM, niddy noddy wrote:
> SO what exactly is "OOK"  ??

OOK    On-Off Keyed (one carrier, keyed on and off, e.g., CW)
FSK    Frequency Shift Keyed (keying between two different carrier 
frequencies, e.g., RTTY)
PSK    Phase Shift Keyed (keying the phase of a carrier, e.g., PSK31)

With FSK, the modem's duty is to guess whether it is more likely that a 
Mark was sent, or whether it is the Space that was sent.  Guessing 
wrong causes a bit error.

When OOK is used in an FSK modem, it is asked to guess what was sent 
based on only inspecting the mark tone ("Mark-only" detection) or based 
on only inspecting the space tone ("space-only" detection).

Since you are only looking at the power from one of the tones, copy is 
degraded compared to looking at both tones.  However, if one of the 
tones is under severe QRM and the other is not, detection with 
Mark-only or Space-only can provide usable copy while Mark/Space 
detection does not print at all.

73
Chen, W7AY