[RTTY] RTTY Screwed by FCC?

[Joe Subich, W4TV]

Bill, 

> For a signal to be "digital", the data has to represent numbers. That
> is what the word "digital" means. In the case of RTTY, the bits are
> purely analog signals, which is why they can be decoded with an analog
> computer, namely a teletype machine. There is no number crunching
> involved. You can, of course, digitize the signal just as with any
> analog signal and process it, but the original signal was and is
> analog.

I don't know if you are being dense or just being intentionally difficult. 

For a mode (specifically a "mode of emission") to be digital it is only 
necessary for the signal to take a limited (finite) number of distinct 
states as opposed to an infinite number of states between a set of 
limits (amplitude, frequency etc.).  

Putting that aside, CW, RTTY, PSK31, etc. are still all digital by 
your definition of digital.  RTTY is a five bit code of 32 "numbers" 
- each of those numbers is assigned a value, some even more than one 
value based on the shift state.  Although it was not first  
conceived as such, CW is a variable length code (also known as 
varicode).  Each character is actually a numeric value starting 
at zero (three "space" bits) representing the letter space and 
getting progressively longer/larger through the prosigns. 

> If CW is digital, it then follows that dit-dah and dit-dit have 
> the same numeric value and are therefore the same character. 

Here is where you are demonstrably wrong again ... dit-dit is 
the varicode 101 (5 decimal) while dit-dah is 10111 (23 decimal). 
This is the nature of a variable length code.  

> CW and RTTY both have "bits" of different lengths, and that is 
> crucial to their decoding. Both are analog signals which *can* 
> be processed digitally, but the original signal is analog.

Dead wrong! It does not matter what the original data is - it 
is only the MODE OF EMISSION or the "coding" that matters.  Any 
signal can be transmitted using digital modes of emission.  

73, 

   ... Joe, W4TV