[GreenKeys] Special sequences

Tue, 23 Apr 2002 08:14:44 -0400

Wow!  This is worth saving.  Thanks!

Paul Wills

----- Original Message ----- 
From: "cswiger" <[email protected]>
To: "TTY Friends" <[email protected]>
Sent: Tuesday, April 23, 2002 7:05 AM
Subject: [GreenKeys] Special sequences

> Aha - I've wondered about some character sequences we
> sometimes see here. Now I found a book at the last
> hamfest which reveals all:
> 
> The use of Sequences of Telegraph Characters for Special Purposes
> 
> Start of message        ZCZC
> 
> End of telegram         ZZZZ  or
>                         ++++        Used in retransmission systems
>                                     and store and forward devices.
> End of message          NNNN
> 
> 
> 
> Suppression of delay
> signals                 HHHH        Used to prevent the retrans-
>                                     mission of delay signals used
>                                     for error-corrected radio-
>                                     telegraph channels
> 
> 
> Connection of re-
> perforator or
> equivalent device      CCCC         Switching into the circuit by
>                                     remote control a reperforator
>                                     or equivalent device
> 
> 
> Disconnection of
> reperforator or
> equivalent device      FFFF
> 
> 
> Connection of
> data equipment         SSSS
> 
> 
> 
> Source: "Telecommunication and the computer", James Martin, 1969
> 
> 
> _______________________________________________
> GreenKeys mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/greenkeys
> 
>