Teletype services

tony duell ard at
Thu Nov 5 15:18:50 CST 2015

> The Baudot thing sure brings back some memories.   I still recall hooking
> teletype's up thru KW-7 boxes, and performing ryryryryryryryryr  test.
> I don't recall enough of the specifics, but it was either
> Y = 10101
> R = 01010
> or reversed.

Ah yes... One of the classic tests for problems in the receiver and comms link, but
not the only one. A system with poor low frequency response (for example) might
handle alternating mark and space correctly but fall down on things like 11110

I have a test message generator that can sent that, various alternating signals (without
start and stop bits), user-entered characters (on a row of switches) and so on. And
distort them by lengthening and shortening pulses to check how well the receiving 
device copes with mangled signals. I also have the distortion measuring set, a special
oscilloscope to check for distorted signals, test relays for contact bounce, bias and 
transit time, etc.

I really must get my Creed 7E and 444 running again...


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