[GreenKeys] Re: Ancient Technology

[Don Robert House]

Thanks Jim,  The "pull boxes" for police or fire as I recall are "enunciators"
Don



At 5:29 PM -0600 10/27/2003, jhaynes@alumni.uark.edu wrote:
>Thanks to Ben for that fine treatise on ancient technology.  I'll add a
>few things that come to mind.  There is something in the phone business,
>believe it is called a "pen register", that is used to record the phone
>numbers that someone dials.  Mostly used for law-enforcement
>investigations, where the cops want to track who is being called by
>someone they are watching.  I believe this takes almost the same kind
>of court order as one for wiretapping.
>
>Landline Morse telegraphers ceased to use the pen recorder as soon as they
>were able to convince their bosses that they could indeed copy by ear from
>the clicks the machine made.  Recorders continued to be used at some
>stations, where the operator had other duties and was not always available
>to copy code by ear.
>
>Ink recorders were used on trans-Atlantic cables.  The cable code is like
>Morse code except it is tri-state: one polarity for dot, the opposite for
>dash, and no current for the spaces.  The cables were worked above the
>Nyquist rate; that is, signals were sent so fast that the current in the
>cable did not reach full strength when a single dot was sent.  It was up
>to the operators to look at the wiggles on the tape and figure out what
>had been sent.  There are some samples of this in the Western Union
>Technical Review and other publications.
>
>Then with radio in the 1930s and 40s there was very high speed Morse
>telegraphy: 500 or 1000 wpm.  This was transmitted from punched paper
>tape and received on ink recorders.  Then the tape was pulled past an
>operator at a typewriter who transcribed it.  Examples of this equipment
>can be seen in advertisements of the T. R. McElroy Co. in the back of
>the ARRL Handbooks of the 40s and 50s.
>
>Western Union had an ink recorder called an "undulator"   I believe this
>was used as test equipment.  You could look at signals coming from a
>TTY, for example, and see if any of the transmitter contacts were bouncing
>or operating at the wrong times.
>
>The burglar alarm system Ben described is very much like the fire alarm
>systems, and also like the messenger-call system used by Western Union.
>Sometimes you see the call boxes at antique dealers' - an oval shaped
>porcelain base with a metal cover in white and blue enamel, and a handle
>sticking out.  A later model was a yellow box.  You wind up the handle
>and release it, and the spring-loaded mechanism sends out a short message
>in dots and dashes.  This gets recorded at the W.U. office on a paper
>tape, where the messenger superviser reads it and sends out a messenger.
>This continued in service into the 1950s at least.  Of course it would
>have been a lot easier just to call W.U. on the telephone.
>
>
>
>--
>
>jhaynes at alumni dot uark dot edu