TELECOM Digest OnLine - Sorted: Re: X-Bar Switch Noise Levels

Re: X-Bar Switch Noise Levels

Carl Navarro (
Thu, 22 Jun 2006 05:20:51 GMT

On Wed, 21 Jun 2006 06:50:29 -0700, Sam Spade <>

> TELECOM Digest Editor noted in response to Scott Dorsey:

>> [TELECOM Digest Editor's Note: I know that in the early/middle 1960's
>> the Chicago-Wabash central office -- in fact all of Chicago -- was
>> either crossbar or stepping switch and you could hear it a block away
>> on a hot summer night walking down the street, mainly because they
>> did not have air conditioning in those days and all the windows would
>> be open wide. When it started to rain, someone would go around and
>> close all the windows. Quite deafening. PAT]

> During busy traffic, a large stepper was much louder than a No. 5 Crossbar.

In a college town, Wednesday night was the day the kids called home,
as Thursday night was drinking night :-)

I'm not sure if a normal Wednesday night in SATT or the Blizzard of
'78 was the worst. On Wednesdays, the rotary switches had to find
available ticketers. The noise was incredible as they cycled through
the steps to find an idle path, then the ticketers dumped calls to the
paper tape punches at the end of the call. During the blizzard, we
just didn't have any availabe trunks and/or busied out circuits.

My hearing was excellent and still is today. I made it a practice to
not hang around the SATT area on busy nights.


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