[GreenKeys] OT - rotary dial telephone specs

[Olaf DL8OBH]

Hello,

any interest on german specs and description of mesurement-equipment ??

Olaf   DL8OBH / AF0A


Am 03.06.2013 23:23, schrieb gil at baudot.net:
> Sheesh, a lot of off-list replies to this --thanks all. I'll reply 
> on-list with a summary, as I think this thread might appeal to quite a 
> few telephone folks on greenkeys:
>
> So it seems that 10-pulses-per-second (about 100ms period for 
> break/make) was typical, with the break time being perhaps as low as 
> 50ms or so (with 50 ms make), to about 66ms (with 33 ms make).  Some 
> exchanges may have run faster.
>
> With a possibly-unadjusted dial regulator, combined with maybe some 
> goop or grit in the mechanism, the dialing pulses probably varied a 
> lot, so I guess it stands to reason that the exchanges would allow a 
> fair amount of latitude on the dialing waveform.
>
> I wonder what the exchanges considered the minimum inter-digit make 
> time?  In my arduino program, I place no constraints on the break 
> time, but look at the make time between pulses as about 400-ms max 
> before I consider it to be an inter-digit pause.  I have not tested 
> how quickly I can dial 1-1 (as Jim pointed out) to look for the 
> minimum empirical pause, but my test setup is currently disconnected.
>
> I did notice just how noisy the dialer switches were.  I am used to 
> debouncing a typical pushbutton with a delay of about 5ms, as they 
> seem to settle pretty quickly, but the dialers were incredibly-noisy 
> switches, with lots of high-frequency make/break stuff going on for 
> almost 10 ms.  I could easily improve this but lowering the impedance 
> into which the switch feeds, and a simple RC filter, but that would 
> defeat the purpose of the debounce-in-software experiment.
>
> Anyway, fun stuff.  In these days of disposable technology and 
> standards in the software world that change fluidly every few months, 
> it is really nice to find that my 80- and 90-year old phones not only 
> pass audio on today's landlines, but dial flawlessly as well.  Of 
> course, that's why we all like teletype machines as well.
>
> gil
>
>
>
> gil smith
> greenkeys moderator
> gil at baudot.net <mailto:gil at baudot.net>
>
>
>     -------- Original Message --------
>     Subject: Re: [GreenKeys] OT - rotary dial telephone specs
>     From: Sam Hallas <s.hallas at ntlworld.com
>     <mailto:s.hallas at ntlworld.com>>
>     Date: Mon, June 03, 2013 1:06 pm
>     To: gil at baudot.net <mailto:gil at baudot.net>, aaa-greenkeys
>     <greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net>>
>
>     gil at baudot.net <mailto:gil at baudot.net> wrote:
>     > So my question is what was the design standard for a dial phone's
>     > pulse-widths? They both work just fine on my Centurylink
>     landline, and
>     > I dialed up my cell phone and left myself a message with each phone.
>     > Perfect dialling and audio sounded good in both directions too.
>
>     It depends on the switching system, but the timing for the Strowger
>     step-by-step switches used here in the UK was 66 ms break to 33ms
>     make
>     at 10 pulses per second.
>
>     I can't remember what the inter-digit pause is supposed to be. I'd
>     have
>     to look it up.
>
>     Cheers,
>     Sam
>
>
>
>
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