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Rotary Phones are digital?!??

Started by JimH, December 12, 2009, 12:36:22 AM

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JimH

I just came across this very interesting paragraph on the Porticus website:

The irony of rotary verses touch-tone is that rotary dials produced DIGITAL data that was used by the equipment in the central office whereas today's modern touch-tone dials produce ANALOG signals.  All the hype about us being in the digital age is not true of our touch-tone phones - until we get to the central office where the tones are converted to digital format.  So when someone asks you why you have an old-fashioned rotary phone, simply tell them that it's really very modern since it's dial is digital and not analog!  Who would be caught dead with an old analog touch-tone dial when they could have a "modern" digital dial! :-)

Who knew?  We were and are ahead of our time!
Jim H.

JorgeAmely

This is true. A rotary phone uses OOK (on-off keying) to transmit information related to the number dialed. A 10 pulses per second rate was initially selected to give enough time for relays to settle down before a new pulse train arrived.

A TT phone transmits a pair of tones for every key pressed, which is translated at the central office into digital information. These days an analog to digital converter plus a simple micro-controller would be enough to do the translation. The same micro-controller with slightly different software could also accept OOK and translate that to digital data.


Jorge

dsk

#2
I do agree!
The term digital and analog telephony is probably in hence to the central office equipment.
The sound is quite analog too.

With this in mind, and speak recognition as a coming option, we are back to basic. Lift the handset, tell the other end what connection you need, and the operator puts you through .
Listening on all connections are made today, but some years ago the operator knew when you were at the neighbours, and putted the connection through  where you were, even without telling the exchange ;D

dsk

bellsystemproperty

Since rotary phones are digital, that means we can throw away all those low tech analog touch-tone phones. We're on the leading edge, using digital equipment while the masses are stuck with their analog devices.  ;)

Tonyrotary

Yep, we have cutting edge technology!