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Author Topic: Historical perspective on digital equalization (multi-tap filters)  (Read 282 times)

Scott Holtzman

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One of the many things I take pleasure in is placing technology in historical perspective.  While we think of things as new often times they are new applications for existing technology.  Much of the work we do is refinement rather than discovery.

I was reading through the archives of Bell Labs and came upon this article.  The author was trying to improve digital filters for MODEM's.  and important task in 1979 when 1200 baud was ripping fast. 

What is being discussed is an implementation of what we now call FIR filters.  Excellent examples of cumulative delay are given.

I thought some of you may enjoy the read:

https://archive.org/stream/bstj58-2-301#page/n0/mode/2up

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Scott AKA "Skyking" Holtzman
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John Roberts {JR}

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Re: Historical perspective on digital equalization (multi-tap filters)
« Reply #1 on: October 12, 2017, 06:02:41 pm »

Bell labs is where a lot of milestone technology was pioneered (Guys like Shannon and Schafer, and.....) Those were the good old days.

JR
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Scott Holtzman

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Re: Historical perspective on digital equalization (multi-tap filters)
« Reply #2 on: October 12, 2017, 06:10:18 pm »

Bell labs is where a lot of milestone technology was pioneered (Guys like Shannon and Schafer, and.....) Those were the good old days.

JR

Claude Shannon and Harry Nyquist defined the fundamentals of information transmission before digital computers existed.

The North American Digital Hierarchy that formed the TDM PCM telephone network was designed in the 50's based on these principles.

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Scott AKA "Skyking" Holtzman
River Delta Audio is now:

Ghost Audio Visual Solutions, LLC
Cleveland OH
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Ivan Beaver

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Re: Historical perspective on digital equalization (multi-tap filters)
« Reply #3 on: October 13, 2017, 07:42:52 am »

Bell labs is where a lot of milestone technology was pioneered (Guys like Shannon and Schafer, and.....) Those were the good old days.

JR
Yeah-back when companies were allowed to make a decent profit, they could have whole sections (bell labs) where engineers could just "think" and not have the pressure to produce products.

A LOT of innovations in our industry came out of Bell labs.  So many things we take for granted today.
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John Roberts {JR}

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Re: Historical perspective on digital equalization (multi-tap filters)
« Reply #4 on: October 13, 2017, 09:03:41 am »

Yeah-back when companies were allowed to make a decent profit, they could have whole sections (bell labs) where engineers could just "think" and not have the pressure to produce products.

A LOT of innovations in our industry came out of Bell labs.  So many things we take for granted today.
Bell was broken up for anti-trust reasons. Some of the baby bell companies reassembled but completely different industry today.

JR
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