Date:         Sun, 6 Aug 2000 19:00:38 -0400
Reply-To:     David Beierl <dbeierl@attglobal.net>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@attglobal.net>
Subject:      Re: Air vs. Water - pro's and con's
Comments: To: John <johnpatt@warwick.net>
In-Reply-To:  <398CC3F6.6CF3@warwick.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 21:48 8/5/2000, John wrote:
>Lastly, and I'm no expert here, Digifant is a true digital
>processor(like BMW Motronic) while the Digijet is a slower analog
>processor(like BMW L-Jetronic). Being born of later computer
>electronics, Digifant is faster and more efficient. If this is not
>correct, there's probably not more than 40 or 50 computer gurus on the
>list who will crucify me for this blasphemy!

There's much to be said for digital processing, but speed isn't one of it
<g>.  If you need speed, analog wins hands down, since any digital system
working in the real world has to convert the real-world analog signals to
digital, process them, then probably turn them back to analog control
signals.  A big virtue of digital systems is resistance to signal
degradation by noise.  They pay for it by using far more data to pass the
same amount of information.  The other virtue is programmability.

Without having taken one apart, I'm pretty confident that both DJ and DF
have a microprocessor, which is by nature a digital device; and that it is
plenty fast for the application.  The DF controls ignition as well as fuel,
that's a win in several directions; but I don't think it gains all that
much from digital signal processing.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"