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From: harrison@sunny.DAB.GE.COM (Gregory Harrison)
Newsgroups: comp.dsp
Subject: Re: More digital mixer stuff
Message-ID: <2453@ge-dab.GE.COM>
Date: 19 Oct 89 17:23:58 GMT
References: <9238@pyr.gatech.EDU> <2437@ge-dab.GE.COM> <227@nems.dt.navy.mil>
Sender: news@ge-dab.GE.COM
Reply-To: harrison@sunny.UUCP (Gregory Harrison)
Organization: GE Simulation & Control Systems Dept., Daytona Beach, FL
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Distribution:USA

In article <227@nems.dt.navy.mil> curt@dtix.dt.navy.mil (Curt Welch) writes:
>In article <2437@ge-dab.GE.COM> harrison@sunny.DAB.GE.COM (Gregory Harrison) writes:
>>How about Gray Code?
>
>Gray codes won't work because there is no easy way to make a Gray Code
>to Analog converter.  The only way I can think of doing it is to first
>convert the Gray Code to binary, and this of course defeats your reason
>for using Gray code.

Perhaps the Gray Code could be converted to binary (if need be) interior
to the intergrated circuit DAC, at a much lower power than required to 
transmit the data between chips.  I would assume that most of the ICs
that drive the datalines to the DAC, and the DAC inputs, allow much
more current (charge) to flow than would be required to actually 
perform the Gray code to binary conversion on the chip semiconductor
surface.  There are probably some very low power, low EMI digital 
circuitry technologies that would be applicable.

This may represent an improvement in preserving the S/N of the 
analog sections (reducing digital noise), but samplingand holding the
signal after the switching spike subsides would probably be sufficient.

Greg Harrison
My opinions are not intended to express those of GE