Topband: Analog to Digital converter for 1.8MHz

[CHARLES HUTTON]

The 71.5 dB is actually S/N, not dynamic range. The Spurious Free Dynamic 
Range (SFDR) is listed in the spec sheet as 90 dB which is respectable if 
not top of the line.

Chuck


>From: "Richard (Rick) Karlquist (N6RK)" <richard at karlquist.com>
>To: "Steve Ireland" <sire at iinet.net.au>, <topband at contesting.com>
>Subject: RE: Topband: Analog to Digital converter for 1.8MHz
>Date: Fri, 2 Jul 2004 08:38:35 -0700
>
>You certainly want to bandpass filter the input
>to get rid of AM BCB signals.  Assuming a passband
>250 kHz wide and a stopband 500 kHz wide, you only
>need to sample at 1 MSample/s.  (Of course you still
>need an "analog bandwidth" of at least 1.8 MHz.)
>However, the dynamic range of 71.5 dB may not do
>so well in a contest with lots of strong signals.
>
>Rick N6RK
>
> > -----Original Message-----
> > From: topband-bounces at contesting.com
> > [mailto:topband-bounces at contesting.com]On Behalf Of Steve Ireland
> > Sent: Thursday, July 01, 2004 10:06 PM
> > To: topband at contesting.com
> > Subject: Topband: Analog to Digital converter for 1.8MHz
> >
> >
> > G'day
> >
> > It seems that the days of converting 1.8MHz signals from analog to 
>digital
> > at our antennas seem just about here.  On October 14 last year Texas
> > Instruments released its ADS7881 A to D converter - good to 1.8MHz and
> > retailing at about US$7 each.
> >
> >
> > >Analog-to-Digital Converter achieves 4 msps.
> >
> > >Model ADS7881 combines 12-bit resolution, 1 LSB linearity, -91
> > dB harmonic
> > distortion, 71.5 dB signal-to-noise, and 95 mW power dissipation. It
> > addresses high-speed data acquisition needs by providing
> > specification with
> > input signal frequency as high as 1.8 MHz. Suited for optical 
>networking,
> > imaging, and telecommunications, SAR-based unit integrates internal
> > reference and reference buffer, and has pseudo-differential,
> > unipolar input
> > range of 0–2.5 V.
> >
> > -----------------------------------------------
> >
> > I'd be interested to hear from anyone on the reflector who has started 
>to
> > think about a topband receiver along these lines - a very sharp front 
>end
> > filtering system (the old Cohn filters are pretty good), an A to D
> > converter followed by a dsp board to do all the filtering.
> >
> > Vy 73
> >
> > Steve, VK6VZ
> >
> >
> >
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> >
> >
>
>
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