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From: mbutts@mentor.com (Mike Butts)
Newsgroups: rec.ham-radio,sci.electronics
Subject: New cheap 200 kHz ADC: good for digital receiver?
Message-ID: <1989Sep19.171259.1670@mentor.com>
Date: 19 Sep 89 17:12:59 GMT
Organization: engr
Lines: 28

The current Electronic Design (9/14/89) has a piece on the new Burr-Brown
PCM1705P, a monolithic dual analog-to-digital converter.  It runs at 200 kHz,
gives 14-bit accuracy and 18-bit resolution, and costs $27 in 1K quantity (I'd
guess <$50 in onesies).  It's designed for high-end home audio, DAT and effects
and such, but the article is mostly about how you can hook it to a DSP & use
it for medical, telecommunications, spectrum analysis, imaging, etc.

I wonder if any DSP radio experts out there can comment on whether this chip,
with an 80 kHz or so IF front end on the input and a DSP on the output might
make a practical HF receiver, using the DSP for most of the selectivity, gain
control, and demodulation?  Is it reasonable to use that low an IF?  Could you
use both ADCs on the chip to alternatively sample a higher IF, like 160 kHz?

Imagine how fast, cheap ADCs and DSPs could cause a revolution in receiver
design (especially when we get cheap ADCs and DSPs that can handle several
MHz IFs, and direct digital synth chips to match):

  Antenna ---> Mixer ---> LPF/gain --> ADC -----> DSP -----> DAC -----> audio
                 ^                                |
                 |                                |
              DDSynth                             \------> data

A few real RF stages + cheap digital VLSI = high-performance receiver?
-- 
Michael Butts, Research Engineer       KC7IT           503-626-1302
Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton, OR 97005
!{sequent,tessi,apollo}!mntgfx!mbutts         mbutts@pdx.MENTOR.COM
Opinions are my own, not necessarily those of Mentor Graphics Corp.