Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!agate!ucbvax!hplabs!hp-pcd!hplsla!tomb
From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: Truth about "18-bit" digital audio products
Message-ID: <5170045@hplsla.HP.COM>
Date: 19 Jul 89 16:31:31 GMT
References: <19037@vax5.CIT.CORNELL.EDU>
Organization: HP Lake Stevens, WA
Lines: 28

mmm@cup.portal.com (Mark Robert Thorson) writes:
>henry@utzoo.uucp (Henry Spencer) says:
>
>> And then of course there is the HP 3458A digital multimeter, which has a
>> 28-bit ADC.
>> 
>> Really.
>
>Except for the calibration of reference standards, I can't think of any 
>applications for this device.  Could someone mention a few?
>----------

A couple to get you started, having to do not _just_ with the ultimate
ADC precision:
- measurement of voltages applied to the quadrupole filter in a
  mass spectrometer.  Nice to have better than ppm resolution if
  you are designing these things.  There are other measurements
  of voltages related to physical/chemical phenomena that would
  also benefit from such precision.
- In another mode, very fast readings at reduced resolution.  If
  it's the only voltmeter I have, I can use it for moderate-speed
  data acquisition.  E.g., monitor a line for small "glitches" of
  short duration.
- Ability to deliver reduced spec performance over a wider temp
  range (or time span) than "lesser" instruments.  I.e., where I
  before might have had to do very frequent calibrations and operate
  in a controlled temp environment, there is the possibility to
  operate longer and in a less controlled temperature.