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VRF-Frequency_Generator

Question asked by VRFuser on Apr 22, 1998
send q VRF-Frequency_Generator vrf

from: Greg Goebel / HP-MXD
      gvg@lvld.hp.com / 800-452-4844
      website:  ftp://fcext3.external.hp.com/dist/mxd/index.html
to:   VRF-Mike Mancuso
date: Thursday, 23 April 1998 1245 MDT

Regarding accuracy of the Frequency Generator object:

I don't know the precise algorithms and we've never characterized this --
we've never been asked about this before -- but generation of simple
waveforms is a trivial operation that I could concoct in a few short BASIC
programs.

We use 64-bit floating-point math and it's just a small set of normal
arithmetic and trig operations -- meaning that with 64-bit computations the
amount of error in the computation is without doubt far smaller than the
amount of error in your ARB.

If this remains a concern, I suggest generating a simple waveform with a
known period with the Frequency Generator and using a pocket calculator to
doublecheck the data.  However, the pocket calculator's level of error is
probably only slightly better than VEE's ... an uncertainty principle
applies.

Of course with any sampled waveform you can have uncertainties due to the
sample period.  For example, if you have a square wave, one sample will be
a 1 and the next will be a 0 ... the actual transition could be somewhere
in between those values.  But this is purely theoretical as well, since that
would apply to an ARB as well as a VEE-generated waveform.

[<>] regards -- gvg

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