On 3/23/16 4:11 AM, Bob Camp wrote:
Hi
If you can see harmonics down to -60 dbc, that is about the most a normal
spectrum
analyzer will do for you on a frequency standard. This *assumes* the part has a
sine
wave output. Most standards are in the 10 MHz range, so an analyzer that will
work to
= 40 MHz is probably a good idea.
Can you do this with a USB gizmo? Sure you can. Can you trust the results? That
will
depend on the exact unit you get and your ability to calibrate it. Might it
“only” be useful
to -50 dbc? Might it work to -100 dbc? That is part of the “did you pay $X or
10 times
that much question.
Spectrum analyzers are also nice when debugging a new circuit..
unexpected oscillations at other frequencies, spurs, etc.
For this kind of thing, limited dynamic range isn't as big a problem.
Would the difference between a 8 bit and more bits in the ADC make a
difference? Maybe, maybe not.
However, with respect to this new analyzer, the thing to really look at
is the software that runs it. Does it do what you need it to do,
*today*? Does it work on your PC platform (Win, Mac, *nix), *today*?
Today is important. There may be all sorts of planned upgrades (and
hey, lots of folks do "open source", so conceivably, someone else could
do the upgrade), but they may never materialize: the people doing the
work may get onto another project; there's not enough market for what
you want.
More than one software controlled device I've worked with worked fine
with the supplied software, but what I was really interested in was
controlling it with other software, and the promised open API never
really existed, was documented, or delivered.
This is particularly pervasive in the amateur radio community, where the
original developer was motivated to "scratch an itch", solved their
problem, and then cast their product out to the big wide world, along
with grand plans to make it even better, then found that it was more
work, and work that didn't scratch the itch.
Likewise with products/software that are the result of somone's masters
or PhD thesis. They get far enough along to finish the dissertation,
publish it as open source (good for them and us), but there it
languishes, 85% complete, with all the (useful to me) corner cases
untested or undeveloped.
In neither of these last two, would I cast aspersions on the authors (or
even forge and machine aspersions<grin>): they did what they said they
were going to do, and in general, their description of what they
actually did matches what they did.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
