[GreenKeys] 1khz reference tone...

[Pete Lancashire]

Examples via Google

http://www.janascard.cz/PDF/An%20ultra%20low%20distortion%20oscillator%20with%20THD%20below%20-140%20dB.pdf

There is a 'lower performance" version mid way through the PDF.

Both TI (National) and Linear Technology have app notes on low distortion
reference designs.

>that the tone generated by your
>computer sound card is better than any but lab-grade AF generators,
>because they either suffer from very similar limitations if they are
>digital, or are limited to whatever cheap uncalibrated AF oscillator
>they have if they are analog.

I had the chance to test a few PC sound cards with a Audio Precision 2700
and a Tektronix AA5010.
All the cards had issues. But then if one is looking for 1KHz via your
telephone the sound cards did
just fine.

If this is something you going to be doing on a regular basis and want more
than just 1KHz, there
are quite a few surplus instruments on the market. I have one made in
Germany but can remember
the make/model, if you lived in Oregon you could come and get it (Im not
going to pack it up). It
was built for doing distortion testing.

HP made a few genearator for the telco industry, The 3336A/B/C comes to
mind. I got one off
epay for $50, .Its call to fame is the accuracy of its amplitude.
Distortion is OK
but not great.



On Tue, Jun 6, 2017 at 8:38 AM, Ethan Blanton <elb at kb8ojh.net> wrote:

> Jeffrey D Angus wrote:
> > On 6/6/2017 8:54 AM, kn7sfz wrote:
> > >
> > >Plenty of pure tone generators online....here's one:
> > >
> > >http://www.szynalski.com/tone-generator/
> >
> > Nice, but it says nothing about the accuracy of the tone.
>
> It really can't.  Software-generated tones are limited in accuracy by
> 1) your sound card's DAC clock accuracy (probably pretty poor), and 2)
> artifacts created by interactions between sampling frequency and tone
> frequency (probably irrelevant for your purposes).
>
> It's very easy to numerically create a "perfect" sine wave in
> software, modulo the above limitations.  This software probably does.
> I haven't used it, but I'd assume any programmer worth his salt can
> create a suitable tone.  What happens to it after that is more or less
> out of the software's hands.
>
> All of that said, you can rest assured that the tone generated by your
> computer sound card is better than any but lab-grade AF generators,
> because they either suffer from very similar limitations if they are
> digital, or are limited to whatever cheap uncalibrated AF oscillator
> they have if they are analog.
>
> Ethan
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