What are you using for an inexpensive frequency counter?

[dspswede]

Assume the DSP can do measure THD including generating the test pattern

Feeding its own digital stream over spidf or I2S back into itself would set a baseline.

Color noise generation and frequency domain analysis should also be vanilla stuff.

(the DSP = ADAU1467)

 

[SyncTronX]

I did a quick and dirty non warm up check with my HP3551A, measuring 1kHz output @ 0db. The Shibasoku 725D showed about -55dB on the distortion meter.

A spot check at 10KHz showed about -54 on the distortion meter.

Now I'm not sure if that even was a sine wave and I don't have time to do another check right now. No scope and no bench still. It is what it is. The bench is getting closer again to being finished.

If I use Duke's Linear Tech Accuracy Translator chart, and find -55dB, then go across to percent scale, it is about .18 percent (between .1% and .2%).

We aren't talking anything spectacular here, but it works as intended and my digital readouts on both displays show the same frequency.

I've attached it here also.

Cheers,

 

[anatech]

Hi Sync,
Okay, so what I thought. A bit better than the FG series of function generators along with having more accurate and stable frequency and amplitude. The function generator will still give you triangle and square waveforms.

Yes, they were sine waves as triangle and square waves would run about 45% THD

Thanks for doing that Sync.

-Chris