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FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator

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wasyoungonce:
Quick stupid question.  Can the fy6600 fy6800 or dy5300 output dual encoder type pulses to simulate a dual channel encoder. 

Let’s say ttl pulses ch a leading b by 90degrees or b leading a.

I wanted to simulate an encoder that seperates the pulses by 90 degrees but I’d also need to alter pulse period and keep same phase split.

I know I could do the pulses but not sure about locking the phase split relationship

????



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Miti:
Yes, it can. You set the wave to CMOS, phase to 90 or 270 degree then press SYNC. Now if you press CH1 > FREQ, you can adjust the frequency on both channels simultaneously and the phase will stay the same. Same procedure for DUTY.

wasyoungonce:
Excellent thanks miti.... I’ll read all the thread to get a full picture but as said need to simulate encoder channels ....plus other uses.

soundtec:
I performed a few audio tests on my 66' and 68' hundred.
I used a program called 'visual analyser' ,which does Scope FFT and spectrum , thd+noise etc. 'Room Eq Wizard' is another software that can do this ,it will even list the % points of the individual Harmonics 2,3,4,5,6th  , for this test I went with 'VA' for simplicity of setup ,and I felt thd+ noise was adequate for the purpose of the test.

What I noticed was , well what we'd always known , that certain spot frequencies along the way , 3.5khz being one, perform very  much better in terms of THD than other frequencies , it looked like a comb filter effect. as I went up or down the frequency range , the distortion rises and falls in a fairly predictable manner , across most of the middle audio frequencies it reads within spec of .5% ,but at fairly regular intervals along the way it drops to a very much lower number like .002% or even less. The effect of amplitude on distortion wasnt nearly as big a concern as I had thought it might be either ,as expected at very low output levels a higher contribution of noise pushes up the thd+n numbers , the usb sound card input tops out somewhere well down below full output of the gen ,harmonic spikes are visible the moment the sound interface is over driven .

Now supposing we want to make a very low distortion audio 'frequency stepped' test tone on the fy 6600 , by choosing the individual frequencies of the stepped waveform from the bands of sweet spots across the frequency range we could do very much better than .5%thd  of the spec . 
I should have plotted the frequencies  , its obviously a function of DSP clocking frequency ,there must be at least 50 points across the band 20hz -20khz , its easily visible on an FFT though , when you hit the sweet spot all forms of noise and distortion dramatically drop , as much as 20-30 db over worst case .

Hopefully someone  will be able to confirm my results , 





 

Cliff Matthews:

--- Quote from: soundtec on April 14, 2019, 03:03:12 pm ---..I used a program called 'visual analyser' ,which does Scope FFT and spectrum , thd+noise etc.

--- End quote ---
Thanks! Interesting software. http://www.sillanumsoft.org/news.htm

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