Discussion in 'General Electronics Discussion' started by westpoint, Feb 19, 2012.

1. ### westpoint

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Feb 19, 2012
Hi folks, I am working on a big project. One of the most important steps is to produce sin and cos (quadrature singal) singal. The singal must be low-noise and the frequency of the two singals can be controlled by computer, i.e.

computer (gives a votalge V)--> circuit --> analog sin(A*V*t) and cos(A*V*t)

the votalge given by the computer is between -10 and 10 V. And A is some constant factor determined by the circuit.

can we do that?

2. ### twister

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Feb 12, 2012
Be careful not to produce too much sin, you will have to ask Jesus to forgive you, if you want to go to heaven. ha
Sine waves I know. Cosines, not much. Someone smarter than me will have to help you on that.

3. ### GonzoEngineer

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Dec 2, 2011
Are you a student at Westpoint?

1,252
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Apr 4, 2010
5. ### westpoint

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Feb 19, 2012
The expected frequency is 20KHz and it should be very stable with less than 1Hz noise. And A is just some factor, so A*V is around 20KHz.

6. ### westpoint

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Feb 19, 2012
No, I'm a graduate student of Physics.

7. ### Laplace

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Apr 4, 2010
So the real problem is not quadrature generation but rather building a very stable voltage-controlled oscillator. From your answer I gather that the VCO signal is not sin(A*V*t) but instead sin(A*{K+V}*t)=20khz where K>>V.

8. ### GonzoEngineer

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Dec 2, 2011
Whew! I was worried there for a moment.

BTW....it is spelled signal.

9. ### Laplace

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Apr 4, 2010
Rats! I was fascinated by the prospect of low-noise sin with SinGal, and the magnitude of the forgiveness I would seek.