trj1
Electrical
- May 12, 2005
- 7
I am trying to measure the phase difference between three signals.
The signals are given mathematically by the equations:
X = sin(2w) - cos(w)
Y = -sin(-2w) - cos(w)
Z = cos(2w) - cos(-w)
where w = 1800Hz
The 3 double frequnecy components are 120 +/- 12 degrees apart. The single frequency components are 0 +/- 5 degrees apart.
Mathematically the easiest thing to do (i.e. for phase between X & Y) would be to be use the MATH function on the scope and add a cos(w) to X & Y, however, the problem is (I believe) there is a phase shift between the cos(w) of the measured signal and the input cosine signal and so the components do not cancel each other out completely. (I do not have acces to the individual signals components on the module). When I simulate the signals myself, it works out great, becasue I am using the same cosine signal at the same phase shift, however, in my reality, I cannot get this to work.
Are there any suggestions on methods (or equipment) I can use to perform this measurement? I have also tried a NAII Phase Angle Voltmeter model 227 and either I did something wrong or it will not make the measurement either.
I would prefer to do this in either software (Labview or C) or with test equipment, preferably test equipment. I do not want to add hardware to my test fixture at this point.
Thanks in advance for any input. My deadline is looming...
The signals are given mathematically by the equations:
X = sin(2w) - cos(w)
Y = -sin(-2w) - cos(w)
Z = cos(2w) - cos(-w)
where w = 1800Hz
The 3 double frequnecy components are 120 +/- 12 degrees apart. The single frequency components are 0 +/- 5 degrees apart.
Mathematically the easiest thing to do (i.e. for phase between X & Y) would be to be use the MATH function on the scope and add a cos(w) to X & Y, however, the problem is (I believe) there is a phase shift between the cos(w) of the measured signal and the input cosine signal and so the components do not cancel each other out completely. (I do not have acces to the individual signals components on the module). When I simulate the signals myself, it works out great, becasue I am using the same cosine signal at the same phase shift, however, in my reality, I cannot get this to work.
Are there any suggestions on methods (or equipment) I can use to perform this measurement? I have also tried a NAII Phase Angle Voltmeter model 227 and either I did something wrong or it will not make the measurement either.
I would prefer to do this in either software (Labview or C) or with test equipment, preferably test equipment. I do not want to add hardware to my test fixture at this point.
Thanks in advance for any input. My deadline is looming...
