How to enter the phase of a signal and get in return its corresponding voltage?

[marylydie]

HI !

I am a beginner in LabView and i am developping this application where by entering the phase of the signal it must give me the corresponding voltage. Then i will send the cooresponding voltage to an elctronic board.The voltages goes from 0 to 15 V and the phase from 0 to 180 degrees with 5 degrees accuracy. I need a lead to start. I was thinking of using array but the data are not from the same type.

Thank you in advance for the light.!!

[smercurio_fc]

What do you mean by "the data are not from the same type"? You have numbers: 0 to 15 and 0 to 180. Looks like a simple line equation V = (15/180) * phase.

[marylydie]

I already have all my voltages as Vin and their corresponding phase in degrees as i simulate it in matlab.

Vin=[0 2 4 6 8 10 12 13 14 15]

Phase= [0.00 11.21 30.16 89.61 134.12 155.54]

The equation does not give me the same answer. I want to be able to send via a parallel port, by inputting the phase, the correspondant voltage.

Thanx for giving me a lead.

[smercurio_fc]

Well, for one thing your array max is 155.54, not 180 as you initially said. Also, you have more voltage values than phase values. So, does 11.21 correspond to a voltage of 2, or 4, or both, or neither?

[johnsold]

Are you simulating a known waveform such as a sine wave?. If you are and you know the frequency and amplitude, you can calculate the voltages directly.

Lynn

[marylydie]

My mistake because i did not wrote the arrays entirely:

v=[0 2 4 6 8 10 12 13 14 15]

phase=[0.00 11.21 30.16 89.61 134.12 155.54 168.05 172.58 176.43 179.67]

[marylydie]

The voltages i have got come from the phase shifters of an antenna. I want to steer the main beam electronically so by sending these voltages to the phase shifters via an electronic board.

[smercurio_fc · Accepted solution]

When you plot Voltage vs Phase it looks like this:



This is clearly not linear. Thus, in order to get the required voltage for a specific phase you will either need to generate a curve fit for the graph and use the curve fit function to get the required voltage for a phase, or use the Threshold 1D Array and Interpolate 1D Array functions. The latter is shown by this example:





Message Edited by smercurio_fc on 06-18-2008 09:29 AM

[marylydie]

Thanx for your help. will get back to you when i`ll succeed!!

[smercurio_fc]

If you want to try one of the curve fit functions, there's a number of curve fit functions that ship with LabVIEW. Unfortunately, I don't have time right now to whip up an example. Gotta get back to work.