08-29-2010 02:58 PM
I want to generate sine waves of varying frequencies, say, from 1 Hz to 1 kHz. Sometimes, a frequency swept sine wave. The problem is I wish to maintain the 'sampling frequency to signal frequency ratio' a constant. That means, the sampling frequency should be 20 or 30 times the signal frequency. This has to be done automatically. For example, for a sweep of 1-10 Hz, if the desired sampling frequency is 30 Hz at the beginning, it should be automatically updated to 300 Hz as the signal frequency reaches 100 Hz. Can some one suggest a possible solution ?
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08-29-2010 08:01 PM
What hardware? What software? What have you tried?
08-30-2010 10:28 AM
Thanks for the queries. I am using daq card USB-6221 and Labview. Used analog out put with function generator, sine wave and sine pattern VI. I am successful to generate sine waves using the 6221 card, which will trigger an electro-optic modulator.
But the problem is that sampling frequency remains fixed throughout the entire band width.
I am not an experienced labview programmer.
08-30-2010 12:09 PM
I would suggest you look at the LabVIEW examples. Example finder>>Hardware Input and Output>>DAQmx>>Voltage>>Cont Gen Voltage Wfm-Int Clk-Variable Rate.vi.
Hope this helps.
08-31-2010 09:56 AM - edited 08-31-2010 09:58 AM
The Basic Function Generator function has an input called 'sampling info'. This is a cluster and one of the elements is number of samples. You simply have to set this based on your frequency.
I would strongly suggest you take the LabVIEW 101 course.
09-03-2010 03:00 PM
Thank you Knutson. The scheme works excellent !