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Single frequency points measurements

Question asked by Shehzad on Jun 23, 2015
Latest reply on Jun 29, 2015 by mcee

Hi Everyone,

 

I'm trying to measure a complex impedance from a frequency range of 10Hz up to 1KHz with 1Hz resolution. I've a programmable MCLK source. I have the following issues:


1. How could I correctly measure impedance at a single frequency? Currently I'm measuring with a desired Start frequency and using frequency_increment = 0, and number_of_increments = 0. Is this correct?


2. For the desired frequency output, I'm calculating MCLK by using the formula:

                             MCLK = Output_freq * 16 * 1024 / Number_of_settling_time_cycles

    Is this formula correct? (I have found it out here: https://ez.analog.com/message/204632#204632)


3. While observing the excitation output, I observe spikes at each frequency sweep time instant. i.e. whenever a frequency sweep is initiated by the command, a spike is observed in the output which is causing erroneous impedance results.


4. Is there any optimum criteria for determining the number of settling time cycles?


Please help!


Thanks and regards,

Shehzad

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