Fluke PM-3394B, PM-3380B, PM-3390B, PM-3370B, PM-3384B user manual Program Example

Read the FFT trace from memory register m1.1 using the TRACe? M1_1 query.

3 - 54 USING THE COMBISCOPE INSTRUMENTS

PROGRAM EXAMPLE:

The following program example converts a relative or absolute FFT trace of 512 samples of 1 or 2 bytes from the signal on channel 1 via the MATH1 feature as follows:

•Before running this program, first make the FFT selections desired via the front panel, such as:

>MATH - MATH1 "on" and "fft".

>CURSORS "on" and "m1.1".

>MATH - PARAM - FILTER "hamming", "hanning", or "rectang".

>MATH - PARAM - READOUT "rel" to select relative FFT.

>MATH - PARAM - READOUT "abs" to select absolute FFT.

+ CURSORS - READOUT "dBm + 50Ω", "dBm + 600Ω", "dBμV", or "Vrms".

•Request the following values:

>The acquisition length using the TRACe:POINts? CH1 query.

>The sweep time to calculate the MTB using the SENSe:SWEep:TIME? query.

MTB = (sweep_time * 50) / (acquisition_length - 1).

The calculation factor to determine the sample point frequencies is determined as follows:

calc = 1250 / (acquisition_length * MTB * 50).

>The peak-to-peak voltage to calculate the attenuation using the SENSe:VOLTage:RANGe:PTPeak? query.

Attenuation = peak-to=peak / 8.

>The FFT type, i.e., ABSolute or RELative, using the CALCulate:TRANsform:FREQuency:TYPE? query.

•

•Convert and print the frequency and amplitude values of the FFT trace sample points according to the formulas as explained before.

Note: The program prints the calculated values in groups of 20 sample points on the screen of your computer.

Note: The program is supplied on floppy under file name EXFFTTRC.BAS.