HP 8590 E & L Series Spectrum Analyzers and HP 8591C Cable TV ...

FFTCONTS
FFT Continuous Sweep
Performs a fast Fourier transform (FFT) continuously on the current signal.
Syntax
Equivalent Softkey: CONTINUS FFT .
Prerequisite Commands: LN, Sl?
Related Commands: FFTOFF, FFTSNGLS.
Example
OUTPUT 718; “SP OHZ; ” Sets the spectrum analyzer to zero span.
OUTPUT 718; “LN; ” Changes the amplitude scale to linear:
OUTPUT 718;"FFTCONTS;" Starts the continuous FlT
Description
FFT.CONTS FFT Continuous Sweep
You should change the frequency span to 0 Hz and the amplitude scale to linear before
executing FFTCONTS. When FFTCONTS is executed, the spectrum analyzer does the following:
� Changes to the continuous sweep mode.
� If the current detector is the peak detector, changes to the sample detector.
Does an FFI’ on trace A. Trace A is then placed in both the clear-write and store-blank
modes. (When the spectrum analyzer is in both the clear-write and store-blank modes, the
trace data is still taken from the spectrum analyzer input during every measurement sweep,
but the trace is not shown on the spectrum analyzer display.)
� Places the results in trace B (trace B is placed in the view mode).
You can use the results of the FFTCLIP command to determine if the FFI’ data is valid. If you
want to view the input data (trace A), execute “TRDSP TRA,ON; ‘I.
Restrictions
Executing FFTCONTS turns off the following functions: windows display mode (WINON),
N dB point measurement (NDBPNT), gate utility functions (GDRVUTIL), TO1 measurement
(TOI), marker table (MKTBL), peak table (PKTBL), percent AM (PCTAM), peak zoom
(PKZOOM), power menu measurements (ACP, ACPE, CHP, and OBW), or Analog+ display mode
(ANLGPLUS).
FFTCONTS uses the following when performing an FFT:
� The flat top filter window. See “FFT” for more information about the flat top filter window.
w Trace B and trace C. If you want to save the trace data that is in trace B or trace C, you
should save the trace data before executing FFTAUTO, FFTCONTS, or FFTSNGLS. (See
“SAVET” for more information about saving trace data.)
� The FFTMKR command to turn on the FFI markers (you can use the MKA or MKF to
determine the amplitude or frequency of the marker).
You should execute the FFTOFF command when you are finished using the FFT measurement.
Programming Commands 5-167