Tektronix 2715, Руководство пользователя

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Spectrum Analyzer Menus
2715 User Manual
6–31
33. To store the MEAN value of the spectrum in register A, press
[DSPL] [1] [4] [8].
34. Press [1] from the ENSEMBLE AVERAGING submenu to start averaging.
35. At the prompt, press [W] to overwrite the previously stored max/min
average.
Again, the mean value of the noise appears to be halfway between the max
and min values. The average MEAN is what you get if you add successive
maximum and minimum values in dB from the MAX/MIN display, divide
by two, and average the results. The MEAN average is a visual mean, not a
true mean, that can be very useful in making weak signals visible.
36. Turn on the D register to see the current sweep with its visual mean and
average maximum and minimum values superimposed.
The mean along with the max and min values provide an estimate of the
variability of the signal.
The signal peak does not appear to have changed because the calibration signal is
essentially constant (little or no variability), so its min, max, and mean amplitude
are all about the same. This can be used to advantage.
37. Turn off the A, B, and C registers.
38. Set the reference level to +58.8 dBmV.
The calibration signal third harmonic is almost lost in the noise.
39. Now ensemble average the spectrum MEAN values and store the result in A.
The mean spectrum leaves little doubt as to the presence or location of the
signal peak. Sometimes you can achieve even better results using the average
minimum.
40. Experiment if you like before proceeding, then clear the A, B, and C
registers and leave only the D register active.