Tektronix 2715, User Manual

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Spectrum Analyzer Menus
6–34
2715 User Manual
If the waveform in B gets so much larger than that in A that the result goes
off-screen, subtract the average MEAN noise from the MAX HOLD signal plus
noise. This provides a measure of the maximum signal variations about the mean
noise level.
9. Press [DSPL] [2] to disable B, C MINUS A mode.
10. Ensure the center frequency is set to 400 MHz and the reference level to
18.8 dBmV.
11. Turn off the calibrator and store a 24 sweep MEAN average of the noise in
register A (you need to overwrite the display currently stored in register A).
12. After the average is complete, turn the calibrator back on and activate MAX
HOLD in register B.
The resulting traces are shown in Figure 6–6.
MAX HOLD plus noise
Average MEAN noise
Figure 6–6: Average MEAN Noise and MAX HOLD Signal-Plus-Noise
13. Turn off the A register.
14. Press [DSPL] [2] to enter the B, C MINUS A mode.
The resulting noise floor is approximately two divisions down from the
reference level, but some of the calibration signal peaks fold over and point
downward. See Figure 6–7.
15. Press [DSPL] [3].
The waveform is now nearer the bottom of the screen where you can see it
more clearly.