HP 54645A, User'S And Service Manual

Page: 149 / 301

To reduce the random noise on a signal
If the signal you are applying to the oscilloscope is noisy, you can set up the
oscilloscope to reduce the noise on the waveform. First, you stabilize the
displayed waveform by removing the noise from the trigger path. Second,
you reduce the noise on the displayed waveform.
1
Connect a signal to the oscilloscope and obtain a stable display.
2
Remove the noise from the trigger path by turning on either
high-frequency reject or noise reject.
High-frequency reject (HF reject) adds a low-pass filter with the 3-dB point
at 50 kHz. You use HF reject to remove high-frequency noise, such as AM or
FM broadcast stations, from the trigger path.
HF Reject
Refer to chapter 2, “Front-Panel Overview,” for more information.
3 dB down point
Pass
Band
dc
0 dB
50 kHz
Figure 5-4
Making Measurements with HP 54645A/D Oscilloscopes
To reduce the random noise on a signal
5-8