Tektronix TDS5054, Руководство пользователя

Страница: 81 / 361

Acquiring Waveforms
3- 14
TDS5000 Series User Manual
This section contains background information that can help you more effectively
set up the acquisition window of each channel.
Input.
Keep in mind that this oscilloscope samples in real time or random
equivalent time; both sampling systems provide pretrigger information by using
the trigger to stop an already running acquisition. Both sampling systems also
sample the input after it is scaled, providing improved input protection and
dynamic range.
CAUTION.
To prevent damage to the instrument, do not overdrive the inputs.
Observe static-safe procedures.
Autoset Considerations. Autoset acquires samples from the input signal and
attempts to take the following actions based on the input data:
H
Evaluate the amplitude range of the input signals and set the size and vertical
offset of the vertical acquisition window to acquire the signal with good
resolution, but without clipping.
H
Set the trigger to the approximate midlevel of the signal being Autoset and
switches to edge trigger mode.
H
Evaluate the signal transitions and set the horizontal scale to produce a
waveform display of 2 or 3 cycles of the input signal.
Sometimes Autoset cannot produce a correct display due to the nature of the
input signal. If so, you may have to adjust the scale, trigger, and acquisition
controls manually. Some conditions that can cause Autoset to fail are:
H
No signal present
H
Signals with extreme or variable duty cycles
H
Signals with multiple or unstable signal periods
H
Signals with too low amplitude
H
No recognizable trigger signal
H
Signals with a frequency
<
20 Hz
H
Signals with a frequency above the bandwidth of the oscilloscope
Vertical Acquisition Window Considerations.
You can set the vertical size,
position, and offset of each channel independently of other channels. Vertical
scale and offset specify the vertical acquisition window for each channel. Parts of
the signal amplitude that fall within the vertical window are acquired; parts
outside (if any) are not.
Input Conditioning
Background