Tektronix XYZs, Manual

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Waveform Capture Rate
All oscilloscopes blink. That is, they open their eyes a given number of
times per second to capture the signal, and close their eyes in between.
This is the waveform capture rate , expressed as waveforms per second
(wfms/s). While the sample rate indicates how frequently the oscilloscope
samples the input signal within one waveform, or cycle, the waveform
capture rate refers to how quickly an oscilloscope acquires waveforms.
Waveform capture rates vary greatly, depending on the type and
performance level of the oscilloscope. Oscilloscopes with high waveform
capture rates provide significantly more visual insight into signal behavior,
and dramatically increase the probability that the oscilloscope will quickly
capture transient anomalies such as jitter, runt pulses, glitches and
transition errors. (Refer to Figures 51 and 52.)
Digital storage oscilloscopes (DSOs) employ a serial-processing
architecture to capture from 10 to 5,000 wfms/s. Some DSOs provide
a special mode that bursts multiple captures into long memory, temporarily
delivering higher waveform capture rates followed by long processing dead
times that reduce the probability of capturing rare, intermittent events.
Most digital phosphor oscilloscopes (DPOs) employ a parallel-processing
architecture to deliver vastly greater waveform capture rates. Some DPOs
can acquire millions of waveforms in just seconds, significantly increasing
the probability of capturing intermittent and elusive events and allowing
you to see the problems in your signal more quickly. Moreover, the DPO’s
ability to acquire and display three dimensions of signal behavior in real
time – amplitude, time and distribution of amplitude over time – results in
a superior level of insight into signal behavior.
Record Length
Record length, expressed as the number of points that comprise a
complete waveform record, determines the amount of data that can be
captured with each channel. Since an oscilloscope can store only a
limited number of samples, the waveform duration (time) will be inversely
proportional to the oscilloscope’s sample rate.
XYZs of Oscilloscopes
Primer
Figure 51. A DSO provides an ideal solution
for non-repetitive, high-speed, multi-channel
digital design applications.
Figure 52. A DPO enables a superior level of
insight into signal behavior by delivering
vastly greater waveform capture rates and
three-dimensional display, making it the best
general-purpose design and troubleshooting
tool for a wide range of applications.
Figure 53. Capturing the high frequency
detail of this modulated 85 MHz carrier
requires high resolution sampling (100 ps).
Seeing the signal’s complete modulation
envelope requires a long time duration (1 ms).
Using long record length (10 MB), the
oscilloscope can display both.
Time Interval =
Record Length
Sample Rate