HP 54520 Series - Repetitive;Real-Time Softkey

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Repetitive/Real Time Softkey
Repetitive/Real Time Softkey
The repetitive/real time softkey selects one of the two acquisition
modes used by the oscilloscope: repetitive and real time.
Repetitive
The repetitive mode (also known as equivalent time) sets the oscilloscope to
acquire data in the repetitive acquisition mode. In this mode, the data from
many acquisitions may be interleaved, which can result in a greater effective
sample rate. At 50 ns/div and slower, enough data is acquired on each
acquisition that interleaving acquisitions is not required. In the repetitive
mode, the sample rate is dependent on the time/div setting. The sample rate
from 500 ps/div to 20 ns/div is 1 GSa/s. At settings slower than 20 ns/div, the
sample rate is reduced, depending on the selected time/div setting. For
example, at 50 ns/div the sample rate is 1 GSa/s, and at 50 ps/div the sample
rate is 1 MSa/s. You can calculate the number of points captured on one
trigger and plotted to the screen in both the real-time and repetitive modes
with the following formula.
Number of points = sample rate x time/div setting x 10
The repetitive mode is typically used on repetitive signals. You can still use
the repetitive mode for single-shot applications. However, because the
interpolation filter is turned off in the repetitive mode, the maximum
single-shot frequency you can reasonably view and also avoid aliasing is about
one-tenth the current sample rate. Also, the record length is the size of the
screen,
Because the oscilloscope is in the repetitive mode, the sample rate is
dependent on the time base setting. To ensure a full screen display of 500
points on the slower time base ranges, as the time base is slowed down the
sample rate is also slowed down.
You can view the data using the normal, averaged, and envelope display
modes. You can average data from multiple acquisitions by selecting
averaging in the display menu, or you can choose to display data for a
definable period of time (persistence) by using normal in the display menu.
Chapter 7, “Display Menu," for information on acquisition modes.