7
STORE and RECALL MENUS
There are ten storage locations from which
setup data may be recalled. One of these
locations, number 0, contains default setup data,
the other nine locations contain setup
information that was stored by the user. Because
the information is stored in nonvolatile RAM, it
will be available for recall even if the instrument
is turned off.
All of the instrument's settings are stored, even
those which are not currently active: for
example, the external trigger threshold is saved
even though the instrument is operating on
internal trigger.
Operating data is stored by pressing the STORE
key, one digit (1-9) to specify the storage
location, and the EXC (execute) key. Mistakes
may be edited with the BSP (backspace) key.
Instrument settings are recalled from storage by
pressing the RECALL key, one digit (0-9), and
the EXC (execute) key. If the stored data has
been corrupted since it was saved, the error
message "Recall Error" will be displayed. The
error message can be removed by pressing any
key. A defective Lithium battery or very noisy
ac line voltages will cause "Recall Errors".
ACCURACY, DRIFT, AND JITTER
Each of the delay channels, A, B, C and D, may
be programmed to time out from 0 to 1000
seconds with a resolution of 5 ps. The factors,
which detract from this ideal performance, are
discussed here.
ACCURACY
The error in the time delay between any two outputs
is less than (1500 ps [500 ps typical] + Timebase
error x Time between Outputs). (This specification
is exclusive of time shifts due to slew rates at the
outputs, i.e., it should be measured with both
outputs set for the same logic levels driving the
same loads). The timebase error depends on the
timebase being used:
Standard
<25 ppm
0-50 °C
Option 03
<1 ppm
0-50 °C
External
Source spec + 0.0002ppm
Using the typical error figure, for a time delay of 1.0
ms, this table implies an absolute error of ±25 ns,
±1.5 ns and ±0.5 ns respectively for the standard,
optional and external timebases (assuming a 0.01
ppm external source specification). If A=100.000µs
and B=100.01µs, the error with respect to T0 will be
±2.6 ns with the standard timebase, however the
accuracy of A with respect to B will be ±500 ps.
A graph showing the maximum time error as a
function time delay is shown in Figure 3. The four
curves show the time error for the standard,
optional, 0.01 ppm external, and ideal external
timebases. The excess error for time delays longer
than 1 second on the "ideal external source " curve
is due to drift in the analog jitter compensation
circuits.
