User manual

Table Of Contents
3152B User Manual Publication No. 980935 Rev. M
3-2 Operation Astronics Test Systems
configuration.
Example 2, Model 3100M/R-
3152B, default instrument format is
Modern
form:inst leg modifies the
commands set from Modern to
Legacy, *rst is automatically forced and the 3152B parameters
are modified to accept the defaults of the Legacy mode.
*rst restores factory defaults for Legacy operation.
Output
Termination
Output signals should
be properly terminated to minimize signal
reflections or power loss due to an impedance mismatch.
For the
best performance, use 50 coaxial cables for the
OUTPUT and
SYNC OUT outputs, and terminate the receiving end of each cable
with a 50 load.
Load impedance accuracy affects the
accuracy of the waveform
amplitude and DC offset levels. These output levels will
not match
the amplitude and offset settings when using loads other than 50
.
To correct for a load that is greater than 50 , pr
ogram the actual
load impedance and the 3152B will automatically adjust
the output
level to compensate. Use the following command:
outp:load <value>
where <value> is the load impedance in ohms.
The default at
power-up is 50 Ω.
Correction is not available for loads less than 50 Ω.
If the loads are high impedance (1 MΩ or greater), use the
above
command with the actual impedance value, and then use the
following command to achieve maximum accuracy:
outp:load:cal 1M
This
activates a separate set of calibration constants for accurately
driving into a high-
impedance load. If, after using this command,
you wish to drive a 50 load, use the following comman
d to revert
back to the calibration constants for a 50 Ω load:
outp:load:cal 50
The default at power-up is 50 Ω.
If you are using high-
impedance loads with legacy 3152A software
that does not include the outp:load <value> command, you may still
benefit from the high-
impedance calibration table by sending the
outp:load:cal 1M
command outside of your software. You might
send this command before initializing your software, or use a
software wrapper to insert this command before driving high-
impedance loads. If you use this command, the output level will still