Agilent Technologies E1437A, User Manual

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Parameter Definitions:
selects either a phase continuous or phase reset transition when the freq =
0. . The state of this parameter does not affect any transition where freq
≠
0.
Whether the real or complex data is saved and ultimately sent to the output port is
determined by the DATA:TYPE command.
parameter
value
cmplxdc parameter definition
0 OFF causes phase to be reset to zero when combined with a frequency change to zero
1
ON combined with a frequency change to zero does not reset the phase, thereby
generating a complex DC measurement at baseband.
controls when a frequency transition is implemented.
parameter
value
sync parameter definition
0 OFF allows an immediate frequency change.
1
ON. In multiple-module systems, setting this parameter ON prepares the modules for a
frequency change, but does not actually bring about the change until the next ADC clock
corresponding to the next assertion of the shared SYNC signal. The SYNC transition is
generated by calling the MEAS:CONTROLcommand. Note that returning sync to OFF
before the SYNC signal transition has occurred forces an immediate asynchronous
frequency change.
is a number between -0.5 and +0.5, which will be interpreted as a fraction of the
sample frequency.
freq
is the desired center frequency divided by the ADC sample
frequency. For example, selecting .25 witha sample clock frequency of 20 MHz will
yield a center frequency of 5.0 MHz. The ADC sample frequency is returned by the
CLOCK:FS? command. Negative frequencies select the negative image of the signal,
which is spectrally inverted from the input signal.
Comments:
Although the freq parameter is a double floating point number, its effective
resolution is 1/(1024*10^9) or 20
µ
Hz when fs =20.48 MHz. The actual frequency will
be set to the nearest available value. This value is returned by the
FREQUENCY:CENTER? command. In multi-module systems this value represents
the pending value rather than the current value when a frequency change is
incomplete due to a pending SYNC signal transition.
In multiple-module systems it is often desirable to force the frequency change to
occur synchronously in order to preserve the phase relationship of the LOs. This is
accomplished by setting the sync parameter to ON for all the modules which are to
be changed. See the first example below.
In configurations involving synchronous operation of multiple E1437 modules, the
FREQUENCY:SETUP command provides a mechanism to force all LOs to the same
phase. This can be done by first setting the frequency to zero. See the second
example below.
E1437A FREQUENCY:SETUP
ASCII Overview and Commands command/query
5-27
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