Agilent Technologies E1439 User Manual page 139

AGE1439_CMPLXDC_OFF, combined with a frequency change to zero, causes phase to be reset
to zero.
AGE1439_CMPLXDC_ON, combined with a frequency change to zero, does not reset the phase
thereby generating a complex dc measurement at baseband. The state of this parameter does not
affect any transition where freq is nonzero. Whether the real or complex data is saved and
ultimately sent to the output port is determined by the age1439_data_type function
cmplxDCPtr points to the current actual value of cmplxDC.
sync when set to
systems.
In multiple-module systems, setting this parameter to
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 age1439_meas_control function. Note that returning sync to OFF before
the Sync signal transition has occurred forces an immediate asynchronous frequency change.
syncPtr points to the value of sync.
Comments
Although the freq parameter is a double precision floating point number, its effective resolution is
1/(2^19 × 5^9 × 19). This allows exact specification of any multiple of 10 mHz when fs=95 MHz.
The actual frequency is set to the nearest available value. This value is returned by the age1439_
frequency_center_get function. 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. You may accomplish this by
setting the sync parameter to ON for all the modules which are to be changed.
In configurations involving synchronous operation of multiple Agilent E1439 modules, the
age1439_frequency_setup function provides a mechanism to force all LOs to the same phase.
You can do this by first setting the frequency to zero and then synchronously changing the
frequency to the desired value.
Example
The example program multichan.exe shows how to correctly perform synchronous frequency
changes in a multi-module system.
Return Value
AGE1439_SUCCESS indicates that a function was successful.
Values other than AGE1439_SUCCESS indicate an error condition or other important status
condition. To determine the error message, pass the return value to
page
AGE1439_SYNC_OFF
102.
Agilent E1439 Programmer's Reference
allows an immediate frequency change in single-module
AGE1439_SYNC_ON
Functions listed alphabetically
prepares the
"age1439_error_message" on
129