Using the Agilent E1439
Managing multiple modules
Here is the sequence of operations:
1.Put all modules into either the AGE1439_REAR_SYNC_EXT_SAMP mode or the AGE1439_FRNT_SYNC_EXT_SAMP mode with the age1439_clock_setup command.
2.Issue the age1439_ext_sample_sync (AGE1439_EXT_SAMPLE_SYNC_ENABLE) command to reset the counters within all the E1439s.
3.Generate the external sample sync pulse simultaneously into all modules. One way to do this is to use one of the VXI TTLTRG lines and reclock the signal with the falling edge of the sample clock. Note: If you are using an E1439A module with a serial number lower than US41140000, you will need some user supplied hardware to convert TTLTRG to ECL because older E1439As do not support TTL trigger.
4.Issue the age1439_clock_recover command to all modules since the DSP clock was interrupted between the age1439_ext_sample_sync command and the external sync signal on the Trigger input.
5.Sync the digital filters:
•Force all modules to idle (age1439_meas_control).
•Send the age1439_filter_sync command to all modules.
•Assert and release the sync line from the master module (age1439_meas_control).
•Release all modules from idle (age1439_meas_control).
6.Sync the digital local oscillators:
•Force all modules to idle (age1439_meas_control).
•Set all module frequencies to zero (age1439_frequency_center).
•Assert and release system Sync (age1439_meas_control).
•Set the LO frequencies to the desired ones (age1439_frequency_center).
•Toggle system Sync again to synchronously set the LO frequencies (age1439_meas_ control).
•Finally release all modules from idle (age1439_meas_control).
7.Now you may take a measurement:
•Issue an age1439_meas_start.
•Retrieve data from the modules when valid.
In the event that you do not supply a synchronizing signal in a reasonable length of time (or you change your mind about it), the DSP clock can be restored by issuing age1439_ext_sample_sync (AGE1439_EXT_SAMP_SYNC_CANCEL) followed by an age1439_clock_recover.
You should not need to perform the external sample sync operation again unless the external clocks are interrupted or the clock setup changed.
See also the diagrams earlier in this section that show the physical setup. All the functions mentioned above are described in “Functions listed alphabetically” in chapter 4.
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