User`s guide

Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 97
Optimizing Performance
Using Internal Channel Correction—(Requires Option U01 or Greater)
Using Internal Channel Correction—(Requires Option U01 or Greater)
The internal channel correction feature corrects the 100 MHz baseband bandwidth flatness and phase
for arbitrary center frequencies. This feature is off by default, as the switching speed performance of
the instrument is impacted when this feature is on.
This calibration should be run when the ambient temperature has varied by at least ±5 degrees
Celsius from the ambient temperature at which the previous calibration was run.
NOTE There is an internal calibration routine that can be run to collect correction data for both
the baseband and RF magnitude and phase errors over the entire RF frequency range on any
unit with options 651, 652, or 654. The internal channel correction cannot be turned on until
after the correction has been executed once.
For new instruments, shipped with firmware version A.01.60 and above, the internal flatness
correction calibration has already been run.
When this feature is off, the box will behave as it always has. When this feature is on, the internal
I/Q path is active, the I/Q Correction Optimized Path is RF Output, and the frequency is changed by
more than 1 kHz, the firmware will calculate a channel correction filter ±50 MHz about the specified
frequency. For List/Sweep, the calculation will be done prior to the first sweep using the specified
frequencies when either waveform sweep is active or the baseband is on and the instrument is
optimized for the internal path. This calculation will cache corrections for up to the maximum
number of cache points (256). For list/sweep, the sweep will pause and recalculate the correction
caches before running again.
CAUTION In the case of arbitrary frequency switching, once the correction cache is full (256
unique frequency points), the oldest frequency corrections will be forgotten as new
frequencies are selected.
Whenever I/Q Timing Skew, I/Q Delay, Quadrature Angle Adjustment, or the Int
Equalization Filter is adjusted, all caches are forgotten.
Additional characteristics of the internal channel correction:
• When the internal channel correction is on, arbitrary frequency switching while the baseband is
on will take up to an additional 290 ms (72 ms typical) the first time that frequency is specified.
After the first time that a frequency is selected, switching to that frequency again takes an
additional 1 ms.
• If a frequency sweep is activated, then the calculation and caching will occur up front for the
first 256 unique frequencies, and all additional unique frequencies will have the characteristics of
arbitrary frequency switching.
• If the I/Q Correction Optimized Path softkey is set to Ext I/Q, then only the baseband corrections
will be applied and the frequency switching will be unaffected.
• If active, the ACP Internal I/Q Channel Optimization filter and the Equalization filter, will be
convolved with the internal channel correction. A hamming window is applied and the resulting
filter will be truncated to 256 taps.