Agilent Technologies E4428C, Руководство пользователя

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248 Chapter 7
Digital Signal Interface Module
Operating the N5102A Module in Input Mode
4.
Press the
Clock Phase
softkey.
From the menu that appears, the phase of the clock relative to the data can be changed in 90 degree
increments. The selections provide a coarse adjustment for positioning the clock on the valid portion of
the data. Selecting 180 degrees is the same as selecting a negative clock polarity.
The 90 degree and 270 degree selections are not available when the clock rate is set below 10 MHz or
above 200 MHz. If 90 degrees or 270 degrees is selected when the clock rate is set below 10 MHz or
above 200 MHz, the phase will change to 0 degrees or 180 degrees, respectively.
NOTE
The clock phase and clock skew may need to be adjusted any time the clock rate setting is
changed. Refer to “Clock Timing for Phase and Skew Adjustments” on page 228 .
5. Enter the required phase adjustment.
6. Press the
Return
softkey to return to the clock setup menu.
7. Press the
Clock Skew
softkey.
This provides a fine adjustment for the clock relative to its current phase position. The skew is a phase
adjustment using increments of time. This enables greater skew adjustment capability at higher clock
rates. For clock rates below 25 MHz, this softkey is inactive.
The skew has discrete values with a range that is dependent on the clock rate. Refer to “Clock Timing for
Phase and Skew Adjustments” on page 228 for more information on skew settings.
8. Enter the skew adjustment that best positions the clock with the valid portion of the data.
Table 7-9 Clock Source Settings and Connectors
Clock Source Softkeys
N5102A Module Connection
Reference
Frequency
Clock Rate
1
1. For the Internal selection, this sets the internal clock rate. For the External and Device selections, this
tells the interface module the rate of the applied clock signal.
Freq Ref Ext Clock In Device Interface
External
• •
Device
• •
Internal
2
2. There should be no clock signal applied to the Ext Clock In connector when Internal is being used.
• • •