Agilent Technologies U2781A manual System Reference Clock

Features and Functions 3

Figure3-4Block diagram of the 10 Mhz Reference Clock and External Trigger In

System Reference Clock

The 10 MHz reference clock can come from two sources; internal backplane oscillator and external clock source.

The internal oscillator on the USB backplane supplies an independent 10 MHz system reference clock to each of the USB slot. This 10 MHz reference clock is driven through an independent buffer. Refer to Figure 3- 4 for the block diagram. Every clock trace is in equal distance to ensure that the slot to slot skew is at minimum. Users can use this common reference clock signal to synchronize multiple modules in a measurement or control system.

The default SCPI command of ACQuire:RSIGnal AUTO will scan thru and detect if there is any valid clock source from the external BNC connector. If non is found, then the internal 10 MHz clock source will be used.

The SCPI command below will direct the reference clock source to the internal 10 MHz:

ACQuire:RSIGnal INT

U2781A User’s Guide 33