Agilent Technologies J-BERT N4903B, Руководство пользователя, Страница: 143 / 572

Bit Rate - Reference
The
Bit Rate Setup
window contains the following elements:
Clock Source
Clock source can be one of the following:
• Internal: The clock generator uses the internal oscillator.
• 10 MHz Ref: The clock generator uses the 10 MHz Reference that must be
connected to the 10 MHz Ref Input.
• External: The pattern generator uses the external clock that must be connected
to the Clock Input. You can choose between “Automatic and Manual Mode”
on page 143 .
• External PLL: The pattern generator uses the external clock that must be
connected to the Clock Input. This clock is routed internally through a PLL. You
can choose between “Automatic and Manual Mode” on page 143 .
Automatic and Manual Mode
The
Manual Adjustment
checkbox is available if you have chosen an external clock
source.
In automatic mode, the external clock frequency is continually measured. When
the external clock frequency changes, the bit rate changes as well.
In manual mode, you can enter the expected frequency or press the
Measure &
Set
button.
Measure & Set
requires that the external clock generator is connected
and active. Its frequency is measured once and determines the bit rate. When the
external clock frequency changes,
PG Clock Loss
is signaled.
External Clock Divider
The internal clock (i.e. the bitrate) is the external clock divided by the value
specified in the clock divider field. The external clock divider field is available if you
have closen an external clock source.
Setting up the Pattern Generator
4
Agilent J-BERT N4903B High-Performance Serial BERT 143