82
Chapter 3
Theory of Operation
Theory of Operation
Th
eo
ry o
f Oper
atio
n
Figure 3-8
Multiple Module Synchronous Trigger Timing Diagram
Cable Length and Skew
The cabling requirements are as follows:
Sample Clock
Skew less than 10 mm between modules. The absolute SYNC cable
length is given by the following formula as a function of the Sample
clock frequency:
Equation 3-1
Sample Clock Skew Formula 1
Expressed in millimeters, where n is an arbitrary integer and f is the
sample clock frequency in MHz.
It should be noted that n is the number of 1/2 SYNC clock cycles of total
delay between the modules.
This can also be expressed in terms of delay:
Equation 3-2
Sample clock Skew Formula 2
Expressed in nanoseconds, where n is an arbitrary integer and f is the
sample clock frequency in MHz.
For the external Sample clock the formulas apply over the frequency
range of 625 MHz to 1.25 GHz
Length
n
(
686
1250
MHz
(
)
f
)
⁄
×
×
394
–
[
]
=
Cabledelay
n
3.29
1250
MHz
(
)
f
⁄
×
×
(
)
1.89
–
=
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