AlazarTech ATS850, User Manual

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ATS850 User Manual 41
Optional Trigger Out Upgrade
Many ultrasound applications require the digitizer to generate
a Trigger Output signal synchronous with its internal sampling
clock.
Such synchronization is almost essential if multiple
acquisitions have to be averaged.
ATS850 uses a high quality crystal-controlled clock
oscillator as its timebase.
It should be noted that crystal oscillators are one of
the most reliable and repeatable types of clock
source available.
Crystal oscillators also provide far superior long-term
jitter performance compared to PLL based clocking
schemes.
The same qualities that make crystal oscillators such
an ideal clock source also make it impossible to
synchronize them to an external signal, such as an
external trigger input or a 10 MHz reference clock.
As such, the best way to fully synchronize the acquisition
system to a signal source, such as a pulser-receiver, is to
trigger the pulser-receiver with a trigger signal that has
already been synchronized to the ADC sampling clock.
Hence the Optional Trigger Out Upgrade.