Use of the External Clock feature in ETS2k permits users to synchronize the ETS system* clock with certain other instruments. This feature can be employed in two ways: 1) ETS clock drives a clock input line to another instrument; or, 2) A clock is provided to the ETS system to be used as the Test Rate clock.

ETS Provides the Clock
This application is simple. Just connect a standard BNC cable to the Clock Out BNC connector on the front of the ETS system. Connect the cable to the 50 ohm input of a scope; you should see an "active lo" TTL clock. Clock pulses should be "lo" for 10ns, with the leading edge of each pulse providing a rate of the same frequency as the Test Rate entered on your Run Setup window. Here's an example:


Accessing "Clock Out" for External Use

ETS Uses Your Clock
If your goal is to provide and control a clock source that will be used as the "Test Rate" in Run Setup, use the Clock In BNC connector on the front of the ETS system. Your clock source needs to provide a TTL active-lo or "lo-going" pulse of 10ns width, regardless of the input frequency you are using. Use the Test ExtClock button to see the pulse rate as sampled by the tester.

Running ETS on an External Clock

Also See:

Q'nApp #24: Data and Clock Rates

Qe27.zip is a zipped Word file of this Q'nApp.

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