Gage CompuScope 14100C, Hardware Manual And Driver Installation Manual

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CompuScope 82GC 101
CompuScope 82GC External Clock
External clocking is a very powerful feature in a digitizer. It allows the user to synchronize the digitizer to an
external system.
On the CompuScope 82GC, external clock signal must be a continuous sine wave signal of amplitude between
225 mV RMS and 500 mV RMS. Note that the external clock input is AC coupled, so DC biases get canceled.
The allowable external clock frequency is between 1 GHz and 10 MHz. An SMA connector is employed for the
External Clock input because of its superior high frequency response at 1 GHz – BNC connectors start running
into bandwidth limitations at such high frequencies.
PLEASE NOTE:
THE EXTERNAL CLOCK ILLUSTRATIONS IN THIS SECTION DEPICT THE CLOCK SIGNAL
AS A SQUARE WAVE FOR CLARITY, PLEASE FOLLOW THE RECOMMENDATIONS ABOVE
TO ACHIEVE PROPER OPERATION.
In single channel mode, sampling is done on both the “rising” and “falling” edge of the sine wave.
Figure 63: External Clocking in single channel mode
In dual channel mode, sampling is done on only the “rising” edge of the sine wave.
Figure 64: External Clocking in dual channel mode
Note that high-speed waveform digitizers are very sensitive to phase noise and duty cycle of the external clock
input. All efforts should be made to minimize jitter and distortion on the external clock signal.
Care should be taken not to inject a TTL or CMOS signal (0 to 5 Volts) into the external clock input, as it may
result in saturation of the input circuitry.