HP 8753E manual Device Response in the Frequency Domain

4. To better view the measurement trace, press:

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F’igure 2-64 shows the frequency domain reflection response of the cables under test. The complex ripple pattern is caused by reflections from the adapters interacting with each other. By transforming this data to the time domain, you can determine the magnitude of the reflections versus distance along the cable.

Figure 2-64. Device Response in the Frequency Domain

5.To transform the data from the frequency domain to the time domain, press:

6.To view the time domain over the length (~4 meters) of the cable under test, press:

The stop time corresponds to the length of the cable under test. The energy travels about

1 foot per nanosecond, or 0.3 meter& in free space. Most cables have a relative velocity of about 0.66 the speed in free space. Calculate about 3 ns/foot, or 10 &meter, for the stop time when you are measuring the return trip distance to the cable end.

Making Measurements 2-88