Tektronix WFM 601i, Руководство пользователя

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WFM 601i Serial Component Monitor
3–5
Measurement Applications
The WFM 601i is capable of making a broad variety of measurements, ranging
from the familiar analog component measurements to methods for evaluating the
wideband serial digital channel. This section will describe several representative
measurements.
Measuring Serial Sources
A typical serial transmission system consists of a transmitter (source), the
coaxial cable channel, and a receiver. To facilitate signal interchange, standards
organizations have established specifications for these three components. Many
of the specifications describe the acceptable output waveform from a serial
source. These include signal amplitude, aberrations, risetime, and jitter.
The WFM 601i can accurately make these four measurements using the EYE
mode. Connect the serial source to the monitor with a short (<2 meter) length of
75
Ω
cable. High quality, low loss coaxial cable, such as Belden 8281, should be
used. A 75
Ω
terminator with at least 25 dB return loss to 300 MHz should be
placed on the other side of the loopthrough input. Figure 3-5 shows a typical test
connection.
WFM 601i
A or B Input
Channel
Serial
Source
75
Ω
Termination
Figure 3-5: Measuring a source.