Tektronix TDS5032, Руководство пользователя

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Operating Basics
Area Option Description
Where Amplitude is the peak-to-peak amplitude for the
corresponding signaling rate and the Fall time is calculated
based on the lower level of the inner vertical eye height
reference levels
Signal Quality Check Monotonic Property (For High Speed only) Measures the Monotonic Signal if the data [i] < data [i-1] where
data[l] is the record point in the acquired waveform. This is in the
case of consistently increasing (rising Slope) only. If the data [i]
> data [i-1] in case of consistently decreasing) falling Slope) and
never increasing in value where i ranges from 0 to n, the signal I
is said to be monotonic
Note: The USB2.0 specifications recommend that you should test the signal
quality for upstream and downstream traffic. In upstream testing, the application
captures the signals transmitted from the device to the host. In downstream
testing, the application captures the signals transmitted from the host to the
device.
Downstream testing is performed on ports of a hub. When testing a hub, you need
to connect the USB2.0 unit to Tier 6 to ensure the worst case. Each hub level is
referred to as a Tier. The hub under test is connected to the Tier 5, so that you
can test the hub on the Tier 6.
Inrush Current Check
The application can perform an Inrush current check to verify that the unit under
test does not draw current higher than that specified in the USB2.0 specifications
when connected to a USB2.0 system. If the measured current drawn is higher
than a specified value, the other USB2.0 devices connected to the bus may not be
able to function properly.
When a unit is connected, there is a sharp intake of current followed by a
comparatively less steep decay. Small humps or perturbations are noticed in the
current trace, depending on when the unit resets.
The TDSUSB2 application automatically sets up the oscilloscope. The
application gives a direct readout of Charge (µC) and Capacitance (µF) values.
The application displays the details of the results after comparing the test results
with the USB2.0 specifications.
30 TDSUSB2 Universal Serial Bus Measurement Package