Tektronix TDSUSB2, Руководство пользователя

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Measurement Algorithms
About Measurement Algorithms
The TDSUSB2 package performs measurements for USB2.0 compliance. This
section contains information about the algorithms used by the application to
perform each measurement.
Cross-Over Voltage for Low Speed and Full Speed Signals
You can define the Cross-Over point as the point where the Data+ line voltage
crosses the Data– line voltage. The voltage value at this point is called the Cross-
Over Voltage and the time value is called the Cross-Over time.
In the following figure, C1, C2, C3, C4 and C5 are called Cross-Over Points and
R1, R2, R3, R4, R5, R6 and R7 are called Reference points.
The following figure explains the interpolation technique used to find the actual
Cross-Over where p1 and p2 are the adjacent data points after q2:
TDSUSB2 Universal Serial Bus Measurement Package
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