Tektronix TDSUSB2, Руководство пользователя

Страница: 205 / 250

Measurement Algorithms
Cross-Over Voltage for High-Speed Signals
The Cross-Over is defined as that point where the Differential line voltage
becomes zero. The voltage value at this point is called the Cross-Over Voltage
and the time value is called the Cross-Over Time.
The following algorithms are used for High Speed signals for Cross-Over
voltage.
for High Speed y=0
If,
If,
Where: p1 and p2 are the consecutive data points of a single-ended signal, x and
y are the coordinates of the point where the Differential line voltage becomes
zero and t1 and t2 are the time values for the data points p1 and p2.
Note 1: Low Speed and Full Speed Signals are acquired with single-ended
probes that enable finding the Cross-Over Voltage.
Note 2: For High Speed devices, the signal is differential, Cross-Over voltage is
zero and cross-Over time is the interpolation of two data points at zero crossings.
TDSUSB2 Universal Serial Bus Measurement Package 191