Tektronix TDS5032, Manual

Page: 211 / 248

Measurement Algorithms
For Falling slope, f(x) is a differential signal if
for all values of x till the last data point.
Rising Edge Rate
The Rising Edge Rate in V/us is calculated using the following equation:
Rising Edge Rate = Amplitude/Rise Time
Where: Amplitude is the difference between the positive and negative thresholds
that vary for each of the signaling rates.
Rise time is calculated using the higher level of the inner vertical eye height
reference levels and is ~80% of the signal amplitude.
This is applicable both to differential and single-ended waveforms.
Signaling Rates Positive Threshold Negative Threshold
LS 2.8 V 0.4 V
FS 2.5 V 0.8 V
HS 0.175 V – 0.175 V
Falling Edge Rate
The Falling Edge Rate in V/us is calculated using the following equation:
Falling Edge Rate = Amplitude/Fall Time
Where: Amplitude is the difference between the positive and negative thresholds
that vary for each of the signaling rates.
Fall time is calculated using the Lower level of the inner vertical eye height
reference levels and is ~20% of the signal amplitude.
This is applicable both to differential and single-ended waveforms.
Signaling Rates Positive Threshold Negative Threshold
LS 2.8 V 0.4 V
FS 2.5 V 0.8 V
HS 0.175 V – 0.175 V
TDSUSB2 Universal Serial Bus Measurement Package 197