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Appendix B: Automatic Measurements Reference

B-52

CSA8000B & TDS8000B User Manual

Table B- 8: NRZ Measurements - Timing (cont.)

Name Definition

NRZ Fall Tim e NRZ Fall Tim e characterizes the negati ve sl ope of the NRZ eye by com puting the t ime interval

between the mean crossings of the high reference level and the low reference level.

RZ Fall Time = TcrossL -- TcrossH

Where TcrossL is the mean of the histogram of the crossing of the low reference level, and

TcrossH is the mean of the histogram of the crossing of the high reference level. See NRZ

Measurement Reference Levels on page B--63.

The adjustable low reference and high reference l evels def ault to 10% and 90% of the NRZ eye

amplitude.

If enabled, measurement gates constrain the measurement region to the area between the Start

Gate (G1) and Stop Gate (G2). See To Localize a M easurem ent on page 3--83.

This measurement requires the use of a waveform database. When this measurement is turned

on, it will automat ically set the measurement system to use a waveform database if available.

See Use a Waveform Database on page B--70.

NRZ Frequency NRZ Frequency is defined as half of the inverse of the time interval between two consecutive

eye crossing points (i. e. the reciprocal of the Period). It would be the frequency of a digital

signal of a 0--1--0--1… stream.

Where Tcross1 and Tcross2 are t he mean of t he histogram of t he t wo crossings. See NRZ

Crossings on page B--64.

If enabled, measurement gates constrain the measurement region to the area between the Start

Gate (G1) and Stop Gate (G2).

This measurement requires the use of a waveform database. When this measurement is turned

on, it will automat ically set the measurement system to use a waveform database if available.

NRZ Frequency =

(2 × (Tcross2 − Tcross1))

NRZ Period NRZ Period is twice the time interval between two consecutive eye-crossing points. It would be

the period of a di gital signal of a 0--1--0--1… stream.

NRZ Period = 2 * (Tcross2 – Tcross1)

Where Tcross1 and Tcross2 are t he mean of t he histogram of t he t wo crossings of the eye

diagram.

If enabled, measurement gates constrain the measurement region to the area between the Start

Gate (G1) and Stop Gate (G2).

This measurement requires the use of a waveform database. When this measurement is turned

on, it will automat ically set the measurement system to use a waveform database if available.

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Tektronix CSA8000B Manual do Utilizador Página 314