Tektronix 071-0590-00 user manual Ensure Accuracy Of Bit-Error Rate Tests

BERT Technical Articles

Technical Article from 5/9/91 Electronic Design magazine

Ensure Accuracy Of Bit-Error Rate Tests

By Dan Wolaver and James Hanley, Tektronix

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To properly evaluate digital transmission systems, users must understand their BER tester’s specifications.

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A critical element in a digital transmission system is how error-free its transmissions are. This measurement is made by a bit-error-rate tester (BERT), which replaces one or more of the system’s components during a test transmission.

A BERT must be able to mimic normal and stress conditions and must not be the first component to fail when the system is stressed. Moreover, a BERT’s data pattern and clock quality typically differ from those of the system under test.

Consequently, users must know how to obtain and understand these important specifications to ensure an accurate picture of their system’s capabilities.

A digital transmission system (see figure below) includes a data source-such as computer memory, a voice digitizer, or a multiplexer--that originates a digital signal, D.

C		D		F		H
Clock	Data	Driver	System	Line	Decision	Data
Source	Source		under test	Receiver	circuit
					G	Clock
	Input				Clock
					Recovery
C
D
Threshold
F
Sampling instant
G
H

Figure 1. In a typical digital transmission system, the data signal, D is corrupted by noise and pulse dispersion. As a result, the received signal, F, is distorted.

GB1400 User Manual B-21