Measurement Conditions - YOKOGAWA TA220 User Manual

2.4

Measurement Conditions

Measurement Block
Upper and Lower Limits of the Pulse Width <<For procedures, see section 4.1>>
Input Impedance <<For procedures, see section 4.2>>
Input Coupling <<For procedures, see section 4.2>>
IM 704610-01E
The TA220 repeats a three-part process of measurement, data processing, and display.
The smallest unit that is measured during the first part of this process is called a
measurement block. In the figure below, N is the number of samples (number of data)
acquired in a single pass of the process, and the measurement, data processing, and
display of these samples is considered to be one block of measurement. The range of
measured blocks is specified by the gate time described below.
Pulse Width Measurement
1 block
Measurement block
S1 S2 S3
Measurement input signal
Optical disc signals are pulse signals having time widths that are integer multiples of a
reference item width T (for example, 2T–14T, etc.). The pulses can experience
variations (jitter), such that for example a 3T pulse signal may include time widths of 2.9T
or 3.1T. You can specify to measure only pulse signals within a certain range of these
variations (for example a range from 2.5T to 3.5T).
To attenuate the measured signal and reduce distortions, you must adjust to the output
impedance of the signal under test. You can select an input impedance for the
measurement input terminal of 50 Ω or 1 MΩ.
Measurement of only the amplitude (AC component) of the measurement input signal or
only signals superimposed with a specific DC voltage is simplified by removing the DC
component of the signal. There are also times when you wish to measure the input
signal without removing the DC component. In these cases, you can change the input
coupling setting and apply the signal to the input amp. The following types of input
coupling are available.
AC
Input is passed through a capacitor, removing the DC component. This coupling should
be used when measuring only the amplitude of the signal, or when measuring only
signals superimposed with a specific DC voltage.
Measurement input terminal
DC
Inputs the signal directly. Use this setting if you wish to measure the entire input signal
(DC component and AC component).
Measurement input terminal
Note
When the equalizer is ON, the signal is AC-coupled through the cutoff frequency of 10 kHz
inside the equalizer regardless of the above coupling setting.
Preparing for measurement
Data processing
-display
SN
Input
amp
Input
amp
1 block
Measurement block
S1 S2 S3
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