YOKOGAWA TA220 User Manual page 25

2.4 Measurement Conditions
Equalizing RF Signals (Equalizer) <<For procedures, see section 4.3>>
Binarization of the RF Signal
2-8
You can equalize the signal amplitude in the high frequency region. The signal
amplitude in the high frequency region attenuates due to the frequency characteristics of
the optical pickup. By passing the RF signal that is applied to the measurement input
terminal through the equalizer, you can obtain a signal that has frequency characteristics
that do not attenuate up to the high frequency region (better frequency characteristics
than the optical pickup).
Frequency characteristics of
the signal applied to the
measurement input terminal
Frequency
The signal used to measure the pulse width and phase difference is a data signal
binarized from the RF signal applied to the measurement input terminal. Using the slicer
of the TA220, the RF signal is binarized by setting the portion of the signal that is greater
than the given slice level* to the positive side and the portion that is less than the slice
level to the negative side.
* The slice level changes depending on the trigger mode setting. For information on setting the
trigger mode and slice level, see "Trigger Mode and Slice Level" below.
RF signal
Data signal
Auto Slice
To correct the asymmetrical signal waveforms typical of optical disks, a slice level is
automatically detected such that the time ratio of the positive and negative sides of the
RF signal is 50%. The RF signal is binarized using the detected slice level. The auto
slice function operates when the trigger mode is set to "auto mode" or "auto + manual
mode" as described below.
RF signal
Data signal
Frequency characteristics
of the equalizer
Frequency
Positive side
Negative side
Slice level
Positive side
Negative side
Slice level
Frequency characteristics
of the signal after passing
through the equalizer
Frequency
IM 704610-01E