Pulse or digital communications – Equalizers – Automatic
Reexamination Certificate
1999-01-11
2001-07-17
Le, Amanda T. (Department: 2634)
Pulse or digital communications
Equalizers
Automatic
C375S350000, C708S323000
Reexamination Certificate
active
06263018
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an equalizer, and more particularly, to an apparatus for adaptive equalizer.
2. Description of Related Art
In general, equalizers play a rule to correct a distorted signal into a signal having a desired form while a data passes through a channel.
Hereinafter, an apparatus for adaptive equalizer according to prior art will be described with reference to the accompanying drawing.
FIG. 1
is a fundamental schematic of a magnetic recording system according to the background art, in which the system includes: a recording amplifier
1
for amplifying an input recorded data to a predetermined level; a tape
2
on which the data amplified at the recording amplifier is recorded; a reproducing amplifier
3
for reproducing the data recorded on the tape
2
and amplifying it to a predetermined level; an equalizing section
4
for outputting the waveform of a signal generated by compensating for distortion included in the signal amplified at the reproducing amplifier
3
; and a detecting section
5
for detecting a data from the signal compensated for distortion at the equalizing section
4
.
The equalizing section
4
includes a pulse slimming equalizer
4
a
for reducing interference between signals amplified at the reproducing amplifier
3
, and a delay adder
4
b
for summing the output signal of the pulse slimming equalizer
4
a
and a signal generated by delaying the signal by time T.
The pulse slimming equalizer
4
a
is a cosine equalizer.
The operation of an apparatus for adaptive equalizer having the construction according to prior art will be described with reference to the accompanying drawing.
First, the recording amplifier
1
amplifies an input recorded data to a predetermined level and records it on the tape
2
.
The reproducing amplifier
3
reproduces the data recorded on the tape
2
and amplifies it to a predetermined level.
Then equalizing section
4
compensates for distortion included in the signal amplified at the reproducing amplifier
3
.
That means, the pulse slimming equalizer
4
a
in the equalizing section
4
reduces interference between isolated reproduced pulses amplified at the reproducing amplifier
3
.
Then, the delaying adder
4
b
outputs the sum signal of the output signal of the pulse slimming equalizer
4
a
and the signal delayed by time T.
Accordingly, the detecting section
5
detects the original data from the distortion-compensated signal of the equalizing section
4
.
Such an apparatus for adaptive equalizer according to prior art may maintain its performance as an equalizer with fixed parameters when a data is recorded and reproduced in the same system. If reproduction is performed in another system, however, it is impossible to perform an appropriate equalization and the performance may be deteriorated.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an is apparatus for adaptive equalizer that substantially obviates one or more of the limitations and disadvantages of the related art.
An object of the present invention is to provide an apparatus for adaptive equalizer which has its performance improved to satisfy the performance of a system for different channels and reduce the convergent time required for adaption.
Additional features and advantages of the invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, an apparatus for adaptive equalizer which has a first pulse slimming equalizing section and a third delaying and adding section includes: an error signal extracting section for extracting an error from a signal delayed for a predetermined period of time at the third delaying and adding section; and a coefficient calculating and updating section for calculating the coefficients of the signal of the first pulse slimming equalizing section and the error signal extracted at the error signal extracting section, and updating the coefficients.
The signal k of the coefficient calculating and updating section is calculated with an equation given by:
k
n+1
=k
n
−&mgr;e
n+1
(&ggr;
n
+&ggr;
n−2
)
where k
n
is the initial value of the coefficient calculating and updating section, &ggr;
n
+&ggr;
n−2
is the signal U
n
of the first pulse slimming equalizing section, &mgr; is a step coefficient and e
n
is the signal of the error signal extracting section.
If times of e
n
and &ggr;
n
+&ggr;
n−2
are not equal to input signals, the coefficient is calculated and updated with an equation given by:
k
n+1
=k
n
−&mgr;e
n
(
z&Lgr;
n
+&Lgr;
n−2
)
where k
n
is the initial value of the coefficient calculating and updating section, z&Lgr;
n
is the three-level quantized value of z
n
and z&Lgr;
n−2
is the previous value of the three-level quantized value of z&Lgr;
n
.
In another aspect of the present invention, an apparatus for adaptive equalizer which has a second pulse slimming equalizing section and a fifth delaying and adding section includes: a reference signal generating section for bypassing a signal delayed for a predetermined period of time at the fifth delaying section, or processing the delayed signal to generate a reference signal; a second adding section for summing the signal bypassed at the reference signal generating section and the reference signal generated from the reference signal generating section; a fourth mixing section for mixing the sum signal of the second adding section and a step adjusting coefficient; a fifth mixing section for mixing the mixed signal of the fourth mixing section and the signal of the second pulse slimming equalizing section; and a first integrating section for integrating the mixed signal of the fifth mixing section.
The reference signal generating section includes: a first comparing section for bypassing the delayed signal of the fifth delaying and adding section, or comparing the delayed signal and an upper threshold; a first offset adjusting section for adjusting the signal of the first comparing section to the offset of a predetermined level; a second comparing section for comparing the delayed signal and a lower threshold; a second offset adjusting section for adjusting the signal of the second comparing section to the offset of a predetermined level; and a first adding section for summing the signals of the first and second offset adjusting sections.
In further another aspect of the present invention, an apparatus for adaptive equalizer which has a third pulse slimming equalizing section and a seventh delaying and adding section includes: an analog-to-digital converting section for converting a signal delayed for a predetermined period of time at the seventh delaying and adding section to a digital signal; a control signal generating section for processing the digital signal of the analog-to-digital converting section to generate a control signal; an eighth mixing section for mixing the control signal generated from the control signal generating section and a step adjusting coefficient; and a second integrating section for integrating the mixed signal of the eighth mixing section.
The control signal generating section includes: a three-level determining section for detecting the level of the digital signal of the analog-to-digital converting section and determining a three level signal; a third adding section for summing the digital signal of the analog-to-digital converting section and the three-level signal determined at the three-level determining section; an eighth delaying section for delaying the tree-level signal of the three-level determining section for a predetermined
Le Amanda T.
LG Electronics Inc.
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