Telecommunications – Transmitter and receiver at same station – With frequency stabilization
Reexamination Certificate
2000-05-18
2003-05-13
Congle, Thanh (Department: 2684)
Telecommunications
Transmitter and receiver at same station
With frequency stabilization
C455S260000, C375S376000
Reexamination Certificate
active
06564040
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a communication device, a communication method, and a recording medium for recording a program employed to carry out the communication method. More particularly, the present invention relates to a communication device which is capable of reducing noises due to higher harmonic components of a clock so as to avoid the disturbance over its receiving function and its transmitting function by setting an oscillation frequency of the clock easily at a high speed and with high precision such that the higher harmonic components of the clock which drives processing means such as LSI's being built in the communication device can go farthest from a receiving frequency or a transmitting frequency, a communication method of operating the communication device, and a recording medium.
In recent years, in various communication devices having the receiving function and the transmitting function, a microcomputer, a digital signal processor (DSP), or special-purpose LSI's, etc. are incorporated and also an oscillating means for oscillating an LSI operation clock to drive these LSI's is provided. However, this LSI operation clock contains many higher harmonic components. When mixed into a receiving band or a transmitting band, the higher harmonic components disturb the receiving function and the transmitting function. For this reason, several techniques which avoid noises due to the LSI operation clock have been proposed in the prior art.
FIG. 9
is a schematic view showing a configuration of “A receiver device equipped with a clock oscillator circuit” disclosed in Unexamined Patent Application Publication Hei 8-102689 (first prior art). In
FIG. 9
, the receiver device comprises a receiver portion
506
having a received data decision circuit
507
, a control voltage generator portion
505
, and an oscillator circuit portion. The oscillator circuit portion comprises a crystal oscillator
501
, an inverter
502
, a capacitor
503
, a variable capacitor (variable capacity diode)
504
, and a resistor R.
The crystal oscillator
501
is caused by the inverter
502
to oscillate. According to capacitance values of the capacitor
503
and the variable capacitor
504
, an oscillation frequency of an operation clock CLK
5
, which is generated by the oscillator circuit portion, can be decided. In this case, the capacitance of the variable capacitor
504
can be controlled by a control voltage which is output from the control voltage generator portion
505
, and the control voltage can be decided based on information from the received data decision circuit
507
of the receiver portion
506
.
Next, an operation of the receiver device in the first prior art will be explained hereunder. First, the received data decision circuit
507
of the receiver portion
506
makes decision of the received data during reception and then detects whether or not disturbance due to the operation noise of the microcomputer built in the receiver device is caused. If the disturbance is detected at that time, the received data decision circuit
507
outputs a control signal CTL
5
to the control voltage generator portion
505
so as to change the control voltage, which is output from the control voltage generator portion
505
, such that the oscillation frequency of the operation clock CLK
5
can be slightly changed. Then, the oscillation frequency of the operation clock CLK
5
of the microcomputer is still changed until such disturbance cannot be detected, so that degradation of the radio performance (receiving function) of the receiver device can be avoided.
Also,
FIG. 10
shows a configuration of another receiver device having a noise canceling function (second prior art). In
FIG. 10
, the receiver device comprises a microcomputer
607
and the oscillator circuit portion. The oscillator circuit portion comprises a crystal oscillator
601
, an inverter
602
, capacitors
603
,
604
, a variable capacitor
605
, a transistor
606
, and the resistor R.
The crystal oscillator
601
is caused by the inverter
502
to oscillate. According to capacitance values of the capacitor
603
and
604
, an oscillation frequency of an operation clock CLK
6
, which is generated by the oscillator circuit portion, can be decided. However, if the microcomputer
607
causes the transistor
606
to turn ON via a control signal CTL
6
, the oscillation frequency of the operation clock CLK
6
can be decided based on a total capacitance value of the capacitance values of the capacitor
603
,
604
and the capacitance value of the variable capacitor
605
.
Next, an operation of the receiver device in the second prior art will be explained hereunder. First, normally the microcomputer
607
outputs an “L” level signal as the control signal CTL
6
and then turns OFF the transistor
606
via the resistor R. At that time, the oscillation frequency of the operation clock CLK
6
supplied to the microcomputer
607
can be decided according to the capacitance values of the capacitors
603
and
604
in the oscillator circuit portion. However, in the event that higher harmonics of the oscillation frequency of the operation clock CLK
6
exist in the neighborhood of a receiving frequency to thus cause the degradation of the radio performance (receiving function), the microcomputer
607
outputs an “H” level signal as the control signal CTL
6
to shift the transistor
606
into its ON state. Accordingly, the oscillation frequency of the operation clock CLK
6
can be changed into a frequency which is decided by the capacitance values of the capacitors
603
,
604
and the variable capacitor
605
in the oscillator circuit portion. Thus, the higher harmonics of the oscillation frequency of the operation clock CLK
6
are separated away from the neighborhood of the receiving frequency, so that degradation of the radio performance (receiving function) can be prevented.
However, in the above receiver device in the first prior art, since the control voltage of the control voltage generator portion
505
is decided based on the decision result of the received data decision circuit
507
of the receiver portion
506
, a time is needed to some extent until the control voltage has been decided. As a result, there have been the problems such that the response is not good until change/adjustment of the oscillation frequency of the operation clock CLK has been completed and that the period which is contained within a predetermined time but has low reliability of the received data still remains.
Furthermore, in the above receiver device in the second prior art, since the capacitance values in the oscillator circuit portion are changed according to the ON/OFF control of the transistor
606
based on the control signal CTL
6
, adjustment precision of the oscillation frequency is very rough. Thus, there have been the problems that it is difficult to adjust the higher harmonic components of the operation clock CLK
6
of the microcomputer
607
so as to go away from the receiving frequency and that deterioration of the radio performance (receiving function) cannot be perfectly prevented.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems in the prior art, and it is an object of the present invention to provide a communication device which is capable of reducing noises due to higher harmonic components of a clock and also avoiding the disturbance over its receiving function and its transmitting function by setting an oscillation frequency of the clock easily at a high speed and with high precision such that the higher harmonic components of the clock for driving processing means such as LSI's built in the communication device can positioned farthest from a receiving frequency or a transmitting frequency, a communication method of operating the communication device, and a recording medium.
In order to overcome the above subjects, according to first aspect of the present invention, a communication device comprises a clock generating means for generating a clock, a pr
Congle Thanh
Pearne & Gordon LLP
Trinh Tan
LandOfFree
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