Electric lamp or space discharge component or device manufacturi – Apparatus
Reexamination Certificate
2001-04-04
2004-09-14
Nguyen, Tony T. (Department: 2685)
Electric lamp or space discharge component or device manufacturi
Apparatus
C455S067140, C455S208000, C455S214000
Reexamination Certificate
active
06790116
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radio communication apparatus and radio frequency correcting method thereof, and more particularly to a radio frequency correcting method for a radio communication system for producing a radio frequency synchronizing with a transmission path frequency of digital data transmitted from a wire digital transmission path and so on.
BACKGROUND OF THE INVENTION
FIG. 7
is a block diagram of a structural example of a base station in a conventional radio communication system of the same sort. In
FIG. 7
, a digital data such as sounds, images, or texts transmitted from a switching center that is not shown in figures via a wire transmission path is inputted, the transmitted data is modulated by a preset modulating method, the modulation signal is converted into a radio frequency, and the signal is radio-transmitted to a mobile device that is not shown in the figures.
In
FIG. 7
, transmission path data transmitted from the switching center via a digital transmission network are inputted to a data generating portion
3
and a transmission path frequency reference clock producing portion
1
. The transmission path data are, as is described above, sound, image, or text data, and are data digitized and formatted in a predetermined form.
The transmission path frequency reference clock producing portion
1
extracts a transmission timing of the transmitted digital data (a reference clock signal) from the inputted transmission path data by using a transmission timing generator
11
with a method such as clock extraction, and sends the extracted transmission timing
11
a
to the data generating portion
3
. Moreover, the transmission timing generator
11
also sends the reference clock signal to a dividing/multiplying device
12
for implementing processes such as multiplying or dividing as the need arises. The multiplied or divided output
12
a
is sent to a data converter
32
.
A data generating portion is composed of a data generator
31
and a dada converter
32
, both for decoding the transmission path data so as to convert the data into a data system to be modulated into a radio modulation signal. The data system is outputted from the data generator
31
as digital data
31
a,
and is sent to the data converter
32
at a timing of the transmission timing signal
11
a.
The data converter
32
orthogonal-modulates the obtained digital data, converts its frequency into a radio intermediate frequency (IF frequency) (
32
a
), and sends the data to a D/A converter
5
. The D/A converter
5
produces a radio IF modulation signal
5
a
converted into the IF frequency on the basis of the inputted data. Although functions such as wave-shape formation or band limitation that are necessary for transmitting codes are actually added to the D/A converter
5
, they are not particularly shown in the figures. The generated radio IF modulation signal
5
a
is inputted to a frequency converting portion
6
.
A frequency converting portion
6
is composed of a local oscillator
61
to which a PLL (phase locked loop) technique is applied, a mixer
62
, and a filter (BPF)
63
. It produces the radio frequency signal at the mixer
62
on the basis of a local oscillation signal generated by the local oscillator
61
, removes unnecessary waves from the signal by using the filter
63
, and then outputs the radio frequency signal to a radio circuit.
The digital PLL technique, which can provide a frequency according to a voluntary dividing step from a reference frequency generator
21
in accordance with the inputted digital data, is applied to the local oscillator
61
. The explanation thereof is omitted since the technique is well known. The local oscillator
61
produces the local oscillation signal synchronizing with the reference frequency signal
23
a
outputted from the reference frequency generating portion
2
. The reference frequency generating portion
2
includes the reference signal generator
21
and the dividing/multiplying device
23
for dividing or multiplying the reference signal as the need arises.
In
FIG. 7
, a radio intermediate frequency modulation signal (radio IF modulation signal)
5
a
being a base of a radio modulation signal
63
a
is directly produced by a D/A converter
5
. The signal
5
a
is mixed with a local oscillation frequency oscillated by a local oscillator
61
at a mixer
62
, and becomes a radio modulation signal
63
a.
At this time, frequency stability of the radio modulation signal
63
a
depends on a reference signal generated by a reference frequency generator
21
and a reference signal generated by a reference clock producing portion
1
synchronizing with a clock obtained by clock-extraction from transmitted data at a transmission path.
Normally, according to the fact that the transmission path, which is sufficient to refer data during a voluntary timing, and the radio frequency, which is required to have stability based on Electric Wave Law for strongly restricting illegal radiation, are inputted and outputted respectively, it is natural that, concerning the stability of the frequencies, precision of the reference frequency generator
21
is higher than that of the transmission timing generator
11
in comparison.
According to this, the frequency stability of the radio modulation signal
63
a
is largely dominated by a reference clock producing portion
1
so that the frequency stability is deteriorated. It is very important point how the frequency stability of the part can be improved, or how the frequency difference can be compensated in improving the frequency stability of the radio modulation signal
63
a.
SUMMARY OF THE INVENTION
Here, it is object of the present invention to provide a radio communication apparatus that can improve the stability of the radio frequency, and a radio frequency correcting method thereof.
A radio communication apparatus according to the present invention includes:
an intermediate frequency modulation signal producing means for producing a modulation signal at an intermediate frequency out of transmitted data from a transmission path by using the first reference signal synchronizing with the data;
a radio frequency converting means for converting the intermediate frequency modulation signal into a radio frequency by using the second reference signal being more stabile than the first reference signal; and
a radio frequency correcting means for detecting a frequency difference between the first reference signal and the second reference signal, and for correction-controlling the radio frequency at the radio frequency converting means in accordance with the frequency difference.
Moreover, the radio frequency correcting means includes a means for detecting the frequency difference of the first reference signal on the basis of the second reference signal, and a means for correction-controlling a frequency of a local oscillation signal at the radio frequency converting means in accordance with the frequency difference. The intermediate frequency modulation signal producing means includes a modulating means for modulating the transmitting data with an orthogonal modulating method by using the first reference signal.
A radio communication apparatus according to the present invention includes:
a buffer means for temporarily storing transmitted data from a transmission path synchronously with the first reference signal;
a reference signal generating means for generating the second reference signal being more stabile than the first reference signal;
an intermediate frequency modulation signal producing means for reading-out data from the buffer means synchronously with the second reference signal so as to produce a modulation signal at an intermediate frequency out of the read-out data by using the second reference signal; and
a radio frequency converting means for converting the intermediate frequency modulation signal into a radio frequency by using the second reference signal. The intermediate frequency modulation signal producing means includes a modulating means for modulating the
NEC Corporation
Nguyen Tony T.
Whitham Curtis & Christofferson, PC
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