Telecommunications – Carrier wave repeater or relay system – Transmitter/receiver feedback compensation
Reexamination Certificate
2000-09-12
2004-10-19
Corsaro, Nick (Department: 2684)
Telecommunications
Carrier wave repeater or relay system
Transmitter/receiver feedback compensation
C455S126000, C370S315000
Reexamination Certificate
active
06807399
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a relay system, and more particularly to a transmitting/receiving apparatus.
2. Description of the Background Art
FIGS. 1 and 2
illustrate a transmitting apparatus
100
and a receiving apparatus
110
of a repeater system.
As shown in
FIG. 1
, the receiving apparatus
100
of a repeater system includes a receiving antenna
11
for receiving a weak signal propagated from a base station; a band-pass filter
12
for filtering the signal received through the receiving antenna
11
; a low noise amplifier
13
for low-noise amplifying the frequency signal (S_Rx) outputted from the band-pass filter
12
; and a mixer
14
for mixing the output signal of the low noise amplifier
13
and a local signal (LO) to obtain a downwardly converted intermediate frequency signal (IF_Rx).
As shown in
FIG. 2
, the transmitting apparatus
110
of the repeater system includes a mixer
21
for mixing the intermediate frequency (IF_Tx) outputted from the receiving apparatus
100
and a local signal (LO) to obtain an upwardly converted radio frequency (RF) signal, a power amplifier
22
for amplifying the radio frequency (RF) signal outputted from the mixer
21
; a low-pass filter
23
for removing an unnecessary component from the output signal of the power amplifier
22
; and a transmitting antenna
24
for transmitting the transmission signal (S_Tx) outputted from the low-pass filter
23
.
The operation of the transmitting and receiving apparatuses
100
and
110
of the repeater system constructed as described above will now be explained.
Generally, a repeater system receives a weak signal through a receiving antenna from the base station, amplifies it to transmission signal with a relatively high power and transmits it through a transmitting antenna.
In detail, in the receiving apparatus of a repeater system, the receiving antenna
11
receives a weak signal propagated from the base station and provides it to the band-pass filter
12
, which extracts a frequency signal (S_Rx) existing in a certain range of the received signal. The low-noise amplifier
13
low-noise amplifies the frequency signal (S_Rx) outputted from the band-pass filter
12
, and the mixer
14
mixes the local signal (LO) with the output signal of the low-noise amplifier
13
to obtain the downwardly converted intermediate frequency signal (IF_Rx).
Meanwhile, in the transmitting apparatus
110
of the repeater system, the mixer
21
mixes the local signal (LO) with the intermediate frequency (IF_Tx) signal to obtain the upwardly converted radio frequency (RF) signal, and the power amplifier
22
amplifies the radio frequency signal outputted from the mixer
21
. The low-pass filter
23
removes the unnecessary component from the output signal of the power amplifier
22
and provides it to the transmitting antenna
234
. Then, the transmitting antenna
24
transmits the transmission signal (S_Tx) outputted from the low-pass filter
23
toward a destination.
However, as for the conventional repeater system, since the weak signal received through the receiving antenna
11
from the base station is amplified to a transmission signal with a relatively high power, when the receiving apparatus
100
of the repeater system, where the transmitting apparatus and receiving apparatus coexist, receives the next signal from the base station, the transmission signal (S_Tx) transmitted from the transmitting antenna
24
happens to be inputted to the receiving apparatus. At this time, the transmission signal (S_Tx) has a phase difference in proportion to the distance between the transmitting antenna
24
and the receiving antenna
11
, a propagation loss and a gain of the receiving antenna
11
.
As a result, due to the transmission signal, the output signal of the band-pass filter
12
includes a frequency component (S_Tx′) besides the frequency signal (S_Rx), and the output signal of the mixer
14
includes an intermediate frequency signal (IF_Rx′) besides the intermediate frequency signal (IF_Rx). Thus, a base noise is inevitably generated with the output of the of the active devices such as the low-noise amplifier and the frequency mixer
14
which are to receive the frequency component (S_Tx′). Doubtlessly, the noise degrades the performance of the low-noise amplifier and the frequency mixer
14
, resulting in degradation of performance of the receiving apparatus.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a transmitting/receiving apparatus of a repeater system which is capable of removing a frequency component generated in a receiving apparatus due to a transmission signal to thereby improve performance of a repeater system.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a transmitting apparatus and a receiving apparatus of a repeater system in which a signal received by the receiving apparatus from a base station is amplified to a high-powered transmission signal by the transmitting apparatus so as to be transmitted to a destination, wherein the transmitting apparatus varies a phase and a magnitude of the transmission signal and applies a compensation signal to the receiving apparatus, and the receiving apparatus adds the inputted compensation signal and a signal inputted through a receiving antenna and removes an unnecessary frequency component caused due to interference of the transmission signal.
In order to achieve the above object, the receiving apparatus includes a receiving antenna for receiving a signal propagated from a base station; a band-pass filter for filtering the output of the receiving antenna; an adder for adding the output of the band-pass filter and a compensation signal; a low-noise amplifier for amplifying the output signal of the adder; and a first mixer for mixing a local signal with the output of the low-noise amplifier to convert it to an intermediate frequency signal.
In order to achieve the above object, the transmitting apparatus includes a second mixer for mixing the intermediate frequency signal outputted from the first mixer and a local signal to generate a radio frequency signal; a power amplifier for amplifying the radio frequency signal outputted from the second mixer; a low-pass filter for filtering the output signal of the power amplifier; a transmitting antenna for transmitting the output signal of the low-pass filter toward a destination; a phase converter for converting by ±180° a phase of the signal amplified by the power amplifier; and a variable amplifier for variably amplifying the output signal of the phase converter and generating a compensation signal.
REFERENCES:
patent: 4317217 (1982-02-01), Davidson et al.
patent: 4383331 (1983-05-01), Davidson
patent: 4475243 (1984-10-01), Batlivala et al.
patent: 5835848 (1998-11-01), Bi et al.
patent: 5963847 (1999-10-01), Ito et al.
patent: 6327312 (2001-12-01), Jovanovich et al.
Corsaro Nick
Fleshner & Kim LLP
LG Electronics Inc.
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