CA2072335C - Radio repeater - Google Patents
Radio repeaterInfo
- Publication number
- CA2072335C CA2072335C CA 2072335 CA2072335A CA2072335C CA 2072335 C CA2072335 C CA 2072335C CA 2072335 CA2072335 CA 2072335 CA 2072335 A CA2072335 A CA 2072335A CA 2072335 C CA2072335 C CA 2072335C
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- Canada
- Prior art keywords
- signals
- frequency
- frequencies
- radio repeater
- transmission
- Prior art date
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- Radio Relay Systems (AREA)
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Abstract
A radio repeater receives signals having reception frequencies, converts the received signals into signals having carrier frequencies, and transmits the converted signals. The radio repeater is applicable to communication in a cordless telephone system, a land-mobile radiotelephone system, or the like. With a conventional radio repeater, receivers and transmitters have to be installed for respective frequencies, respectively. With this radio repeater, an intermediate-frequency converter and a transmission power amplifier are used for both transmission and reception of signals in common, thereby reducing the number of component parts, and making the repeater compact.
Description
-RADIO REPEATER
BACKGROUND OF T~E INVENTION
1. Field o~ the Invention:
This invention relates to a radio repeater, and more particularly to a radio repeater to be installed in a main set so as to relay signals to and from sub-sets in a cordless telephone system or a land-mobile radiotelephone system.
BACKGROUND OF T~E INVENTION
1. Field o~ the Invention:
This invention relates to a radio repeater, and more particularly to a radio repeater to be installed in a main set so as to relay signals to and from sub-sets in a cordless telephone system or a land-mobile radiotelephone system.
2. Description o~ the Related Art:
Fig. 4 of the accompanylng drawings is a block diagram showing the configuration of a conventional radio repeater for a land-mobile radiotelephone system. The block diagram is based on the drawings on pages 96 to 99 of "Mobile eommunication System - Prlnciple and Design", published by Electronic Communications Society. FIG. 5 shows the allocation of carrier frequencies for the radio repeater of FIG. 4.
The radio repeater comprises radio repeater units la and lb, and a cable 5 connecting these repeater units.
The repeater units la and lb communicate with mobile stations 2a and 2b, respectively.
The repeater unit la includes a duplexer 9a, a .. .~ .
.
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receiver 7a, a synthesizer lOa, a transmitter 8a, and a control circuit lla. An external antenna 6~ is connected to the duplexer 9a.
A radio signal having a -~requency f(RXl) arrives at the receiver 7a from the mobile station 2a via the antenna 6a. The transmitter 8a transmits a signal having a frequency f(TXl), which is received by the receiver 7a via the antenna 6a. The duplexer 9a is interposed between the antenna 6a and the receiver 7a, thereby enabling the antenna 6a to be used for transmission and reception Or the signals.
The synthesizer lOa produces high frequency signals, which are supplied to both the receiver 7a and the transmitter 8a. The synthesizer lOa, receiver 7 and transmitter 8a are controlled by a control circuit lla.
The repeater unit lb includes a duplexer 9b, a receiver 7b, a synthesizer lOb, a transmitter 8b and a control circuit llb, all of which are identical to those o~ the repeater unit la.
A radio signal having a frequency ~(RX2) arrives at the repeater unit lb from the transmitter 8b via an external antenna 6b connected to the repeater unit lb. A
duplexer 9b is interposed between the antenna 6b, receiver 7b and transmitter 8b, so that the antenna 6b is applicable to both signal transmission and receptlon.
The synthesizer lOb produces high frequency signals, which are supplied to the receiver 7b and the transmitter 8b. The synthesizer lOb, receiver 7b and transmitter 8b are controlled by the control circuit llb.
The receiver 7a and the transmitter 8b are connected by a signal line 5a of the cable 5, so that a baseband signal is output from the receiver 7a to the transmitter 8b. Therefore, the radio signal output from the mobile station 2a and having the frequency f(RX1) is converted into a signal having a frequency f(TX1) by the transmitter 8b, being received by the mobile station 2b via the antenna 6b.
The receiver 7b and the transmitter 8a are connected by a signal line 5b of the cable 5, so that a baseband signal is output from the receiver 7b to the transmitter 8a. Therefore, the radio signal of a frequency f(RX2) and from the mobile station 2b is converted into a signal having a frequency f(TX1) by the transmitter 8a, being received by the mobile station 2a.
The control circuits lla and llb are connected by a signal line 5c of the cable 5, so that a variety of data . :
.
.
; ~ ' , are relayed between the repeater un:lts la and lb so as to operate them cooperatively.
As shown in FIG. 5, the transmission frequencies f(TX1) and f(TX2) are allocated very closely. The same holds true to the reception frequencies f(RX1) and f(RX2). To prevent interference, these transmission and reception frequencies are therefore allocated in frequency bands which are remote from each other with a sufficient space therebetween as shown in FIG. 5.
SUMMARY OF TnE INVENTION
With the fore~oing radio repeater, the number of transmitters and receivers depends upon the number of radio frequencies to be used. The transmitters and receivers are installed individually and independently, which would disadvantageouly increase the number of component parts and the cost, and prevent a reduction in the apparatus size.
It is therefore an obJect of this invention to provide a compact radio repeater which can solve the foregoing problems of the conventional apparatus by common use of circuits so as to reduce the number o~
components.
According to the invention, there is provided a radio repeater comprising: means -for recelving incomlng signals and for outputting received signals: converters for converting carriers of the received signals into signals having other frequencies: transmitters for transmitting the converted signals: first intermediate-frequency converters for converting the received signals into signals having frequencies in a first intermediate-frequency band; second intermediate-frequency converters for converting the signals in the first intermediate-frequency band into signals having frequencies in a second intermediate-frequency band; a plurality of detectors for detecting the signals having the frequencies in the second frequency band and for outputting a plurality of baseband signals; and modulators for modulating the baseband signals with carriers having different frequencies.
With this arrangement, a plurality of signals can be received and detected so that the received signals are demodulated into baseband audio signals.
It is preferable that the first intermediate frequency converters include first reception local oscillators, first mixers for mixing output signals from the first reception local oscillators and the received signals, and ~irst intermediate-frequency filters for selecting slgnals havlng the flrst lntermedlate-frequency band ~rom the signals output ~rom the mlxer. The recelved slgnals can be effectlvely converted lnto slgnals havlng the ~requencles in the ~lrst lntermedlate frequency band.
It ls also preferable that the second lntermedlate-frequency converters lnclude a second reception local oscillator, a second mixer for mixing a signal output from the second reception local oscillator and the signals in the flrst lntermediate-frequency band, and second intermediate-frequency filters for selecting the signals in the second lntermediate-frequency band from the signal output by the second mlxer.
This arrangement allows signals to be output by the second intermediate-frequency filters according to the ~requencies o~ the received signals. Provlsion of a plurality of second reception local oscillators enables the oscillation frequencles of the oscillators to be varied according to the received signals.
The second reception local oscillators may generate signals having the same oscillation ~requency, and the second intermediate-frequency filters may have different , .- .
central frequencies in the passband.
In addition, the second receptlon local oscillators may generate signals having dlfferent oscillation frequencies, and the second intermediate-frequency filters may have the same central frequency ln the passband. In this case, all the filters can have the same parameters, so that they can be designed with ease.
Further, the second reception local oscillators may generate signals having different oscillation frequencies, and the second intermediate-frequency filters have different central frequencies in the passband. In this case, all the parameters of the oscillators and filters are variable so that they may be optimum for respective frequencies of the received slgnals.
It is preferable that the modulators include transmission local oscillators associated with respective baseband signals, a plurality of modulator members for modulating the baseband signals with the signals output from the transmission local oscillators, each of the modulator member being associated with each of the transmission local oscillator, an up-converter for summing the signals output from the modulator members, outputting a signal lndicating the sum o~ the output signals, and convertlng the sum signal into M slgnal having a transmission -frequency, and a transmisslon ~ilter for selecting the signal having the transmission frequency~ from the signal output by the up-converter.
This arrangement enables efficient modulation of a plurality of baseband audio signals.
In the radio repeater, the modulator also includes a plurality of instantaneous deviation controllers (IDC) for limiting amplitudes of the baseband signals, so that the modulator members modulate the amplitude-limited signals. The modulated signals never deviate from the frequency band determined for communication.
BRIEF DESCRIPTION OF TEE DXAWINGS
FIG. 1 is a block diagram showing the configuration of a radio repeater according a first preferred embodiment of the invention;
FIG. 2 is a block diagram showing the configuration of a radio repeater according a second embodiment;
FIG. 3 is a block diagram showing the configuration of a radio repeater according to a third embodiment;
FIG. 4 ls a block diagram showing the configura~ion of one o~ conventional radio repeaters; and . ~
FIG. 5 ~hows an example o~ frequencles allocated for a cordless telephone system or a land-mobile radiotelephone system.
DETAILFD DESCRIPTION OF ~K~KED EMBODIMENTS
As shown in FIG. 1, a radio signal arriving via an antenna 144 is separated by a gyrator 145, and is input to a receiver 148. The receiver 148 converts the radio signal into a baseband audio signal by using a detector 128. Then, the baseband audio signal is output to a transmitter 147 from a transmission output terminal 129 via a signal line 105a in a cable 105.
The transmitter 147 modulates the baseband audio signal with a predetermined carrier frequency, transmitting the modulated signal to the antenna 144 via the duplexer 145.
The operation of the receiver 148 will be described in detail. The radio signal input to the receiver 148 is firstly ampllfied by a high frequency amplifier 121. A
mixer 122 mixes the amplified signal with a signal from a reception local oscillator 141 of a synthesizer 146. The mixed signal is ~iltered by a first intermediate-frequency (IF) filter 123, thus being converted into a first IF signal.
, , - ~
. :
The reception radio frequencies are very close to each other as described with reference to the conventional apparatus. With this invention, the two receptlon radio ~requencies are designed to have wider passbands than those of the conventional apparatus so that these radio frequencies can be converted into signals having the same intermediate frequency. In other words, the first intermediate frequency signal is composed of signal components of two different frequencies. One o~ these signal components is selected and separated by second mixers.
The second mixers 124a and 124b mi~ the first IF
signals with signals supplied via second local oscillators 125a and 125b. The mixed signals are filtered by a second IF filters 126a and 126b. The output signals ~rom the second IF filters 126a and 126b contain only one each of the reception radio frequency signals, respectively.
In the following description, the components indicated by the numbers and letter "a" constitute the circuit system A, while those indicated by the numbers and letter "b" constitute the circuit system B.
The embodiment features that one receiver has two /
:.; , .
, second IF ~ilters to receive two reception radio ~requencies.
The second IF filters 126a and 126b output di~*erent IF slgnals, respectively. The second IF
signals are ampli*ied by second IF ampli~iers 127a and 127b, being converted into baseband audlo signals by FM
detectors 128a and 128b, respectively.
The baseband audio signals are output to transmission output terminals 129a and 129b, and are supplied to transmission input terminals 137a and 137b o~
the transmitter 147 via communication lines 105a and 105b o~ the cable 5.
The transmitter 147 trans~ers the baseband audio signals to modulators 134a and 134b via instantaneous deviation controllers (IDC) 136a and 136b. The modulators 134a and 134b modulate the baseband audio signals with transmission modulation signals received via transmission modulation oscillators 135a and 135b. The outputs from the modulators 134a and 134b are combined to obtain one signal, the frequency o~ which is raised, by the up-converter 133 with an oscillation ~requency o* a transmission local oscillator 142, to a desired carrier ~requency. This carrier signal passes through the :. ' . , :
~ ' ;~ . . -~.
~7 transmission ~ilter 132, is ampli~led by a common amplifier lSl, and is output to the antenna 144 vla the duplexer 145.
Operatlon of this embodiment wlll be described hereinafter.
It is assumed that f(RX1) and F(RX2) represent the two reception frequencies and f(fl) represents the oscillation frequency of the reception local oscillator 141. Two output signals having the following two frequencies are produced by the first IF filter 123.
f(mla) = f(RX1) - ~(rl) ... (1) f(mlb) = f(RXl) - ~(r2) ... (2) The signal having the ~requency ~(mla) is converted into the signal having the frequency f(m2a) by the second mixer 124a.~
f(m2a) = f(mla) - f(r2a) ... (3) where f(r2a) stands for an oscillation frequency of the second local oscillator 125a. Although a signal containing a sum component of the two frequencies is also produced during the conversion expressed by the formula (3), only the signal having the frequency f(m2a) is selected by the second IF filter 126a.
The signal having the frequency f(m2a) is converted ,, '~ , ' . , into the signal of the frequency f(m2b) by the second mixer 124b as ~ollows.
f(m2b) = f(mlb) - f(r2b) ... (4) where ~(r2b) stands ~or an osclllation ~requency of the second local oscillator 125b. Although a signal containing a sum component of the two ~requencies is also produced during the conversion expressed by the formula (4), only the signal having the frequency f(m2b) ls selected by the second IF filter 126b.
Thus, the signals corresponding the reception frequencies f(RX1) and f(RX2) are obtained at outputs of the second IF filters 126a and 126b, respectively. The FM detectors 128a and 128b demodulate these signals to obtain baseband audio signals corresponding to the reception frequencies.
Conventionally, two independent receivers are used for the two reception frequencies. On the contrary, this embodiment is characterized in that the high frequencY
amplifier 121, first mixer 122 and first IF filter 123 are commonly used for the signals having the two reception frequencies, which enables a reudction in the number of component parts to be used.
The two bansband audio signals are sub~ect to , ~ ' .
amplitude limitation by the IDCs 136a and 136b of the transmitter 147, being modulated by the modulators 134a and 134b. The signals output by the modulators 134a and 134b have frequencies ~(tla) and f(tlb) when f(tla) and f(tlb) represent output frequencies o~ the transmission local oscillators 135a and 135b. These two output signals are converted into signals having frequencies f(TX1) and F(TX2) by the up-converter 133 as follows.
f(TX1) = f(tla) ~ f(t2) ... (5) f(TX2) = f(tlb) t f(t2) ... (6) where ~(t2) represents an oscillation frequency of the transmission local oscillator 133. Since the outputs of the modulators 134a and 134b also contain components corresponding to the difference between the output signals, the transmission filter 132 selects only the signals expressed by the formulas (5) and 16). The signals having the carrier frequencies f(TX1) and f(TX2) are ampli~ied by the common amplifier 131, and are transmitted via the duplexer 145 and the antenna 144.
This embodiment is characterized in that the up-converter 133, transmission filter 132 and common ampllfier 131 are commonly used for the two transmission ~requencies, thereby enabling a reduction in the number 207233~
of component parts to be used.
The reception frequencles f(RXl) and f(RX2) are variable depending upon the oscillation frequency of the reception local oscillator 141, as described above. In this case, the frequencies f(RX1) and f(RX2) should have the relationship as follows.
f(RX1) - f(RX2) = f(mla) - f(mlb) = {f(m2a) ~ f(r2a)}
- {f(m2b) I f(r2b)} ... (7) Therefore, the difference between these frequencies is constant. The transmission frequencies f(TX1) and f(TX2) are also variable depending upon the oscillation frequency of the transmission local oscillator 142. In this case, the transmission frequencies should have the following relationship.
~ TX1) - f~TX2) = f~tla) - f~tlb) ~-. (8) The difference between these frequencies is kept constant.
As described so far, the radio repeater of this embodiment can be made compact since some of the circuits are used for both transmission and reception of the signals, compared with the conventional apparatus in which the number of transmitters and receivers depends upon the number of transmission and receptlon frequencles. In addition, the two transmission frequencies and the two reception frequencies can be varied as desired by changing the oscillation frequencies of the reception and transmission local oscillators 141 and 142, respectively, while keeping the constant separation between the reception frequencies f(RX1) and f(RX2) and the transmission frequencies f(TXl) and f(TX2), respectively. Therefore, the radio repeater allows communication between mobile stations by using an idle channel.
A radio repeater according to the second embodiment will be described with reference to FIG. 2. This radio repeater differs from the repeater of the first embodlment ln that a receiver 248 includes one second local oscillator 225 and one second mixer 224, which means a further reduction in the number of components of the radio repeater. This embodiment is a simplified ~orm of the flrst embodiment.
In the first embodiment, the second local oscillators 125a and 125b output the signals having different frequencies. When both the second local oscillators 125a and 125b output the signals having the .
207233~
same ~requency, the signals output by the second mixers 124a and 124b also have the same ~requency. In thls case, one second local oscillator 125a (or 125b) and one second mixer 124a (or 124b) are enough to per~orm the ~oregoing function. There~ore, the radlo repeater o~ the second embodiment includes only one second local oscillator and one second mixer, thereby reducing the number of component parts.
In this embodiment, the second IF filters 226a and 226b should have di~ferent passing center ~requencies so as to output reception signals having di~ferent ~requencies.
This embodiment also differs from the ~irst embodiment in the following manner. The transmitter 247 includes synthesizing modulators 238a and 238b, which serve as the transmission local oscillator, modulator and up-converter of the ~irst embodiment. This means a ~urther reduction in the number of components parts. The synthesizing modulators 238a and 238b receive re~erence ~requencies directly ~rom a re~erence oscillator 243.
The second embodiment o~ the invention offers the radio repeater which is compatible with the two reception ~requencies f(RX1) and ~(RX2) and two transmission frequencles f(TX1) and f(TX2), whlch can be varJed as desired with the separation kept constant therebetween.
Therefore, the radio repeater enables communication to and from the mobile stations by selecting any idle channel. Since the oscillation frequencies of the first and second local osclllators are the same, the number of oscillators is reduced to half compared with those of the first embodiment.
FIG. 3 shows the configuration of a radio repeater according to the third embodiment of the invention. This embodiment differs from the first embodiment in that the receiver 248 includes one local oscillator 325 and one second mixer 324. In other words, the radio repeater of th~s embodiment includes the transmitter of the first embodiment and the receiver of the second embodiment.
In this embodiment, the second IF filters 326a and 326b should have different passing frequencies, so that the signals having different reception frequencies can be identified.
In the foregoing description, this invention is descrlbed wlth reference to the embodiments for the cordless telephone system or land-mobile radiotelephone system of the frequency scanning type. It is to be 207233~
understood that the technical concept of the invention is also applicable to any other type of radlo transmlsslon systems.
In additlon, separate antennas may be used Yor the transmission and reception signals, respectively.
,~
.
.
Fig. 4 of the accompanylng drawings is a block diagram showing the configuration of a conventional radio repeater for a land-mobile radiotelephone system. The block diagram is based on the drawings on pages 96 to 99 of "Mobile eommunication System - Prlnciple and Design", published by Electronic Communications Society. FIG. 5 shows the allocation of carrier frequencies for the radio repeater of FIG. 4.
The radio repeater comprises radio repeater units la and lb, and a cable 5 connecting these repeater units.
The repeater units la and lb communicate with mobile stations 2a and 2b, respectively.
The repeater unit la includes a duplexer 9a, a .. .~ .
.
207233~
receiver 7a, a synthesizer lOa, a transmitter 8a, and a control circuit lla. An external antenna 6~ is connected to the duplexer 9a.
A radio signal having a -~requency f(RXl) arrives at the receiver 7a from the mobile station 2a via the antenna 6a. The transmitter 8a transmits a signal having a frequency f(TXl), which is received by the receiver 7a via the antenna 6a. The duplexer 9a is interposed between the antenna 6a and the receiver 7a, thereby enabling the antenna 6a to be used for transmission and reception Or the signals.
The synthesizer lOa produces high frequency signals, which are supplied to both the receiver 7a and the transmitter 8a. The synthesizer lOa, receiver 7 and transmitter 8a are controlled by a control circuit lla.
The repeater unit lb includes a duplexer 9b, a receiver 7b, a synthesizer lOb, a transmitter 8b and a control circuit llb, all of which are identical to those o~ the repeater unit la.
A radio signal having a frequency ~(RX2) arrives at the repeater unit lb from the transmitter 8b via an external antenna 6b connected to the repeater unit lb. A
duplexer 9b is interposed between the antenna 6b, receiver 7b and transmitter 8b, so that the antenna 6b is applicable to both signal transmission and receptlon.
The synthesizer lOb produces high frequency signals, which are supplied to the receiver 7b and the transmitter 8b. The synthesizer lOb, receiver 7b and transmitter 8b are controlled by the control circuit llb.
The receiver 7a and the transmitter 8b are connected by a signal line 5a of the cable 5, so that a baseband signal is output from the receiver 7a to the transmitter 8b. Therefore, the radio signal output from the mobile station 2a and having the frequency f(RX1) is converted into a signal having a frequency f(TX1) by the transmitter 8b, being received by the mobile station 2b via the antenna 6b.
The receiver 7b and the transmitter 8a are connected by a signal line 5b of the cable 5, so that a baseband signal is output from the receiver 7b to the transmitter 8a. Therefore, the radio signal of a frequency f(RX2) and from the mobile station 2b is converted into a signal having a frequency f(TX1) by the transmitter 8a, being received by the mobile station 2a.
The control circuits lla and llb are connected by a signal line 5c of the cable 5, so that a variety of data . :
.
.
; ~ ' , are relayed between the repeater un:lts la and lb so as to operate them cooperatively.
As shown in FIG. 5, the transmission frequencies f(TX1) and f(TX2) are allocated very closely. The same holds true to the reception frequencies f(RX1) and f(RX2). To prevent interference, these transmission and reception frequencies are therefore allocated in frequency bands which are remote from each other with a sufficient space therebetween as shown in FIG. 5.
SUMMARY OF TnE INVENTION
With the fore~oing radio repeater, the number of transmitters and receivers depends upon the number of radio frequencies to be used. The transmitters and receivers are installed individually and independently, which would disadvantageouly increase the number of component parts and the cost, and prevent a reduction in the apparatus size.
It is therefore an obJect of this invention to provide a compact radio repeater which can solve the foregoing problems of the conventional apparatus by common use of circuits so as to reduce the number o~
components.
According to the invention, there is provided a radio repeater comprising: means -for recelving incomlng signals and for outputting received signals: converters for converting carriers of the received signals into signals having other frequencies: transmitters for transmitting the converted signals: first intermediate-frequency converters for converting the received signals into signals having frequencies in a first intermediate-frequency band; second intermediate-frequency converters for converting the signals in the first intermediate-frequency band into signals having frequencies in a second intermediate-frequency band; a plurality of detectors for detecting the signals having the frequencies in the second frequency band and for outputting a plurality of baseband signals; and modulators for modulating the baseband signals with carriers having different frequencies.
With this arrangement, a plurality of signals can be received and detected so that the received signals are demodulated into baseband audio signals.
It is preferable that the first intermediate frequency converters include first reception local oscillators, first mixers for mixing output signals from the first reception local oscillators and the received signals, and ~irst intermediate-frequency filters for selecting slgnals havlng the flrst lntermedlate-frequency band ~rom the signals output ~rom the mlxer. The recelved slgnals can be effectlvely converted lnto slgnals havlng the ~requencles in the ~lrst lntermedlate frequency band.
It ls also preferable that the second lntermedlate-frequency converters lnclude a second reception local oscillator, a second mixer for mixing a signal output from the second reception local oscillator and the signals in the flrst lntermediate-frequency band, and second intermediate-frequency filters for selecting the signals in the second lntermediate-frequency band from the signal output by the second mlxer.
This arrangement allows signals to be output by the second intermediate-frequency filters according to the ~requencies o~ the received signals. Provlsion of a plurality of second reception local oscillators enables the oscillation frequencles of the oscillators to be varied according to the received signals.
The second reception local oscillators may generate signals having the same oscillation ~requency, and the second intermediate-frequency filters may have different , .- .
central frequencies in the passband.
In addition, the second receptlon local oscillators may generate signals having dlfferent oscillation frequencies, and the second intermediate-frequency filters may have the same central frequency ln the passband. In this case, all the filters can have the same parameters, so that they can be designed with ease.
Further, the second reception local oscillators may generate signals having different oscillation frequencies, and the second intermediate-frequency filters have different central frequencies in the passband. In this case, all the parameters of the oscillators and filters are variable so that they may be optimum for respective frequencies of the received slgnals.
It is preferable that the modulators include transmission local oscillators associated with respective baseband signals, a plurality of modulator members for modulating the baseband signals with the signals output from the transmission local oscillators, each of the modulator member being associated with each of the transmission local oscillator, an up-converter for summing the signals output from the modulator members, outputting a signal lndicating the sum o~ the output signals, and convertlng the sum signal into M slgnal having a transmission -frequency, and a transmisslon ~ilter for selecting the signal having the transmission frequency~ from the signal output by the up-converter.
This arrangement enables efficient modulation of a plurality of baseband audio signals.
In the radio repeater, the modulator also includes a plurality of instantaneous deviation controllers (IDC) for limiting amplitudes of the baseband signals, so that the modulator members modulate the amplitude-limited signals. The modulated signals never deviate from the frequency band determined for communication.
BRIEF DESCRIPTION OF TEE DXAWINGS
FIG. 1 is a block diagram showing the configuration of a radio repeater according a first preferred embodiment of the invention;
FIG. 2 is a block diagram showing the configuration of a radio repeater according a second embodiment;
FIG. 3 is a block diagram showing the configuration of a radio repeater according to a third embodiment;
FIG. 4 ls a block diagram showing the configura~ion of one o~ conventional radio repeaters; and . ~
FIG. 5 ~hows an example o~ frequencles allocated for a cordless telephone system or a land-mobile radiotelephone system.
DETAILFD DESCRIPTION OF ~K~KED EMBODIMENTS
As shown in FIG. 1, a radio signal arriving via an antenna 144 is separated by a gyrator 145, and is input to a receiver 148. The receiver 148 converts the radio signal into a baseband audio signal by using a detector 128. Then, the baseband audio signal is output to a transmitter 147 from a transmission output terminal 129 via a signal line 105a in a cable 105.
The transmitter 147 modulates the baseband audio signal with a predetermined carrier frequency, transmitting the modulated signal to the antenna 144 via the duplexer 145.
The operation of the receiver 148 will be described in detail. The radio signal input to the receiver 148 is firstly ampllfied by a high frequency amplifier 121. A
mixer 122 mixes the amplified signal with a signal from a reception local oscillator 141 of a synthesizer 146. The mixed signal is ~iltered by a first intermediate-frequency (IF) filter 123, thus being converted into a first IF signal.
, , - ~
. :
The reception radio frequencies are very close to each other as described with reference to the conventional apparatus. With this invention, the two receptlon radio ~requencies are designed to have wider passbands than those of the conventional apparatus so that these radio frequencies can be converted into signals having the same intermediate frequency. In other words, the first intermediate frequency signal is composed of signal components of two different frequencies. One o~ these signal components is selected and separated by second mixers.
The second mixers 124a and 124b mi~ the first IF
signals with signals supplied via second local oscillators 125a and 125b. The mixed signals are filtered by a second IF filters 126a and 126b. The output signals ~rom the second IF filters 126a and 126b contain only one each of the reception radio frequency signals, respectively.
In the following description, the components indicated by the numbers and letter "a" constitute the circuit system A, while those indicated by the numbers and letter "b" constitute the circuit system B.
The embodiment features that one receiver has two /
:.; , .
, second IF ~ilters to receive two reception radio ~requencies.
The second IF filters 126a and 126b output di~*erent IF slgnals, respectively. The second IF
signals are ampli*ied by second IF ampli~iers 127a and 127b, being converted into baseband audlo signals by FM
detectors 128a and 128b, respectively.
The baseband audio signals are output to transmission output terminals 129a and 129b, and are supplied to transmission input terminals 137a and 137b o~
the transmitter 147 via communication lines 105a and 105b o~ the cable 5.
The transmitter 147 trans~ers the baseband audio signals to modulators 134a and 134b via instantaneous deviation controllers (IDC) 136a and 136b. The modulators 134a and 134b modulate the baseband audio signals with transmission modulation signals received via transmission modulation oscillators 135a and 135b. The outputs from the modulators 134a and 134b are combined to obtain one signal, the frequency o~ which is raised, by the up-converter 133 with an oscillation ~requency o* a transmission local oscillator 142, to a desired carrier ~requency. This carrier signal passes through the :. ' . , :
~ ' ;~ . . -~.
~7 transmission ~ilter 132, is ampli~led by a common amplifier lSl, and is output to the antenna 144 vla the duplexer 145.
Operatlon of this embodiment wlll be described hereinafter.
It is assumed that f(RX1) and F(RX2) represent the two reception frequencies and f(fl) represents the oscillation frequency of the reception local oscillator 141. Two output signals having the following two frequencies are produced by the first IF filter 123.
f(mla) = f(RX1) - ~(rl) ... (1) f(mlb) = f(RXl) - ~(r2) ... (2) The signal having the ~requency ~(mla) is converted into the signal having the frequency f(m2a) by the second mixer 124a.~
f(m2a) = f(mla) - f(r2a) ... (3) where f(r2a) stands for an oscillation frequency of the second local oscillator 125a. Although a signal containing a sum component of the two frequencies is also produced during the conversion expressed by the formula (3), only the signal having the frequency f(m2a) is selected by the second IF filter 126a.
The signal having the frequency f(m2a) is converted ,, '~ , ' . , into the signal of the frequency f(m2b) by the second mixer 124b as ~ollows.
f(m2b) = f(mlb) - f(r2b) ... (4) where ~(r2b) stands ~or an osclllation ~requency of the second local oscillator 125b. Although a signal containing a sum component of the two ~requencies is also produced during the conversion expressed by the formula (4), only the signal having the frequency f(m2b) ls selected by the second IF filter 126b.
Thus, the signals corresponding the reception frequencies f(RX1) and f(RX2) are obtained at outputs of the second IF filters 126a and 126b, respectively. The FM detectors 128a and 128b demodulate these signals to obtain baseband audio signals corresponding to the reception frequencies.
Conventionally, two independent receivers are used for the two reception frequencies. On the contrary, this embodiment is characterized in that the high frequencY
amplifier 121, first mixer 122 and first IF filter 123 are commonly used for the signals having the two reception frequencies, which enables a reudction in the number of component parts to be used.
The two bansband audio signals are sub~ect to , ~ ' .
amplitude limitation by the IDCs 136a and 136b of the transmitter 147, being modulated by the modulators 134a and 134b. The signals output by the modulators 134a and 134b have frequencies ~(tla) and f(tlb) when f(tla) and f(tlb) represent output frequencies o~ the transmission local oscillators 135a and 135b. These two output signals are converted into signals having frequencies f(TX1) and F(TX2) by the up-converter 133 as follows.
f(TX1) = f(tla) ~ f(t2) ... (5) f(TX2) = f(tlb) t f(t2) ... (6) where ~(t2) represents an oscillation frequency of the transmission local oscillator 133. Since the outputs of the modulators 134a and 134b also contain components corresponding to the difference between the output signals, the transmission filter 132 selects only the signals expressed by the formulas (5) and 16). The signals having the carrier frequencies f(TX1) and f(TX2) are ampli~ied by the common amplifier 131, and are transmitted via the duplexer 145 and the antenna 144.
This embodiment is characterized in that the up-converter 133, transmission filter 132 and common ampllfier 131 are commonly used for the two transmission ~requencies, thereby enabling a reduction in the number 207233~
of component parts to be used.
The reception frequencles f(RXl) and f(RX2) are variable depending upon the oscillation frequency of the reception local oscillator 141, as described above. In this case, the frequencies f(RX1) and f(RX2) should have the relationship as follows.
f(RX1) - f(RX2) = f(mla) - f(mlb) = {f(m2a) ~ f(r2a)}
- {f(m2b) I f(r2b)} ... (7) Therefore, the difference between these frequencies is constant. The transmission frequencies f(TX1) and f(TX2) are also variable depending upon the oscillation frequency of the transmission local oscillator 142. In this case, the transmission frequencies should have the following relationship.
~ TX1) - f~TX2) = f~tla) - f~tlb) ~-. (8) The difference between these frequencies is kept constant.
As described so far, the radio repeater of this embodiment can be made compact since some of the circuits are used for both transmission and reception of the signals, compared with the conventional apparatus in which the number of transmitters and receivers depends upon the number of transmission and receptlon frequencles. In addition, the two transmission frequencies and the two reception frequencies can be varied as desired by changing the oscillation frequencies of the reception and transmission local oscillators 141 and 142, respectively, while keeping the constant separation between the reception frequencies f(RX1) and f(RX2) and the transmission frequencies f(TXl) and f(TX2), respectively. Therefore, the radio repeater allows communication between mobile stations by using an idle channel.
A radio repeater according to the second embodiment will be described with reference to FIG. 2. This radio repeater differs from the repeater of the first embodlment ln that a receiver 248 includes one second local oscillator 225 and one second mixer 224, which means a further reduction in the number of components of the radio repeater. This embodiment is a simplified ~orm of the flrst embodiment.
In the first embodiment, the second local oscillators 125a and 125b output the signals having different frequencies. When both the second local oscillators 125a and 125b output the signals having the .
207233~
same ~requency, the signals output by the second mixers 124a and 124b also have the same ~requency. In thls case, one second local oscillator 125a (or 125b) and one second mixer 124a (or 124b) are enough to per~orm the ~oregoing function. There~ore, the radlo repeater o~ the second embodiment includes only one second local oscillator and one second mixer, thereby reducing the number of component parts.
In this embodiment, the second IF filters 226a and 226b should have di~ferent passing center ~requencies so as to output reception signals having di~ferent ~requencies.
This embodiment also differs from the ~irst embodiment in the following manner. The transmitter 247 includes synthesizing modulators 238a and 238b, which serve as the transmission local oscillator, modulator and up-converter of the ~irst embodiment. This means a ~urther reduction in the number of components parts. The synthesizing modulators 238a and 238b receive re~erence ~requencies directly ~rom a re~erence oscillator 243.
The second embodiment o~ the invention offers the radio repeater which is compatible with the two reception ~requencies f(RX1) and ~(RX2) and two transmission frequencles f(TX1) and f(TX2), whlch can be varJed as desired with the separation kept constant therebetween.
Therefore, the radio repeater enables communication to and from the mobile stations by selecting any idle channel. Since the oscillation frequencies of the first and second local osclllators are the same, the number of oscillators is reduced to half compared with those of the first embodiment.
FIG. 3 shows the configuration of a radio repeater according to the third embodiment of the invention. This embodiment differs from the first embodiment in that the receiver 248 includes one local oscillator 325 and one second mixer 324. In other words, the radio repeater of th~s embodiment includes the transmitter of the first embodiment and the receiver of the second embodiment.
In this embodiment, the second IF filters 326a and 326b should have different passing frequencies, so that the signals having different reception frequencies can be identified.
In the foregoing description, this invention is descrlbed wlth reference to the embodiments for the cordless telephone system or land-mobile radiotelephone system of the frequency scanning type. It is to be 207233~
understood that the technical concept of the invention is also applicable to any other type of radlo transmlsslon systems.
In additlon, separate antennas may be used Yor the transmission and reception signals, respectively.
,~
.
.
Claims (9)
1. A radio repeater comprising:
(a) a means for receiving incoming signals and for outputting received signals;
(b) converters for converting carriers of the received signals into signals having other frequencies;
and (c) a transmitter for transmitting the converted signals;
said converters including:
(i) first intermediate-frequency converters for converting the received signals into signals having frequencies in a first intermediate-frequency band, and (ii) second intermediate-frequency converters for converting the signals in the first intermediate-frequency band into signals having frequencies in a second intermediate-frequency band;
said transmitter including (i) a plurality of detectors for detecting the signals having the frequencies in the second frequency band and for outputting a plurality of baseband signals, and (ii) modulators for modulating the baseband signals with carriers having different frequencies.
(a) a means for receiving incoming signals and for outputting received signals;
(b) converters for converting carriers of the received signals into signals having other frequencies;
and (c) a transmitter for transmitting the converted signals;
said converters including:
(i) first intermediate-frequency converters for converting the received signals into signals having frequencies in a first intermediate-frequency band, and (ii) second intermediate-frequency converters for converting the signals in the first intermediate-frequency band into signals having frequencies in a second intermediate-frequency band;
said transmitter including (i) a plurality of detectors for detecting the signals having the frequencies in the second frequency band and for outputting a plurality of baseband signals, and (ii) modulators for modulating the baseband signals with carriers having different frequencies.
2. A radio repeater according to claim 1, wherein said first intermediate-frequency converters include:
(a) first reception local oscillators;
(b) first mixers for mixing output signals from said first reception local oscillators and the received signals; and (c) first intermediate-frequency filters for selecting signals having the first intermediate-frequency band from the signals output from said mixer.
(a) first reception local oscillators;
(b) first mixers for mixing output signals from said first reception local oscillators and the received signals; and (c) first intermediate-frequency filters for selecting signals having the first intermediate-frequency band from the signals output from said mixer.
3. A radio repeater according to claim 1, wherein said second intermediate-frequency converters include:
(a) a second reception local oscillator;
(b) a second mixer for mixing a signal output from said second reception local oscillator and the signals in the first intermediate-frequency band; and (c) second intermediate-frequency filters for selecting the signals in the second intermediate-frequency band from the signal output by said second mixer.
(a) a second reception local oscillator;
(b) a second mixer for mixing a signal output from said second reception local oscillator and the signals in the first intermediate-frequency band; and (c) second intermediate-frequency filters for selecting the signals in the second intermediate-frequency band from the signal output by said second mixer.
4. A radio repeater according to claim 1, wherein said second intermediate-frequency converters include:
(a) a plurality of second reception local oscillators;
(b) a plurality of second mixers for mixing signals of said reception local oscillators with the signals in the first intermediate-frequency band, each said second mixer being associated with each said second reception local oscillator; and (c) a plurality of second intermediate-frequency filters for selecting signals in the second intermediate-frequency band, each said second intermediate-frequency filter being associated with each said second mixer.
(a) a plurality of second reception local oscillators;
(b) a plurality of second mixers for mixing signals of said reception local oscillators with the signals in the first intermediate-frequency band, each said second mixer being associated with each said second reception local oscillator; and (c) a plurality of second intermediate-frequency filters for selecting signals in the second intermediate-frequency band, each said second intermediate-frequency filter being associated with each said second mixer.
5. A radio repeater according to claim 4, wherein said second reception local oscillators generate signals having the same oscillation frequency, and said second intermediate-frequency filters have different central frequencies in the passband.
6. A radio repeater according to claim 4, wherein said second reception local oscillators generate signals having different oscillation frequencies, and said second intermediate-frequency filters have the same central frequency in the passband.
7. A radio repeater according to claim 4, wherein said second reception local oscillators generate signals having different oscillation frequencies, and said second intermediate-frequency filters have different central frequencies in the passband.
8. A radio repeater according to claim 1, wherein said modulators include:
(a) transmission local oscillators associated with respective baseband signals;
(b) a plurality of modulator members for modulating the baseband signals with the signals output from said transmission local oscillators, each said modulator member being associated with each said transmission local oscillator;
(c) an up-converter for summing the signals output from said modulator members, outputting a signal indicating the sum of the output signals, and converting the sum signal into a signal having a transmission frequency; and (d) a transmission filter for selecting the signal having the transmission frequency from the signal output by said up-converter.
(a) transmission local oscillators associated with respective baseband signals;
(b) a plurality of modulator members for modulating the baseband signals with the signals output from said transmission local oscillators, each said modulator member being associated with each said transmission local oscillator;
(c) an up-converter for summing the signals output from said modulator members, outputting a signal indicating the sum of the output signals, and converting the sum signal into a signal having a transmission frequency; and (d) a transmission filter for selecting the signal having the transmission frequency from the signal output by said up-converter.
9. A radio repeater according to claim 8, wherein said modulator includes a plurality of instantaneous deviation controllers (IDC) for limiting amplitudes of the baseband signals, and said modulator members modulate the amplitude-limited signals.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15498691A JPH057173A (en) | 1991-06-27 | 1991-06-27 | Radio relay transmitter-receiver |
| JP3-154986 | 1991-06-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2072335A1 CA2072335A1 (en) | 1992-12-28 |
| CA2072335C true CA2072335C (en) | 1998-01-06 |
Family
ID=15596220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2072335 Expired - Fee Related CA2072335C (en) | 1991-06-27 | 1992-06-25 | Radio repeater |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH057173A (en) |
| CA (1) | CA2072335C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005531202A (en) * | 2002-06-21 | 2005-10-13 | ワイデファイ インコーポレイテッド | Wireless local area network repeater |
| JP6836862B2 (en) * | 2016-08-19 | 2021-03-03 | ホーチキ株式会社 | Alarm system |
| JP6752094B2 (en) * | 2016-09-23 | 2020-09-09 | ホーチキ株式会社 | Inter-group transfer device for warning system |
| JP7044490B2 (en) * | 2017-06-28 | 2022-03-30 | ホーチキ株式会社 | Alarm system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4325457Y1 (en) * | 1965-07-12 | 1968-10-25 | ||
| JPS6367832A (en) * | 1986-09-09 | 1988-03-26 | Nec Corp | Relay system |
| JPS6429129A (en) * | 1987-07-24 | 1989-01-31 | Sharp Kk | Low noise converter for satellite broadcast reception |
-
1991
- 1991-06-27 JP JP15498691A patent/JPH057173A/en active Pending
-
1992
- 1992-06-25 CA CA 2072335 patent/CA2072335C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH057173A (en) | 1993-01-14 |
| CA2072335A1 (en) | 1992-12-28 |
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