JPS6313529A - Transmitter-receiver for radio telephony - Google Patents

Abstract

PURPOSE:To reduce the number of components by using each high frequency circuit conventionally provided to each transmission/reception unit in common as one common circuit. CONSTITUTION:A received signal from each radio telephone set inputted from a reception antenna 22 is converted into a lower frequency than a radio frequency by an input frequency conversion circuit 27 and inputted to a MODEM unit 25. The received signal converted into a low frequency and inputted to the MODEM unit 25 is demodulated into a voice band signal by a demodulation circuit 30 and the result is sent to a telephone exchange 24. The voice band signal outputted from the telephone exchange 24 is supplied to the MODEM unit 25, where it is modulated to a transmission signal by a modulation circuit 31. Then the transmission signal sent from the unit 25 is converted into a radio frequency by an output frequency conversion circuit 33, automatically controlled to a specified power by a power control circuit and sent from a transmission antenna 21. Thus, no high frequency circuit is required to be assembled in each MODEM unit 25.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a small-scale wireless telephone system in which a telephone exchange and each wireless telephone terminal are connected by radio, and in particular, the present invention relates to a small-scale wireless telephone system in which a telephone exchange and each wireless telephone terminal are connected by radio. The present invention relates to a wireless telephone transmitting/receiving device that wirelessly connects to a wireless telephone.

[Prior Art] A small-scale wireless telephone system is generally configured as shown in FIG. That is, in the wireless telephone station 1, there are transmitting/receiving units 3 and one telephone exchange II 4 corresponding to the number of installed wireless telephone terminals 2 wirelessly connected to the wireless telephone station 1.
is installed. Then, the telephone exchange 4 connects the telephone line 5
connected to.

Each of the transmitting/receiving units 3 of (1) to (N) is connected to the N(1)
1 to Nn N wireless telephone terminals 2 are supported.

Further, a common receiving antenna 6 and a common transmitting antenna 7 are connected to each transmitting/receiving unit 3.

Each of the transmitting/receiving units 3 is configured as shown in FIG. 3, for example. The high frequency reception signal of several hundred MH2 transmitted from each radio telephone terminal 2 and received by the reception antenna 6 is
The signal passes through the power divider 8 in the transmitter/receiver unit 3, is amplified by the high frequency amplifier 9, is mixed with the signal from the receiving local oscillator 11 by the frequency converter 10, is converted into an intermediate frequency signal, and is input to the demodulator circuit 12. Ru. The intermediate frequency signal input to the demodulation circuit 12 is demodulated into a voice band signal using a signal from another low frequency oscillator 13. Then, the signal from the wireless telephone terminal a2 demodulated into a voice band signal is sent to the telephone exchange I! It is input to lI4.

On the other hand, the voice band signal output from the telephone exchange 4 is input to the modulation circuit 14 of the transmitting/receiving unit 3. Modulation circuit 1
The audio band signal input to the VCXO (voltage controlled oscillator) 15 is modulated into an FM signal of several tens of MHI using a reference signal from a VCXO (voltage controlled oscillator) 15. The FM signal modulated by the modulation circuit 14 is
Furthermore, after being mixed with the signal from the transmitting local oscillator 17 in the frequency converter 16 and converted into a transmitting signal of several hundred MHz,
The power amplifier 18 amplifies the power to a desired power value. The transmission signal amplified by the power amplifier 18 is combined with the transmission signals from other transmitting/receiving units 3 by the power combiner 19 and transmitted from the transmitting antenna 7.

Note that 20 in the figure is a buffer amplifier for compensating for power loss in the power divider 8.

[Problems to be Solved by the Invention] However, even in the wireless telephone system configured as described above, there are the following problems.

That is, in general, the frequency of wireless communication between the wireless telephone station 1 and each wireless telephone terminal 2 is extremely high, at several hundred MHz. Each transmitting/receiving unit 3 also includes a high frequency amplifier 91, a frequency converter 10, a 16° receiving local oscillator 11. Transmission local valve 1 cylinder 17. A power amplifier 18 is incorporated.

Therefore, the number of components of the entire wireless system increases,
Not only does the number of parts increase, but also the amount of adjustment work for each component increases. In particular, since the transmission power of the transmission signal output from the transmission antenna 7 is strictly regulated by standards, for example, when you want to add a transmission/reception unit 3, each component of all the transmission/reception units 3 must be It is necessary to readjust the total transmission power value so that it does not exceed the regulation value.

Further, as described above, since a very high frequency is used, there is a concern that signal interference may occur between the respective transmitting/receiving units 3. Furthermore, in order to process high frequency signals, it is necessary to use carefully selected and expensive parts suitable for high frequencies for the components used in each of the above-mentioned components.
There is a problem that the overall manufacturing cost increases.

The present invention has been made based on these circumstances, and its purpose is to take out each high frequency circuit that was conventionally provided for each multi-transmission/reception unit and make it into one common circuit, so that each unit can An object of the present invention is to provide a wireless telephone transmitting/receiving device that can reduce the number of component parts, greatly improve the efficiency of adjustment work, and reduce the manufacturing cost of the entire device.

[Means for Solving the Problems] 5. The wireless telephone transmitting/receiving device of the present invention has an input frequency that converts the frequency of the received signal from each wireless telephone terminal inputted from the receiving antenna to a frequency lower than the radio frequency. A conversion circuit, a received signal whose frequency has been converted by this input frequency conversion circuit, is demodulated into a voice band signal, and sent to a telephone exchange *m circuit, and a voice band signal output from this telephone exchange is sent to a wireless telephone terminal. a plurality of modulation/demodulation units comprising a modulation circuit that modulates the transmission signal into a transmission signal; an output frequency conversion circuit that converts the frequency of the transmission signal output from the modulation circuit of each of these modulation/demodulation units to a radio frequency; and this output frequency conversion circuit. and a power control circuit that automatically controls the transmission power of the transmission signal output from the transmission antenna to a predetermined power value.

[Function] If the wireless telephone transmitter/receiver is configured as described above,
The received signal from each radio telephone terminal inputted from the receiving antenna is converted to a frequency lower than the radio frequency by an input frequency conversion circuit and inputted to the modulation/demodulation unit 6. The received signal input to the modulation/demodulation unit and converted to a low frequency is demodulated into a voice band signal by a demodulation circuit and sent to the telephone exchange. The voice band signal output from the telephone exchange is input to a modulation/demodulation unit, and modulated into a transmission signal by a modulation circuit within the modulation/demodulation unit. The transmission signal sent out from the modulation/demodulation unit is converted into a radio frequency by an output frequency conversion circuit, and further automatically controlled to a specified power value by a power control circuit, and then transmitted from a transmission antenna. Therefore, it is not necessary to incorporate a high frequency circuit into each modulation/demodulation unit. Further, the transmission power output from the transmission antenna is collectively controlled by a power control circuit.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a wireless telephone transmitting/receiving device according to an embodiment. The wireless telephone transmitter/receiver of this embodiment is broadly divided into a common circuit 23 for converting the frequency of a reception signal received by a reception antenna 21 and a transmission signal transmitted from a transmission antenna 22, and for controlling transmission power. , N of (1) to (N) corresponding to each of the radio telephone terminals Nα1 to NαN that demodulate the received signal output from the common circuit 23 and modulate the voice band signal output from the telephone exchange 24, respectively. The modulation/demodulation unit 25 is comprised of two modulation/demodulation units 25.

High frequency reception signals of several hundred MH2 transmitted from each radio telephone terminal (not shown) and received by the reception antenna 21 are input to the common circuit 23. The high-frequency reception signal input to the common circuit 23 is amplified by the high-frequency amplifier circuit 26, and then mixed with the signal from the reception local oscillator 28 by the input frequency conversion circuit 27, and frequency-converted into an intermediate frequency signal of several tens of Mlb. . This intermediate frequency signal is output from the common circuit 23 and input to the modulation/demodulation unit 25. The intermediate frequency signal input to the modulation/demodulation unit 25 passes through the power divider 29 and is input to the demodulation circuit 30. The intermediate frequency signal input to the demodulation circuit 30 is demodulated into a voice band signal. The signal from the wireless telephone terminal demodulated into a voice band signal is then input to the telephone exchange 24.

On the other hand, the voice band signal output from the telephone exchange 24 is
The signal is input to a modulation circuit 31 in the modulation/demodulation unit 25, and modulated by this open circuit 31 into an FM signal of several tens of MHz. The transmission signal FM-modulated by the modulation circuit 31 is combined with the transmission signal from another modulation/demodulation unit 25 by the power combiner 32 and input to the common circuit 23 . The combined transmission signal from each modulation/demodulation unit 25 inputted to the common circuit 23 is mixed with the signal from the transmission local oscillator 34 in the output frequency conversion circuit 33, and is mixed with the signal from the transmission local oscillator 34, which is a radio frequency of several hundred M which is actually transmitted. )lx transmission signal, the power amplifier 35
The signal is amplified to a desired power value and then transmitted from the transmitting antenna 22.

A portion of the transmission power transmitted from the transmission antenna 22 is rectified by the detector 36, and the rectified signal is fed back to the power amplifier 35. The power amplifier 35 monitors the feedback power level and controls the amplification factor so that the transmission power of the transmission signal output from the transmission antenna 22 is always within a specified power value. Thus, the power amplifier 35 and the detector 36 constitute a power control circuit.

Note that 37 in the figure is a buffer amplifier for compensating for power loss in the power divider 29.

If the wireless telephone transmitter/receiver is configured in this way,
High frequency amplifier 91 frequency converter 10.16. built into each transmitter/receiver unit 3 in the conventional system of FIG.
Each component to which a high frequency signal of several hundred M)lz is input/output, such as the power amplifier 18, is removed from each transmitting/receiving unit 3,
As shown in FIG. 1, they are integrated into one common circuit 23. That is, a received signal of several hundred MHz input from the receiving antenna 21 is frequency-converted to several tens of MHz by the input frequency conversion circuit 27 of the common circuit 23,
The signal is sent to each modulation/demodulation unit 25. Further, the transmission signal of several tens of MHz outputted from each modulation/demodulation unit 25 is converted into a transmission signal of several hundred MHz by the output frequency conversion circuit 33 of the common circuit 23.

Therefore, each modulation/demodulation unit 25 does not need to incorporate the components that process the high-frequency signals described above, so the number of components of each modulation/demodulation unit 25 can be reduced.

Note that since the number of each component forming the common circuit 23 is limited to a few, the number of components of the entire wireless telephone system can be significantly reduced.

Furthermore, the number of carefully selected and expensive parts used for each component constituting the common circuit 23 that processes high-frequency signals is also reduced. Furthermore, a power divider 29 and a power combiner 32
It is also possible to construct it with ordinary inexpensive parts without using high-frequency parts. As a result, in addition to the effect of reducing the overall number of parts, the manufacturing cost of the entire wireless telephone system can be significantly reduced.

In addition, since the transmission power value of the transmission signal output from the transmission antenna 22 is controlled within the standard power value by a power control circuit composed of a power amplifier 35 and a wave detector 36, even if the wireless telephone terminal Even if it becomes necessary to increase the number of installed modulation/demodulation units 25 due to an increase in the number of installed transmitters, the transmission power value output from the transmission antenna 22 is automatically controlled within the specified power value. There is no need to readjust all modulation/demodulation units 25 as in the conventional device shown in the figure. As a result, the efficiency of adjustment work can be greatly improved.

Furthermore, since each modulation/demodulation unit 25 does not include a high frequency circuit, it is possible to prevent interference between the modulation and demodulation units 25 and deterioration of communication quality due to unstable operation.

By providing the power control circuit, even if the transmitting antenna 22 fails and becomes impedance mismatched, excessive power is prevented from flowing to the transmitting antenna 22, and the final output of the output frequency conversion circuit 33 is suppressed. stage amplifiers are protected.

[Effects of the Invention] As explained above, according to the present invention, each high frequency circuit, which was conventionally provided for each transmitting/receiving unit, is taken out and made into one common circuit. Therefore, the number of components in each unit can be reduced, the number of high-frequency parts can be reduced, and the manufacturing cost of the entire device can be reduced. Furthermore, by providing a power control circuit at the input stage of the transmitting antenna, the efficiency of adjusting the transmitting power value can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a wireless N-talk transmitter/receiver according to an embodiment of the present invention, FIG. 2 is a block diagram showing the entire conventional wireless telephone system, and FIG. 3 is a schematic diagram of the conventional wireless telephone system. FIG. 2... Wireless telephone terminal, 21... Transmitting antenna, 2
2...Receiving antenna, 23...Common circuit, 24...
・Telephone exchange, 25...modulation/demodulation unit, 26...
High frequency amplifier, 27... Input frequency conversion circuit, 29.
... Power divider, 30 ... Demodulation circuit, 31 ... Modulation circuit, 32 ... Power combiner, 33 ... Output frequency conversion circuit, 35 ... Power amplifier, 36 ... Detection circuit ,
37...! 10% amplifier.

Claims (1)

[Claims] In a wireless telephone transmitter/receiver that is connected to a telephone exchange and connects the telephone exchange and a plurality of wireless telephone terminals by wireless communication, the frequency of the received signal from each of the wireless telephone terminals input from the receiving antenna is determined. an input frequency conversion circuit that converts to a frequency lower than a radio frequency; a demodulation circuit that demodulates the received signal whose frequency has been converted by the input frequency conversion circuit into a voice band signal and sends it to the telephone exchange; and the telephone exchange. a plurality of modulation/demodulation units comprising a modulation circuit that modulates the voice band signal output from the radio telephone terminal into a transmission signal to the wireless telephone terminal; and a power control circuit that automatically controls the transmission power of the transmission signal output from the output frequency conversion circuit to the transmission antenna to a predetermined specified power value. Wireless telephone transmitter/receiver.