JPS6055742A - transceiver - Google Patents

Abstract

PURPOSE:To reduce the influence upon a receiving system and suppress spurious disturbance by switching the first- the third on/off switching circuits at a transmission time and a reception time in a transmitter and receiver capable of bi-directional communication. CONSTITUTION:An antenna 38 and a mixer 26 are used for transmission as well as reception; and at a reception time, a receiving signal from the antenna 38 is converted to an intermediate frequency and is selected by a band-pass filter 28 through a switching circuit 27 and is demodulated and outputted. In this case, switching circuits 25 and 33 are in the nonconductive state. At a transmission time, switching circuits 25 and 33 are in the conductive state, and the switching circuit 27 is in the nonconductive state, and an oscillation signal is modulated by a modulating signal from an input terminal 37 and has the band limited, and thereafter, the oscillation signal from an oscillator 32 is received through the switching circuit 33 by the mixer 26 and has the frequency converted and is transmitted from the antenna 38 through the switching circuit 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a transmitter and a receiver, and particularly to a transmitter and receiver capable of bidirectional communication.

[Background of the invention]

A conventional transceiver for two-way communication is shown in FIGS. 1 and 2.

The first factor is a block diagram showing a conventional transceiver, which shows a transceiver in which a transmitting system and a receiving system are individually combined.

In Figure 1, 1 is a transmitting antenna, 2 is a mixer, and 3
is an oscillator, 4 is a bandpass filter, 5 is a modulator, 6 is a modulated signal generator, 7 is a modulated signal input terminal, 8 is a receiving antenna, 9 is a mixer, 10 is an oscillator, 11 is a bandpass filter, 12 13 is an amplifier, 13 is a demodulator, and 14 is a demodulated signal output terminal.

During transmission, the modulator 5 modulates the signal from the signal generator 6 using the modulation signal from the input terminal 7, and the mixer 2 receives the excitation of the oscillation signal from the oscillator 3 via the bandpass filter 4. After frequency conversion, the signal is output from antenna 1.

Also, during reception, the signal received by the antenna 8 is sent to the mixer 9, where it is frequency-converted into an intermediate frequency signal for excitation of the oscillation signal from the oscillator 1o, and this is sent to the bandpass filter 1.
1), amplified by the amplifier 12, demodulated by the demodulator 13, and outputted as a signal from the output terminal 14.

This type of transmitter/receiver has the characteristics of being able to respond to large fluctuations in the reception level and being unaffected by the transmission output with a large signal level during reception, but the same system is It has the disadvantage that the circuit size is large because it requires multiple sets.

FIG. 2 is a block diagram showing another conventional example of a transceiver.

In FIG. 2, 15 is an antenna, 16 is a directional coupler, and 17 is an ASK (ArrLplitude 5hif
t Kgying) modulation signal input terminal, 1B is a modulator,
19 is a directional coupler, 20 is a mixer, 21 is an amplifier, 2
2 is an intermediate frequency output terminal, and 23 is an oscillator.

During transmission, the oscillation signal from the oscillator 25 is input to the modulator 18 via the directional coupler 19, modulated using the modulation signal from the input terminal 17, and then sent to the antenna 15 via the directional coupler 16. Send from.

During reception, the received signal from the antenna 15 is input to the mixer 20 via the directional coupler 16,
The signal from the oscillator 23 is frequency-converted into an intermediate frequency signal, amplified by the amplifier 21, and then output from the output terminal 22.

This type of transmitter/receiver has the advantage that the circuit configuration can be simplified compared to the conventional example shown in FIG. 1, but when the transmission output is large, it may be difficult to There is a drawback that the transmitting output does not affect the receiving circuit system, and therefore, when transmitting and receiving are performed simultaneously, the magnitude of the transmitting output must be limited. Furthermore, there are drawbacks such as spurious interference (leakage of oscillation signals, etc.) during reception.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to provide a two-way communication transmitter/receiver that has a simple circuit configuration, sufficiently reduces the influence of transmitted signals on the receiving circuit system, and produces less spurious interference. be.

[Summary of the invention]

According to the present invention, an antenna and a mixer are used for both transmitting and receiving purposes, and a receiving amplifier and a first on/off switching circuit that can short-circuit the input and output terminals of the amplifier are connected in parallel between the antenna and the mixer. a second on/off switching circuit between the mixer and the transmitting circuit, a third on/off switching circuit between the mixer and the receiving circuit;
Or without connection, the first. This is achieved by switching and operating the second and third on/off switching circuits at the time of sending and receiving the test, respectively.

[Embodiments of the invention]

FIG. 3 is a block diagram showing one embodiment of the present invention.

In FIG. 3, 38 is a transmitting and receiving antenna, 24 is an amplifier, 25 is a switching circuit, 26 is a mixer, 27 is a switching circuit, 28 is a bandpass filter, 29 is an amplifier, 3
0 is a demodulator, 31 is a demodulated signal output terminal, 32 is an oscillator,
36 is a switching circuit, 34 is a band pass filter, 35
36 is a modulated signal generator, and 37 is a modulated signal input terminal.

During reception, the received signal from the antenna 38 is sent to the amplifier 24.
The mixer 26 receives the excitation of the oscillation signal from the oscillator 32 and converts the frequency into an intermediate frequency signal.
After selecting, the signal is amplified by the amplifier 29, demodulated by the demodulator 30, and outputted from the output terminal 31. At this time, switching p switching circuit 2
5 is in a non-conducting state and operates so that the received signal passes through the amplifier 24. Further, the switching circuit 33 is also in a non-conducting state and operates to prevent a modulated signal having a large signal output from being input to the mixer 26. Further, the switching circuit 27 is in a conductive state.

By the way, the amplifier 24 connected between the antenna 38 and the mixer 26 has the effect of suppressing spurious interference from the antenna (such as signal leakage from the antenna of the oscillator 52) during reception.

Next, in the transmitting state, the switching circuits 25 and 65 are each in a conductive state, and the switching circuit 27 is in a non-conducting state. First, the oscillation signal from the signal generator 36 is modulated in the modulator 35 using a modulation signal from the input terminal 37, and the band is limited by the bandpass filter 34. The frequency is converted by receiving the excitation of the oscillation signal from the oscillator 32, and the switching circuit 25
The signal is transmitted to the antenna 58 via the antenna 58.

Note that switching the switching circuit 27 is not necessarily necessary, and can be handled by adopting a signal input method that ignores the received signal at the time of transmission.

By the way, if the switching circuits 25, 27, and 53 are switched periodically, transmission and reception operations are performed in a time-division manner, making bidirectional communication possible. FIG. 3 is a block diagram showing an embodiment in which a single-balanced mixer with a diode phase shifter and a phase shifter configured with a microstrip line is adopted as the mixer 26;

In FIG. 4, the same functions 9 as in FIG. 6 are designated by the same numbers, and their explanations will be omitted. 39 is an intermediate frequency one-wave signal output terminal, 40 is a modulated signal input terminal, 41 is a switching circuit, 42 is a filter, 46 is a phase shifter,
44 and 45 are diodes, respectively.

In this embodiment, a switching circuit 41 is placed in the modulated signal input path to the mixer in the transmission system to prevent the transmission signal from entering the mixer and the reception circuit system during reception. Further, 43 is a phase shifter composed of a microstrip line, and has a line length corresponding to 172 wavelengths with respect to the signal frequency of the oscillator S2.

If the modulated frequency at the time of transmission 48 is selected to be equal to the intermediate signal frequency at the time of reception, the bandpass filter 42 can be shared, but if the respective frequencies are different, it can be deleted and the bandpass filter 42 can be used from the output terminal 39 and the input terminal 40. It is sufficient to arrange corresponding bandpass filters in the signal path.

〔Effect of the invention〕

According to the present invention, with a simple circuit configuration, the influence of a transmitted signal having a large signal level during reception is small, and
It is possible to realize a transmitter/receiver that can suppress leakage of oscillation signals from the antenna, which causes spurious interference. Furthermore, by periodically switching the switching circuit, p1 transmission and reception are performed in a time-division manner, making bidirectional communication possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first conventional example of a transceiver, FIG. 2 is a block diagram also showing a second conventional example, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. is a block diagram showing another embodiment of the present invention. 1. Go to 8.1 58... Antenna 2. Go to 9.2 26.
... Mixer 5, 10.21.52 ... Oscillator 7, 17.57.40 ... Modulation signal input terminal 16.
19... Directional couplers 25, 27. ! i3141...Switching circuit 43
...Phase shifter 4445...Diode agent patent attorney Akio Takahashi

Claims (1)

[Claims] 1) A transmission signal from a transmission circuit is transmitted via a mixer and an antenna, and a reception signal from the antenna is guided to a reception circuit via the mixer and received. In a transmitter/receiver that is used for both transmitting and receiving, a parallel circuit consisting of a receiving amplifier and a first on/off switching circuit that can short-circuit the input and output terminals of the amplifier is connected between the antenna and the mixer, and the mixer and the transmitting circuit are connected together. A second on/off switching circuit is connected between the mixer and the receiving circuit, and a third on/off switching circuit is connected between the mixer and the receiving circuit, or the third on/off switching circuit is connected between the mixer and the receiving circuit. At the same time, if the third on-fist off switching circuit is connected, it is turned off, and at the time of reception, the first on-fist off switching circuit is turned on.
and a transmitter/receiver characterized in that the second on/off switching circuit is turned off, and if a third on/off switching circuit is connected, it is turned on. 2. The transmitter/receiver according to claim 1,
Said 1st. A transceiver characterized in that the second and third on/off switching circuits are operated periodically so that transmission and reception are performed in a time-sharing manner.