JPH09144402A - Transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized transmitter-receiver. SOLUTION: This transmitter-receiver has a microcomputer 16, a transmitter- receiver antenna 24, a filter 26, in which a signal in a specified frequency band containing frequency f1 and the frequency f2 of a signal from a fixed transmitter-receiver 12 is passed, an antenna changeover switch 28, an oscillation circuit 30 oscillating the signal of frequency f1 modulated by a signal from the microcomputer 16, an RF amplifier 32 amplifying a signal from the oscillation circuit 30, an RF amplifier 34 amplifying a signal from the antenna changeover switch 28, a mixer 36 mixing a signal from the RF amplifier 34 and a signal from the oscillation circuit 30 and coverting the mixed signals into an intermediate-frequency signal and a detector 38 detecting an original signal from the intermediate-frequency signal of f0 (f2 -f1 ). The generation of a transmitter-receiver signal and local oscillation in demodulation are conducted by one oscillation circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transceiver having a superheterodyne receiver.

[0002]

2. Description of the Related Art In a keyless entry system that locks and unlocks a vehicle door or starts and stops an engine using weak radio waves, whether or not an operation content instructed by a remote controller such as an electronic key is executed. A response signal is sent from the fixed transceiver installed on the vehicle body when the operation is executed so that the driver can confirm whether the operation is executed, and the display provided on the remote controller when the remote controller receives this response signal. There is a demand for a bidirectional transmission / reception system in which the unit lights up.

[0003]

However, the conventional transceiver is large to be stored in the electronic key.

The present invention has been made to solve the above problems, and an object thereof is to provide a small-sized transceiver.

[0005]

A transceiver according to the present invention has a frequency difference from a frequency of a reception signal by mixing a transmission / reception section for transmitting and receiving a signal and an input signal of a predetermined frequency and a reception signal. A frequency conversion circuit for converting to an intermediate frequency signal, a detection circuit for detecting an original signal from the intermediate frequency signal, and a signal of the predetermined frequency is input to the frequency conversion circuit, and the signal of the predetermined frequency modulated by the original signal is input. And an oscillating circuit that oscillates.

In this transmitter / receiver, in reception, a signal is received by the transmitter / receiver, while the oscillator circuit oscillates a signal of a predetermined frequency. Then, the frequency conversion circuit mixes the signal of the predetermined frequency input from the oscillation circuit with the reception signal to convert the signal into an intermediate frequency signal having a frequency different from the frequency of the reception signal, and then the detection circuit converts the intermediate frequency signal from the intermediate frequency signal. Detect the original signal.

On the other hand, in transmission, the oscillating circuit oscillates a signal of a predetermined frequency modulated by the original signal, and the transmitting / receiving section transmits this signal.

In the above-mentioned transceiver, since the generation of the transmission signal modulated with the original signal and the local oscillation in the demodulation are performed by one oscillation circuit, the number of parts can be reduced and the size can be reduced.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a remote controller 10 according to an embodiment of the present invention and this remote controller 1.
The schematic configuration of a vehicle bidirectional transmission / reception system 14 including a fixed transceiver 12 according to an embodiment of the present invention, which is mounted on a vehicle body and transmits / receives signals to / from 0, is shown.

The remote controller 10 is a micro controller.
Connected to the computer 16 and the microcomputer 16.
And a plurality of switches (not shown) are provided.
Lock the vehicle door by operating two switches or
Within operations such as unlocking or starting or stopping the engine
Key operation unit 18 for designating the
Of the remote controller 10 connected to the computer 16
Transmission and reception with the display unit 20 having an LED or the like provided on the surface
Connected to the antenna 24 and the transmitting / receiving antenna 24
Frequency f₁, F_Two(In this embodiment, 290 MHz, 3
Signal within a specified frequency band including
Connect the filter 26 and the microcomputer 16
Antenna switch 28 and the micro computer
Connected to the computer 16 and output from the microcomputer 16
Frequency f modulated by the signal ₁The signal that generates
The oscillation circuit 30 and the oscillation circuit 30 connected to the oscillation circuit 30.
These signals are amplified and output to the antenna switch 28 side
From the RF amplifier 32 and the antenna selector switch 28
RF amplifier 34 that amplifies the signal of
The signal output from the oscillator and the signal from the oscillator circuit 30
The frequency of the signal from the RF amplifier 34 and the oscillation circuit 30
Intermediate frequency with a frequency that is the difference from the frequency of these signals
A mixer (frequency mixing circuit) 36 for converting into a signal, and a predetermined
Frequency f₀(F_Two−f₁And in the present embodiment, 1
The original signal is detected from the intermediate frequency signal of 0 MHz)
Detection circuit 38 for outputting the signal to the microcomputer 16
And are equipped with.

The microcomputer 16 controls a CPU for controlling the remote controller 10 as a whole, a program for controlling the remote controller 10 as a whole, a control routine to be described later, an ID code for identifying the vehicle bidirectional transmission / reception system 14, and a vehicle door. RTC (real-time clock) for synchronization with a memory that includes a ROM that stores instruction codes for instructing to lock, unlock, start and stop the engine, and a RAM that functions as a transmission / reception buffer and a work area And can be configured by, for example, one chip.

The antenna changeover switch 28 selectively connects the filter 26 and the RF amplifier 32 or the RF amplifier 34, normally connects the filter 26 and the RF amplifier 32, and is output from the microcomputer 16. The filter 26 and the RF amplifier 34 are connected by the reception mode switching signal, and the filter 2 is similarly transmitted by the transmission mode switching signal output from the microcomputer 16.
6 and the RF amplifier 32 are connected.

Next, the structure of the fixed transceiver 12 will be described. The same components as those of the remote controller 10 are designated by the same reference numerals and the description thereof will be omitted.

The fixed transceiver 12 has a key operation section 18
Also, the microcomputer 40 does not have the display unit 20, and the CPU controls the fixed transceiver 12 as a whole.
And a program for controlling the fixed transceiver 12 as a whole, a control routine described later, and a corresponding remote controller 1
A microcomputer including a ROM that stores the same ID code as the ID code stored in the ROM of 0, a memory that includes a RAM that functions as a transmission / reception buffer and a work area, and an RTC for synchronization. A door lock drive control circuit 42 that is connected to 40 and controls locking and unlocking of the vehicle door,
The engine drive control circuit 44 connected to the microcomputer 40 for controlling the drive of the engine is provided, and the frequency f ₂ (300 MHz in this embodiment) of the signal oscillated by the oscillation circuit 48 is the oscillation circuit of the remote controller 10. The remote controller 10 is different from that of the remote controller 10 in that the antenna changeover switch 50 normally connects the filter 26 and the RF amplifier 34.
It should be noted that the door lock drive control circuit 42 and the engine drive control circuit 44 are circuits necessary for control of locking and unlocking the vehicle door and engine drive control, for example, if the door lock drive control circuit 42 is a key position. Includes switches and courtesy switches.

Next, the bidirectional transmission / reception system 1 for this vehicle
The operation of No. 4 will be described with reference to FIGS.

In FIG. 2, C of the remote controller 10 is shown.
The PU control routine is shown.

When the power source (not shown) is turned on, the remote controller 10 has the filter 26 and R as described above.
In the transmission mode in which the F amplifier 32 is connected, the process waits. In step 100, it is determined whether or not there is an input from the key operation unit 18. If it is not input, the process waits. If it is input, In step 102, which switch of the key operation unit 18 has been operated is determined, and the instruction code and ID code corresponding to the switch operated by the key operation unit 18 are read from the memory, and the read ID code and instruction code are included. Create code data as the original signal.
In the next step 104, the generated code data is output to the oscillation circuit 30.

As a result, the oscillator circuit 30 oscillates the transmission signal (frequency: 290 MHz) modulated by the code data, and the RF amplifier 32 amplifies the transmission signal and the filter 2
The transmission signal from which the noise is removed by 6 is transmitted from the transmission / reception antenna 24.

In the next step 106, the reception mode switching signal is output to the antenna switch 28, and in step 108 a continuous wave is output to the oscillation circuit 30.

As a result, the antenna changeover switch 28
Connects the filter 26 and the RF amplifier 34, and the filter 26 allows only signals within a predetermined frequency band of radio waves received by the transmission / reception antenna 24 to pass. Next, the RF amplifier 34 amplifies the signal output from the filter 26,
The mixer 36 converts the amplified signal into an intermediate frequency signal having a frequency difference between the frequency of this signal and the frequency f ₁ (290 MHz) of the signal from the oscillation circuit 30. Next, the detection circuit 38 detects the original signal from the intermediate frequency signal of the predetermined frequency f ₀ (10 MHz), and the detected original signal is stored in the memory of the microcomputer 16.

In the next step 110, while monitoring the state of the memory, whether a response signal from the corresponding fixed transceiver 12, that is, the same ID code as the ID code stored in the memory, is received within a predetermined time. To judge.

If the response signal is not received within the predetermined time, the process proceeds to step 114. If the response signal is received within the predetermined time, the display unit 20 is operated at step 112.
Is turned on for a predetermined time, and the process proceeds to step 114.

In step 114, the transmission mode switching signal is output to the antenna changeover switch 28, and step 1
At 16, the continuous wave output is stopped and the routine is ended.

On the other hand, FIG. 3 shows a control routine of the CPU of the fixed transceiver 12 which is turned on regardless of whether the ignition switch of the vehicle is on or off.

The fixed transceiver 12 is on standby with the antenna changeover switch 50 connecting the filter 26 and the RF amplifier 34 as described above and outputting a continuous wave to the oscillation circuit 48. The filter 26 allows only signals within a predetermined frequency band of the radio waves received by the transmission / reception antenna 24 to pass. The RF amplifier 34 amplifies the signal output from the filter 26, and the mixer 36 outputs the amplified signal to the frequency of this signal and the frequency f ₂ (3
(00 MHz) and an intermediate frequency signal having a frequency difference. Next, the detection circuit 38 outputs a signal having a predetermined frequency f ₀
The code data is detected from the intermediate frequency signal of, and the detected code data is stored in the memory of the microcomputer 40.

In step 150, it is determined whether code data is received while monitoring the state of the memory.
If the code data is not received, the process waits. If the code data is received, in step 152, the ID code included in the received code data and the ID code stored in the memory are read, and the step At 154, it is determined whether the two match.

If they do not match, step 150
Returning to step 2, if both match, the instruction code included in this code data is read and decoded in step 156. In the next step 158, the operation content designated by the instruction code is executed via the door lock drive control circuit 42 or the engine drive control circuit 44.

At the next step 160, a transmission mode switching signal is output to the antenna switch 50. As a result, the antenna changeover switch 50 connects the filter 26 and the RF amplifier 32.

In the next step 162, the ID code stored in the memory is read and this is output to the oscillation circuit 48 as a response signal.

As a result, the oscillation circuit 48 oscillates the transmission signal (frequency 300 MHz) modulated by the response signal,
The RF amplifier 32 amplifies the transmission signal, and the transmission signal from which noise has been removed by the filter 26 is transmitted / received by the transmitting / receiving antenna 2
Sent from 4.

In the next step 164, a reception mode switching signal is output to the antenna switching switch 50, and the routine ends.

As described above, in the vehicle bidirectional transmission / reception system 14 according to the embodiment of the present invention, one oscillator circuit 30 performs the local oscillation in the generation and the demodulation of the transmission signal modulated by the code data. Therefore, the remote controller 10 can be downsized by reducing the number of parts.

For the same reason, in the vehicle bidirectional transmission / reception system 14, the fixed transceiver 12 can be downsized.

The bidirectional transmission / reception system 1 for vehicles described above
4, the transmission / reception antenna 24, the filter 26, the antenna changeover switch 28 (or 50), the RF amplifier 34, the mixer 36, the oscillation circuit 30 (or 48), the detection circuit 38, and the microcomputer 16 (or 40) are of the superheterodyne system. Obtaining the advantages of a superheterodyne receiver that configures a receiver, has very good frequency selectivity, can obtain high gain, and can obtain a required bandwidth according to the purpose of use. You can

A SAW (surface acoustic wave) oscillator or a crystal oscillator can be used for the oscillator circuits 30 and 48.

Further, in the above embodiment, the fixed transceiver 12 is continuously in the reception mode except in the transmission mode, but is intermittently set to the reception mode, and when the signal is received, the reception mode is set. May be extended.

The transceiver according to the present invention can be applied to a bidirectional transmission / reception system other than the bidirectional transmission / reception system for vehicles.

[0039]

According to the present invention, the generation of the signal for transmission modulated by the original signal and the local oscillation in the demodulation are performed by one oscillation circuit, so that it is possible to reduce the size by reducing the number of parts. It has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a vehicle bidirectional transmission / reception system including a remote controller and a fixed transceiver to which a transceiver according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a control routine of a CPU of a remote controller of the vehicle bidirectional transmission / reception system of FIG.

3 is a flowchart showing a control routine of a CPU of a fixed transceiver of the bidirectional transceiver system for vehicle of FIG.

[Explanation of symbols]

 10 Remote Controller 12 Fixed Transmitter / Receiver 14 Bidirectional Transmitter / Receiver System for Vehicle 24 Transmitter / Receiver Antenna 26 Filter 28 Antenna Changeover Switch 30 Oscillation Circuit 32 RF Amplifier 34 RF Amplifier 36 Mixer 38 Detection Circuit 48 Oscillation Circuit 50 Antenna Changeover Switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04Q 9/00 301 H04Q 9/00 301B 321 321A

Claims (1)

[Claims] 1. A transmission / reception unit for transmitting and receiving a signal, a frequency conversion circuit for mixing an input signal of a predetermined frequency and a reception signal and converting the mixture into an intermediate frequency signal having a frequency different from the frequency of the reception signal. A detection circuit for detecting an original signal from the intermediate frequency signal; and an oscillation circuit for inputting the signal of the predetermined frequency to the frequency conversion circuit and for oscillating the signal of the predetermined frequency modulated with the original signal. Transceiver.