JP2001211092A - Radio transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional receiver is expensive due to the fact that the conventional receiver needs to integrated a reference frequency source such as a crystal oscillator to convert the received modulating radio frequency signal into a medium frequency signal, and also to solve the problems that the oscillators generate frequency fluctuation, are scattered and destroyed under bad environments, with respect to temperature, humidity, vibration, acceleration, shock, etc., and that the quality of the received data is easily deteriorated and the function of the receiver itself is degraded. SOLUTION: In the radio receiver, a modulated radio frequency signal and an unmodulated carrier defined as the modulated frequency intermediate frequency are simultaneously transmitted from a radio transmission device so as to generate an intermediate frequency signal at the inner part of the receiver which receives both of the modulated signal and the unmodulated carrier. Therefore, a fundamental frequency signal source as a local oscillator is in no need of the receiver, so the cost of the receiver itself is reduced and environmental condition against temperature, humidity, vibration, acceleration and shock, etc., are extensively relieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmission system, and more particularly to a radio transmission system in which radio frequency signals from a plurality of radio transmission devices are simultaneously received and the absolute value of the difference between these radio frequency signals is used as an intermediate frequency signal. The present invention relates to a wireless transmission system in which a receiver does not require a reference frequency signal source such as a local oscillator.

[0002]

2. Description of the Related Art Equipment operating under severe environmental conditions, such as an all-weather data logger system for recording weather data, on-board equipment used for crash safety tests, equipment mounted on rockets and artificial satellites, and the like, are subjected to temperature and humidity. ,vibration,
When the evaluation is performed using environmental test equipment such as acceleration and shock, the apparatus includes a wireless transmission device that transmits a control signal for remotely controlling these devices under test during a test, and a receiver that receives the control signal. Many wireless transmission systems are used. However, since this type of receiver is connected to a device under test and is placed in a test environment facility together with the device under test, stable data reception quality is required even under poor environmental conditions.

FIG. 4 is a conceptual diagram of a conventional wireless transmission system, and FIG. 5 is a block diagram showing an example of a receiver used in this system. As shown in FIG. 4, the system includes a wireless transmitter A in which a local oscillator 5, a modulator 4, a transmitter 3, and a transmission antenna 2 are connected in series, and a reception antenna installed in an environmental test facility 20. And a device under test 19 connected to a control signal output terminal 17 of the receiver 1. Also, as shown in FIG. 5, the receiver 1 includes a receiving antenna 11, a high-frequency amplifier 12, and a mixer 14.
, Intermediate frequency filter and amplifier 15, and device under test 1
The mixer 14 is connected in series with a demodulator 16 having nine control signal output terminals 17, and the other end of the mixer 14 is connected to the output end of the local oscillator 13.
Hereinafter, the operation of the illustrated conventional example will be described in detail.

The modulator 4 of the radio transmitting apparatus A includes a local oscillator 5
A control signal of the device under test 19, such as a power on / off command, an input / output signal level setting and a measurement command, is input to the 110 MHz frequency output and modulated, and the modulated wave is power-amplified by the transmitter 3. The signal is transmitted from the transmitting antenna 2 to the receiver 1 as a radio frequency signal f1. The receiver 1 receives the radio frequency signal f1 by the receiving antenna 11, amplifies it to a predetermined level by the high frequency amplifier 12, and inputs the amplified signal to the mixer 14. Mixer 14
To the other input terminal of the local oscillator 13
Since the frequency output is input, the mixer 14 takes the frequency difference between the two waves, generates an intermediate frequency signal of 10 MHz, and supplies it to the intermediate frequency filter and the amplifier 15. The intermediate frequency filter and amplifier 15 shapes the intermediate frequency signal with an intermediate frequency filter, amplifies the intermediate frequency signal to a predetermined level by an amplifier, and supplies the amplified signal to a demodulator 16, thereby receiving the intermediate frequency signal from the radio frequency signal f1 transmitted from the radio transmitter A. By demodulating the control signal of the test equipment 19 and supplying the control signal to the equipment under test 19, the equipment under test 19 during the environmental test is controlled.

[0005]

However, in the conventional radio transmission system described above, (1) the receiver includes a local oscillator signal for converting a radio frequency signal from the radio transmission device into an intermediate frequency signal. A stable and robust crystal oscillator is required to ensure stable frequency transmission while maintaining poor frequency conditions such as temperature, humidity, vibration, acceleration, and shock. (2) In particular, when operating the receiver under severe temperature conditions, for example, under test conditions such as -40 to -50 ° C, a local oscillator is required. In order to prevent the deterioration of the reception quality of the transmission data due to the large fluctuation of the oscillation frequency of the oscillator, an oscillator using a thermostatic oven (thermal oven crystal oscillator) is used. Frequency is disadvantageously also and power consumption takes a long time to become stable large. SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems associated with the conventional wireless transmission system as described above, and a local oscillator which is a reference frequency signal of a receiver without complicating equipment and / or system configuration. It is an object of the present invention to provide a wireless transmission system that does not require a wireless communication.

[0006]

In order to achieve the above object, the present invention provides a first radio transmitting apparatus for transmitting a modulated radio frequency signal, and a radio communication apparatus which is separated from the modulated radio frequency by an intermediate frequency. A second radio transmission device that transmits a modulated radio frequency signal, and a radio transmission system including a receiver, wherein the receiver simultaneously receives radio frequency signals from the two radio transmission devices, the received Means are provided for enabling generation of an intermediate frequency signal from the absolute value of the difference between the modulated radio frequency signal and the unmodulated radio frequency signal.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a conceptual diagram of a wireless transmission system according to the present invention, FIG. 2 is a block diagram of an embodiment of a receiver according to the present invention, and FIG. 3 is an embodiment of a mixer used in the receiver according to the present invention. It is a circuit diagram. The same components and signals as those shown in FIGS. 4 and 5 of the conventional example are denoted by the same symbols and names below. As shown in FIG. 1, this system includes a radio transmitting apparatus A in which a local oscillator 5, a modulator 4, a transmitter 3, and a transmitting antenna 2 are connected in series, a local oscillator 9, a transmitter 8, and a transmitting antenna 7
Are connected in series, a receiver 6 provided with a receiving antenna 11 installed in an environmental test facility 20, and a device under test 19 connected to a control signal output terminal 17 thereof. . As shown in FIG. 2, the receiver 6 includes a reception antenna 11, a high-frequency amplifier 12, and a mixer 18.
And intermediate frequency filter and amplifier 15 and control output terminal 1
A mixer 16 is connected to a demodulator 16 in series, and another input terminal of the mixer 18 is connected to an output terminal of the high-frequency amplifier 12. Further, as shown in FIG. 3, the mixer 18 used for the receiver 6 is a high-frequency amplifier 1
2 and the input terminals a and b, capacitors C1 and C2 are inserted in series, respectively, and the output terminals of both capacitors are connected, the base of the transistor Tr1, the power supply Vcc and the ground GND. Is connected to the midpoint of the resistors R1 and R2 inserted between the power supply Vcc and the capacitor C3 between the collector of the transistor Tr1 and the power supply Vcc and between the emitter and the ground. Circuit with the primary winding of the tuned transformer T1 and the resistor R3 and the capacitor C4
Is connected, one of the secondary windings of the tuning transformer T1 is connected to the ground GND, and the output taken from the other end c is supplied to the intermediate frequency filter and the amplifier 15. Hereinafter, the operation of the illustrated embodiment will be described in detail.

In the present embodiment, in addition to the modulated radio frequency signal f1 = 110 MHz modulated by the control signal of the device under test 19 transmitted from the same radio transmitting apparatus A as shown in FIG. Radio frequency signal f2, which is an unmodulated carrier separated by 10 MHz at the intermediate frequency of receiver 6 above or below, f2 = 110 MHz + 10 MHz or 110 MHZ
A new radio transmission device B for transmitting -10 MHz is provided,
The receiver 6 receives the two radio frequency signals f1 and f2 at the same time, inputs the radio frequency signals f1 and f2 to the mixer 18, generates an intermediate frequency signal from a frequency component obtained by mixing the f1 and f2 obtained by the mixer 18, and generates a reference frequency source. Device under test 1 without having
9 enables demodulation of the control signal. Hereinafter, f
2 = 100 MHz (modulated radio frequency signal -10 MHz)
The case will be described.

The process of transmitting the radio frequency signal f1 modulated by the control signal of the device under test 19 by the radio transmitting apparatus A is the same as that of the conventional example, so that the description is omitted. The transmitter 8 of the radio transmitting apparatus B amplifies the 100 MHz frequency output signal of the local oscillator 9 to a predetermined level, and transmits a radio frequency signal f2, which is a non-modulated carrier, from the transmitting antenna 7. When the radio frequency signals f1 and f2 are transmitted from the radio transmitters A and B, the receiver 6 receives both waves by the receiving antenna 11, and the high frequency amplifier 12 amplifies the f1 and f2 signals to predetermined levels and mixes them. To the inputs a and b of the vessel 18. The mixer 18 receives the radio frequency signals f1 and f2, which are the outputs of the high frequency amplifier 12, and amplifies them with the transistor Tr1. At this time, the output of the transistor Tr1 is different depending on how the DC bias is applied. A current shunted from the power supply Vcc to the ground GND from the resistor R2 through the resistor R1 so as to easily generate a mixed signal of (f1 ± f2) and an integer multiple of each of the frequency components of f1, f2. From the base of the transistor Tr1 to the emitter and the resistor R3
And the current flowing to it. From the collector output including the desired frequency component amplified by the transistor Tr1, the parallel resonance circuit of the primary side of the tuning transformer T1 inserted between the power supply Vcc and the collector of the transistor Tr1 and the capacitor C3 is tuned to a frequency of 10 MHz. By extracting only f1-f2 = 10 MHZ from the mixed signal, an intermediate frequency signal is generated and supplied to the intermediate frequency filter and the amplifier 15 from the secondary output terminal c of the tuning transformer T1. Thus, the control signal of the EUT 19 can be demodulated from the radio frequency signal f1. When the receiver 6 shown in FIG. 2 receives only one of the radio frequency signals f1 and f2 with the antenna 11, the output amplified by the high frequency amplifier 12 is mixed with the mixer 18.
, The collector output of the transistor Tr1 generates only harmonics of an integral multiple of f1 or f2, so that the parallel resonance circuit of the mixer 18 does not tune to the intermediate frequency of 10 MHz and outputs the same. No intermediate frequency signal is generated at the end c. Accordingly, the intermediate frequency filter of the receiver 6 and the circuits subsequent to the amplifier 15 do not operate, and the control signal of the device under test 19 at f1 is not demodulated. in this way,
The receiver 6 according to the present invention operates only when both the radio frequency signals f1 and f2 are transmitted from the radio transmitters A and B, respectively. For example, first, the unmodulated carrier f2 is transmitted, and then the device under test is The f1 modulated by the control signal of 19 is transmitted, and when the transmission of the control signal of the device under test 19 is completed, f1 and f2 are simultaneously stopped, thereby preventing the risk of the control signal being cut off at the time of simultaneous transmission of both waves. You can do it. In the present invention, the receiver 6 receives the data in the embodiment. However, the receiver 6 is configured to be able to demodulate in response to any other modulated signal such as voice transmitted by the wireless transmission device A. Obviously you can.

Further, in the receiver 6, the method in which the f1 and f2 signals amplified by the high-frequency amplifier 12 are supplied to the mixer 18 to extract a desired frequency component has been exemplified, but the mixer 6 can be used without using the high-frequency amplifier 12. If the bias is set in advance so that the collector output of the transistor 1 in the transistor 18 becomes non-linear, and the f1 and f2 signals are supplied directly from the antenna 11 to the mixer 18, the harmonics of the f1 and f2 signals will be efficiently output to the collector output. Since it occurs frequently, the intermediate frequency signal can be similarly extracted with a simple configuration. Also,
In the mixer 18 of the embodiment, if a SAW filter tuned to the intermediate frequency and the frequencies f1 and f2 is inserted instead of the tuning transformer T1 and the capacitors C1 and C2, a lower noise and higher quality intermediate frequency signal can be obtained. Can be generated.

[0011]

According to the present invention, a radio frequency signal modulated by data such as a control signal of a device under test transmitted from a radio transmitting apparatus during an environmental test, and a radio frequency signal separated by an intermediate frequency of a receiver from the radio frequency signal. The receiver transmits the modulated carrier wave at the same time, and the receiver installed in the environmental test equipment and connected to the equipment under test can receive both of these waves at the same time and generate an intermediate frequency signal. The local oscillator, which is the signal source, can be eliminated, and the receiver can reduce the cost and ensure the quality of the received data even under severe environmental conditions. Is great.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a wireless transmission system according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a receiver according to the present invention.

FIG. 3 is a circuit diagram of an embodiment of a mixer according to the present invention.

FIG. 4 is a conceptual diagram of a conventional wireless transmission system.

FIG. 5 is a block diagram illustrating an example of a conventional receiver.

[Explanation of symbols]

1,6 receiver, 2,7 transmitting antenna, 3,8
Transmitter, 4,8 modulator, 5,9,13 local oscillator, 10 missing number, 11 receiving antenna, 12 high frequency amplifier, 14,18 mixer, 15 intermediate frequency and amplifier, 16 demodulator, 17 control of equipment under test Signal output terminal, 19 equipment under test, 20 environmental test equipment, C1-C3 capacitor, R1-R3 resistor, Tr1 transistor, T1 tuning coil

Claims (1)

[Claims] A first radio transmitting apparatus for transmitting a modulated radio frequency signal; a second radio transmitting apparatus for transmitting an unmodulated radio frequency signal separated by an intermediate frequency from the modulated radio frequency; A radio transmission system comprising a receiver and a receiver, wherein the receiver simultaneously receives radio frequency signals from the radio transmitters, and calculates a difference between the received modulated radio frequency signal and the unmodulated radio frequency signal. A wireless transmission system for generating an intermediate frequency signal from an absolute value.