JPH0537405A - Transmitter - Google Patents

Abstract

PURPOSE:To switch a frequency optimum for ionospheric communication without using human labor in the case of transmitting radio waves by using an ionosphere. CONSTITUTION:A high frequency signal from an oscillator 1 to generate the high frequency is turned to a higher harmonic wave by a higher harmonic wave generator 2. This higher harmonic wave is turned to one frequency signal by a filter 4 equipped with a voltage variable capacity diode 3. The power of this frequency signal is amplified by a power amplifier 5, and the signal is switched to a transmitting state by an antenna switcher 6 and supplied to an antenna 7. The radio waves reflected by the ionosphere are received by the antenna 7, switched to a receiving state by the antenna switcher 6 and supplied to a receiver 8. The signals demodulated by the receiver 8 are impressed to a peak detector 9. The peak detector 9 detects the maximum value of the demodulated signal. This maximum value is converted to a control voltage by a controller 10 and supplied to the voltage variable capacity diode 3. Thus, since the frequency optimum for ionospheric reflection is selected by the filter 4 and supplied to the power amplifier 5, the optimum frequency can be automatically switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter for radiating radio waves into the air, and more particularly to a transmitter for the short wave band utilizing an ionosphere.

[0002]

2. Description of the Related Art As a short-wave band transmitter using the ionosphere, as shown in FIG. 3, a multi-frequency oscillator 101 that oscillates a plurality of frequencies, a switch 103 that switches the output frequency of the oscillator 101, Generally, it has a power amplifier 105 that amplifies the output of the switch 103, and an antenna 107 that radiates the output of the power amplifier 105 as a radio wave and radiates it.

In this transmitter, the oscillator 101
The signal of the frequency oscillated in 1 is switched by the switch 103 to be one frequency signal. This frequency signal is power-amplified by the power amplifier 105 and supplied to the antenna 107. This power amplified frequency signal is transmitted to the antenna 10
It is converted into a radio wave and radiated at 7.

[0004]

In such a conventional transmitter, it is necessary to select the maximum frequency reflected by the ionosphere in order to transmit radio waves to a distant place, and it is necessary to manually switch the switch. Since the output frequency of the oscillator was switched, it was difficult to automate because manpower was required.

An object of the present invention is to solve the above-mentioned problems and to provide a transmitter capable of automatically selecting the optimum frequency for ionospheric propagation.

[0006]

In order to achieve the above object, a transmitter of the present invention comprises an oscillator for generating a high frequency,
A harmonic generator that generates harmonics from the high frequency from the oscillator; and a variable filter that selects one of the desired high frequencies from the output of the harmonic generator with a voltage variable capacitance diode controlled by a control voltage, A power amplifier that power-amplifies the output signal from the filter; and an antenna switching device that is connected to the power amplifier and switches between radio wave radiation and reception.
An antenna connected to the antenna switching device, a receiver that demodulates and amplifies received radio waves given from the antenna switching device, a peak detector that detects a maximum output from an output signal from the receiver, and the peak detection A controller for generating a control voltage for controlling the voltage variable capacitance diode based on an output signal of the device, and a switcher for temporally switching between radiation and reception of radio waves.

The present invention uses a variable filter including a voltage variable capacitance diode, and can automatically select the frequency of the radio wave most reflected by the ionosphere at the present time. As a result, radio waves can be efficiently transmitted to a distant place, and manpower is not required to select the optimum frequency.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a transmitting apparatus according to the present invention. The transmitter shown in FIG. 1 has an oscillator 1 and a harmonic generator 2. The oscillator 1 generates a high frequency. This oscillator 1 is connected to a harmonic generator 2 and gives an oscillating high frequency to the high frequency generator 2. The harmonic generator 2 converts the input high frequency into an integral multiple harmonic. The harmonic generator 2 is connected to a filter 4 including a voltage variable capacitance diode 3 and supplies the harmonic to the filter 4. The filter 4 selects a desired high frequency from the high frequency signals. The output of the filter 4 is connected to the power amplifier 5 and supplies the selected high frequency signal to the power amplifier 5. The power amplifier 5 power-amplifies the output signal from the filter 4 to a predetermined value. The output of the power amplifier 5 is connected to the antenna 7 via the antenna switching device 6. Further, the antenna switching device 6 is connected to the receiver 8. The antenna switching device 6 is
The power amplifier 5 is connected to enable the emission of radio waves, and the receiver 8 is connected to switch to enable reception.
The receiver 8 demodulates and amplifies the received radio wave given from the antenna switching device 6. The output of the receiver 8 is connected to the peak detector 9, and the received signal of the receiver 8 is given to the peak detector 9. The peak detector 9 detects the maximum output from the output signal from the receiver 8. The peak detector 9 is connected to the controller 10. The controller 10 creates a control voltage for varying the band of the filter 4 based on the signal from the peak detector 9. The output voltage of the controller 10 is applied to the voltage variable capacitance diode 3. As a result, the filter 4 changes the filtering frequency according to the control voltage of the voltage variable capacitance diode 3. The switch 11 is
It is connected to the harmonic generator 2, the controller 10, the receiver 8 and the antenna switching unit 6, and switches so as not to perform transmission / reception at the same time.

The operation of such a transmitter will be described.

The output oscillated by the oscillator 1 is converted by the harmonic generator 2 into a high frequency that is an integral multiple. This harmonic generator 2
The high frequency signal from is input to the filter 4. Filter 4
Then, a desired frequency is selected from the input high frequency signals and is supplied to the power amplifier 5. The power amplifier 5 amplifies power that can be radiated as a radio wave and supplies the power to the antenna 7 via the antenna switching device 6. The power-amplified high-frequency signal is radiated from the antenna 7 into the air as a radio wave.

This radio wave is reflected by the ionosphere and is received again by the antenna 7. The radio signal received by the antenna 7 is input to the receiver 8 via the antenna switching device 6. The receiver 8 receives the radio wave, amplifies it, and inputs it to the peak detector 9. The peak detector 9 detects the peak value of the received signal and gives it to the controller 10. The controller 10 supplies a control voltage to the voltage variable capacitance diode 3 included in the filter 4 so as to select the frequency of the radio wave reflected most in the ionosphere at the current time.

As a result, the antenna 7 radiates a radio wave having the optimum frequency for being reflected by the ionosphere.

The switching unit 11 controls the antenna switching unit 6 for radiating and receiving radio waves, as well as transmitting from the oscillator 1 to the controller 11 and performing temporal control so that reception is not performed simultaneously. ..

FIG. 2 is a block diagram showing another embodiment of the transmitting apparatus according to the present invention. In the transmitter shown in FIG. 2, a modulator 12 is added to the oscillator 1, and the modulator 12 frequency-modulates the oscillation frequency of the oscillator 1 so that a radio wave to which a modulation signal is applied can be radiated. The point is that it was done. Therefore, since the other components are not changed at all, the same reference numerals as those in the first embodiment are used and the description thereof will be omitted.

According to this embodiment, the same effect as that of the first embodiment can be obtained, and the radio wave to which the modulated signal is applied can be radiated.

[0017]

As described above, the present invention makes it possible to automatically select the frequency of the radio wave most reflected by the ionosphere at the present time by using the variable filter including the voltage variable capacitance diode. As a result, it becomes possible to efficiently transmit radio waves to a distant place, and it is possible to eliminate the need for manpower for frequency switching.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a transmission device according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional transmitter.

[Explanation of symbols]

 1 Oscillator 2 Harmonic Generator 3 Voltage Variable Capacitance Diode 4 Filter 5 Power Amplifier 6 Antenna Switcher 7 Antenna 8 Receiver 9 Peak Detector 10 Controller 11 Switcher 12 Modulator

Claims (1)

Claim: What is claimed is: 1. An oscillator that generates a high frequency, a harmonic generator that generates a harmonic from the high frequency from the oscillator, and one of a desired high frequency from the output of the harmonic generator. A variable filter that is selected by a voltage variable capacitance diode controlled by a control voltage, a power amplifier that power-amplifies an output signal from the filter, and an antenna switching device that is connected to the power amplifier and switches between radiation and reception of radio waves. An antenna connected to the antenna switch, a receiver that demodulates and amplifies the received radio wave given from the antenna switch, and a peak detector that detects the maximum output from the output signal from the receiver, A controller that generates a control voltage that controls the voltage variable capacitance diode based on the output signal of the peak detector, and switches the radiation and reception of radio waves in time. Transmitting apparatus characterized by comprising a switch that.