JPS61177802A - Amplitude modulating transmitter - Google Patents

Abstract

PURPOSE:To improve power efficiency and to reduce operation cost by adding an energy accumulator so that a modulator is allowed to execute logically 100% switching operation. CONSTITUTION:The output of a pulse width modulator 21 for modulating the pulse width of the positive side part of a low frequency signal to be modulated is supplied to a modulation switch 1 for executing switching operation in accordance with the pulse train. On the other hand, the output of a pulse width modulator 22 for modulating the negative side part of a low frequency signal is supplied to a modulation switch 2 for executing switching operation in accordance with its pulse train. The outputs of each switches 1, 2 are supplied to the energy accumulators consisting of inductances 25, 26 and capacitors 27, 28, respectively, demodulated and supplied to a modulating transformer 5. Since the modulator executes logically 100% switching operation, its power efficiency is improved and the operation cost is reduced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a radio transmitter in long wave, medium wave and short wave bands.
In particular, it relates to amplitude modulated transmitters.

<Prior Art> Conventionally, this type of radio transmitter has, as shown in FIG. 6, coupling capacitor 7, power supply 8, transmitter final stage 9, its filament'
As shown in FIG. 4, (a) is a point A of the final stage 9 of the transmitter.
(b) is a low frequency signal at amplification element 10 point B, (C) is a low frequency signal at amplification element 20 point C, (d) is a demodulated signal at point E, (e) is demodulated at point E. Each represents a signal.

Problems to be Solved> However, since the above-mentioned conventional radio transmitter is amplitude-modulated by a modulator of class B operation, the theoretical efficiency of the modulator of class B operation is π/4, as is well known. Transmitters that handle large amounts of power suffer from extremely large losses and have high operating costs.

The present invention solves the above-mentioned problems and provides an amplitude modulation transmitter in which the power efficiency of the transmitter is increased.

Means for Solving the Problems -> In order to solve the above problems, the configuration of the amplitude modulation transmitter according to the present invention is such that the operating DC voltage at the final stage of the transmitter depends on the amplitude of the low frequency signal to be modulated. In an amplitude modulation transmitter that increases or decreases, the modulation amplifier operates to increase or decrease the DC voltage at the final stage of the transmitter by periodically opening and closing with a switching frequency that is between the frequency of the low frequency signal to be modulated and the carrier frequency of the transmitter. an energy storage device comprising an operative switch and converting a pulse train pulse width modulated by the low frequency signal into an alternating current that varies in accordance with the amplitude of the low frequency signal, modulating the voltage supplied to the transmitter final stage; It is equipped with a low frequency transformer.

<Example> Next, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of an amplitude modulation transmitter according to the present invention.

FIG. 2 is a waveform diagram showing signals of various parts in the same embodiment.

In the figure, 1 and 2 are modulation switches, 3 and 4 are filament power supplies, 5 is a low frequency transformer (modulation transformer), 6 is a modulation choke coil, 7 is a coupling capacitor, 8 is a power supply, and 9 is a transmitter final stage , IO is a filament power supply, 1) is a high frequency choke coil, 12 is a coupling capacitor, and 13 is a bypass capacitor. Further, 21 and 22 are pulse width modulators, 2
3.24 is a flywheel diode, 25 and 26 are inductors, n.

The edict is a capacitor.

The output of the pulse width modulator 21, which pulse width modulates the positive side portion of the low frequency signal to be modulated, is supplied to the modulation switch 1, which performs a switching operation in accordance with the pulse train. On the other hand, the output of the pulse width modulator 22 that pulse width modulates the negative side portion of the low frequency signal is supplied to the modulation switch 2 that performs a switching operation according to the pulse train.

The output of each modulation switch is an inductor 25,
26 and capacitors 27 and 28, demodulated, and supplied to a low frequency transformer (modulation transformer) 5.

The final stage 9 of the transmitter is supplied with power by a power source 8, and during modulation, the output of a low frequency transformer (modulation transformer) 5 is modulated by a coupling capacitor 7 and a modulation choke 6.

In addition, (a) shown in FIG. 2 is a high frequency signal at point A of the transmitter final stage 9, (a) is a low frequency signal applied to the pulse width modulator 21, and (C) is a low frequency signal applied to the pulse width modulator 22. (d) is the demodulated signal at point E, (e) is the demodulated signal at point E, (f) is the pulse width modulated signal at point F, (g) is the pulse width modulated signal at point G, ( Xun represents the signal at point H.

<Effects of the Invention> As explained above, according to the amplitude modulation/modulation transmitter according to the present invention, by theoretically performing 100% switching operation of the ataxia device, its efficiency can be increased, and the operational efficiency can be increased. This has the effect of reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an amplitude modulation transmitter according to the present invention. FIGS. 2(a) to (hl) are waveform diagrams showing signal waveforms at each point in the same embodiment. FIG. 3 is a circuit diagram showing a conventional wireless transmitter. FIG. 4(a) - (e) are waveform diagrams showing signal waveforms at each point in the radio transmitter. 1.2... Modulation switch 3.4... Filament power supply 5... Low frequency transformer (modulation transformer 6... Modulation choke coil 7... Coupling capacitor 8... Power supply 9... Transmitter final stage lO... Filament power supply 1)... High frequency choke coil 12... Coupling capacitor L3. ... Bypass capacitor 19.20 ... Pulse width modulation signal 21 , 22 ... Pulse width modulator 23 , 24 ... - Flywheel diode 25 ,
26...Inductor 27, 28...Capacitor

Claims (5)

[Claims] (1) In an amplitude modulation transmitter in which the operating DC voltage at the final stage of the transmitter increases or decreases depending on the amplitude of the low frequency signal to be modulated,
A switch is provided that is operated by periodic opening and closing at a switching frequency that is intermediate between the frequency of the low frequency signal to be modulated and the carrier wave frequency of the transmitter so as to operate a modulation amplifier that increases or decreases the DC voltage at the final stage of the transmitter. and an energy storage device that converts a pulse train whose pulse width is modulated by the low frequency signal into an alternating current that fluctuates according to the amplitude of the low frequency signal, and an energy storage device that modulates the voltage supplied to the final stage of the transmitter. An amplitude modulation transmitter comprising a frequency transformer. (2) The amplitude modulation transmitter according to claim (1), wherein the power source that supplies power to the final stage of the transmitter and the power source voltage that supplies power to the switch are the same. . (3) The switch is configured with a double-end push-pull connection and performs a switching operation using the pulse width modulated pulse, one switch being in charge of the positive side of the low frequency signal to be modulated, and the other being in charge of the positive side of the low frequency signal to be modulated. An amplitude modulation transmitter according to claim 1 or claim 2, wherein the switch takes charge of the negative side of the signal. (4) Pulse width modulate the positive side signal of the low frequency signal and connect its output to one of the switches, pulse width modulate the negative side signal of the low frequency signal and connect the output to the other switch. The amplitude modulation transmitter according to claim 3, further comprising a pulse width modulator connected to the switch. (5) The amplitude modulation transmitter according to any one of claims (1) to (4), wherein the switch is constructed of a vacuum tube or a semiconductor element.