JP3418879B2 - PSK modulation circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PSK modulation circuit having a resonance circuit and changing the phase of a carrier wave according to a transmission code (data). 2. Description of the Related Art FIG. 1 shows a circuit in which a resonance circuit is connected to a PSK (Phase-Shift Keying) modulation circuit. That is, the amplifiers 11a, whose phases are mutually changed by 180 degrees, are supplied to the carrier wave power supply 10.
11b are connected in parallel, a switch circuit 12 for switching this in accordance with a transmission code (data) is connected to form a PSK modulation circuit, and a coil L and a capacitor C are connected to the output side via an output amplifier 13. LC resonance circuit 1
4 is connected. In the circuit described above, when the phase is changed by the transmission code (data) shown in FIG. 2A, the output is output from the output amplifier 13 with the waveform shown in FIG. 2B. When this output is disassembled, FIG. FIG. 2D shows the waveform before the change, and FIG. 2D shows the waveform after the change. When the waveform before the change in FIG. 2C is switched, there is a damped oscillation whose amplitude decreases after the phase change point as shown in FIG. 2d at the beginning of the amplitude after the change in FIG.
As shown in f, there is a forced vibration having a small amplitude, and the sum of the damped vibration and the forced vibration intervenes as an incomplete waveform (amplitude change) during the phase change period to become a complete waveform. There is a problem that it takes time, and it is not possible to realize high-speed modulation on the carrier frequency. In order to realize the above-described high-speed modulation, the time constant of damped oscillation or forced oscillation is reduced, and the Q (Qu
It is possible to reduce the quality factor (the amount indicating the sharpness of resonance of the resonance circuit), but if Q is reduced, there is a problem that the loss of electric energy becomes very large. SUMMARY OF THE INVENTION An object of the present invention is to provide a PSK modulation circuit capable of realizing high-speed modulation on a carrier frequency without loss of electric energy during a phase change period of modulation. I do. SUMMARY OF THE INVENTION The present invention is a PSK modulation circuit having a resonance circuit at the output, wherein the PSK modulation circuit synchronizes with a phase change by the modulation circuit during a phase change period. A PSK modulation circuit in which a switch circuit for stopping the resonance operation is connected to the resonance circuit. According to the PSK modulation circuit of the present invention, the resonance operation of the resonance circuit is stopped by the switch circuit in synchronization with the change in the phase during the phase change of the modulation. The electric energy is stored in the coil L or the capacitor C of the resonance circuit, and by releasing the stop of the resonance operation of the resonance circuit after the modulation, the electric energy stored in the resonance circuit is output, and the amplitude at the phase change point is output. There is no damped vibration or forced vibration, and there is no change in the amplitude of the modulation output. As described above, according to the present invention, the electric energy is stored during the phase change period of the modulation, and the stored energy is output after the change, so that the amplitude change of the modulation output can be eliminated. , And because of the conservation of electrical energy,
Can be used, high-speed PSK modulation can be realized, and since Q is large, there is no loss of electric energy. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 3 shows a PSK modulation circuit to which a resonance circuit is connected, in which amplifiers 21a and 21b whose phases are mutually changed by 180 degrees are connected in parallel to a carrier wave power supply 20, and the phase is switched according to data (transmission code). First switch circuit 2
2 is connected to form a PSK modulation circuit, and a coil L and a capacitor C
, And the second switch circuit 25 is connected in parallel to the coil L. The above-mentioned second switch circuit 25 is set so as to execute a switching operation in synchronism with a phase change due to the modulation so as to stop the resonance operation of the resonance circuit 24 during the phase change period. The above-described resonance circuit 24
LC is set to LC = 1 / ω ² with respect to the angular frequency ω of the carrier power supply 20. In the PSK modulation circuit configured as described above, when the first switch circuit 22 is operated to switch the phase with the data (transmission code) of FIG. 4B, a signal having the waveform of FIG. At the same time, in synchronization with the phase change due to the switching of the phase of the first switch circuit 22, the second switch circuit 25 switches the phase as shown in FIG.
When the resonance operation of the resonance circuit 24 is stopped during the 0-degree phase change period, the electric energy during that period is stored in the coil L, and the stored electric energy is output after the above-described period has elapsed. The current shown in FIG. 4D flows through the coil L, so that there is no occurrence of damped oscillation or forced oscillation in the amplitude at the change point, and the modulation output is output with a complete waveform (amplitude) without change in amplitude. The circuit shown in FIG. 5 is a second embodiment.
The difference from the circuit of the first embodiment shown in FIG. 3 is that the second switch circuit 25 is connected in series with the coil L before the capacitor C. Since the function of each component is the same as that in FIG. 3, the same reference numerals are given and the details are omitted. In the circuit of FIG. 5, when the phase is switched by operating the first switch circuit 22 with the data (transmission code) of FIG. 6B, a signal having the waveform of FIG. When the second switch circuit 25 stops the resonance operation of the resonance circuit 24 during the 180-degree phase change period, as shown in FIG. Is stored in the capacitor C, and the stored electric energy is output after the above-described period has elapsed, so that the current shown in FIG. 6D flows through the coil L, and the amplitude at the change point becomes There is no occurrence of damped vibration or forced vibration, and the output is a complete waveform with no change in the amplitude of the modulation output. As described above, according to the first and second embodiments, by storing electric energy during the phase change period of the modulation and outputting the stored energy after the change, it is possible to eliminate a change in the amplitude of the modulation output,
Furthermore, since the electric energy is conserved, a resonance circuit having a large Q can be used, so that high-speed PSK modulation can be realized. Further, since the Q is large, there is no loss of electric energy. FIG. 7 shows the second switch circuit 25 described above.
This switch circuit comprises two inverter circuits 31 and 32 constituting a delay circuit, an exclusive OR circuit 33, a one-shot multivibrator 34,
When the data (transmission code) shown in FIG. 8A is input, the inverter circuits 31 and 32 delay the signal as shown in FIG. 8B, and are configured by an exclusive OR circuit. 33 outputs the signal of FIG. 8c, and the one-shot multivibrator 34 outputs the time-adjusted switch signal shown in FIG. 8d.
The output width of the switch signal corresponds to a phase change period of 180 degrees in FIGS.

[Brief description of the drawings] FIG. 1 is a diagram of a conventional PSK modulation circuit. FIG. 2 is an explanatory diagram of a waveform. FIG. 3 is a diagram showing a PSK modulation circuit according to the first embodiment of the present invention. FIG. 4 is a waveform diagram of a main part of FIG. 3; FIG. 5 is a PSK modulation circuit diagram according to a second embodiment of the present invention. FIG. 6 is a waveform chart of a main part of FIG. 5; FIG. 7 is a circuit diagram of a second switch circuit. FIG. 8 is a waveform chart of a main part of FIG. 7; [Explanation of symbols] 24 ... Resonant circuit 25 ... second switch circuit

Claims (1)

(57) Claims 1. A PSK modulation circuit having a resonance circuit at an output, wherein the resonance circuit synchronizes with a phase change by the modulation circuit during a phase change period. A PSK modulation circuit in which a switch circuit for stopping operation is connected to a resonance circuit.