JPS58125940A - Modulating circuit of microwave - Google Patents

Abstract

PURPOSE:To eliminate a frequency converting part to simplify the constitution of circuit and to perform the modulation with a digital signal, by providing a PLL circuit to a microwave modulating circuit and supplying the digital signal of a microwave band directly to a VCO. CONSTITUTION:A frequency synthesizer of PLL constitution is added to a microwave modulating circuit, and a data signal 10 is fed directly to a voltage control oscillating part 21 of the PLL circuit. The signal of a microwave band sent from the part 21 is branched by a power distributing part 22, and one of the branched two signals is amplified by a power amplifier 26 to be fed to an antenna part through a terminal 16. The other output given from the part 22 is applied to a PLL circuit part 24 to receive a phase wave detection with the output given from a reference crystal oscillating part 25. The control signal sent from the part 24 is fed back to the part 21. Then the frequency of the synthesizer is controlled at the control circuit part 25. Thus a frequency converting part is eliminated to simplify the circuit constitution. Then the modulation is possible with a digital signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modulation circuit in the microwave band, and provides a microwave band modulation circuit that can realize digital modulation in the microwave band with a simple circuit.

Due to the characteristics of the active elements used, digital modulation in the microwave band conventionally involves performing digital modulation on a carrier wave at a relatively low frequency, mixing it with the desired microwave band frequency, and performing frequency conversion. This method is used. In this method, IC is used for signal processing at low frequency.
Although it has advantages such as being easy to convert, as a modulation circuit system,
This requires a frequency conversion section, generates an unnecessary signal (spurious) in this mixing section, and requires a removal circuit to remove this unnecessary signal, making the circuit configuration complicated.

FIG. 1 shows a conventional modulation circuit of this type. The modulation signal is
A low frequency carrier wave generator 14 is applied from the terminal 10;
The modulation section 11 digitally modulates the signal. Mixing part 1
2 is used to convert the frequency of the signal from the carrier wave generator 15 in the microwave band and send it to the antenna section from the terminal 16 through the amplification section 13. In this case, two kinds of carrier wave generating sections are required: a carrier wave generating section 14 for the low frequency phase and a carrier wave generating section 160 for the microwave band, and a large number of spurious signals are also generated due to the frequency conversion in the mixing section 12. A circuit for removing the spurious is required, which has the disadvantage of requiring a complicated circuit configuration.

The present invention solves the above-mentioned conventional drawbacks by directly performing modulation in the microwave band without a frequency converter.

That is, a terminal that constitutes a microwave band voltage controlled oscillation section and externally controls the frequency of the voltage controlled oscillation section is connected to two terminals.
This makes it possible to modulate the carrier wave frequency at the same time as digital modulation.

FIG. 2 shows an embodiment of the present invention. Voltage controlled oscillator 21
directly generates a microwave band frequency, and the data signal 10 is input to one terminal to perform frequency modulation.
The output from the voltage controlled oscillator 21 is branched at the power distribution section 22, and one side is sent to the antenna section from the terminal 16 via the transmission power amplification section 26. Power distribution section 22
The other output from the input terminal enters the phase-locked loop circuit section 24, performs phase detection 8:f: with the reference crystal oscillation section 23, and returns the control signal to the other terminal of the voltage-controlled oscillation section 21 to form a feedback loop. and configure a frequency synthesizer. Frequency control of the synthesizer is performed through the control circuit section 25.

This circuit modulates the data signal directly in the microwave band and can create a stable modulated signal.

FIG. 3 shows a specific configuration of the voltage controlled oscillation section.

Although the bipolar transistor 36 is used as an active element for oscillation, it may also be an FET. A resonant circuit configuration is used in which a resonant line 33 is used and variable capacitors are mounted on both ends of the resonant line 33. Among the voltage variable capacitance elements 31 and 32, one of the voltage variable capacitance elements 31 has high frequency voltage sensitivity for channel changing, and the other voltage DI variable capacitor 32 has low sensitivity for data modulation. This makes it possible to set a frequency channel in the microwave band and simultaneously modulate low frequencies. A modulating digital signal is applied to the terminal 34, and a feedback signal from the phase lock loop for frequency installation N is applied to the terminal 32vc.

As an example of the present invention, if we consider a microwave band of 1500 MHr, for example, the frequency band is 50 MHr.
Assuming MHz, it is sufficient that the frequency sensitivity of the variable capacitance element 32 constituting the synthesizer is 10, and it is sufficient that the variable capacitance element 31 has a sensitivity of 30 KHz/V. In this way, by changing the sensitivity of the elements 31 and 32 to the two voltage variable capacitors, it is possible to sufficiently modulate even a digital signal with a low transmission rate.

As described above, the present invention provides a microwave modulation circuit in which a microwave band digital signal is input to a voltage controlled oscillator and directly modulated, and is configured with a simple circuit without a frequency converter. It has the advantage of being able to

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a conventional microwave modulation circuit.
FIG. 2 is a block diagram of a microwave modulation circuit according to an embodiment of the present invention, and FIG. 3 is a wiring diagram showing the circuit configuration of a voltage controlled oscillation section thereof. 21... Voltage controlled oscillation section 22... Power distribution section 123... Reference crystal oscillation section 24...
... PLL circuit section, 25, ..., control circuit section,
26,,,,,. Power amplification section. Name of agent: Patent attorney Toshio Nakao and 1 other person11
115Il j4 Figure 2 1 Figure 3

Claims (1)

[Claims] a voltage controlled oscillator having first and second input terminals; a power distribution unit that branches the output from the voltage controlled oscillation unit; and a phase lock into which one of the signals branched by the power distribution unit is introduced.・It has a loop circuit section, a crystal oscillation section as a reference oscillation section, and a control circuit section that controls the frequency of the phase-locked loop circuit section, and directly sends a microwave band signal to the first terminal. The phase-locked loop circuit unit compares the phase of one of the signals branched by the power distribution unit with the crystal oscillator unit, and the output is sent to the voltage-controlled oscillator unit. 1. A microwave modulation circuit characterized in that it is configured such that fc is fed back through two input terminals.