JPH03254508A - Microwave receiver - Google Patents

Abstract

PURPOSE:To eliminate a local oscillator and to prevent a local oscillation signal component from leaking into an output signal by applying amplitude modulation (or phase modulation) to a microwave input signal with a switching source signal, amplifying the modulated signal as a microwave detected signal and applying phase detection (or detection). CONSTITUTION:A switching amplitude modulator 2 amplitude-modulates a microwave input signal IN coming from a microwave input terminal 3 with a switching source signal SSW whose frequency is fSW from a switching source oscillator 1. When an output signal component is detected by a microwave detector 3, a signal whose frequency is fSW the same as the frequency of the switching source signal SSW is generated. The signal is amplified by an intermediate frequency amplifier 4, and subject to phase detection at a phase detector 6 by using the original switching source signal SSW as a reference signal and the phase of the reference signal is matched with the phase of the signal from the intermediate frequency amplifier 4 by passing the reference signal through the phase shifter 5. Even when the microwave input signal IN in the presence only is modulated by the switching amplitude modulator 2, an output signal VD of the phase detector 6 appears, from which the DC component and an AC component in a band of the phase detector 6 are detected.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a microwave receiving device.

[Conventional technology]

Conventionally, microwave receivers use a heterodyne reception method, in which a received signal at a frequency fS and a local oscillation signal at a frequency fL, which is shifted by an intermediate frequency flF from this frequency fS, are mixed by a nonlinear element such as a diode or a transistor. It was configured to create a signal with frequency fif, amplify it, and detect it.

[Problem to be solved by the invention]

The above-mentioned conventional microwave receiving device has a drawback that a component of the local oscillation signal leaks from the output because the frequency fL of the local oscillation signal is close to the frequency fs of the received signal.

An object of the present invention is to provide a microwave receiving device that can eliminate leakage of local oscillation signal components.

[Means to solve the problem]

The microwave receiving device of the first invention includes a switching source oscillator that generates a switching source signal of a predetermined frequency;
A switching amplitude modulator that amplitude modulates a microwave input signal using the switching source signal, a microwave detector that detects an output signal of this switching amplitude modulator, and an intermediate frequency amplifier that amplifies an output signal of this microwave detector. and a phase shifter that adjusts and outputs the phase of the switching source signal, and a phase detector that detects the phase of the output signal of the intermediate frequency amplifier using the output signal of the phase shifter as a reference.

A microwave receiving device according to a second invention includes a switching source oscillator that generates a switching source signal of a predetermined frequency;
a phase modulator that modulates the phase of a microwave input signal using the switching source signal; a microwave detector that detects an output signal of the phase modulator; and an intermediate frequency amplifier that amplifies the output signal of the microwave detector; It has a detector that detects the output signal of this intermediate frequency amplifier.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

This embodiment uses a switching source signal SS of frequency fsW.
A switching source oscillator 1 that generates W, a switching amplitude modulator 2 that amplitude modulates the microwave input signal IN using the switching source signal SSW, and a microwave detector 3 that detects the output signal of the switching amplitude modulator 2. An intermediate frequency amplifier 4 that amplifies the output signal of the microwave detector 3, a phase shifter 5 that adjusts the phase of the switching source signal SSW, and outputs the output signal of the intermediate frequency amplifier 4 based on the output signal of the phase shifter. The configuration includes a phase detector 6 that detects the phase of the signal.

Next, the operation of this embodiment will be explained.

The switching amplitude modulator 2 converts the microwave input signal IN input from the microwave input terminal 3 into a switching source signal SS of frequency fSw from the switching source oscillator 1.
W submodulates the vibration.

When this output signal component is detected by the microwave detector 3, a signal having the same frequency fSw as the switching source signal SSW is generated.

This signal is amplified by an intermediate frequency amplifier 4 and then phase detected by a phase detector 6 using the original switching source signal Ssw as a reference signal. Adjust the phase difference with the amplifier 4 system to zero.

Since the switching amplitude modulator 2 modulates only when the microwave input signal IN is present, the output signal V of the phase detector 6
D appears, and a DC component and an AC component within the band of the phase detector 6 are detected from this output signal VD.

FIG. 2 is a block diagram of a second embodiment of the invention.

This embodiment uses a switching source signal SS of frequency fsW.
A switching source oscillator 1 that generates W, a phase modulator 7 that phase-modulates the microwave input signal IN using the switching source signal SSW, a microwave detector 3 that detects the output signal of the phase modulator 7, and a microwave detector 3 that detects the output signal of the phase modulator 7. Wave detector 3
The configuration includes an intermediate frequency amplifier 4 that amplifies the output signal of the intermediate frequency amplifier 4, and a detector 8 that detects the output signal of the intermediate frequency amplifier 4.

This embodiment has the same operating principle as the first embodiment, except that a phase modulator 7 is provided in place of the switching amplitude modulator 2, and a detector 8 is provided in place of the phase detector 6. This is a feature.

The phase modulator 7 has the advantage of having smaller modulation loss than the switching amplitude modulator 2, but its circuit configuration tends to be somewhat complicated.

〔Effect of the invention〕

As explained above, the present invention amplitude modulates (or phase modulates) a microwave input signal with a switching source signal,
By amplifying this modulated signal as microwave detection and then performing phase detection (or detection),
Since there is no local oscillator, it is possible to prevent local oscillation signal components from leaking into the output signal, and the effect is that sensitivity equivalent to that of heterodyne reception can be obtained.

[Brief explanation of drawings]

1 and 2 are block diagrams showing first and second embodiments of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Switching source oscillation circuit, 2... Switching amplitude modulator, 3... Microwave detector, 4... Intermediate frequency amplifier, 5... Phase shifter, 6... Phase detector,
7... Phase modulator, 8... Detector.

Claims (2)

[Claims] (1) A switching source oscillator that generates a switching source signal of a predetermined frequency, a switching amplitude modulator that amplitude modulates a microwave input signal using the switching source signal, and a microwave that detects the output signal of the switching amplitude modulator. a detector, an intermediate frequency amplifier that amplifies the output signal of the microwave detector, a phase shifter that adjusts the phase of the switching source signal and outputs it, and a A microwave receiving device comprising: a phase detector that detects the phase of an output signal. (2) A switching source oscillator that generates a switching source signal of a predetermined frequency, a phase modulator that phase modulates a microwave input signal using the switching source signal, and a microwave detector that detects the output signal of this phase modulator. and,
A microwave receiving device comprising: an intermediate frequency amplifier that amplifies the output signal of the microwave detector; and a detector that detects the output signal of the intermediate frequency amplifier.