JPS6269177A - Rader equipment - Google Patents

Abstract

PURPOSE:To obtain different resolutions with the same offnadir angle by controlling oscillation frequency of a VCO voltage-controlled oscillation part. CONSTITUTION:The VCO voltage-controlled oscillation part 2 is controlled with a VCO control and arithmetic part 7 by a command or a control signal corresponding to the desired distance resolution and the signal band width of the oscillation frequency is changed to the signal band width corresponding to the desired distance resolution. Accordingly, since the distance resolution can be variable without changing offnadir angle differing from the case where the signal band width is fixed, the various resolutions are obtained with respect to the same offnadir angle, namely, the same target.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device mounted on a flying object such as an artificial satellite or an aircraft.

[Prior Art] In side-looking radar, which is a radar device mounted on a conventional artificial satellite or aircraft, so-called bulls compression is used to ensure the required average power without increasing the peak value output of the transmitted pulse. technology is used. Instead of narrowing the transmitted pulse, it lengthens the pulse width and adds linear frequency modulation (linear FM) to it, widening the occupied bandwidth of the signal, and after receiving it, it uses a distributed delay system with reverse frequency vs. delay time characteristics. This is a technique in which the energy in the signal is concentrated at one point through a wire or an equivalent matched filter, and a sharp pulse is output. In this case, the distance separation power δr is expressed by equation (1), as shown in the geometry diagram of FIG. 2, where the signal bandwidth is Δf, the speed of light is C1, and the elevation angle is ψ.

δ・=0・nu・1・−1−(1) ■ π 7
Vf-cos ψ Also, the elevation angle ψ is obtained from the following equation using the altitude H1, the earth's radius Re, and the off-nadir angle α.

Re+H.

ψ = cas ” ((-f d-) sin a'
t (2) [Problems to be solved] In the radar device using the conventional pulse compression technology described above, the signal bandwidth Δf is fixed, so the only way to vary the distance resolution is to change the off-nadir angle α. There is a drawback that different resolutions cannot be obtained at the same off-nadir angle.

[Means for Solving the Problems] The radar device of the present invention that solves the above problems is a radar device mounted on a flying object such as an aircraft, which uses voltage-controlled oscillation in which the oscillation frequency can be changed by controlling the voltage. and a control unit that determines the optimal signal bandwidth to achieve a desired distance resolution using an external command or control signal and determines the voltage control range of the voltage controlled oscillation unit, By controlling the oscillation frequency, the signal bandwidth can be changed and the distance resolution can be varied for a certain off-nadir angle.

[Example] Hereinafter, the present invention will be described in detail using the same drawing showing a preferred example.

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

The radar device of this embodiment includes a reference signal generation section 1, a Vco voltage controlled oscillation section 2, an oscillation section 3. Receiving section 4゜Isolator 5
, an antenna 6, and a Vco control calculation section 7.

The reference signal generator 1 has a function of generating an arbitrary frequency signal as a reference, and the transmitter 3 amplifies the transmit signal controlled by the Vco voltage control oscillator 2 to a predetermined level, and transmits the signal via the isolator 5. It has a function of outputting to the antenna section 6,
The receiving section 4 has a function of amplifying the received signal output from the antenna section and detecting it with a local signal to create a video signal, and the antenna section 6 has a function of transmitting and receiving radar signals.

The Vco voltage control oscillation unit 2 is synchronized with the output signal of the reference signal generation unit 1, controls the oscillation frequency by the voltage control signal from the Vco control calculation unit 7, and adjusts the frequency so that the signal bandwidth corresponds to the desired distance resolution. It has a function to control the sweep width. Further, the Vco control calculation section 7 decodes the command or control signal including desired distance resolution information, and generates the Vco voltage control oscillation section 2 around the frequency that is the output of the reference signal generation section 1.
It has the function of generating a voltage control signal that controls the frequency sweep width corresponding to the distance resolution of .

As described above, in the radar device of this embodiment, the Vco control calculation unit 7 controls the Vco voltage control oscillation unit 2 using a command or control signal corresponding to a desired distance resolution, and the oscillation frequency controlled by the Vco voltage control oscillation unit 2 Since the signal bandwidth of Δf is changed to the signal bandwidth corresponding to the desired distance resolution, unlike the conventional case where the signal bandwidth Δf is fixed, as is clear from equations (1) and (2) described in It becomes possible to make the distance resolution variable without changing the nadir angle α.

[Effects of the Invention] As explained above, the present invention provides Vc by a command or control signal corresponding to a desired distance resolution.

By controlling the voltage of the voltage controlled oscillator and controlling the signal bandwidth of the transmitted signal to a predetermined bandwidth corresponding to the distance resolution, the distance resolution of the radar can be improved without changing the off-nadir angle. This has the effect of being variable and providing various resolutions for the same off-nadir angle, that is, the same target.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a radar device according to an embodiment of the present invention, and FIG. 2 is a geometry diagram of a side-looking radar mounted on an aircraft or the like. 1: Reference signal oscillation section 2: Vco voltage control oscillation section 3: Transmission section 4: Receiving section 5 Near isolator 6: Antenna section 7: Vco control calculation section

Claims (1)

[Claims] In radar equipment mounted on flying objects such as aircraft,
A voltage controlled oscillator whose oscillation frequency can be changed by controlling the voltage and an external command or control signal are used to determine the optimal signal bandwidth to achieve a desired distance resolution and calculate the voltage of the voltage controlled oscillator. A radar device comprising: a control section that determines a control range; the signal bandwidth can be changed by controlling the oscillation frequency of the voltage-controlled oscillation section, and the distance resolution can be varied for a certain off-nadir angle.