JPS6361982A - Synthetic aperture radar - Google Patents

Abstract

PURPOSE:To automatically perform accurate sensitive time control(STC) over a received time automatically and applying it as control timing. CONSTITUTION:A transmission part 1 modulates and amplifies a pulse signal to generate a sent wave and a transmission/reception branching filter part 2 separates a sent wave and a received wave; and the sent wave is transmitted to the ground from a transmitting and receiving antenna 3 and its reflected wave from the ground is received. A reception part 3 demodulates the received wave to detect the pulse signal. Then an STC automatic control part 11 has a function 12 for detecting the reception start timing of the received wave on then basis of the transmission timing of the sent wave as a start point and a function 13 for setting the STC start timing of the received wave automatically by using the detected timing. The STC automatic control part 11 uses a comparator and a counter to measure the actual delay from the sent wave to the received wave and controls the STC start timing with the value.

Description

[Detailed description of the invention] [Industrial application field] Control
This invention relates to a satellite-mounted synthetic aperture radar that automatically controls the start timing of STC (hereinafter referred to as STC).

[Conventional technology]

Fig. 3 is a functional diagram of a synthetic aperture radar using a conventional receiver STC start timing control system, in which (1) shows a transmitter for modulating and amplifying a pulse signal to generate a transmission wave;
2) is a transmitting/receiving demultiplexing section for separating the transmitted wave and the received wave, (
3) is a transmitting and receiving antenna, and (4) is a receiving section for demodulating received waves and detecting pulse signals.

(5) is a ground station that calculates the STC start timing on the ground and sends that value as a command to the satellite-mounted synthetic aperture radar; (6) is a receiver that receives the command; (7) is ( 6) is an STC control unit that performs STC control of received waves by applying the STC start timing obtained by the command received in step 6).

Next, the operation will be explained. FIG. 4 shows a timing chart of the conventional system.

(8) is the transmitted wave, (9) is the received wave reflected from the ground,
This is the delay time from the transmitted wave to the received wave given by a command from the ground, that is, the STC start time, and this value was used to determine the timing for starting control. In this way, conventionally, the orbit and attitude conditions of the satellite are taken in on the ground, and the pre-calculated delay time is sent to the satellite using a command.The second synthetic aperture radar uses this value to determine the STCO start timing of the received wave. I was in control.

[Problem that the invention seeks to solve]

Conventional synthetic aperture radar uses the above-mentioned method for controlling the received wave STC, so the delay time from the transmitted wave to the received wave must be calculated in advance on the ground. It is necessary to strictly analyze the orbital conditions and attitude conditions of the satellite, and since these are calculated values, there are problems such as a lack of accuracy to the actual delay time.

This invention was made to solve the above-mentioned problems. Conventionally, the delay time, that is, the STC start time, had to be calculated on the ground.

It can be automatically determined within the synthetic aperture radar, and since the value is actual raw data, it can be used to compare received waves and ST.
STC that can reliably match the timing of C control
The purpose of this study is to obtain a synthetic aperture radar that can be automatically controlled.

[Means for solving problems]

The synthetic aperture radar according to the present invention automatically counts the control start time, that is, the delay time from the transmitted pulse to the received wave, within the synthetic aperture radar when performing STC control on the received waves of the satellite-mounted synthetic aperture radar.

This aims to automate the STC start timing.

[For production]

The synthetic aperture radar according to the present invention automatically determines the actual control start delay time in the STO of the received wave and applies it as the control start timing, making it much easier than conventional methods. , the control start timing and the reception timing of the received wave can be more accurately aligned.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) to (4) are the same as the conventional one.

U is a 3TC automatic control unit, and this control unit αυ has a function α which detects the reception start timing of the reception wave using the transmission timing of the transmission wave as a starting point, and uses the detected timing to determine the STC start timing of the reception wave. Equipped with a function to automatically set (I).

The STC automatic control unit uses a comparator and a counter to measure the actual delay time from the transmitted wave to the received wave, and controls the STC start timing based on the measured value.

First, a certain voltage amplitude level is set as a threshold level for the voltage amplitude level of the received wave as a basis for determining that the received wave has been received.

Next, in accordance with the output timing of the transmitted wave, the comparator starts detecting the presence or absence of the received wave, and at the same time starts operating the counter. Thereafter, the counter continues to operate until the comparator detects a reception level equal to or higher than a certain level set as the threshold level of the reception wave, and stops at the same time as the comparator detects the reception wave.

As a result, the STC automatic control unit U accurately detects the delay time from the transmitted wave to the received wave, uses that timing to generate an STC gate signal for STC control, and automatically adjusts the STC of the received wave. can be controlled.

FIG. 2 shows a timing chart when the method according to the present invention is used, and (1) is the same as the conventional one. α4 indicates a received wave with a certain threshold level set, haze indicates a certain threshold level set for the received wave, and α0 indicates STC start timing controlled by the STC automatic control method.
This is the gate signal for TC control, where T2 is in the STC automatic control section.

This is the STC start time determined by determining the presence or absence of a received wave using a comparator and counting the delay time of the received wave accordingly. This value is used to accurately determine the timing for starting control.

〔Effect of the invention〕

As described above, according to the present invention, in the satellite-mounted synthetic aperture radar, a method is used that can automatically control the STC start timing of the received wave, so there is no need to perform calculations or send commands on the ground. Furthermore, since the control is performed using values actually obtained using hardware, there is an effect that highly accurate control can be performed easily.

[Brief explanation of drawings]

FIG. 1 is a functional diagram according to an embodiment of the present invention, FIG. 2 is a timing chart showing an operating situation using the STC automatic control method of the present invention, and FIG. 3 is a functional diagram according to a conventional method.
FIG. 4 is a timing chart showing the operating situation using the conventional method. In the figure, (1) is a transmitting section, (2) is a transmitting/receiving demultiplexing section, (
3) is a transmitting and receiving antenna, (4) is a receiving section, and (5) is a ground station. (6) is a command receiving section, (7) is an STC control section, (8
) is the transmitted wave, (9) is the received wave, α1 is the STC gate signal, 11) is the STC automatic control unit, ■ is the function of detecting the reception timing of the received wave provided in the STC automatic control unit, α is It is provided in the 8TC automatic control section. A function that automatically sets the STC start timing of the received wave, α9 is the received wave with a certain threshold level set, α9 is the certain threshold level set for the received wave, α
0 is an STC gate signal whose timing is controlled by the STC automatic control section. In the figures, the same reference numerals indicate the same or equivalent parts. Patent Output Industrial Technology Director S4 Moxibustion Bi @ 1 Figure + r: src automatic benefit uF = Il! 2nd figure 3rA Figure 4

Claims (1)

[Claims] a transmitting section for modulating and amplifying the pulse signal to generate a transmitting wave; a transmitting/receiving demultiplexing section for separating the transmitting wave and the receiving wave;
A transmitting/receiving antenna that transmits the transmitted wave to the ground and receives the reflected wave from the ground, a receiving section that demodulates the received wave and detects the pulse signal, and a receiver that demodulates the received wave and detects the pulse signal. Sensitive time control of received waves is achieved by the function of detecting the reception start timing and the detection of the above-mentioned timing.
What is claimed is: 1. A synthetic aperture radar for use on a satellite, comprising a sensitive time control automatic control unit having a function of automatically setting the start timing of the control.