JPH0414758B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] In the transponder system applied to radar buoys, etc., in the conventional system, a predetermined frequency deviation, etc. was set in the frequency between the transmitter and the receiver for isolation between the transmitter and the receiver. became complicated, and there were problems with detection and identification functions.

The present invention was made in order to solve this problem, and is a repeater-type device that uses a delay line to control ON/OFF of the received radar pulse at a predetermined period (for example, 1/2 duty) and simply amplifies it and sends it back. It is a transponder. The circuit configuration is simple, the transmitting and receiving frequencies are completely the same, and the detection and identification functions can be greatly improved.

[Industrial application field]

The present invention relates to the improvement of transponders as radar application devices, and relates to a new radio wave response method that can be applied to radar buoys and the like to improve detection and identification functions.

[Conventional technology]

Traditionally, radar buoys have been used to confirm the position of dropping fishing nets in deep-sea fishing and as markers for marine construction. This radar buoy has the function of a so-called radio beacon, which has the function of sending back radio waves of a predetermined frequency in response to reception of radar waves from a radar device. In order to prevent mutual interference between the transmitted wave and the received radar wave, the frequency of the transmitted wave is usually different from the frequency of the received radar wave and is sent back. For this reason, on the radar device side, a special receiver is required in addition to the radar receiver to receive the return waves from the radar buoy.

As a countermeasure to this problem, there is a method of sweeping the frequency of the returned radio waves, but this method has the disadvantage of complicating the overall configuration. Furthermore, in this case, the return wave cannot be sent at the timing of receiving the radar wave, but must be sent after the reception is complete, resulting in poor distance accuracy and the problem of interfering with signals from other targets.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transponder that has a simple configuration and improves detection and identification functions from the radar side. In addition, this invention
The objective is to provide an improved transponder that has good isolation between transmission and reception, is less susceptible to effects such as clutter, and is improved so that its own radio waves do not interfere with other targets. .

[Means for solving problems]

Simply put, in order to achieve the above objectives, this invention alternately switches reception and transmission in a time sufficiently smaller than the reception pulse width of radar waves, and does not radiate transmission waves during the reception period. , is characterized by a new transponder configuration that returns the delayed amplified output of the received radar wave during the transmission period.

〔Example〕

Preferred embodiments of the present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of a transponder according to the present invention, in which 1 is an antenna for transmitting and receiving, 2 is a switch for switching between transmitting and receiving, and 3 is a block diagram showing the basic configuration of a transponder according to the present invention.
is a microwave delay line, 4 is a microwave amplifier, and 5 is a microwave delay line.
is an oscillator for switch control. The switch 2 for switching between transmission and reception has the configuration of a diode switch consisting of, for example, a pin diode, and functions to periodically connect the output of the amplifier 4 to the antenna 1 using a control signal from the oscillator 5. The period of the switching control signal from the oscillator 5 is set to be sufficiently smaller than the pulse width of the received radar wave, and is determined so that transmission and reception are repeated a plurality of times (1/2 duty) within the pulse width. Further, the total delay time of the delay time of the microwave delay line 3 and the signal delay time of the amplifier 4 is set to match the reception period determined by the control signal from the oscillator 5.

FIG. 2 is a waveform diagram for explaining an example of the operation of the transponder, in which a shows the pulse waveform of the received radar wave, b shows the waveform of the switching signal from the oscillator 5, and c shows the waveform of the switching signal from the oscillator 5. It shows the envelope waveform of the transmitted wave. The oscillator 5 continuously oscillates asynchronously, and provides an on/off signal to the switch 2 multiple times within the pulse width A of the received radar wave to alternately switch between the transmission period T and the reception period R. In this way, the delayed amplified output of the radar wave received at each timing of the reception period R is transmitted from the common antenna at the timing of each subsequent transmission period T.

Normally, the pulse width of radar waves is from 100nsec.
Although the pulse width is approximately 2.5 μsec, it is preferable to determine the oscillation frequency of the oscillator 5 so that transmission and reception are repeated several times within this pulse width. For example, when the radar pulse width A is 100 nsec, the transmission period T and the reception period R are each 10 nsec, and transmission and reception are repeated five times during one pulse period. In this case, the delay time by the microwave delay line 3 and the microwave amplifier 4 is also set to 10 nsec so that the delayed amplified output of the radar wave received at the reception period R is emitted exactly at the transmission period T.

According to the method described above, the frequency of the radar wave and the frequency of the transmission wave returned from the transponder naturally match. Moreover, the problem of isolation between transmitting and receiving does not occur due to the transmitting and receiving operations. Therefore, the radar device side can receive the returned waves without requiring any modification or accessory equipment.

FIGS. 3a and 3b are diagrams showing a comparison between the frequency spectrum of a radar wave and the frequency spectrum of a transmission wave from a transponder. As shown in figure b, the transmission spectrum spreads considerably due to the influence of the transmission period T, but the center frequency of the received radar wave _{is 0.}
Since it shows the maximum power at , it is easy to obtain a sufficient level for identification on the radar equipment side.

〔effect〕

As is clear from the above description, in short, the transponder of the present invention solves the problem of transmission/reception isolation by switching the timing of transmission and reception within the pulse width of the received radar waves, and The gist of this is that the delayed amplified output of the same frequency is transmitted as a return wave. Therefore, according to the present invention, there is no need for a special receiver for the transponder on the radar device side, and the identification function is significantly improved. Furthermore, the fact that the radar device can detect at a high signal level means that it is less susceptible to the effects of sea clutter and ground clutter, making it easier to identify. Furthermore, since the return radio wave is transmitted within the width of the radar pulse, the radar device has the advantage of having good distance accuracy when identifying targets and not interfering with other targets.

Therefore, this invention exhibits great effects when applied to radar buoys and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a transponder according to the present invention, and FIG. 2 is a waveform diagram for explaining an example of operation, in which a is a pulse waveform of a received radar wave, and b is a transmission/reception switching signal. waveform, c
3 shows the envelope waveform of the transmitted wave, and FIGS. 3a and 3b are diagrams showing a comparison between the frequency spectrum of the radar wave and the frequency spectrum of the transmitted wave from the transponder. In the figure, 1 is a transmitting/receiving antenna, 2 is a transmitting/receiving switch, 3 is a microwave delay line, 4 is an amplifier, and 5 is an oscillator.

Claims (1)

[Claims] 1. A transponder that emits the required radio waves in response to the reception of transmission waves from a radar device, which includes an antenna for both transmission and reception, and a switch circuit that alternately switches the antenna between transmission and reception at a predetermined period. , a delay circuit that delays the radar waves received during the reception period by a time corresponding to the period; an amplifier that amplifies the delayed radar waves; and transmitting and receiving the output of the amplifier through the switch circuit during the transmission period following the reception period. A transponder comprising a circuit connected to a shared antenna, and further comprising an oscillation circuit that controls the switching cycle of the switch circuit so that reception and transmission are repeated a plurality of times within the pulse width of the received radar wave. .