JPH0666930A - Radar apparatus - Google Patents

Abstract

PURPOSE:To make it possible to perform pulse Doppler processing in a short transmitting time by transmitting two different transmission repeating frequencies (PRF) at the same time, providing two receiving systems, and receiving the signals at the same time. CONSTITUTION:In a transmission control circuit 1, two different PRFs (PRFa and PRFb) are synthesized by changing the transmitting frequencies. A transmitter 2 is controlled so as to generate an intended transmitting pulse train. In the transmitter 2, the transmitting signals having the different pulse frequencies corresponding to the PRF and the PRFb are formed. The signals are radiated from an antenna 4 through a duplexer 3. The signal reflected from a target is received with the antenna 4 and sent to receivers 5 and 6 through the duplexer 3. The received signals corresponding to the PRFa and the PRFb are received by the receivers 5 and 6, respectively. The received signals undergo the processings such as clutter suppression and target-speed detection in Doppler filters 7 and 8. Then, the signals are recorded in memories 9 and 10.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly to a pulse Doppler radar for which the transmission time is shortened.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional pulse Doppler radar device disclosed in, for example, Merrill Eye Skollnik "Radar Handbook" published by McGraw-Hill, Inc. in 1970. In FIG. Is a transmitter, 3 is a duplexer, 4 is an antenna, 5 is a receiver,
7 is Doppler filter, 9 is memory (1), 10 is memory
(2) and 11 are ranging circuits.

FIG. 8 is a diagram for explaining the operation of the pulse Doppler radar. Next, the operation will be described. In the pulse Doppler radar, since the transmission repetition frequency (PRF) is higher than the detection distance, it is necessary to perform transmission with a plurality of PRFs and obtain the target distance by the ranging process. Here, for simplicity, 2PR of PRF1 and PRF2
A case of performing ranging with F will be described.

In the transmission control circuit 1, as shown in FIG. 8 (a), a pulse train in which PRF1 and PRF2 are combined in a time division manner is generated, and the transmitter 2 generates a transmission signal in accordance with this. The transmission signal is radiated into space from the antenna 4 via the duplexer 3.

The reflected signal from the target is received by the antenna 4, sent to the receiver 5 via the duplexer 3, amplified,
Receive processing such as detection.

The detected received signal passes through a Doppler filter 7 for clutter suppression and target velocity detection, and is PR
The received signal of F1 is recorded in the memory (1) 9 and the received signal of PRF2 is recorded in the memory (2) 10.

At this time, since only the information within the transmission repetition period can be stored in the memory as shown in FIGS. 8 (c) and 8 (d), the target distance becomes unclear. Therefore, the ranging circuit 11 performs a correlation process on both PRFs to obtain the target distance. Details of the ranging process are omitted here because they are not directly related to the present invention.

[0008]

Since the conventional pulse Doppler radar is constructed as described above, the structure shown in FIG.
As shown in (a), PRF1 and PRF2 must be transmitted in a time-division manner, which causes a problem that the transmission time is long.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a radar apparatus capable of performing pulse Doppler processing in a short transmission time.

[0010]

In order to reduce the time required to transmit 2PRF of a pulse Doppler radar, the radar apparatus according to the present invention changes the transmission frequencies of PRF1 and PRF2 and transmits at the same time. Two systems are provided so that signals can be received at the same time.

[0011]

The radar device according to the present invention includes PRF1 and PRF1.
Since the frequency of RF2 is changed and transmitted at the same time, and two reception systems are provided for simultaneous reception, 1PRF of the conventional radar is used.
2PRF ranging processing can be performed in the time for transmission.

[0012]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, 1 is a transmission control circuit for controlling the transmission waveform and frequency, 2 is a transmitter, 3 is a transmission / reception switcher, 4 is an antenna, 5 and 6 are receivers for receiving the transmission frequencies of PRF1 and PRF2, respectively. , 8 are PRF1 respectively,
A Doppler filter for processing the received signal of PRF2,
Reference numerals 9 and 10 denote memories for recording received signals of PRF1 and PRF2, respectively, and 11 denotes a ranging circuit for obtaining a target distance from the received signals of PRF1 and PRF2.

FIG. 2 is a diagram for explaining the operation of the above radar device. (A) and (b) show the repeated transmission of PRF1 and PRF2, and (c) shows the synthesized transmission by changing the transmission frequencies of PRF1 and PRF2. Waveforms, (d) shows the time corresponding to the target distance, (e) and (f) show recording of the target signals received by PRF1 and PRF2 in the memory, and (g) shows the target signal after ranging.

Next, the operation will be described. In the transmission control circuit 1, the signals of PRF1 and PRF2 shown in (a) and (b) of FIG. 2 are combined by changing the transmission frequency to generate a transmission pulse train as shown in (c) of FIG. Control 2 In the transmitter 2, as shown in (c) of FIG.
The pulse corresponding to the frequency of f1 and the pulse corresponding to PRF2 generate the transmission signal of frequency f2.
Is radiated into the space from the antenna 4 via.

The signal reflected from the target is received by the antenna 4 and sent to the receiver (1) 5 and the receiver (2) 6 via the transmission / reception switch 3. Since the receiver (1) 5 is tuned to receive the frequency of f1 and the receiver (2) 6 is to receive the frequency of f2, the received signal corresponding to PRF1 is the receiver (1) 5, The received signal corresponding to PRF2 is the receiver
(2) It will be received at 6.

The received signal amplified and detected by the receiver (2) 6 in the receiver (1) 5 is processed by the Doppler filter (1) 7 and the Doppler filter (2) 8 for clutter suppression, target speed detection, etc. After receiving, the received signal of PRF1 is stored in the memory (1) 9.
The received signal of PRF2 is recorded in the memory (2) 10.

The subsequent operation is the same as the conventional operation, and the ranging circuit 11 performs correlation processing on both PRFs,
You can get the target distance.

In such a radar apparatus of this embodiment, P
Since the frequencies of RF1 and PRF2 are changed and transmitted at the same time, and two receiving systems are provided to simultaneously receive,
The ranging process of 2PRF can be performed in the time for 1PRF transmission of the conventional radar, and the transmission time can be shortened.

[Embodiment 2] In the above embodiment, the case where the 2PRF transmission of the pulse Doppler radar is combined by changing the frequency is shown. However, the present invention combines ordinary pulse and pulse Doppler, It can also be applied when shortening the transmission time.

FIG. 3 shows the configuration of the second embodiment of the present invention as described above. In the figure, the same reference numerals as those in FIG. 1 indicate the same parts, and 12 is a pulse radar processing circuit. FIG. 4 shows an operation waveform diagram of the present embodiment. In FIG.
Then, the high PRF of pulse Doppler (P
The RF1 and PRF2) pulses and the normal low PRF pulse shown in FIG. 4 (b) are combined by changing the transmission frequency and transmitted to generate a transmission pulse train as shown in FIG. 4 (c). Control the machine 2.

Also in the second embodiment as described above, since the low PRF transmission of the pulse radar and the high PRF transmission of the pulse Doppler radar are transmitted at different frequencies within the same time zone, they are time-divided. It is possible to shorten the transmission time as compared with the case of performing.

[Third Embodiment] Further, according to the present invention, transmission of a long pulse for detecting a long-distance target and low PRF and transmission of a short pulse for detecting a short-distance target and high PRF are combined, and the transmission time is It can also be applied when shortening.

FIG. 5 shows the configuration of the third embodiment of the present invention as described above. In the figure, the same reference numerals as those in FIG. 1 indicate the same parts, 12 is a pulse radar processing circuit (1), and 13 is a pulse radar. It is the processing circuit (2). FIG. 6 shows an operation waveform diagram of this embodiment. In FIG. 5, the transmission control circuit 1 shown in FIG.
It consists of long pulse and low PRF pulse for long-distance target detection shown in (a) and short pulse and high PRF pulse for short-distance target detection shown in (b) of FIG. The transmitter 2 is controlled so as to generate the transmission pulse train shown.

Also in the third embodiment, the transmission of the long pulse / low PRF for detecting the long-distance target and the transmission of the short pulse / high PRF for detecting the short-distance target are controlled within the same time zone. Since the transmission is changed, the transmission time can be shortened as compared with the case of performing these in time division.

[0025]

As described above, according to the radar device of the present invention, the pulse Doppler radars of different PRFs are simultaneously transmitted while changing the frequency in the same time zone,
Alternatively, the low PRF transmission of the pulse radar and the high PRF transmission of the pulse Doppler radar are transmitted at different frequencies within the same time zone, or long pulse for long range target detection,
Low-PRF pulse radar transmission and short-pulse, high-PRF pulse radar transmission for short-range target detection are transmitted at different frequencies within the same time zone so that multiple receivers can receive them simultaneously. Therefore, there is an effect that the transmission time can be shortened as compared with the conventional case where these transmissions are performed by time division.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of an embodiment of the present invention.

FIG. 3 is a block diagram of a radar device according to a second embodiment of the present invention.

FIG. 4 is an operation explanatory view of the second embodiment of the present invention.

FIG. 5 is a block diagram of a radar device according to a third embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the third embodiment of the present invention.

FIG. 7 is a block diagram of a conventional radar device.

FIG. 8 is an operation explanatory diagram of a conventional radar device.

[Explanation of symbols]

 1 transmission control circuit 2 transmitter 3 duplex switch 4 antenna 5 receiver (1) 6 receiver (2) 7 Doppler filter (1) 8 Doppler filter (2) 9 memory (1) 10 memory (2) 11 ranging circuit 12 pulse radar processing circuit (1) 13 pulse radar processing circuit (2)

Claims (3)

[Claims] 1. A means for transmitting a plurality of different transmission repetition frequencies (hereinafter referred to as PRF) of a pulse Doppler radar by changing the frequency in the same time zone, and a reflection of a transmission wave by the transmission means by a target. A radar apparatus comprising: a plurality of receivers that simultaneously receive waves; and a means for obtaining a distance to a target from signals received by the plurality of receivers. 2. The radar device according to claim 1, wherein the transmitting means transmits low-PRF transmission of the pulse radar and high-PRF transmission of the pulse Doppler radar by changing the frequency within the same time zone. A radar device characterized by the above. 3. The radar device according to claim 1, wherein the transmitting means has a long pulse for detecting a long range target and a low PR.
A radar device characterized in that transmission of a pulse radar of F and transmission of a short pulse high-PRF pulse radar for detecting a short-range target are performed by changing the frequency within the same time zone.