JPS6281589A - Pulse doppler radar apparatus - Google Patents

Abstract

PURPOSE:To dispense with the correction of a speed and to uniformize accuracy, by controlling the frequency of a transmitting wave and the repeated frequency of the pulse generated from a pulse generation circuit and obtaining output from the same filter number even if transmitting frequency changes. CONSTITUTION:A transmitting wave synchronous to the pulse generated from a pulse generation circuit 10 is transmitted toward a moving target and the reflected wave thereof is inputted to a Doppler filter 6 so as to detect the speed of the objective target from a filter number generating output. At this time,a control means 8 is provided to control the repeated frequency of the pulse of the pulse generation circuit 10 and the frequency of a transmitter 9 so as to always obtain output from the same filter number of the Doppler filter 6 even if the frequency of the transmitting wave changes. By this method, it becomes unnecessary to correct a speed and the effect of transmitting frequency on measuring accuracy is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a pulse Doppler radar device that detects the speed of a moving target by transmitting a transmission wave toward a moving target and generating a reflected wave that is reflected from the moving target. Regarding.

[Conventional technology]

Conventionally, there has been a pulse Doppler radar device of this type as shown in FIG.

FIG. 3 is a configuration diagram of a conventional pulsed Doppler radar device.

In the figure, 9 is a transmitter for transmitting a transmission wave toward a moving target, 10 is a pulse generation circuit that generates a pulse for synchronizing the transmission waves generated by the transmitter, and 1) is the transmitter 9. A transmission frequency switching circuit that switches the frequency of the transmitted waves to be generated; 1 is an antenna for transmitting and receiving the transmitted waves and reflected waves; 2 is a transmitting/receiving switch for switching between transmitting the transmitting waves and receiving reflected waves; 4 is a reflection Receiver that receives waves, 5 is range gate when passing reflected waves, 6 is N point F
This is a Doppler filter consisting of FT.

Here, the receiver 4, range gate 5, and Doppler filter 6 constitute a receiving system of the pulsed Doppler radar device.

Further, 12 is a speed correction circuit for correcting the speed of the moving target detected by the Doppler filter 6 based on information from the transmission frequency switching circuit 1).

Next, the operation will be explained. The transmitting frequency switching circuit 1) causes the transmitter 9 to generate a transmitting wave having either the frequency F+ or the frequency F2. It radiates through the antenna l.

If the transmitted wave is reflected by a moving target with velocity V,
The Doppler frequency of the reflected wave is C (where C is the speed of light) when the transmission frequency is Fl and the frequency fd2 is F2, and it is received again from the antenna 1 through the transmitter/receiver switch 2. , a receiver 4. The speed is detected by a Doppler filter 6 using N-point FFT after passing through a range gate 5.

At that time, the filter number of the Doppler filter 6 to which the received signal from the moving target is output is set to m when the frequency is fd+,
If the time of the frequency fd2 is n, then the pulse repetition frequency is fr, and the filter bandwidth of the Doppler filter 6 is b, then b c fr .

Here, since the frequencies of the transmitted waves are different, F 2'
>F 1, then Q>m, and even if the velocity V of the moving target is the same, the filter numbers will be different. This situation is shown in FIG.

In addition, the accuracy of radar speed measurement is as follows: when the transmission frequency is Fl, it is v/m, and when it is F2, it is v/n (n>m), and in this case, frequency @F2 is better than frequency F1. It will be different.

Therefore, it is necessary to correct the output of the Doppler filter 6 based on the difference in the frequency of the transmitted waves. In the case of FIG. 3, the frequency information of the transmitted wave is input from the transmission frequency switching circuit 1) to the speed correction circuit 12 for correction, but if the frequency F2 is used as a reference, the ratio F 2 / By correcting the filter number m using F1 as a coefficient, the filter output becomes m=n.

[Problem that the invention seeks to solve]

In this way, in conventional devices, velocity detection when the transmission frequency changes is difficult because the received signal from the moving target is output from different Doppler filter numbers.
There was a problem in that speed correction had to be performed, and the speed measurement accuracy also varied depending on the transmission frequency.

This invention was made to solve the above problems, and even if the transmission frequency changes, the received signal from the moving target is output from the same filter number of the Doppler filter, thereby correcting the speed. It is an object of the present invention to provide a pulsed Doppler radar device that eliminates the need for such a device and can also maintain the same velocity measurement accuracy.

[Means for solving problems]

Therefore, the pulsed Doppler radar device according to the present invention has
Control to always output a reflected wave from the same filter number even if the frequency of the transmitted wave changes by controlling the frequency of the transmitted wave and the repetition frequency of the pulse generated from the pulse generation circuit in accordance with the frequency of the transmitted wave. This feature is characterized by the provision of means.

[Effect]

The control means according to the present invention controls the frequency of the transmitted wave and the repetition frequency of the pulse generated from the pulse generation circuit corresponding to the frequency of the transmitted wave, so that even if the frequency of the transmitted wave changes, the same filter is always used. Make sure that reflected waves are output from the number.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

Note that the same components as those in the prior art are given the same numbers and their explanations will be omitted.

Further, the discussion will proceed assuming that the frequency of the transmission wave generated by the transmitter can be switched in two ways, and that the repetition frequency of the pulse generated in the pulse generation circuit can also be changed in two ways accordingly.

FIG. 1 is a block diagram showing an embodiment of the present invention, and in the figure, reference numeral 8 denotes a control means for controlling the frequency of the transmitted wave and the repetition frequency of the pulse.

Next, the operation will be explained.

The control means 8 sets the frequency of the transmission wave generated by the transmitter 9 to Fl.
Alternatively, the frequency is controlled to be either F2.

In addition, when the frequency of the transmitted wave is Fl, the repetition frequency of the pulse generated by the pulse generating circuit 10 is determined as fr.
, when the frequency of the transmitted wave is F2, the frequency is controlled to be fr2.

Here, the frequency F (+F 2 , f r 1.
fr2 are related to each other so that the Dobra filters that output the reflected waves from the moving target have the same number.

Next, we will explain how to find the formula showing this relationship.

When the Doppler filter 6 detects the speed of the moving target based on the reflected wave from the moving target, the Doppler filter output at the transmission frequencies Fl and F2 is as follows, since the filter bandwidth is , and from the above equation, If the filter number n is the same, f
d+ f d2 F2 Fl.

Since the transmission frequency and the repetition frequency are related as described above, even if the transmission frequencies are different as shown in FIG. 2, the same Doppler filter will output the reception signal.

Further, regarding the measurement accuracy of the speed of the radar, since the filter numbers are the same, both Fl and F2 are v/n, which is the same.

〔Effect of the invention〕

As explained above, according to the present invention, the frequency of the transmitted wave and the repetition frequency of the pulses generated from the pulse generation circuit corresponding to the frequency of the transmitted wave are controlled so that even if the frequency of the transmitted wave changes, Since a control means for outputting reflected waves from the same filter number is provided, there is an effect that speed correction is not necessary when detecting the speed of a moving target and the speed measurement accuracy is also the same.

[Brief Description of the Drawings] Fig. 1 is a configuration diagram of a pulsed Doppler radar device according to the present invention, Fig. 2 is an explanatory diagram of detection of a moving target in the pulsed Doppler radar device of the present invention, and Fig. 3 is a configuration diagram of a conventional pulsed Doppler radar device. 4 are explanatory diagrams of detection of a moving target in a conventional pulsed Doppler radar device. 1... Antenna, 2... Transmission/reception switch, 4
...Receiver, 6...Doppler filter,
8... Control means, 9... Transmitter, 10
...Pulse generation circuit. Note that the same numbers in the figures indicate the same or corresponding components. Agent Masuo Oone (and 2 others) 1st Figure 8: System 4! P4 Maki No. 2 Diagram 3 Figure 1 Antenna 2, transmission/reception tnv Kotobuki 1i Procedure amendment group (spontaneous 2, name of invention Pulsed Doppler radar device: 3. Person making the amendment Representative Moriya Shiki 4, agent address Tokyo) 2-2-3-5 Marunouchi, Chiyoda-ku
, a detailed description of the invention subject to amendment, and a drawing column. 6. Contents of amendment (1) In the second line of page 3 of the specification, the phrase "range gate when passing reflected waves" is corrected to "range gate that samples reflected waves according to their distance." . (2) In the 6th line of page 8 of the same book, the phrase ``nominal transmission frequency'' is corrected to ``each transmission frequency.'' (3) In the second line of page 10 of the same book, "reflected waves are output" is corrected to "reflected waves are output". (4) The drawings and Figure 1 shall be amended as shown in the attached sheet. that's all

Claims (2)

[Claims] (1) A Doppler filter that transmits a transmission wave synchronized with the pulses generated from the pulse generation circuit toward a moving target, prompts the reflected wave to be reflected from the moving target, and inputs it to the Doppler filter, which outputs the reflected wave. In a pulse Doppler radar device that detects the speed of a moving target from a filter number,
The frequency of the transmitted wave and the repetition frequency of the pulses generated from the pulse generation circuit corresponding to the frequency of the transmitted wave are controlled to always output reflected waves from the same filter number even if the frequency of the transmitted wave changes. A pulsed Doppler radar device characterized in that it is provided with a control means for controlling the pulsed Doppler radar device. (2) When the frequency of the signal wave is F and the repetition frequency of the pulse is fr, the control means controls the frequency of the signal wave and the repetition frequency of the pulse so that F/fr=a (a is a constant). Claim 1 characterized in that
The pulsed Doppler radar device described in Section 1.