JPS6040982A - Radar equipment - Google Patents

Abstract

PURPOSE:To prevent the interruption of distance tracking, by changing over PRF directly before the transmission period of radar is timewise coincided with a receiving pulse signal. CONSTITUTION:The first PRF transmission pulse from a transmitter 1 is converted to a demodulated signal through a transmission and reception change- over device 2, an antenna 3, an object, the change-over device 2, a gate circuit 4 and a receiver 5 and the demodulated signal is inputted to a distance tracking circuit 6. The circuit 6 sends out the distance R of the object calculated from the apparent range delay time T of the object and the real range delay time Td thereof to a PRF change-over device 7. When the change-over device 7 detects a state directly before a receiving pulse signal is timewise coincided with the transmission period of radar, said device 7 imparts an order for performing transmission by second PRF to the transmitter 1. Second PRF is prescribed by formula I to the approaching object and by formula II to the receding object. In the formulae I , II, FP is a second PRF value and N is a positive integer.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a radar device that tracks a target at a distance by transmitting a transmission pulse signal with a transmission pulse repetition period shorter than the range delay time of the target. It is related to.

(Prior Art) A conventional radar device of this type will be briefly described with reference to FIGS. 1 and 2.

Fig. 1 shows the configuration of a conventional radar device. Fig. 2 shows a received Norse signal in a conventional radar device. Transmission/reception switch, (31 is antenna, (4) is gate circuit, (5) is receiver, (6) is distance tracking circuit, (a) is transmitting/receiving signal, (b) is receiving (r+ pulse signal, ei is the ON/OFF timing of the gate circuit (4).

1 and 2, the constant P RF (Pu1se Repetition F
The transmission pulse signal (requi-ency) is radiated toward the target from the antenna (3) via the transmitting/receiving transmitter (2). On the other hand, the received pulse signal received by the antenna (3) is input to the receiver (5) via the transmission/reception switch (21) and the gate circuit (4) that removes the leakage signal of the transmitted pulse signal. After being amplified and detected, it is input to the distance tracking circuit (6).The k'l cap 11 tracking circuit (6) detects the range delay time T of the target range shown in Fig. 2 (a). do.

Here, the target true range delay time 1'+l It is given by the following equation.

Ta=! +T ・・・・・・・・・(1) However, 9M: Positive integer f: PRF value Therefore, if the positive integer M is known, the target can be determined by continuously detecting the apparent range delay time T of the target. It is possible to perform distance tracking.

By the way, in conventional radar equipment, when the distance to the target changes and the received pulse signal temporally matches the transmission period as shown in FIG. 2(b), the received pulse signal is sent to the gate circuit (4).
This has the disadvantage that distance tracking of the target is interrupted because the transmitted pulse signal is removed along with the leakage signal.

[Summary of the invention]

This invention distinguishes whether the target being tracked is an approaching target or a distant target based on the rate of change in distance of the target,
It is an object of the present invention to provide a radar device which can improve the above-mentioned drawbacks of the conventional art by switching the P-F immediately before the radar transmission period and the received pulse signal coincide in time.

[Embodiments of the invention]

This invention will be explained in detail below using FIGS. 3, υ, and 4.

Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a diagram showing the principle of the PRF switching method in this invention. (7) is the PRF switch, and (2) is the 10th
Transmission/reception timing in PRF, (e) is the received pulse signal from the approaching target just before PRF switching, (f)
is the transmission/reception timing of the second P'RF for the approaching target, (g) is the received pulse signal from the distant target immediately before PRF switching, and (g) is the 20th transmission/reception timing for the distant target.
This is the transmission/reception timing in PRF.

In FIGS. 8 and 4, the first P-F transmission pulse signal generated by the transmitter +11 is radiated from the antenna (31) toward the target via the transmitter/receiver switch (2). On the other hand, the received pulse signal received by the antenna (3) is sent to the receiver (5) via the transmission/reception switch (2) and the gate circuit (4) for removing the leakage signal of the transmitted pulse signal (7). It is input to the distance tracking circuit (6) after being detected with a width of 11.1.Distance Ni1 (>IM tail circuit (6)
Then, the target distance R calculated from the target's apparent range delay time T and the target's true range delay time '1'd is sent to the P-F switch (7).

Here, the relationship between the target true range delay time Td and the target distance hole is given by the following equation.

R = 151 ...... (2) However, C: The speed of light PRF switch (7) detects the change in target distance from the target distance R that is continuously input at minute time intervals. It is determined whether the target being tracked is an approaching target or a distant target. moreover.

The PRF switch (7) uses the criteria expressed by equation (3) for the above-mentioned approaching target and equation (4) for the above-mentioned distant target to change the radar transmission period and the received pulse signal. m
) is monitoring the time point that coincides with T = L...
...(3) At T-7,- =-=-(4): Transmission pulse width fp: Above-mentioned first PRF value Now, the PRF switch (7) changes the radar transmission period and reception. When it is detected that the pulse signals are about to match in time, the transmitter (1) is instructed to transmit at the 20th PRF as shown in FIG.

When this second PRF' is expressed as an equation, it becomes equation (5) for the approaching target, and equation (6) for the -F distance target.

pp=2几 ・・・・・・・・・(6) τ−[ However, Ii'p: the above second P 11. l-value N
: Positive integer and the above second P 几Ffr new first P ItF
The above process is repeated as follows.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to avoid interruption of short-range tracking due to the radar transmission period and the received pulse signal (I+, 5 being coincident).

[Brief explanation of drawings]

Figure 1 shows the configuration of a conventional radar installation FV\. Fig. 2 is a diagram showing the receiving and °1 pulse signals in a conventional radar device, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is the principle of the P-F switching method in the present invention. This is a diagram showing [So1, (11 is a transmitter, (
21 is a transmitting/receiving switch, (31 is an antenna, (41 is a gate circuit, (5) is a receiver, (6) is a distance j tracking circuit, (7
) is a PRF switch. In the figures, the same or corresponding parts are designated by the same reference numerals. Agent Inu Wakamasuo Figure 1! Figure 4

Claims (1)

[Claims] In a radar device configured to perform distance tracking of a target by transmitting a transmission pulse signal at a transmission pulse repetition period shorter than the range delay time of the target, P'
E, F (Pu1se l1cpetitionFr
equenc)') and a means for switching the target range 1.
Fp
is the PRF value, R is the target distance, 0 is the speed of light, 'C/ is the transmission pulse width, and N is a positive integer, then just before the transmission period of the radar and the reception pulse signal coincide in time, the tracking The above PRF is configured to switch so as to satisfy the following formula when the target is an approaching target, and to satisfy the following formula when the target being tracked is a +i;It distant target. A radar device featuring: