JPS5825987B2 - radar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radar device that can be operated without interference from other palace radar stations operating at substantially the same frequency.

Conventionally, when operating two pulse radars simultaneously, a) Change the frequency.

b) Synchronize to keep the phase of each pulse repetition frequency (hereinafter referred to as PRF) constant.

Therefore, simultaneous operation of each on the same frequency was not possible without interference.

Therefore, there are disadvantages such as a) when changing the frequency, the occupied frequency more than doubles, and in the case of a secondary radar, two or more transformers on the target side are required.

Also, when synchronizing and keeping each PRF at a constant phase, if the radar installation locations are different, even if you simply synchronize only the PRF phase, the transmitted pulse that reaches the target will remain constant as the distance from the radar to the target changes. There was a drawback that the radars were not synchronized in phase and sometimes arrived at the same time, causing interference with each other's radars.

This invention was made in order to eliminate the above-mentioned drawbacks, and it controls the phase of the pulse radio waves emitted from the transmitter in response to the pulse radio waves received from other radar devices operating at approximately the same frequency. The present invention provides a radar device that can be operated without interference from other radar devices operating at substantially the same frequency by being equipped with a phase control circuit.

The operating principle of this invention will now be explained.

In order to independently and simultaneously operate two pulse radar devices operating on the same frequency, it is necessary to ensure that the transmission pulses of the respective pulse radar devices that reach the target do not match.

Now, if we consider the case where two radar devices A and B are operated at the same time, the A radar device should receive the return video signal from the target due to the transmission pulse of the B radar device. At this time, check the return video signal of the B radar device. To do this, temporarily stop the transmission of the A radar device.

) A phase synchronization gate with a constant phase from the reply video signal is installed to gate the range of the A radar device (at the beginning of operation, this range gate uses phase information of the predicted distance from the A radar device to the target, that is, communication of the A radar device). It means the predicted position of the video signal, and the return video signal and distance gate are always connected during operation.

) is always within its phase synchronization gate by adjusting the PRF phase of the A radar device by stopping the PRF generation clock. When reaching the target, the phase difference between the above-mentioned B radar device return video signal and the phase synchronization gate can be maintained.

To be more specific, as the distance between the A radar device and the target changes on the time chart in Figure 2,
If the position of the A reply video goes out of the range of the phase synchronization gate set by the A distance gate at a specific position than the B reply video, the position of the A reply video will be phase synchronized by shifting the transmission timing from the A radar device. Try to get it back inside the gate.

At this time, the A-distance gate is also shifted by the amount that the transmission timing is shifted, so that the A-reply video can be continuously captured by the A-distance gate.

In this way, the A and B reply video signals will not overlap and the relationship between them will not be reversed.

For simplicity, the above explanation was made within the distance range specified by the transmission PRF, that is, within the range where the reply video by one transmission pulse returns before the start of the next transmission pulse, but the reply by the first transmission pulse If the video comes back after the second, third, etc. transmission pulse,
It gets a little complicated.

In other words, if the transmission timing of the A radar device mentioned above is shifted, the A distance gate will be shifted step by step from the moment the transmission timing is shifted to a position that is theoretically calculated according to the distance to the target, and the reply video will always be continuous. so that it can be captured.

As described above, it becomes possible for two pulse radar devices to operate independently and simultaneously at the same frequency.

Embodiments of the present invention will be described below with reference to the drawings.

A. FIG. 1 shows a state in which two radar devices operate simultaneously on the same frequency and asynchronously.

In FIG. 1, the transmitted pulses from the A and B radar devices are received by the A and B radar devices as AB reply videos from the target object.

In this case, if the A and B radar devices are operated asynchronously on the same frequency, if the A and B reply videos overlap, it will be impossible to distinguish between the reply videos of the A and B radar devices based on their own transmitted pulses, and normal operation of the radar devices cannot be expected. It disappears.

Therefore, A as shown in Figure 2. To ensure that the B reply video always has a certain phase difference, adjust the phase of the PRF of the A radar by stopping the PRF generation clock (that is, the PRF is determined by counting a certain number of PRF generation clocks, so the time clock is determined by PRF generation circuit counter (If this is not input, the phase will be delayed by that amount of time.

), it becomes possible to reliably select the 82 reply videos, and the 82 radar devices will not interfere with each other.

However, as an initial condition, it is necessary to keep the A distance gate close to the position of the A reply video.

This is because of the hardware configuration, instead of A reply video.
This is because a distance gate is used.

The reason is that even if A reply video is lost, A
This is because it becomes possible to constantly control the distance gate to the predicted course using a computer or the like.

In Fig. 2, the range from t1 to t2 from the B reply video (
If there is an A reply video (=A distance gate) within the phase gate), it is considered normal, and if the phase gate range is 1 When the clock is stopped, the uRF phase is adjusted.

Next, a block diagram of a phase control circuit that performs phase adjustment is shown in FIG. 3 and will be explained.

In FIG. 3, reference numeral 1 denotes a PRF correlation circuit, which removes noise unrelated to PRF (pulse repetition frequency).

Reference numeral 2 denotes a video erasing gate which eliminates the reply video generated by its own transmission pulse.

3 is a counter circuit that counts the phase difference between two reply videos.

4 is a clock generator for determining gate width, 5 and 8 are time t
Preset data set at 1 to t2, and 6 and 7 are comparison circuits.

Reference numeral 9 denotes a gate pulse generation circuit which generates a gate signal for a set time of -Lr1 or (PRF1 period -'7-U).

10 is preset data in which the time is set to 12-11, and 11 is for detecting that the contents of the preset data 10 and the clock counter circuit 12 are 1'&.

13 is a reference frequency generator that serves as a clock for generating PRF of the A radar; 14 is a reference frequency gate that erases the clock of the reference frequency generator 13 during the period of the gate signal generated by the gate pulse generation circuit 9.

Further, 15 is a PRF counter that counts a PRF generation clock and generates a transmission trigger.

The operation of the above will be explained.

In FIG. 3, A is output from the receiver of the radar device.

Noise is removed from the B two return video signals by the PRF correlation gate 1, and the A reply video is also removed by the A distance gate at the video cancellation gate 2, so that only the B reply video becomes the start pulse for the counter circuit 3.

In the counter circuit 3, the A distance gate serves as a stop pulse, and the content (B-A) of the counter circuit 3 becomes equal to the phase difference between the two.

The phase difference (B-A) is determined by the preset data 5 and 8 whose set times are tl and t2 and the comparator circuits 6 and 7 at the set time t.
The gate pulse generation circuit 9 determines whether it is smaller than 1 or larger than t2, and the gate pulse generation circuit 9 generates 51 units or (1 period - j
T-1) generates a gate signal.

If the phase difference (B-A) is smaller than the set time t1, the PRF generation clock of the A radar device generated by the reference frequency generator 13 is stopped for 12T2″1 by the reference frequency gate 14, and the A radar device The PPRF phase of -T
-1 delay.

If the phase difference (B-A) is larger than the set time t2,
-1 Similarly]5. Since it is impossible to advance time, it is possible to advance only Y, so PRF's (1 period 1 -1
,.

1.1) To equal inversion by delaying t2i
t, it is something that advances.

Preset data 10 and matching circuit 1 whose setting time is
1. The clock counter circuit 12 is accurate -1. This is to obtain a gate signal of (PRFI period - 7), and when the clock counter circuit 12 is 0, the gate signal is 5TART, that is, the reference frequency gate 14 generates a reference frequency. When the preset data 10 is set, after counting up to 7 units or (1 period of PRF -!T-!-), the clock is cut off. It is detected by the matching circuit 11 and passes the gate signal 5TOP (ie, the PRF generation clock of the reference frequency generator 13).

). Reference numeral 4 denotes a clock generator, which supplies a lock to the counter circuit 3, gate pulse generation circuit 9, and clock counter circuit 12 as necessary.

With this configuration, two pulse radar devices can be operated independently at the same frequency without causing mutual interference.

In the detailed description of the present invention, the two radar apparatuses have been described as operating at the same frequency, but it is clear that they can also be used when operating at approximately the same frequency.

As explained above, the present invention provides a radar equipped with a phase control circuit that controls the phase of pulse radio waves emitted from a transmitter in response to pulse radio waves received from other radar devices operating at approximately the same frequency. By configuring the device, it can be operated without interference from other radar devices operating at approximately the same frequency.

The above explanation is based on simultaneous operation of two radar devices A and B, and even in simultaneous operation of three or more radar devices A, B, and C, the position of the phase gate is changed for B, C, etc.
. . . Although there are restrictions on how to narrow the width and how to check the A, B, and C reply videos, simultaneous operation is possible by having phase control like this method.

If the target disappears, there is no return video, so the phase of the transmitted pulse is controlled based on the position estimated by a computer, or the radar function is lost, so the operation has to be stopped.

In addition, the squiggle signals of different PRFs are removed as noise in the PRF correlation circuit.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for explaining the operation of two radar devices A and B, Fig. 2 is a waveform diagram showing the phase relationship of the reply video according to the embodiment of this invention, and Fig. 3 is an embodiment of the invention. FIG. 2 is a block diagram showing a phase control circuit according to the present invention. In the figure, 1 is a PRF (Pulse Repetition Frequency) correlation gate, 2 is a video cancellation gate, and 3 is a gate for counting the phase difference between the reflected wave from the target by the own station and the incoming radio wave from other stations. Counter circuit, 4 is a clock generator, 5 and 8 are preset data that determine the set time, 6 and 7 are comparison circuits, 9 is a gate pulse generation circuit that generates gate pulses,
Reference numeral 13 indicates a reference frequency generation circuit which serves as a PRF generation clock, and reference numeral 14 indicates a reference frequency gate circuit which controls the phase of the emitted pulse radio wave from the transmitter. Further, 15 is a PRF counter that counts the PRF generation clock 13 and generates a transmission trigger. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A transmitter A that emits pulsed radio waves R of a predetermined frequency and a receiver a that receives reflected waves from a target object, and that transmits pulsed radio waves B transmitted from another transmitter B. In what can be detected, based on the time when the pulse radio wave B' from another transmitter B received by the receiver a reaches the receiver a,
It is characterized by comprising a phase control circuit that controls the phase of the pulse radio wave X emitted from the transmitter A so that the pulse radio wave X can always be received within a certain phase range from the arrival time of the pulse radio wave. 2. A PRF correlation circuit that passes only a pulse train with a specific repetition period through a phase control circuit, a reflected wave a from a target object, and another pulse radio wave having almost the same repetition period as this reflected wave a. a counter circuit that calculates the time difference when the time difference reaches the receiver a, a comparison circuit that compares the time difference from the counter circuit with a set time, and a gate that generates a gate pulse in accordance with the output of the comparison circuit. The radar device according to claim 1, comprising a pulse generation circuit and a gate circuit that controls the phase of the emitted pulse radio wave from the transmitter in accordance with the gate pulse of the gate pulse generation circuit. 3. The time difference counted by the counter circuit in the phase control circuit is divided into a pulse wave corresponding to the expected time to the target (this is called a distance gate) and a repetition period that is approximately equal to the pulse wave received by receiver a. 3. The radar device according to claim 1, wherein the radar device performs counting using other pulsed radio waves.