JP2024000718A - Radar apparatus and radar signal receiving device - Google Patents

Abstract

[Problem] To enable constant observation of the entire space in a designated coverage area at a high data rate. [Solution] According to the radar device according to the embodiment, it has an antenna with a total number of elements N, the total observation range determined by the element pattern of the antenna is FOVe, and among the antennas with the total number of elements N, Ns( The range that can be observed by one antenna, including a subarray consisting of antennas with Ns ≥ 1) elements, is defined as a partial observation space FOV1 (FOV1 = FOVe/Ns), and the aperture of the antenna is divided into Ns, and each divided aperture (number of elements : M=N/Ns rounded off), different partial observation spaces FOV1 are assigned to each of the partial observation spaces FOV1, a transmission fan beam covering the space FOV1 is formed in each of the partial observation spaces FOV1, and a sub-array DBF is placed in each of the divided apertures. (Digital Beam Forming) to form L (L = M/Ns rounded off) receiving multi-beams and constantly observe the entire observation space FOVe. [Selection diagram] Figure 1

Description

This embodiment relates to a radar device and a radar signal receiving device.

A radar device or a radar signal receiving device scans a beam along a predetermined time series in order to cover an observation space in a designated coverage area. For this reason, when the designated coverage area is wide, it is not possible to constantly observe the entire space, and the data rate becomes low, which poses a problem in that it cannot support high data rate searches for detecting small targets.

DBF (Digital Beam Forming): Yoshida, 'Revised Radar Technology', Institute of Electronics, Information and Communication Engineers, pp.289-291 (1996) FFT (Fast Fourier Transform): Hino, ‘Spectrum Analysis’, Asakura Shoten, pp.193-198 (1977) CFAR (Constant False Alarm Rate): Yoshida, 'Revised Radar Technology', Institute of Electronics, Information and Communication Engineers, pp.87-89 (1996)

An object of this embodiment is to provide a radar device and a radar signal receiving device that can constantly observe the entire space of a designated coverage area at a high data rate.

In order to solve the above problem, the radar device according to the embodiment has an antenna with a total number of elements N, the total observation range determined by the element pattern of the antenna is FOVe, and among the antennas with the total number N of elements, , the range that can be observed by one antenna including a subarray consisting of antennas with Ns (Ns≧1) elements is defined as a partial observation space FOV1 (FOV1=FOVe/Ns), and the aperture of the antenna is divided into Ns, and each divided aperture is (Number of elements: M = N/Ns rounded off) are assigned different partial observation spaces FOV1, a transmission fan beam covering the space FOV1 is formed in each of the partial observation spaces FOV1, and a transmission fan beam is formed in each of the divided apertures. The entire observation space FOVe is constantly observed by forming L (L = M/Ns rounded off) receiving multi-beams using sub-array DBF (Digital Beam Forming).

According to the above configuration, the observation range is divided by the FOV determined by the number of subarray elements, allocated to divided antennas whose apertures are divided by the same number of divisions, and observed with multiple beams by the subarray DBF, thereby enabling constant observation. I can do it.

In addition, the radar signal receiving device according to the embodiment has a total observation range determined by the antenna element pattern as FOVe, and out of the total number of antennas with N elements, one antenna including a sub-array consisting of antennas with Ns (Ns≧1) elements. The range that can be observed with the antenna is defined as a partial observation space FOV1 (FOV1 = FOVe/Ns), and the aperture of the antenna is divided into Ns, and each divided aperture (number of elements: M = N/Ns rounded off) has a different partial observation space. FOV1 is assigned, and L (rounded L=M/Ns) receiving multibeams are formed by sub-array DBF (Digital Beam Forming) in each aperture of the divided apertures to constantly observe the entire observation space FOVe.

According to the above configuration, the observation range is divided by the FOV determined by the number of subarray elements, allocated to divided antennas whose apertures are divided by the same number of divisions, and observed with multiple beams by the subarray DBF, thereby enabling constant observation. I can do it.

Furthermore, in the above radar device and radar signal receiving device, when the arbitrary partial observation range FOV is P (an integer of 1≦P<Ns) times FOV1 (FOVe/Ns) determined by Ns, the antenna aperture is set to Ns/ Divide into P and form a beam.

According to the above configuration, according to the observation range, the radar device or the receiver The equipment allows constant observation.

FIG. 1 is a block diagram showing the configuration of a transmission system and a reception system of a radar device according to a first embodiment. FIG. 2 is a conceptual diagram showing a configuration in which a transmitting/receiving module is used in the antenna device used in the radar device shown in FIG. FIG. 3 is a block diagram showing the configuration of the transmitting/receiving module shown in FIG. 2. FIG. 4 is a conceptual diagram for explaining a beam forming method within an observation range in the first embodiment. FIG. 5 is a conceptual diagram showing how the antenna aperture is divided into Ns parts and each divided aperture is assigned to a space division unit in the first embodiment. FIG. 6 is a diagram illustrating how, in the first embodiment, continuous PRI pulses are transmitted and received at each beam position for each FOV1, and data is output through sliding processing between CPIs, using Doppler axis responses. FIG. 7 is a block diagram showing the configuration of a radar signal receiving device according to the second embodiment. FIG. 8 is a conceptual diagram showing the configuration of an antenna device used in the radar signal receiving device shown in FIG. 7. FIG. 9 is a block diagram showing the configuration of a receiving module for each antenna element of the antenna device shown in FIG. 8. FIG. 10 is a conceptual diagram showing how the antenna aperture is divided into Ns and each divided aperture is allocated to a space division unit in the second embodiment. FIG. 11 is a block diagram showing the configuration of a transmission system and a reception system of a radar device according to a third embodiment. FIG. 12 is a conceptual diagram showing how the antenna aperture is divided into two and each divided aperture is assigned to a space division unit in the third embodiment.

Embodiments will be described below with reference to the drawings.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram showing the configuration of a radar device according to a first embodiment, in which (a) is a block diagram showing the configuration of a transmitting system, and (b) is a block diagram showing the configuration of a receiving system. 2 is a conceptual diagram showing a configuration in which the antenna device used in the radar device shown in FIG. 1 is used for both transmission and reception, and FIG. 3 is a block diagram showing the configuration of a transmission and reception module for each antenna element of the antenna device shown in FIG. 2. .
In the transmission system of the radar device shown in FIG. After converting the radar signal into a radar signal, the pulse modulator 14 performs pulse modulation to generate a radar signal, and a transmission power supply circuit 15 supplies power to M systems of transmission subarrays (1 to M) 16 constituting a transmission antenna for transmission.

On the other hand, in the receiving system shown in FIG. 1(b), M systems of receiving subarrays (1 to M) 21 constituting a receiving antenna receive radar reflected signals, and a frequency converter 22 converts the received signal to baseband. Then, the AD converter 23 converts it into a digital signal. Next, a beam combiner 24 beam-combines radar signals from digital beam forming devices (hereinafter referred to as DBF) between subarrays of each system, and a signal processor 25 performs signal processing for target detection. and output it as received data.

In the system configuration shown in Figure 1, the transmitting subarray of the transmitting antenna and the receiving subarray of the receiving antenna are described separately, but it is also possible to share the transmitting subarray and the receiving subarray if they are at the same location. be.

Figure 2 shows the sub-array system for both transmission and reception, where 31-3i-3n-3Ns are antenna elements, 41-4i-4n-4Ns are transmitting/receiving modules, 5T is a transmitting power supply circuit, and 5R is a receiving power supply circuit. be. FIG. 3 shows the internal system of the transmitting/receiving module 41 that transmits and receives the antenna element 31 in the transmitting/receiving subarray shown in FIG. The amplifier 415 is a phase shifter. Note that the configurations of the other transmitting/receiving modules 42 to 4Ns are the same as that of the transmitting/receiving module 41, so the explanation thereof will be omitted.

In FIG. 3, the transmitting/receiving module 41 which receives the transmitting signal output from the transmitting power supply circuit 5T of FIG. The signal is amplified, guided to the antenna element 31 by the circulator 413, and sent into space. Further, the transmitting/receiving module 41 inputs a signal from the target captured by the antenna element 31, directs it to the receiving system by a circulator 413, amplifies it to an appropriate level by a low noise amplifier 414, and amplifies it to a beam forming direction by a phase shifter 415. A corresponding phase is given to the received signal and outputted to the receiving power supply circuit 5R of FIG. 2.

In this way, the transmitting/receiving module 41 shares the antenna element 31 for transmitting the transmitting signal and inputting the received signal, and performs phase control using the phase shifter 411 of the transmitting system and the phase shifter 414 of the receiving system. It is possible to scan the beam and receive beam.

Next, with reference to FIG. 4, a beam forming method within the observation range will be considered. Generally, to observe an observation range, a pencil beam formed by an antenna with N (N>1) transmitting and receiving elements is scanned over the observation range in time series. At this time, if the observation range is wide and the integration is performed over a long period of time, the data rate will decrease. As a countermeasure for this, as shown in FIG. 4, transmission is performed using a fan beam that covers the entire observation range, and reception is converted into a digital signal for each receiving element to form a multi-beam for observing the entire observation range at once. This makes it possible to constantly observe the observation range and enables high data rate observations.

However, the above configuration is a full DBF that converts each receiving element into a digital signal, which increases the hardware scale. As a countermeasure against this, in this embodiment, a subarray type DBF is used in which subarray synthesis is performed in units of Ns elements and then digital conversion is performed. If Ns=1, it becomes a full DBF.

Since the subarray DBF includes phase shifters for transmission and reception within the subarray, beam scanning is possible in subarray units. However, with the beam width FOV1 (FOV1=FOV/Ns) determined by the number of elements in the subarray, it is often not possible to cover the entire observation range FOV in one go. Therefore, in this embodiment, the entire observation range FOV is divided by the subarray beam width FOV1.

FIG. 5 shows how the antenna aperture is divided into Ns (Ns=FOV/FOV1) and each divided aperture is assigned to a space division unit. In each divided aperture, the number of antenna elements is M (M=N/Ns), and L multi-beams can be formed according to the number of subarrays L (L=M/Ns). Therefore, the subarray can cover the divided observation space FOV1 with a transmitting fan beam and a receiving multibeam with a beam width 1/L smaller than that of the transmitting beam. This makes it possible to constantly observe the entire observation space FOV.

Figure 6 shows that continuous PRI (Pulse Repetition Interval) pulses are transmitted and received to each beam position P1, P2, P3, ..., PNs in each divided observation space FOV1 (a), and sliding processing is performed between CPI (Coherent Pulse Interval). FIG. 6 is a diagram showing how (b) the data is integrated over a long period of time, and (c) the data is output as a response on the Doppler axis.

As shown in FIG. 6, if constant observation is possible, continuous PRI pulses can be transmitted and received at each beam position in each divided observation space FOV1, and multiple PRI pulses can be collectively processed using FFT processing (see Non-Patent Document 2), etc. Output in units of CPI for coherent processing. In this way, data can be output at a high CPI rate by performing sliding processing that is further coherently processed between CPIs. This situation is shown in FIG. 6(c) as a response on the Doppler axis. If the response of this Doppler axis is detected and processed using CFAR (Constant False Alarm Rate) (see Non-Patent Document 3), target detection information can be output.

As described above, the radar device according to the present embodiment can constantly observe the entire space of the designated coverage area and output target detection information at a high data rate.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 7 to 10.
Although the first embodiment describes the case of a radar device that transmits and receives radar signals, the same method can be applied to the case of only receiving radar signals.

FIG. 7 is a block diagram showing a system of a radar signal receiving device according to the second embodiment. Since the receiving device of this embodiment is basically the same as the receiving system of the radar device shown in FIG. 1, the same parts are denoted by the same reference numerals.

In FIG. 7, receiving subarrays 211 to 21M receive radar reflected signals from the observation range, and frequency converter 22 converts the received signals to baseband, and AD converter 13 converts the received signals to digital signals. A beam combiner 14 performs beam combination using sub-array DBF processing, a signal processor 15 performs signal processing for target detection, and outputs the signal as received data.

FIG. 8 shows the system of the reception sub-array, where 61 to 6i to 6n to 6Ns are antenna elements, 71 to 7i to 7n to 7Ns are reception modules, and 8R is a reception power supply circuit.

FIG. 9 shows the internal system of the receiving module 71 that receives the antenna element 61 in the receiving sub-array shown in FIG. 8, where 711 is a low noise amplifier and 712 is a phase shifter. Note that the configurations of the other receiving modules 72 to 7Ns are all the same as that of the receiving module 71, so a description thereof will be omitted.

That is, the signals from the target captured by the antenna elements 61-6i-6n-6Ns are input to the receiving modules 71-7i-7n-7Ns. The receiving module 71 (the same goes for other modules) uses a low-noise amplifier 711 to amplify the received signal to an appropriate level, uses a phase shifter 415 to give the received signal a phase corresponding to the beam forming direction, and sends the received signal to the receiving power supply circuit 8R in FIG. Output. Here, the receiving module 71 is capable of scanning the receiving beam using the subarray by controlling the phase of the phase shifter 712.

Next, with reference to FIG. 10, a beam forming method within the observation range will be considered. Generally, to observe an observation range, a received pencil beam is scanned in time series within the observation range. At this time, if the observation range is wide and the integration is performed over a long period of time, the data rate will decrease.

As a countermeasure against this, a sub-array DBF with a small hardware scale is considered as in the first embodiment. It is assumed that a receiving phase shifter is provided within the subarray, and beam scanning can be performed in subarray units. However, since the beam width FOV1 is determined by the aperture of the subarray, it is often not possible to cover the observation range FOV in one go.

Therefore, in this embodiment, it is considered that the observation range FOV is divided by the subray beam width FOV1. For this purpose, as shown in FIG. 10, the antenna aperture is divided into Ns (Ns=FOV/FOV1), and each divided aperture is assigned to a space division unit. In each divided aperture, the number of antenna elements is M (M=N/Ns), and L multi-beams can be formed according to the number of subarrays (L=M/Ns). Therefore, in reception, the divided space FOV1 can be covered with a receiving multi-beam having a beam width 1/L smaller than that of the space division unit. This makes it possible to constantly observe the entire spatial FOV.

(Third embodiment)
In the first embodiment and the second embodiment, the observation range FOV1 is determined by the number of elements in the subarray, and a reception multi-beam is formed within that range to cover the entire observation range with divided apertures. In this case, if the division aperture is small, the beam width of the received multi-beam is wide and the antenna gain is reduced, so the long-time integration time becomes long in order to ensure the system gain. In this embodiment, this countermeasure will be explained using FIGS. 11 and 12.

FIG. 11 is a block diagram showing the configuration of a transmission system and a reception system of a radar device according to a third embodiment. FIG. 12 is a conceptual diagram showing how the antenna aperture is divided into two and each divided aperture is assigned to a space division unit in the third embodiment. The transmission system and reception system of the radar device according to this embodiment are basically the same as the reception system of the radar device shown in FIG. 1, so the same parts are denoted by the same reference numerals.

The radar device according to this embodiment sends the target detection result obtained by the signal processor 25 to the sub-array controller 26, as shown in FIG. The sub-array controller 26 identifies the range in which the target can exist from the input target detection results, and performs division control on the beam combiner 24 to increase the antenna aperture division unit and narrow the reception beam width.

Generally, in the initial search, the observation range FOV is wide, but as the search progresses, it is often possible to limit the range in which the target can exist based on the processing results of the signal processor 15. The number of elements in the subarray is determined by hardware, and the partial observation range FOV1 is fixed, so if the total observation range FOV becomes smaller, the antenna aperture division unit determined by M = FOV/FOV1 can be increased by subarray control. As a result, as shown in FIG. 12, the reception beam width formed by each divided aperture becomes narrower, and the reception gain can be increased. This has the advantage of shortening the integration time and improving angle measurement accuracy. The antenna aperture division unit may be Ns/P division when the observation range is P (an integer of 1≦P<Ns) times FOV1 (FOVe/Ns) determined by Ns.

Although the beam forming in the above embodiments has been described for one-dimensional subarrays for simplicity, the same method can be extended to two-dimensional subarrays as well.

It should be noted that the present invention is not limited to the above-described embodiments as they are, but can be embodied by modifying the constituent elements within the scope of the invention at the implementation stage. Moreover, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate.

11...Signal generator, 12...Modulator, 13...Frequency converter, 14...Pulse modulator, 15...Transmission power supply circuit, 16...Transmission subarray (1 to M), 211 to 21M...Reception subarray (1 to M) , 221-22M...frequency converter, 231-23M...AD converter, 24...beam combiner, 25...signal processor, 26...sub-array controller.

Claims (4)

It has an antenna with a total number of elements N,
The total observation range determined by the element pattern of the antenna is FOVe,
Among the antennas with the total number of elements N, the range that can be observed with one antenna including a subarray consisting of antennas with Ns (Ns≧1) elements is defined as a partial observation space FOV1 (FOV1 = FOVe/Ns),
The aperture of the antenna is divided into Ns, and a different partial observation space FOV1 is assigned to each divided aperture (number of elements: M = N/Ns rounded off),
forming a transmission fan beam covering the space FOV1 in each of the partial observation spaces FOV1;
A radar device that constantly observes the entire observation space FOVe by forming L (L=M/Ns rounded) receiving multi-beams by sub-array DBF (Digital Beam Forming) in each of the divided apertures. Claim 1: When an arbitrary partial observation range FOV is P (an integer of 1≦P<Ns) times FOV1 (FOVe/Ns) determined by Ns, the beam is formed by dividing the aperture of the antenna by Ns/P. The radar device described. The total observation range determined by the antenna element pattern is FOVe,
Among the antennas with a total number of elements N, the range that can be observed with one antenna including a subarray consisting of antennas with Ns (Ns≧1) elements is defined as a partial observation space FOV1 (FOV1=FOVe/Ns),
The aperture of the antenna is divided into Ns, and a different partial observation space FOV1 is assigned to each divided aperture (number of elements: M = N/Ns rounded off),
A radar signal receiving device that constantly observes the entire observation space FOVe by forming L (L=M/Ns rounded) receiving multi-beams by sub-array DBF (Digital Beam Forming) in each of the divided apertures. 3. When an arbitrary partial observation range FOV is P (an integer of 1≦P<Ns) times FOV1 (FOVe/Ns) determined by Ns, the beam is formed by dividing the aperture of the antenna by Ns/P. The radar signal receiving device described.

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