Distributed frequency source device based on radio microwave synchronization and implementation method thereof

Abstract

The invention provides a distributed frequency source device based on radio microwave synchronization and an implementation method thereof. On one hand, the invention provides a distributed frequency source device based on radio microwave synchronization, on the other hand, the invention further provides a time and phase synchronization method, a dual-tone waveform is designed, high-precision distance measurement between stations can be achieved while remote transmission of reference frequency signals is completed, and the measurement accuracy is improved. And a technical condition is provided for the multi-base radar to obtain high-level coherent gain.

Description

Technical Field

[0001] The present invention belongs to the field of radio technology, and in particular relates to a distributed frequency source device based on radio microwave synchronization and an implementation method thereof. Background Art

[0002] Radar is widely used as a high-precision target detection device. With the development of technology, the requirements for radar target detection distance and resolution are getting higher and higher. Traditional single-base radar improves target detection distance and resolution by improving system efficiency and increasing antenna aperture, but this will significantly increase costs. Distributed multi-base radar is a new radar system that uses a distributed multi-site collaborative detection method to effectively increase the system antenna aperture, thereby increasing radar detection distance and resolution. Compared with single-base radars of similar size and power consumption, its detection distance, accuracy and anti-interference ability will be significantly improved, which is an important research direction of radar.

[0003] The beamforming of distributed multi-base radar requires phase synchronization and time synchronization of radar frequency sources between different sites to ensure that the detection signal is a coherent signal. At the same time, it is also necessary to measure the distance between sites in real time so that the detection signal fully overlaps on the target. The methods commonly used for phase synchronization and time synchronization between distributed sites include synchronization using navigation satellite systems, remote optoelectronic transmission synchronization, and radio microwave synchronization. Synchronization using navigation satellite systems requires external reference signals, while the remote optoelectronic transmission synchronization method does not require external reference signals, but requires that the terrain between sites is simple and the site positions are fixed. The radio microwave synchronization method uses space as the medium for microwave transmission. The positions between sites can be moved in real time, and the application scenarios are flexible. It has great application prospects in mobile radar collaborative detection, such as drone formation collaborative detection and satellite formation collaborative detection.

[0004] In mobile multi-base radars, in order to obtain a high level of coherent gain, the distance measurement between stations must be achieved before the coherence time when the station moves out of the channel. At the same time, the accuracy of the distance between stations needs to be a fraction of the wavelength of the transmitted waveform. According to the CRLB theory, the measurement accuracy is proportional to the spectral dispersion of the echo signal. Among different waveforms, the spectral dispersion of the dual-tone signal is the largest, so the use of the dual-tone signal can obtain better distance measurement accuracy. Summary of the invention

[0005] To this end, the present invention proposes a distributed frequency source device based on radio microwave synchronization and an implementation method thereof. On the one hand, the present invention provides a distributed frequency source device based on radio microwave synchronization, and on the other hand, the present invention also provides a time and phase synchronization method, designs a dual-tone waveform, and can achieve high-precision distance measurement between sites while completing the remote transmission of the reference frequency signal, providing technical conditions for multi-base radar to obtain a high level of coherent gain.

[0006] A distributed frequency source device based on radio microwave synchronization of the present invention comprises a crystal oscillator, a frequency synthesis module, a mixing filter 1, an antenna 1, a corner reflector, an antenna 2, a mixing filter 2, a mixing filter 3, an antenna 3, an antenna 4, and a ranging module.

[0007] The output of the crystal oscillator is connected to the input of the frequency synthesis module. The frequency synthesis module has three outputs, one of which is connected to the input of the mixer filter 1, one of which is connected to the input of the mixer filter 3, and one of which is used as the local frequency source of the distributed frequency source device for output to the external system. The output of the mixer filter 1 is connected to the antenna 1. The signal radiated by the antenna 1 is reflected back by the corner reflector and received by the antenna 2. The output of the antenna 2 is connected to the input of the mixer filter 1, the output of the mixer filter 1 is connected to the input of the mixer filter 2, and the output of the mixer filter 2 is connected to the output of the antenna 4. The signal radiated by the antenna 4 is received by the antenna 3 at a distant site. The output of the antenna 3 is used as the distant site frequency source of the distributed frequency source device and output to the external system. The output of the mixer filter 1 and the output of the antenna 2 are also connected to the input of the ranging module. The specific functions of each device are as follows:

[0008] Crystal oscillator: Crystal oscillator is used to generate reference clock signal;

[0009] Frequency synthesis module: It has three outputs, one for amplifying the input signal, one for multiplying the input signal by 6, and one for multiplying the input signal by 4.

[0010] Mixing filter 1: mixes and filters the input signal and then outputs it;

[0011] Antenna 1: converts electromagnetic wave signals into radio frequency electrical signals;

[0012] Corner reflector: reflects the received electromagnetic wave signal;

[0013] Antenna 2: converts electromagnetic wave signals into radio frequency electrical signals;

[0014] Mixing filter 2: mixes and filters the input signal and then outputs it;

[0015] Mixing filter 3: mixes and filters the input signal and then outputs it;

[0016] Antenna 3: converts electromagnetic wave signals into radio frequency electrical signals;

[0017] Antenna 4: converts electromagnetic wave signals into radio frequency electrical signals;

[0018] Distance measurement module: It is composed of DA and FPGA, and performs pulse compression processing on the input signal to achieve distance measurement.

[0019] A distributed frequency source implementation method based on radio microwave synchronization of the present invention comprises the following steps:

[0020] Step 1: At the local site, a reference signal is generated by a crystal oscillator:

[0021] s1(t)=cos(ω r t+φ r ), where ω r is the reference signal frequency, is the initial phase of the reference signal;

[0022] Step 2: After the signal s1(t) is processed by the frequency synthesis module, three signals are output. One signal is the same as the input signal and is also represented by s1(t). Another signal is output after multiplying the input signal by 6 and is represented by s5(t). Another signal is output after multiplying the input signal by 4 and is represented by s7(t).

[0023] s5(t)=cos(6ω r t+6φ r ),

[0024] s7(t)=cos(4ω r t+4φ r );

[0025] Step 3: Use the mixer filter 1 to mix the input signal s1(t) with the carrier frequency to obtain the following signal:

[0026] s2(t)=cos(ω0t+ω r t+φ r +φ0)+cos(ω0t-ω r t-φ r +φ0);

[0027] Step 4: Signal s2(t) is radiated to the remote site through antenna 1. After being reflected by the corner reflector of the remote site, the signal received by antenna 2 of the local site is:

[0028] s3(t)=cos[ω0(t+2△t)+ω r (t+2△t)+φ r +φ0]+cos[ω0(t+2△t)-ω r(t+2△t)-φ r +φ0];

[0029] Step 5: Use the mixer filter 2 to self-mix the input signal s3(t) to obtain the following signal:

[0030] s4(t)=cos[2ω r (t+2△t)+2φ r ];

[0031] Step 6: Use the mixing filter 3 to mix the input signal s4(t) and the local signal s5(t) to obtain the following signal:

[0032] s6(t)=4ω r (t-△t)+4φ r ;

[0033] Step 7: Signal s6(t) is radiated from antenna 4 to distant antenna 3. The propagation delay time is Δt. Therefore, the signal received by antenna 3 is:

[0034] s7(t)=cos(4ω r t+4φ r );

[0035] Thus, the frequency source reference signal s7 (t) of the local site is restored at antenna 3.

[0036] The beneficial effects of the present invention are

[0037] 1. The frequency source reference signal of the local site can be reproduced at the distant site, achieving the same frequency and phase between different sites. Compared with the existing technology, this solution uses space as the medium for microwave transmission, the positions between sites can be moved in real time, the application scenarios are flexible, and it has great application prospects in mobile radar collaborative detection.

[0038] 2. The spatial transmission waveform is a dual-tone waveform, and the distance measurement accuracy is proportional to the discreteness of the echo signal spectrum. Therefore, the present invention adopts dual-tone signal ranging to achieve better ranging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the working principle of the device of the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, a distributed frequency source device based on radio microwave synchronization of the present invention includes 1-crystal oscillator, 2-frequency synthesis module, 3-mixing filter, 4-antenna, 5-corner reflector, 6-antenna, 7-mixing filter 1, 8-mixing filter 2, 9-antenna, 10-antenna, 11-distance measurement module. The output end of 1-crystal oscillator is connected to the input end of 2-frequency synthesis module. 2-frequency synthesis module has three outputs, one is connected to the input end of 3-mixing filter, one is connected to the input end of 8-mixing filter, and one is used as the local frequency source of the distributed frequency source device and output to the external system. The output end of 3-mixing filter is connected to 4-antenna. The signal radiated by the 4-antenna is reflected by the 5-corner reflector and then received by the 6-antenna. The output of the 6-antenna is connected to the input of the 7-mixing filter. The output of the 7-mixing filter is connected to the input of the 8-mixing filter. The output of the 8-mixing filter is connected to the output of the 10-antenna. The signal radiated by the 10-antenna is received by the 9-antenna at the remote site. The output of the 9-antenna is used as the remote site frequency source of the distributed frequency source device and is output to the external system. The output of the 3-mixing filter and the output of the 6-antenna are also connected to the input of the 11-ranging module. Among them:

[0042] 1-Crystal oscillator: The crystal oscillator is used to generate the reference clock signal.

[0043] 2- Frequency synthesis module: It has three outputs, one for amplifying the input signal, one for multiplying the input signal by 6, and one for multiplying the input signal by 4.

[0044] 3- Mixing filter: Mix and filter the input signal and then output it.

[0045] 4-Antenna: Converts electromagnetic wave signals into radio frequency electrical signals.

[0046] 5- Corner reflector: reflects the received electromagnetic wave signal.

[0047] 6-Antenna: Converts electromagnetic wave signals into radio frequency electrical signals.

[0048] 7- Mixing filter 1: Mix and filter the input signal and then output it.

[0049] 8- Mixing filter 2: Mix and filter the input signal and then output it.

[0050] 9-Antenna: Converts electromagnetic wave signals into radio frequency electrical signals.

[0051] 10-Antenna: Converts electromagnetic wave signals into radio frequency electrical signals.

[0052] 11- Distance measurement module: It is composed of DA and FPGA, and performs pulse compression processing on the input signal to achieve distance measurement.

[0053] The present invention provides a distributed frequency source implementation method based on radio microwave synchronization, and its implementation steps are:

[0054] Step 1: At the local site, a 1-crystal oscillator generates a reference signal as shown below:

[0055] s1(t)=cos(ω r t+φ r ),

[0056] where ω r is the reference signal frequency, is the initial phase of the reference signal.

[0057] Step 2: After the signal s1(t) is processed by the 2-frequency synthesis module, three signals are output. One signal is the same as the input signal, also represented by s1(t), one signal is output after multiplying the input signal by 6, represented by s5(t), and one signal is output after multiplying the input signal by 4, represented by s7(t).

[0058] s5(t)=cos(6ω r t+6φ r ),

[0059] s7(t)=cos(4ω r t+4φ r ).

[0060] Step 3: Use a 3-mixing filter to mix the input signal s1(t) with the carrier frequency to obtain the following signal:

[0061] s2(t)=cos(ω0t+ω r t+φ r +φ0)+cos(ω0t-ω r t-φ r +φ0).

[0062] Step 4: The signal s2(t) is radiated to the remote site through the 4-antenna. After being reflected by the 5-corner reflector of the remote site, the signal received by the 6-antenna of the local site is:

[0063] s3(t)=cos[ω0(t+2△t)+ω r (t+2△t)+φ r +φ0]+cos[ω0(t+2△t)-ω r (t+2△t)-φ r +φ0].

[0064] Step 5: Use the 7-mixing filter to self-mix the input signal s3(t) to obtain the following signal:

[0065] s4(t)=cos[2ω r (t+2△t)+2φ r ].

[0066] Step 6: Use an 8-mixing filter to mix the input signal s4(t) and the local signal s5(t) to obtain the following signal:

[0067] s6(t)=4ω r (t-△t)+4φ r .

[0068] Step 7: The signal s6(t) is radiated to the distant site through the 10-antenna. The propagation delay time is Δt. Therefore, the signal received by the distant site is:

[0069] s7(t)=cos(4ω r t+4φ r ).

[0070] Thereby, the frequency source reference signal s7(t) of the local site is recovered at the distant site.

[0071] The present invention is not limited to the above specific implementations, and the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made to the above implementations based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims

1. A distributed frequency source device based on radio microwave synchronization, characterized in that: Including crystal oscillator, frequency synthesis module, mixing filter 1, antenna 1, corner reflector, antenna 2, mixing filter 2, mixing filter 3, antenna 3, antenna 4, ranging module; The output end of the crystal oscillator is connected to the input end of the frequency synthesis module. The frequency synthesis module has three outputs, one of which is connected to the input end of the mixing filter 1, one is connected to the input end of the mixing filter 3, and one is output as a local frequency source of the distributed frequency source device for use by the external system. The output end of the mixing filter 1 is connected to the antenna 1. The signal radiated by the antenna 1 is reflected back by the corner reflector and is received by the antenna 2. The output end of the antenna 2 is connected to the input end of the mixing filter 1, the output end of the mixing filter 1 is connected to the input end of the mixing filter 2, and the output end of the mixing filter 2 is connected to the output end of the antenna 4. The signal radiated by the antenna 4 is received by the antenna 3 at a distant site. The output end of the antenna 3 is output as a distant site frequency source of the distributed frequency source device for use by the external system. The output end of the mixing filter 1 and the output end of the antenna 2 are also connected to the input end of the ranging module.

2. A distributed frequency source device based on radio microwave synchronization according to claim 1, characterized in that: Crystal oscillator: Crystal oscillator is used to generate reference clock signal; Frequency synthesis module: It has three outputs, one for amplifying the input signal, one for multiplying the input signal by 6, and one for multiplying the input signal by 4. Mixing filter 1: mixes and filters the input signal and then outputs it; Antenna 1: converts electromagnetic wave signals into radio frequency electrical signals; Corner reflector: reflects the received electromagnetic wave signal; Antenna 2: converts electromagnetic wave signals into radio frequency electrical signals; Mixing filter 2: mixes and filters the input signal and then outputs it; Mixing filter 3: mixes and filters the input signal and then outputs it; Antenna 3: converts electromagnetic wave signals into radio frequency electrical signals; Antenna 4: converts electromagnetic wave signals into radio frequency electrical signals; Distance measurement module: It is composed of DA and FPGA, and performs pulse compression processing on the input signal to achieve distance measurement.

3. A method for implementing a distributed frequency source based on radio microwave synchronization, applied to a distributed frequency source device based on radio microwave synchronization as claimed in claim 1 or 2, characterized in that: The following steps are involved: Step 1: At the local site, a reference signal is generated by a crystal oscillator: s1(t)=cos(ω r t+φ r ), where ω r is the reference signal frequency, is the initial phase of the reference signal; Step 2: After the signal s1(t) is processed by the frequency synthesis module, three signals are output. One signal is the same as the input signal and is also represented by s1(t). Another signal is output after multiplying the input signal by 6 and is represented by s5(t). Another signal is output after multiplying the input signal by 4 and is represented by s7(t). s5(t)=cos(6ω r t+6φ r ), s7(t)=cos(4ω r t+4φ r ); Step 3: Use the mixer filter 1 to mix the input signal s1(t) with the carrier frequency to obtain the following signal: s2(t)=cos(ω0t+ω r t+φ r +φ0)+cos(ω0t-ω r t-f r +φ0); Step 4: Signal s2(t) is radiated to the remote site through antenna 1. After being reflected by the corner reflector of the remote site, the signal received by antenna 2 of the local site is: s3(t)=cos[ω0(t+2△t)+ω r (t+2△t)+φ r +φ0]+cos[ω0(t+2△t)-ω r (t+2△t)-φ r +φ0]; Step 5: Use the mixer filter 2 to self-mix the input signal s3(t) to obtain the following signal: s4(t)=cos[2ω r (t+2△t)+2φ r ]; Step 6: Use the mixing filter 3 to mix the input signal s4(t) and the local signal s5(t) to obtain the following signal: s6(t)=4ω r (t-△t)+4φ r ; Step 7: Signal s6(t) is radiated to remote antenna 3 via antenna 4. The propagation delay time is Δt. Therefore, the signal received by antenna 3 is: s7(t)=cos(4ω r t+4φ r ); Thereby, the frequency source reference signal s7(t) of the local site is recovered at the remote end.

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