Disclosure of Invention
The invention aims to solve the problems of complex system construction and high construction cost caused by the fact that an antenna array is required to be configured and clock synchronization is strictly required in the conventional passive direction finding scheme in the co-location, and the problems of complex system structure and high cost.
The above object of the present application is achieved by the following technical solutions:
s1, receiving a signal transmitted by a cooperative node through a static antenna and a mobile antenna to obtain static antenna data and rotary antenna data;
s2, wireless channel value based on rotary antenna dataRadio channel value with stationary antenna dataCalculating a channel ratio;
And S3, carrying out spatial filtering on the channel ratio based on a circular SAR model to obtain a spatial spectrogram, extracting peak points in the spatial spectrogram to obtain an azimuth angle estimated value of the cooperative node, and realizing the non-fuzzy multi-cooperative-node azimuth detection.
Optionally, step S2 includes:
the static antenna and the mobile antenna simultaneously receive signals, and the time steps of the static antenna data and the rotary antenna data are the same;
Wherein, theRepresenting the accumulated phase;
the radio channel ratio is calculated as follows:
Wherein, theRelatively constant over a short period of time.
Optionally, step S3 includes:
Substituting the channel ratio into a circular SAR formula, adjusting the weight to enhance the signal strength of the cooperative node direction, and performing spatial filtering.
A dual-antenna-based fuzzy cooperative node-free azimuth detection system comprises an antenna unit, a radio frequency front end module and an FPGA signal processing unit;
the antenna unit comprises a stationary antenna and a rotary antenna;
the radio frequency front end module is used for receiving and transmitting radio frequency signals;
The antenna unit is used for receiving the signal transmitted by the cooperative node and obtaining static antenna data and rotating antenna data;
the FPGA signal processing unit is used for wireless channel value based on the rotating antenna dataRadio channel value with stationary antenna dataCalculating a channel ratio;
The FPGA signal processing unit is also used for carrying out spatial filtering on the channel ratio based on the circular SAR model to obtain a spatial spectrogram, extracting peak points in the spatial spectrogram to obtain an azimuth angle estimated value of the cooperative node, and realizing the non-fuzzy multi-cooperative-node azimuth detection.
Optionally, the antenna unit is connected with the FPGA signal processing unit;
The radio frequency front end module is connected with the FPGA signal processing unit.
Optionally, the antenna unit adopts an omni-directional wideband antenna with 2 transmission and 2 reception, and the frequency range is 600MHz to 6000MHz.
Optionally, the FPGA signal processing unit adopts a heterogeneous architecture ZYNQMP FPGA.
A computer readable storage medium storing instructions that, when executed, perform a dual antenna based ambiguity free cooperative node position detection method.
The technical scheme provided by the application has the beneficial effects that:
The invention is based on a circular synthetic aperture radar (SYNTHETIC APERTURE RADAR, SAR) model, adopts a rotary antenna to receive data, combines a static antenna to form a wireless channel ratio and performs spatial filtering, and constructs a multi-cooperation node azimuth detection method which has high precision, no ambiguity, low complexity and no clock synchronization without anchor point assistance so as to further reduce the complexity of the system and the construction cost. The method of receiving data by using the static antenna and the dynamic antenna is used for realizing the non-fuzzy multi-cooperation node azimuth detection, does not need to synchronize an antenna array and a clock, reduces the complexity of the system and the construction cost, and is used in the fields of intelligent transportation, unmanned aerial vehicle systems, industrial automation, emergency rescue, smart city, environmental monitoring and the like.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present application, a detailed description of embodiments of the present application will be made with reference to the accompanying drawings.
The embodiment of the application provides a method for detecting the azimuth of a non-fuzzy cooperative node based on double antennas.
Referring to fig. 1, fig. 1 is a non-fuzzy cooperative node azimuth detection model diagram of a non-fuzzy cooperative node azimuth detection method based on dual antennas in an embodiment of the present application, including:
s1, receiving a signal transmitted by a cooperative node through a static antenna and a mobile antenna to obtain static antenna data and rotary antenna data;
s2, wireless channel value based on rotary antenna dataRadio channel value with stationary antenna dataCalculating a channel ratio;
And S3, carrying out spatial filtering on the channel ratio based on a circular SAR model to obtain a spatial spectrogram, extracting peak points in the spatial spectrogram to obtain an azimuth angle estimated value of the cooperative node, and realizing the non-fuzzy multi-cooperative-node azimuth detection.
Specifically, based on the embedded radio receiving and transmitting platform as hardware, data is received by using a static antenna and a dynamic antenna, the ratio of two wireless channels is taken to eliminate the phase difference between independent receiving and transmitting equipment, and the weight is adjusted. And carrying out platform deployment on the circular SAR model, and carrying out unambiguous cooperative node azimuth detection by assisting with corresponding accessories.
Specifically, based on a circular synthetic aperture radar (SYNTHETIC APERTURE RADAR, SAR) model, a rotary antenna is adopted to receive data, and a wireless channel ratio is formed by combining a static antenna and spatial filtering is carried out.
The step S2 comprises the following steps:
the static antenna and the mobile antenna simultaneously receive signals, and the time steps of the static antenna data and the rotary antenna data are the same;
Wherein, theRepresenting the accumulated phase;
the radio channel ratio is calculated as follows:
Wherein, theRelatively constant over a short period of time.
In one embodiment, a dual-antenna-based ambiguity-free cooperative node azimuth detection model diagram is shown in fig. 1, in which transmission and reception are performed on separate devices, and the receiving device is composed of a stationary antenna and a mobile antenna, and the mobile antenna moves along a circle with radius r, similar to a circular synthetic aperture radar. Since the transmission and reception operations performed on the SAR in the past use the same reference clock, the measured radio channel values of the mobile antennasIndependent of frequency, i.e. there are. But actually the SAR, measured radio channel is performed between independent transmitters and receiversDue to the position change, the carrier and sampling frequency offset between the transmitter and the receiver and the influence of phase noise willTo eliminate this accumulated phaseAs shown in fig. 1, one stationary antenna and one mobile antenna are used for reception.
Relatively constant in a short time, so the radio channel ratio isIs a constant multiple of the mobile channel, has no phase accumulation caused by frequency offset and noise, and therefore usesSubstituting the SAR formula, enhancing the signal strength of the incoming wave direction by adjusting the weight, thereby realizing spatial filtering, equivalently obtaining the result of SAR analysis on the incoming wave signal by the wireless receiver under the condition of no frequency offset and no signal noise accumulation, realizing the azimuth detection of the non-fuzzy cooperative node based on double antennas, reducing the complexity and construction cost of the system and having no clock synchronization requirement. The technical scheme of the application can identify a plurality of incoming wave directions, and is particularly characterized in that corresponding peaks appear at each incoming wave direction in the spatial spectrogram after data processing.
The step S3 comprises the following steps:
Substituting the channel ratio into a circular SAR formula, adjusting the weight to enhance the signal strength of the cooperative node direction, and performing spatial filtering.
A dual-antenna-based fuzzy cooperative node-free azimuth detection system comprises an antenna unit, a radio frequency front end module and an FPGA signal processing unit;
the antenna unit comprises a stationary antenna and a rotary antenna;
the radio frequency front end module is used for receiving and transmitting radio frequency signals;
The antenna unit is used for receiving the signal transmitted by the cooperative node and obtaining static antenna data and rotating antenna data;
the FPGA signal processing unit is used for wireless channel value based on the rotating antenna dataRadio channel value with stationary antenna dataCalculating a channel ratio;
The FPGA signal processing unit is also used for carrying out spatial filtering on the channel ratio based on the circular SAR model to obtain a spatial spectrogram, extracting peak points in the spatial spectrogram to obtain an azimuth angle estimated value of the cooperative node, and realizing the non-fuzzy multi-cooperative-node azimuth detection.
The antenna unit is connected with the FPGA signal processing unit;
The radio frequency front end module is connected with the FPGA signal processing unit.
The antenna unit adopts an omnidirectional broadband antenna with 2 transmission and 2 reception, and the frequency range is 600MHz to 6000MHz.
In one embodiment, the present invention is applied to an anchor-free co-location system overall block diagram. As shown in fig. 2. The system is generally divided into an antenna unit, a radio frequency front end module and an FPGA signal processing unit. The antenna unit adopts a 2-transmission 2-reception omnidirectional broadband antenna, the frequency range is from 600MHz to 6000MHz, the radio frequency front end module mainly completes corresponding signal up-down conversion, digital-analog-digital conversion and radio frequency signal receiving and transmitting, and the FPGA signal processing unit mainly completes corresponding signal generation, receiving, processing and other algorithms.
The FPGA signal processing unit adopts a heterogeneous architecture ZYNQMP FPGA.
In one embodiment, the co-locating radio frequency sensor is usually carried on an outdoor mobile platform such as an unmanned vehicle, an unmanned plane and the like, and certain requirements are set on the volume and the power consumption of the sensor, so that the invention designs a radio frequency front end solution based on a radio frequency transceiver integrated chip ADRV 9009. The chip comprises four independent communication links of 2 receiving and 2 transmitting, and can realize the receiving and transmitting of 75MHz to 6000MHz ultra-wideband radio frequency signals. The core control unit adopts a Xilinx company heterogeneous architecture ZYNQMP FPGA, and the inside of the core control unit is composed of FPGA logic (Programmable Logic, PL) rich in resources and 4 ARM architecture 53 hard core processing systems (Processing System, PS). Most Digital Signal Processing (DSP) tasks such as filtering, sequence acquisition tracking, azimuth angle of arrival resolution, and distance estimation are performed at the core control unit.
In one embodiment, fig. 3 shows an implementation manner of the ambiguity-free cooperative node azimuth detection based on dual antennas, where the embedded radio transceiver platform acquires the acquired cooperative node transmitting signal through the ADC of the radio frequency front end, and then changes the acquired cooperative node transmitting signal from an analog signal to a digital signal, and inputs the digital signal into the FPGA for subsequent signal processing. And at the FPGA digital end, after the processing of the low-pass filter, the ratio of the two wireless channels is taken to eliminate the phase difference between the independent receiving and transmitting equipment. And adjusting weights, performing spatial filtering on channel ratios based on a circular SAR formula, and finally extracting peak points in the obtained spatial spectrogram to realize azimuth detection of the cooperative nodes in the view range scene.
Embodiment one:
And selecting an experimental scene consistent with the model shown in fig. 1 for single-target direction-finding verification, wherein the positioning system is deployed in a dark room with weak external multipath interference, as shown in fig. 4, and the receiving and transmitting antennas respectively adopt a directional antenna and an omnidirectional antenna as shown in the figure, and the transmitting power is 26 dBm. The rotary antenna and the radio frequency sensor of the receiving end are both fixed on equipment capable of realizing horizontal 360-degree seamless continuous high-precision electric control rotation, the rotating radius of the antenna is 0.28m, and the static antenna is placed close to the rotary platform.
And taking the coordinate system shown in fig. 4 as a reference, setting target Tx azimuth angles to 90 degrees, 80.54 degrees and 62.8 degrees respectively by moving the transmitting antenna position, driving the rotating antenna to move by the receiving end turntable, recording the current angular position of the rotating antenna every 10 degrees, storing the data received by the rotating antenna and the static antenna at the moment, storing 36 groups in total, and realizing azimuth angle estimation of the cooperative nodes by analyzing the received data.
The data received by the MATLAB analysis antenna is utilized to draw a multi-path profile as shown in fig. 5, wherein the abscissa in the graph is a space angle, the ordinate represents the power spectrum amplitude, and (a), (b) and (c) respectively show the results of azimuth detection on Amplitude Modulated (AM) and Frequency Modulated (FM) signals when the actual incoming wave directions are 90 degrees, 80.54 degrees and 62.8 degrees, the angle corresponding to the wave crest in each sub-graph is the measured incoming wave direction, so that an error table can be obtained, and the error table is shown in table 1:
TABLE 1
In the experimental result graph, only one obvious wave beam exists in each sub-graph, the amplitude of the wave beam is larger than that of other side lobes, the angle corresponding to the wave beam and the error of the actual incoming wave direction are within 1.8 degrees, and the experimental result is ideal.
Embodiment two:
Next, experimental verification was performed in a multi-objective scenario. The multi-objective experimental scenario is shown in fig. 6, and on the basis of fig. 4, a metal plate is placed for manufacturing a reflection path, and the verification waveforms are an FM signal and a sinusoidal signal, both of which have carrier frequencies of 2.56GHz. The signals arrive at the receiving end along the direct path and the reflected path with the azimuth angles of 116.00 degrees and 132.78 degrees respectively, and the rest parameters and experimental conditions are the same as those of the first embodiment. The experimental results are shown in fig. 7:
In fig. 7, each sub-graph has 2 distinct peaks, which correspond to the azimuth angles of the signal reaching the receiving end via two paths, and the angles corresponding to the peaks are observed, so that an error table is shown in table 2:
TABLE 2
The error of the estimated value of the incoming wave direction and the actual azimuth angle are both within 1.5 degrees, and the invention is proved to realize the detection of a plurality of incoming wave directions. In the first embodiment, the results of the first and second embodiments are single measurement results, and the angle estimation error is lower and is basically within 1 degree as the measurement times are increased.
The application also discloses a computer readable storage medium which stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor so as to execute the method for detecting the azimuth of the non-fuzzy cooperative node based on the double antennas.
The above are merely exemplary embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. That is, equivalent changes and modifications are contemplated by the teachings of this disclosure, which fall within the scope of the present disclosure.
This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a scope and spirit of the disclosure being indicated by the claims.