Moving rate determination method based on Zadoff-Chu sequence
阅读说明：本技术 一种基于Zadoff-Chu序列的移动速率测定方法 (Moving rate determination method based on Zadoff-Chu sequence ) 是由 李俊画 魏华 于 2019-09-18 设计创作，主要内容包括：本发明公开了一种基于Zadoff-Chu序列的移动速率测定方法,包括构建信标信号、无线台发射信标信号、移动台接收信标信号、接收信号预处理、多普勒频率与速率测定。本发明通过提出一种利用Zadoff-Chu序列构造生成的信标信号,该信号具有恒包络特性,方便无线台发射,可以方便和有效的实现多普勒频率测定,同时提出一种利用Zadoff-Chu相关性特征来实现精确多普勒频率测定的方法,间接实现高精确和大范围的测定物体运动速度。(The invention discloses a mobile speed measuring method based on a Zadoff-Chu sequence, which comprises the steps of constructing beacon signals, transmitting the beacon signals by a wireless station, receiving the beacon signals by a mobile station, preprocessing the received signals and measuring Doppler frequency and speed. The invention provides a beacon signal generated by utilizing a Zadoff-Chu sequence structure, which has a constant envelope characteristic, is convenient for a wireless station to transmit, can conveniently and effectively realize Doppler frequency measurement, and simultaneously provides a method for realizing accurate Doppler frequency measurement by utilizing the Zadoff-Chu correlation characteristic, thereby indirectly realizing high-accuracy and large-range measurement of the object motion speed.)
1. A moving rate measuring method based on a Zadoff-Chu sequence is characterized by comprising the following steps:
s1: constructing a beacon signal with a frame format consisting of a ZC sequence and a conjugate ZC sequence;
s2: the wireless station transmitting a beacon signal;
s3: receiving beacon signals by the mobile station;
s4: preprocessing the received signal including signal extraction and peak detection;
s5: the Doppler frequency and the rate of movement are measured.
2. The method as claimed in claim 1, wherein the ZC sequence comprises a length NcVector formation of
the conjugate ZC sequence is obtained by conjugating the ZC sequence, and each element is defined as follows
3. The method of claim 1, wherein the wireless station transmits the beacon signal in a manner that: at carrier frequencies f by the transmitting antennac,0，fc,1，...fc,N-1Transmits the constructed beacon signal cyclically over the frequency of (a).
4. The method of claim 1, wherein the receiving the beacon signal is performed by receiving and down-converting a carrier frequency signal.
5. The method of claim 1, wherein the signal preprocessing comprises the following sub-steps:
s41: extracting a beacon signal; the signal extraction process is to input carrier frequency signal into correlator of corresponding sequence, the input of correlator is ykThe output of the correlator of the ZC sequence can be denoted ckThe output of the correlator of the conjugate ZC sequence can be expressed as
S42: the signal peak value detection is to determine the ZC sequence and the peak value of a conjugate ZC sequence correlator, and the time interval between the two peak values is recorded as deltad.
6. The method for determining the slew rate of a Zadoff-Chu sequence according to claim 1, wherein the step S5 comprises the following sub-steps:
s51: doppler frequency measurement, wherein the peak time interval Δ d is subjected to table lookup to obtain the Doppler frequency
S52: measuring the velocity of movement by measuring the Doppler frequency
Where the LUT represents a table lookup and curve fitting operation.
Technical Field
The invention relates to the field of signal processing, in particular to a moving rate measuring method based on a Zadoff-Chu sequence.
Background
Non-contact velocity measurement is a very important and difficult velocity measurement method in practical application, that is, when an object moves/rotates, the problem of how to measure the velocity of the object is solved. The doppler frequency measurement is an excellent method for measuring velocity, and the basic principle is to measure velocity by the doppler effect. The doppler effect indicates that waves receive higher frequencies when the source moves closer to the observer and lower frequencies when the source moves farther away from the observer, and is applicable to all types of waves, including electromagnetic waves. As shown in fig. 1, in the doppler effect of electromagnetic waves, the frequency becomes higher when the mobile station moves to a transmitting base station, and becomes lower when it moves away from the base station. Therefore, the doppler frequency measurement method is an excellent indirect method for measuring velocity, and the basic idea is that when an object moves, the velocity of the object moving can be indirectly measured by measuring the doppler frequency shift of the received electromagnetic wave.
Doppler Frequency (Doppler Frequency) f of radio signaldFollowing the speed of movement v of the object and the carrier frequency f of the radio signalcAnd the speed of light c satisfies the following equation:
therefore, the Doppler velocity measurement and velocity measurement platform of a moving object is composed of two parts, one part is that a wireless station transmits specific wireless electromagnetic waves, and the other part is that the moving object itself performs Doppler frequency measurement on electromagnetic wave signals transmitted by the wireless station. Therefore, when the Doppler frequency of the object movement is accurately measured, the object movement velocity v can be indirectly and accurately measured. However, in the existing velocity measurement, the implementation of measuring the doppler frequency is very complicated and tedious, and for example, the commonly used methods include a passive frequency measurement method (which can be divided into a resonance method and a bridge method) and an active comparison method, which can be divided into a beat frequency method and a difference frequency method. The passive frequency measurement method (usually used for frequency rough measurement, the precision is about 1 percent, and the realization complexity is very high, the active method is to utilize the linear superposition of two signals to generate a beat frequency phenomenon, and then to measure the frequency by detecting the zero beat phenomenon, usually used for low frequency measurement, the precision is higher, but the frequency error range of the measurement is very small, and the complexity is higher.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a moving rate measurement method based on Zadoff-Chu sequences.
A moving rate measuring method based on a Zadoff-Chu sequence comprises the following steps:
s1: constructing a beacon signal with a frame format consisting of a ZC sequence and a conjugate ZC sequence;
s2: the wireless station transmitting a beacon signal;
s3: receiving beacon signals by the mobile station;
s4: preprocessing the received signal including signal extraction and peak detection;
s5: the Doppler frequency and the rate of movement are measured.
The ZC sequence consists of a length NcVector formation of
the conjugate ZC sequence is obtained by conjugating the ZC sequence, and each element is defined as follows
The mode of the wireless station transmitting the beacon signal is as follows: at carrier frequencies f by the transmitting antennac,0，fc,1，...fc,N-1Transmits the constructed beacon signal cyclically over the frequency of (a).
The receiving beacon signal is a down-conversion of a received carrier frequency signal.
The signal pre-processing comprises the following sub-steps:
s41: extracting a beacon signal; the signal extraction process is to input carrier frequency signal into correlator of corresponding sequence, the input of correlator is ykThe output of the correlator of the ZC sequence can be denoted ckThe output of the correlator of the conjugate ZC sequence can be expressed as
S42: the signal peak value detection is to determine the ZC sequence and the peak value of a conjugate ZC sequence correlator, and the time interval between the two peak values is recorded as deltad.
The step S5 includes the following sub-steps:
s51: doppler frequency measurement, wherein the peak time interval Δ d is subjected to table lookup to obtain the Doppler frequency
S52: measuring the velocity of movement by measuring the Doppler frequency
Where the LUT represents a table lookup and curve fitting operation.
The invention has the beneficial effects that: the invention provides a beacon signal generated by utilizing a Zadoff-Chu sequence structure, which has a constant envelope characteristic, is convenient for a wireless station to transmit, can conveniently and effectively realize Doppler frequency measurement, and simultaneously provides a method for realizing accurate Doppler frequency measurement by utilizing the Zadoff-Chu correlation characteristic, thereby indirectly realizing the measurement of the movement speed of an object with high accuracy and large range.
Drawings
FIG. 1 is a schematic diagram of the Doppler effect principle;
fig. 2 is a schematic diagram of a beacon signal frame format;
FIG. 3 is a plot of the correlator output versus Doppler frequency for ZC sequences and conjugate ZC sequences.
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
In this embodiment, a wireless station transmits a part.
Constructing a beacon signal, as shown in FIG. 2, the frame format of the beacon signal is composed of ZC sequence and conjugate ZC sequence, wherein the ZC sequence is composed of a length NcVector structure ofBecome into
where μ is less than NcAnd μ and NcAre relatively prime.
The conjugate ZC sequence is obtained by conjugating the ZC sequence to obtain a conjugate ZC sequence, wherein each element in the conjugate ZC sequence can be expressed as
And (3) signal transmission, wherein the beacon transmission mode is as follows:
the transmitting antenna cyclically transmits a beacon signal composed of a ZC sequence and a conjugate ZC sequence as shown in fig. 2. The transmitting antenna will be at 1 to N carrier frequencies, i.e. at carrier frequencies fc,0，fc,1，...fc,N-1Transmits a beacon signal as defined in figure 2.
In this embodiment, the mobile station receives the part.
Based on the beacon based transmission part, the mobile station uses a simple peak detection to realize the Doppler frequency detection. On the receiving output signal of each carrier frequency, the receiving signal of the mobile station is correlated with the following two ZC sequences and conjugate ZC sequences. The signal input to the correlator after the carrier frequency signal has been down-converted can be written as ykThe output of the correlator of the ZC sequence can be denoted ck(ii) a Similarly, the output of a correlator for a conjugate ZC sequence can be expressed as
In the present embodiment, a doppler frequency measuring section.
After the ZC sequence and the conjugate ZC sequence are subjected to the doppler effect, the positions of the correlation peaks thereof are shifted according to the magnitude of the doppler frequency, as shown in fig. 3. Therefore, the present invention utilizes the Doppler frequency to change the interval distance between the ZC sequence and the peak value of the conjugate ZC sequence correlator, so as to realize the accurate measurement of the Doppler frequency of the mobile station. Thus, assuming that the time interval of the ZC sequence and the conjugate ZC sequence correlator peaks is Δ d on the time axis, the corresponding Doppler frequencies can be generated from a lookup table and function of Δ d, i.e., the measured Doppler frequency can be expressed as
In this example, a rate measuring section.
Obtaining measured Doppler frequency by table look-up and fittingCorresponding rate of movement
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
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