CN112394325A

CN112394325A - Doppler frequency offset estimation system, method and device for ultrasonic positioning signal

Info

Publication number: CN112394325A
Application number: CN201910758469.4A
Authority: CN
Inventors: 向玮晨; 刘广松
Original assignee: Suzhou Touchair Technology Co ltd
Current assignee: Suzhou Touchair Technology Co ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-02-23
Anticipated expiration: 2039-08-16
Also published as: CN112394325B

Abstract

The invention provides a Doppler frequency offset estimation system, a Doppler frequency offset estimation method and a Doppler frequency offset estimation device for ultrasonic positioning signals. The method comprises the following steps: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit; calculating the Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode; and calculating the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first central frequency, the second central frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to that of the secondary ultrasonic positioning signal. Frequency offset correction aiming at the main ultrasonic positioning signal and the secondary ultrasonic positioning signal is realized based on the frequency calibration signal, so that the cost can be saved.

Description

Doppler frequency offset estimation system, method and device for ultrasonic positioning signal

Technical Field

The embodiment of the invention relates to the technical field of positioning, in particular to a Doppler frequency offset estimation system, a Doppler frequency offset estimation method and a Doppler frequency offset estimation device for ultrasonic positioning signals.

Background

With the increasing demand of personal navigation and positioning services, indoor positioning systems have been expanded from initial positioning functions to many aspects, such as business services and security management, which have requirements for higher positioning accuracy and wider coverage area for the navigation positioning of people in various environments. At present, an ultrasonic positioning system becomes one of mainstream positioning systems due to high positioning accuracy and a simple structure which can reach centimeter level, but the ultrasonic positioning system facing a large indoor scene usually needs a plurality of ultrasonic transmitting units to cooperate to completely cover the positioning service in the area.

With respect to the problem of eliminating or reducing the doppler effect of a predetermined spatial localization system, the current solutions are generally: the Doppler shift is estimated and the estimated frequency deviation is compensated. For the estimation of the doppler frequency offset, many solutions have been proposed in the industry and academia, such as adding a measuring device to directly calculate the frequency offset, adding an additional receiver to calculate the frequency offset, and estimating the joint doppler frequency offset and carrier frequency offset based on three-dimensional beamforming.

However, the frequency offset is directly calculated by adding an additional single device, so that the cost is greatly increased.

Disclosure of Invention

In view of this, the embodiments of the present invention provide a system, a method and an apparatus for estimating doppler frequency offset of an ultrasonic positioning signal.

The technical scheme of the embodiment of the invention is as follows:

a system for doppler frequency offset estimation of an ultrasonic locating signal, comprising:

the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter is arranged at the geometric center of the at least three secondary ultrasound transmitters, and frequency calibration signal transmitters are arranged at the periphery of the primary ultrasound transmitter; the main ultrasonic emitter is used for emitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the secondary ultrasonic emitter is used for emitting a secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency; wherein the primary and secondary ultrasonic locating signals are modulated onto a first carrier having a first center frequency; modulating a frequency calibration signal onto a second carrier wave with a second center frequency, wherein the second center frequency is greater than the first center frequency, the first carrier wave and the second carrier wave are not overlapped, and the frequency calibration signal is a narrow-band signal;

the intelligent terminal is used for receiving the main ultrasonic positioning signal, the secondary ultrasonic positioning signal and the frequency calibration signal transmitted by the ultrasonic transmitting unit, calculating the Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode, and calculating the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first central frequency, the second central frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to the Doppler frequency offset of the secondary ultrasonic positioning signal.

A Doppler frequency offset estimation method of ultrasonic positioning signals is suitable for Doppler frequency offset estimation of ultrasonic positioning signals transmitted by an ultrasonic transmitting unit, wherein the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter is arranged at the geometric center of the at least three secondary ultrasound transmitters, and frequency calibration signal transmitters are arranged at the periphery of the primary ultrasound transmitter; the main ultrasonic emitter is used for emitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the secondary ultrasonic emitter is used for emitting a secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency; wherein the primary and secondary ultrasonic locating signals are modulated onto a first carrier having a first center frequency; modulating a frequency calibration signal onto a second carrier wave with a second center frequency, wherein the second center frequency is greater than the first center frequency, the first carrier wave and the second carrier wave are not overlapped, and the frequency calibration signal is a narrow-band signal; the method comprises the following steps:

receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit;

calculating the Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode;

and calculating the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first central frequency, the second central frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to that of the secondary ultrasonic positioning signal.

An apparatus for estimating doppler frequency offset of an ultrasonic locating signal, comprising a processor, a memory and a computer program stored on the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the method for estimating doppler frequency offset of an ultrasonic locating signal as described in any one of the above.

A computer readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method of doppler frequency offset estimation of ultrasound positioning signals as set forth in any of the above.

From the above technical solutions, embodiments of the present invention provide a system, a method, and an apparatus for estimating doppler frequency offset of an ultrasonic positioning signal. The method comprises the following steps: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by an ultrasonic transmitting unit; calculating the Doppler frequency offset of the frequency calibration signal in a phase-locked loop mode; and calculating the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first central frequency, the second central frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to that of the secondary ultrasonic positioning signal. Therefore, frequency offset correction aiming at the ultrasonic positioning signal is realized based on the frequency calibration signal, additional monomer equipment is not required to be introduced, and cost can be saved. Moreover, the intensity comparison results of the signals are calibrated according to the frequencies of different ultrasonic transmitting units so as to select different positioning strategies, and the positioning precision can be improved. In addition, the correction of Doppler frequency offset is added into the positioning system, so that the positioning effect is improved. In addition, the intelligent terminal in the weak positioning signal area is accurately positioned, and the wide coverage of the ultrasonic positioning system is improved.

Drawings

FIG. 1 is an exemplary block diagram of an ultrasound positioning system according to the present invention.

Fig. 2 is an exemplary block diagram of an ultrasound transmission unit according to the present invention.

Fig. 3 is an exemplary frequency distribution plot of an ultrasound locating signal and a frequency calibration signal in accordance with the present invention.

FIG. 4 is an exemplary flow chart for determining a Doppler shift of an ultrasonic locating signal in accordance with the present invention.

Fig. 5 is a schematic diagram of the distribution of the positioning signals of the ultrasonic transmitting unit network according to the invention.

Fig. 6 is a flow chart of a first positioning strategy according to the present invention.

Fig. 7 is a flow chart of a second positioning strategy according to the present invention.

Fig. 8 is a flow chart of a third positioning strategy according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings.

For simplicity and clarity of description, the invention will be described below by describing several representative embodiments. Numerous details of the embodiments are set forth to provide an understanding of the principles of the invention. It will be apparent, however, that the invention may be practiced without these specific details. Some embodiments are not described in detail, but rather are merely provided as frameworks, in order to avoid unnecessarily obscuring aspects of the invention. Hereinafter, "including" means "including but not limited to", "according to … …" means "at least according to … …, but not limited to … … only". In view of the language convention of chinese, the following description, when it does not specifically state the number of a component, means that the component may be one or more, or may be understood as at least one.

The embodiment of the invention provides a positioning scheme for self-adapting a positioning strategy based on the intensity of an ultrasonic positioning signal. In addition, the embodiment of the invention also provides an ultrasonic positioning system based on Doppler frequency offset correction in a complex environment, which can perform double verification on each ultrasonic positioning signal in an overlapping area of a plurality of ultrasonic positioning signals by using the Doppler frequency offset of the frequency calibration signal. Moreover, in the embodiment of the invention, based on Doppler frequency offset correction, the ultrasonic transmitting set is created by using a super-resolution method, so that the intelligent terminal in the weak positioning signal area is accurately positioned, and the wide coverage of the ultrasonic positioning system is further improved.

As shown in fig. 1, the system includes:

a plurality of ultrasound transmission units arranged at respective fixed positions, each for transmitting a respective ultrasound localization signal;

the intelligent terminal is used for comparing the intensity of the ultrasonic positioning signals received from the ultrasonic transmitting units and determining to execute one of the following positioning strategies based on the comparison result: the intensity of the ultrasonic positioning signal transmitted by one ultrasonic transmitting unit is obviously stronger than that of the ultrasonic positioning signals transmitted by other ultrasonic transmitting units; a second positioning strategy that at least two ultrasonic transmitting units transmit strong ultrasonic positioning signals; and the weak ultrasonic positioning signals transmitted by the at least two ultrasonic transmitting units are mutually mashup.

In one embodiment, the number of the ultrasound transmission units is 4, and the arrangement points of the 4 ultrasound transmission units constitute a square.

In one embodiment, the ultrasound localization signals include a primary ultrasound localization signal, a secondary ultrasound localization signal, and a frequency calibration signal (the frequency calibration signal is also an ultrasound signal); the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter disposed at a geometric center of at least three secondary ultrasound transmitters, a frequency calibration signal transmitter disposed at a periphery of (e.g., attached to) the primary ultrasound transmitter; the main ultrasonic emitter is used for emitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the secondary ultrasonic emitter is used for emitting a secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency.

In one embodiment, the intelligent terminal is configured to:

when the difference value between the amplitude of the frequency calibration signal transmitted by one ultrasonic transmitting unit and the amplitude of the frequency calibration signal transmitted by the ultrasonic transmitting units except the ultrasonic transmitting unit is larger than a preset first threshold value, determining to execute a first positioning strategy; or

When the amplitudes of the frequency calibration signals transmitted by the two ultrasonic transmitting units are both larger than a preset second threshold value and the difference value of the frequency calibration signals transmitted by the two ultrasonic transmitting units is smaller than a preset third threshold value, determining to execute a second positioning strategy;

and when the amplitude of the frequency calibration signal transmitted by each ultrasonic transmitting unit is smaller than a preset fourth threshold, or the difference value of the amplitudes of the frequency calibration signals transmitted by any two ultrasonic transmitting units is smaller than a preset fifth threshold, determining to execute a third positioning strategy. Preferably, the first positioning policy includes: calculating the Doppler frequency offset of the main ultrasonic positioning signal transmitted by the ultrasonic transmitting unit which is obviously stronger than the intensity of other ultrasonic positioning signals; performing frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal which are transmitted by the ultrasonic transmitting unit and have the intensity which is obviously stronger than that of other ultrasonic positioning signals by using the Doppler frequency offset; selecting three secondary ultrasonic positioning signals from the secondary ultrasonic positioning signals after the frequency offset correction according to the sequence of the signal-to-noise ratio from large to small; and calculating the coordinates of the intelligent terminal based on the frequency offset corrected main ultrasonic positioning signal and the selected three secondary ultrasonic positioning signals. Preferably, the second positioning strategy comprises: calculating respective Doppler frequency offsets of frequency calibration signals transmitted by at least two ultrasonic transmitting units for transmitting strong ultrasonic positioning signals; respectively carrying out frequency offset correction on the frequency calibration signals transmitted by the at least two ultrasonic transmitting units by using respective Doppler frequency offsets; comparing the signal-to-noise ratios of the main ultrasonic positioning signals of the at least two ultrasonic transmitting units after the frequency offset correction, and selecting the ultrasonic transmitting unit corresponding to the main ultrasonic positioning signal with the largest signal-to-noise ratio as a target ultrasonic transmitting unit; selecting three secondary ultrasonic positioning signals from the secondary ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit according to the sequence of the signal-to-noise ratio from large to small; and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signal and the selected three secondary ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit. Preferably, the third positioning strategy comprises: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the respective Doppler frequency offsets; and calculating the coordinates of the intelligent terminal based on the frequency calibration signals which are corrected by the frequency offset and transmitted by all the ultrasonic transmitting units.

Fig. 2 is an exemplary block diagram of an ultrasound transmission unit according to the present invention. The ultrasound transmission unit includes: the ultrasonic diagnosis device comprises a main ultrasonic transmitting module, a secondary ultrasonic transmitting module and a controller. The primary ultrasonic transmitting module comprises a primary ultrasonic transmitter and a frequency calibration signal transmitter, and the secondary ultrasonic transmitting module comprises at least three secondary ultrasonic transmitters. The primary ultrasound transmitter is disposed at the geometric center of each secondary ultrasound transmitter and the frequency calibration signal transmitter is located next to the primary ultrasound transmitter. Exemplarily, in fig. 2, the respective secondary ultrasound generators are arranged at respective vertices of a cross centered on the primary ultrasound transmitter. In fact, each secondary ultrasound generator may be disposed on a geometric shape such as a circle, a triangle, a hexagon, etc. centered on the primary ultrasound transmitter, which is not limited by the embodiments of the present invention.

The main ultrasonic emitter is used for emitting a main ultrasonic positioning signal S_0,kContaining the positioning information and the ID of the ultrasound transmission unit, where k denotes the kth ultrasound transmission unit. The frequency calibration signal transmitter is used for transmitting a frequency calibration signal S_f,k；S_f,kRepresenting the frequency calibration signal S of the kth ultrasound transmission unit_f. Four secondary ultrasonic transmitters, each for transmitting a secondary ultrasonic positioning signal, S, containing positioning information_1,k、S_2,k、S_3,k、S_4,kIn which S is_1,kFor the kth ultrasonic emissionA secondary ultrasound locating signal emitted by a 1 st secondary ultrasound transmitter of the unit; s_2,kA secondary ultrasound locating signal at a 2 nd secondary ultrasound transmitter frequency of a kth ultrasound transmitting unit; and so on. The controller is used for controlling all the transmitters (including the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter) to simultaneously transmit signals according to preset frequencies, and can be regarded as the clock synchronization of the ultrasonic transmitting unit networking.

The doppler frequency offset estimation process of the ultrasonic positioning signal is explained below.

Assume that in one ultrasound transmission unit shown in fig. 2: the main ultrasonic emitter emits a main ultrasonic positioning signal S₀，S₀The ID of the ultrasonic transmitting unit and the positioning information are contained; frequency calibration signal transmitter transmits a frequency calibration signal S_f,kWherein k represents the kth ultrasound transmission unit; the secondary ultrasonic emitter emits a secondary ultrasonic locating signal S₁、S₂、S₃、S₄In which S is₁、S₂、S₃、S₄Respectively containing positioning information; the controller is used for controlling all the transmitters (including the main ultrasonic transmitter, the secondary ultrasonic transmitter and the frequency calibration signal transmitter) to simultaneously transmit signals according to a preset frequency, and can be regarded as the clock synchronization of the ultrasonic transmitting unit networking.

As can be seen in fig. 3, wherein:

(1) characteristics of the primary and secondary ultrasound localization signals:

assuming that the same ultrasound transmitting unit comprises one main ultrasound transmitter and four sub-ultrasound transmitters, the main ultrasound locating signal and the sub-ultrasound locating signal S transmitted by the ultrasound transmitting unit₀,S₁,S₂,S₃,S₄Including a main ultrasonic locating signal S₀And four secondary ultrasonic positioning signals S₁、S₂、S₃、S₄. Primary and secondary ultrasonic locating signals S₀,S₁,S₂,S₃,S₄Are respectively implemented as CDMThe A orthogonal spread spectrum code has a baseband bandwidth of 1500Hz, can simultaneously serve a plurality of users without information conflict, and can be used as a signal time synchronization technology to measure the arrival time of a signal. The baseband signals of the primary and secondary ultrasonic transmitters are both modulated to a frequency F_C,0On a 18500Hz carrier wave, ultrasonic locating signal S₀,S₁,S₂,S₃,S₄The occupied band bandwidth is 3 kilohertz (KHz), and the frequency range is 17KHz-20 KHz.

(2) Frequency calibration signal characteristics:

transmitting an ultrasonic locating signal S₀,S₁,S₂,S₃,S₄The ultrasound transmission unit of (a) also transmits a frequency calibration signal. The frequency calibration signal is implemented as BPSK modulated Gold code using a frequency band greater than 20KHz (i.e., greater than the maximum frequency of the ultrasonic positioning signal). Each frequency calibration signal bandwidth occupies hundreds of Hz, and the preferred bandwidth interval is [200Hz,500Hz ]]And a narrowband signal.

When multiple ultrasound transmission units are included in an ultrasound positioning system, then there are multiple frequency calibration signals S of different center frequencies_f,k(ii) a Where k denotes the kth ultrasound transmission unit. Frequency calibration signal S of 1 st ultrasonic transmitting unit_f,1Having a center frequency of F_C,1(ii) a Frequency calibration signal S of 2 nd ultrasonic transmitting unit_f,2Having a center frequency of F_C,2.... and so on, the frequency calibration signal S of the kth ultrasound transmission unit_f,kHaving a center frequency of F_C,kAnd k is a positive integer of at least 1.

A guard interval is arranged between two adjacent frequency calibration signals, the bandwidth of the guard interval occupying a few hundred Hz, preferably 200Hz-400 Hz. The center frequencies may be set in advance for the frequency calibration signals corresponding to the respective ultrasonic transmission units, respectively, so that it is possible to determine to which ultrasonic transmission unit the detected frequency calibration signal corresponds by detecting the center frequency of the frequency calibration signal.

For example, the correspondence between the number of the ultrasound transmission unit and the frequency calibration signal transmitted by the ultrasound transmission unit is set in such a manner that the center frequency increases.Examples are: s_f,1Central frequency F of_C,120600 Hz; s_f,2Central frequency F of_C,2(20000+600 x 2) Hz; … S_f,kCentral frequency F of_C,kIs (20000+600k) Hz, wherein S_f,kOccupies 375Hz bandwidth; then, adjacent S_f,kThe transmitting frequency bands are sequentially separated by 600Hz, namely the guard bandwidth between two adjacent groups of frequency calibration signals is 225 Hz.

In fig. 3, the frequency range of the rectangular frame 60 is 17KHZ to 20KHZ, which is the carrier frequency band of the ultrasonic positioning signal. To the right of the rectangular frame 60 are shown exemplary four small rectangular frames. After the corresponding relation between the serial number of the ultrasonic transmitting unit and the frequency calibration signal transmitted by the ultrasonic transmitting unit is set in a mode of increasing the central frequency, the four small rectangular frames are sequentially four frequency calibration signals S_f,1、S_f,2、S_f,3And S_f,4. Wherein, in the order of the direction of the rectangular frame 60, the frequency ranges corresponding to the four small rectangular frames are S_f,1、S_f,2、S_f,3And S_f,4The carrier band of (c). The frequency range of the rectangular frame 70 farthest from the rectangular frame 60 is S_f,4The carrier frequency band of (c); the frequency range of the rectangular frame 61 closest to the rectangular frame 60 is S_f,1The carrier band of (c). That is, the nth small rectangular frame detected based on the direction of the distance from the rectangular frame 60 is the frequency calibration signal of the nth ultrasound transmitting unit.

While four frequency calibration signals corresponding to four ultrasound transmitting units are exemplarily described above, those skilled in the art can appreciate that as the number of ultrasound transmitting units increases, the number of frequency calibration signals also increases accordingly, and the embodiment of the present invention is not limited thereto.

FIG. 4 is an exemplary flow chart for determining a Doppler shift of an ultrasonic locating signal in accordance with the present invention. The method is suitable for performing Doppler frequency offset estimation on an ultrasonic transmitting unit, wherein the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter is arranged at the geometric center of the at least three secondary ultrasound transmitters, and frequency calibration signal transmitters are arranged at the periphery of the primary ultrasound transmitter; the main ultrasonic emitter is used for emitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal which is also an ultrasonic signal; the secondary ultrasonic emitter is used for emitting a secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency; the method comprises the following steps:

step 401: receiving a main ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal which are transmitted by the ultrasonic transmitting unit; wherein the primary and secondary ultrasonic locating signals are modulated onto a first carrier having a first center frequency; modulating a frequency calibration signal onto a second carrier wave with a second center frequency, wherein the second center frequency is greater than the first center frequency, the first carrier wave and the second carrier wave are not overlapped, and the frequency calibration signal is a narrow-band signal;

step 402: the doppler frequency offset of the frequency calibration signal is calculated by a Phase Lock Loop (PLL) method.

Step 403: and calculating the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the first central frequency, the second central frequency and the frequency calibration signal, wherein the Doppler frequency offset of the main ultrasonic positioning signal is equal to that of the secondary ultrasonic positioning signal.

Specifically, the method comprises the following steps: firstly, calculating a frequency calibration signal S of a kth (k is a positive integer greater than or equal to 1) ultrasonic transmitting unit by using a phase-locked loop (PLL)_f,kDoppler frequency shift F_D,k(ii) a Then, calculating the Doppler frequency offset F of the main ultrasonic positioning signal of the kth ultrasonic transmitting unit_D,0Wherein:

the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal of the same ultrasonic transmitting unit is equal and is F_D,0；F_C,0Is the center frequency of the first carrier; f_C,kIs the center of the second carrierFrequency. As can be seen, the number of the first carriers is one, and all the primary ultrasonic positioning signals and all the secondary ultrasonic positioning signals of all the ultrasonic transmitting units are carried on the first carriers; the number of the second carriers is equal to the number of the ultrasonic transmitting units, wherein one second carrier corresponds to one ultrasonic transmitting unit.

For example, when k is 1, the signal S is calibrated based on the frequency of the 1 st ultrasound transmission unit_f,1Calculating the Doppler frequency offset of the ultrasonic positioning signal of the 1 st ultrasonic transmitting unit to be F_D,1. Then, calculating the Doppler frequency offset F of the ultrasonic positioning signal of the 1 st ultrasonic transmitting unit_D,0Wherein

F_C,0Is the center frequency of the first carrier; f_C,1Starting from the direction of the rectangle 60 away, the center frequency of the first subcarrier 61.

For example, when k is 2, the signal S is calibrated based on the frequency of the 2 nd ultrasound transmission unit_f,2Calculating the Doppler frequency offset of the ultrasonic positioning signal of the 2 nd ultrasonic transmitting unit to be F_D,2. Then, calculating Doppler frequency offset F of ultrasonic positioning signal of 2 nd ultrasonic transmitting unit_D,0Wherein

F_C,0Is the center frequency of the first carrier; f_C,1Starting from the direction of the rectangle 60 away, the center frequency of the second subcarrier 62.

When the above doppler frequency offset calculation method is applied to an ultrasonic positioning system, the following steps may be performed: the method comprises the following steps: in the ultrasonic positioning system, an ultrasonic emitter emits an ultrasonic positioning signal, a frequency calibration signal emitter emits a frequency calibration signal at the same time, and all signals are synchronously emitted; step two: the intelligent terminal receives an ultrasonic positioning signal and a frequency calibration signal; step three: the intelligent terminal calculates the Doppler frequency offset of the frequency calibration signal; step four: the intelligent terminal estimates the Doppler frequency offset of the ultrasonic positioning signal based on the Doppler frequency offset of the frequency calibration signal; step five: compensating ultrasonic positioning signalThe Doppler frequency offset of the intelligent terminal is calculated by utilizing the CDMA technology; step six: estimating the relative position of the intelligent terminal by using a TDOA algorithm; step seven: and obtaining the coordinates of the intelligent terminal in the indoor environment, and realizing the accurate positioning of the intelligent terminal. Exemplary, the correction process includes: firstly, the band pass filtering is carried out on the frequency band where the target signal is located so as to eliminate out-of-band noise and interference. Multiplying the signal after band-pass filtering by the original sending carrier wave and performing low-pass filtering to obtain a target baseband signal S (n) which is not subjected to frequency offset correction; for the signal to be corrected, the frequency offset correction formula is:

wherein S (n) is the nth value of the complex sequence of the target signal demodulated to the baseband, F_DIs the frequency offset, F, of the estimated target signal_SFor the frequency at which the audio signal is sampled,

and the nth value of the target signal is obtained after the frequency offset correction.

Fig. 5 is a schematic diagram of the distribution of the positioning signals of the ultrasonic transmitting unit network according to the invention. In fig. 5, four ultrasound transmission units as shown in fig. 2 are included, respectively ultrasound transmission unit 10, ultrasound transmission unit 20, ultrasound transmission unit 30, and ultrasound transmission unit 40, wherein ultrasound transmission unit 10, ultrasound transmission unit 20, ultrasound transmission unit 30, and ultrasound transmission unit 40 are respectively arranged on the vertices of a square.

The shadowless area 41, the shadowless area 42, the shadowless area 43 and the shadowless area 44 respectively have a strongest ultrasonic positioning signal, which can be approximately regarded as that the intelligent terminal only receives the ultrasonic positioning signal service of the ultrasonic transmitting unit above the corresponding area, thereby achieving a better accurate positioning effect. For example, in the unshaded area 41, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 10 has the strongest signal, so that the intelligent terminal roaming to the unshaded area 41 can be regarded as only receiving the ultrasonic positioning signal service of the ultrasonic transmitting unit 10; in the unshaded area 42, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 20 has the strongest signal, so that the intelligent terminal roaming to the unshaded area 42 can be regarded as only receiving the ultrasonic positioning signal service of the ultrasonic transmitting unit 20; in the unshaded area 43, the ultrasonic positioning signal transmitted by the ultrasonic transmitting unit 30 has the strongest signal, so that the intelligent terminal roaming in the unshaded area 43 can be regarded as only receiving the ultrasonic positioning signal service of the ultrasonic transmitting unit 30; in the unshaded area 44, the ultrasonic locating signal transmitted by the ultrasonic transmitting unit 40 has the strongest signal, so the intelligent terminal roaming in the unshaded area 44 can be regarded as only receiving the ultrasonic locating signal service of the ultrasonic transmitting unit 40.

In the unshaded area 41, the unshaded area 42, the unshaded area 43, and the unshaded area 44, a first positioning strategy is performed in which the intensity of the ultrasonic positioning signal transmitted by one ultrasonic transmission unit is significantly stronger than the intensity of the ultrasonic positioning signal transmitted by the other ultrasonic transmission unit.

In diagonally shaded area 51, diagonally shaded area 52, diagonally shaded area 53, and diagonally shaded area 54, there are a plurality of strong ultrasonic locating signals. Also, in the square shaded area 60, there are a plurality of weak positioning signal mashups. In each of the diagonally shaded area 51, the diagonally shaded area 52, the diagonally shaded area 53, the diagonally shaded area 54, and the square shaded area 60, there is a large amount of interference, and the positioning effect is generally not good. For this purpose, the embodiment of the present invention implements the second positioning strategy in which at least two ultrasound transmitting units transmit strong ultrasound positioning signals in the diagonally shaded area 51, the diagonally shaded area 52, the diagonally shaded area 53, and the diagonally shaded area 54.

In the square hatched area 60, a third positioning strategy of mutually mashup of weak ultrasonic positioning signals emitted by the plurality of ultrasonic emitting units is performed. When the intelligent terminal roams to the networking environment of the ultrasonic emission unit, the intelligent terminal determines to adopt a first positioning strategy, a second positioning strategy or a third positioning strategy based on the intensity of the received ultrasonic positioning signal. Since the frequency calibration signal has a better reference value and detection range than the primary ultrasonic positioning signal and the secondary ultrasonic positioning signal, the frequency calibration signal is preferably used as a signal basis for determining whether to adopt the first positioning strategy, the second positioning strategy or the third positioning strategy.

Assume that the frequency calibration signal has N sampling points, A_f,1、A_f,2、......、A_f,kThe amplitude of the frequency calibration signal collected for each sampling point represents the magnitude of the frequency calibration signal energy collected for each sampling point, in dB.

Area judgment conditions:

wherein the content of the first and second substances,

is A_f,iIs determined by the average value of (a) of (b),

is A_f,jAverage value of (d); if the condition is met

The signal intensities of the two ultrasonic transmitting units are considered to be equivalent; on the contrary, the signal intensity of one ultrasonic transmitting unit is considered to be significantly greater than that of the other ultrasonic transmitting unit, and the intelligent terminal is judged to be closer to the transmitter of the stronger frequency calibration signal.

Intelligent terminal resolves average amplitude of received frequency calibration signal

And a comparison is made. When no j signal meets the judgment condition for any i signal, namely the intelligent terminal is in the unshaded area 41, the unshaded area 42, the unshaded area 43 or the unshaded area 44, determining to adopt a first positioning strategy; when only one pair of i and j meets the judgment condition, the intelligent terminal is positioned in a slash shadow area 51, a slash shadow area 52, a slash shadow area 53 and a slash shadow area 54, so that a second positioning strategy is determined to be adopted; when for any i signal, storeIf the 3 j signals meet the above area judgment condition, that is, the signal strength is equivalent, the intelligent terminal is in the square shadow area 60, and therefore, the third positioning strategy is determined to be adopted.

The first positioning strategy, the second positioning strategy and the third positioning strategy are respectively explained in detail below.

1. A first positioning strategy:

in the unshaded area 41, the unshaded area 42, the unshaded area 43, and the unshaded area 44, the judgment condition that the intensity of the ultrasonic positioning signal transmitted by one ultrasonic transmitting unit is significantly stronger than the intensity of the ultrasonic positioning signal transmitted by the other ultrasonic transmitting unit is satisfied, respectively, and thus the first positioning strategy is executed in the unshaded area 41, the unshaded area 42, the unshaded area 43, and the unshaded area 44.

In the unshaded area 41, the unshaded area 42, the unshaded area 43 and the unshaded area 44, since the installation height of the ultrasonic transmitting unit is much larger than the distance between the main ultrasonic transmitter and the secondary ultrasonic transmitter, the doppler frequency shifts generated by the motion state of the intelligent terminal relative to the ultrasonic transmitting units are very close, and it can be assumed that the doppler frequency shifts of the ultrasonic positioning signals received by the intelligent terminal are equal.

The method comprises the following steps: intelligent terminal resolves average amplitude of received frequency calibration signal

And a comparison is made. When there is no j signal meeting the judgment condition for any i signal

i≠j,i∈[1,k],j∈[1,k]Namely, the intelligent terminal is in an unshaded area 41, an unshaded area 42, an unshaded area 43 and an unshaded area 44.

Step two: estimating Doppler frequency offset F of each main ultrasonic positioning signal by using phase-locked loop (PLL)_D,0,kFrequency deviation correction can be carried out on the original main ultrasonic positioning signal and the secondary ultrasonic positioning signal, wherein k represents the kth ultrasonic transmitting unit;

step three: based on the CDMA communication principle, obtaining the time for the ultrasonic positioning signal after the frequency offset correction to reach the intelligent terminal;

step four: based on the TDOA positioning principle, the accurate positioning of the intelligent terminal is realized.

The first positioning strategy is explained below by way of example.

In fig. 5, it is assumed that the 1 st ultrasonic transmission unit (i.e., the ultrasonic transmission unit 10) is arranged in the unshaded region 41 in the upper left corner, the 2 nd ultrasonic transmission unit (i.e., the ultrasonic transmission unit 20) is arranged in the unshaded region 42 in the upper right corner, the 3 rd ultrasonic transmission unit (i.e., the ultrasonic transmission unit 30) is arranged in the unshaded region 43 in the lower left corner, and the 4 th ultrasonic transmission unit (i.e., the ultrasonic transmission unit 40) is arranged in the unshaded region 44 in the lower right corner.

Assuming that the intelligent terminal is located in the unshaded area 41 at the upper left corner, the intelligent terminal receives the ultrasonic positioning signal and the frequency calibration signal of the 1 st ultrasonic transmitting unit and the adjacent ultrasonic transmitting units around the ultrasonic transmitting unit.

The method comprises the following steps: the intelligent terminal resolves the average amplitude of each received frequency calibration signal

Finding a frequency calibration signal transmitted by an ultrasound transmission unit 10

Is much larger than the average amplitude of the frequency calibration signals transmitted by other ultrasound transmitting units, then the intelligent terminal is in the upper left-hand non-shaded area 41 and decides to adopt the first positioning strategy.

Step two: the intelligent terminal uses a phase-locked loop (pll) to estimate the doppler frequency offset F of the main ultrasonic positioning signal of the ultrasonic transmitting unit 10 (i.e. the 1 st ultrasonic transmitting unit, K is 1)_D,0,1。

Step three: at this time, the frequency shifts of the primary and secondary ultrasonic positioning signals of the 1 st ultrasonic transmitting unit are equal, i.e., F_D,0,1≈F_D,1,1≈F_D,2,1≈F_D,3,1≈F_D,4,1Therefore, it should beBy F_D,0,1And correcting the frequency deviation of all the ultrasonic positioning signals (including the primary ultrasonic positioning signal and the secondary ultrasonic positioning signal) of the 1 st ultrasonic transmitting unit.

Step four: the intelligent terminal analyzes the ID of the transmitting unit based on the CDMA technology and calculates the main positioning signal after frequency offset correction

Delay time t to reach intelligent terminal₀；

Step five: the intelligent terminal calculates the secondary positioning signal after each frequency offset correction based on the ID of the transmitting unit and the CDMA technology

Selecting three corrected secondary positioning signals with the maximum SNR as a first secondary positioning signal, a second secondary positioning signal and a third secondary positioning signal respectively;

step six: the intelligent terminal respectively calculates the first delay time t of the first positioning signal to reach the intelligent terminal based on the CDMA technology₁Second delay time t when second positioning signal reaches intelligent terminal₂And a third delay time t when the third positioning signal reaches the intelligent terminal₃；

Step seven: the intelligent terminal acquires relative coordinates (x) of a first-time ultrasonic transmitter for transmitting a first-time positioning signal to the cloud based on the ID of the transmitting unit₁,y₁,z₁) Relative coordinates (x) of a second ultrasonic transmitter for transmitting a second positioning signal₂,y₂,z₂) Relative coordinates (x) of a third ultrasonic transmitter for transmitting a third locating signal₃,y₃,z₃) Relative coordinates (x) of the primary ultrasound transmitter transmitting the primary locating signal₀,y₀,z₀) (ii) a Based on respective delay times t₀,t₁,t₂,t₃And respective relative coordinates (x)₀,y₀,z₀)、(x₁,y₁,z₁)、(x₂,y₂,z₂)、(x₃,y₃,z₃) Computing the phase of an intelligent terminal using a TDOA algorithmTo coordinate (x)_c,y_c,z_c). The intelligent terminal will relative coordinate (x)_c,y_c,z_c) And sending the relative coordinates to a cloud end, wherein the cloud end corresponds the relative coordinates to an indoor map, and shares the relative map to an intelligent terminal in an indoor environment.

2. A second positioning strategy:

in the diagonally shaded area 51, diagonally shaded area 52, diagonally shaded area 53, diagonally shaded area 54, the judgment conditions for at least two ultrasound transmission units to transmit strong ultrasound positioning signals are satisfied, respectively, and thus the second positioning strategy is executed. In the diagonally shaded area 51, the diagonally shaded area 52, the diagonally shaded area 53, and the diagonally shaded area 54, a plurality of strong positioning signal interferences exist.

Only one pair of i and j meets the judgment condition

i≠j,i∈[1,k],j∈[1,k]Then the intelligent terminal is in diagonally shaded area 51, diagonally shaded area 52, diagonally shaded area 53, diagonally shaded area 54.

Step two: at this time, the phase-locked loop (PLL) is used to calculate the frequency calibration signal S_f,kDoppler frequency shift F_D,f,kWherein k represents the kth ultrasound transmission unit;

step three: based on Doppler frequency offset F_D,f,kCalculating Doppler frequency offset F of ultrasonic positioning signal_D,0,k；

Wherein, F_C,0,kLocating a signal S for ultrasound_0,k、S_1,k…S_4,kThe center frequency of (d); f_C,f,kFor frequency-calibrating signal S_f,kThe center frequency of (d);

step four: performing frequency offset correction on the corresponding ultrasonic positioning signals;

step five: the intelligent terminal respectively estimates the signal-to-noise ratio of each frequency offset corrected main ultrasonic positioning signal based on the CDMA technology, and selects the group of positioning signals with larger signal-to-noise ratio;

step six: based on the CDMA communication principle, the time of the ultrasonic positioning signal after frequency offset correction reaching the intelligent terminal is obtained, and based on the TDOA positioning principle, the accurate positioning of the intelligent terminal is realized.

The second positioning strategy is explained below by way of example.

Assuming that the intelligent terminal is in the diagonally shaded area 52, the ultrasonic positioning signals and the frequency calibration signals of the peripheral ultrasonic transmitting units are received.

In which only two frequency calibration signals S are present_f,1、S_f,2The condition is met, and the method meets the requirement,

it is determined that the intelligent terminal is in diagonally shaded area 52 and decides to employ a second positioning strategy.

Step two: the ultrasonic positioning signals of the 1 st ultrasonic transmitting unit and the 2 nd ultrasonic transmitting unit have similar strength and are obviously larger than the ultrasonic positioning signals of other ultrasonic transmitting units, and the intelligent terminal calculates the frequency calibration signal S of the 1 st ultrasonic transmitting unit and the 2 nd ultrasonic transmitting unit by using a phase-locked loop (PLL)_f,1、S_f,2Respective Doppler frequency shift F_D,f,1、F_D,f,2。

Step three: frequency calibration signal S based on 1 st and 2 nd ultrasonic emission units_f,1、S_f,2Respective Doppler frequency shift F_D,f,1、F_D,f,2Intelligent terminal application formula

Doppler for calculating main ultrasonic positioning signals of 1 st and 2 nd ultrasonic transmitting units respectivelyFrequency deviation F_D,0,1、F_D,0,2。

Step four: doppler frequency offset F of main ultrasonic positioning signal of intelligent terminal based on 1 st ultrasonic transmitting unit_D,0,1Performing frequency offset correction on the primary ultrasonic positioning signal and the secondary ultrasonic positioning signal of the 1 st ultrasonic transmitting unit; doppler frequency offset F of main ultrasonic positioning signal of intelligent terminal based on 2 nd ultrasonic transmitting unit_D,0,2And frequency deviation correction is carried out on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal of the 2 nd ultrasonic transmitting unit.

Step five: the intelligent terminal analyzes the ID of the transmitting unit based on the CDMA technology and calculates the main positioning signal after each frequency deviation is corrected

Selecting the group of positioning signals with larger signal-to-noise ratio (SNR); assuming a positioning signal

Has a signal-to-noise ratio greater than

And selecting the 1 st ultrasonic transmitting unit to carry out position calculation on the intelligent terminal.

Step six: intelligent terminal calculates main positioning signal after frequency offset correction based on CDMA technology

Delay time t to reach intelligent terminal₀。

Step seven: the intelligent terminal calculates the secondary positioning signal after each frequency offset correction based on the ID of the transmitting unit and the CDMA technology

The three corrected sub-positioning signals with the highest SNR are selected as the first sub-positioning signal, the second sub-positioning signal and the third sub-positioning signal, respectively.

Step eight: the intelligent terminal respectively calculates the first positioning signal to reach the intelligent terminal based on the CDMA technologyFirst delay time t of terminal₁Second delay time t when second positioning signal reaches intelligent terminal₂And a third delay time t when the third positioning signal reaches the intelligent terminal₃。

Step nine: the intelligent terminal acquires relative coordinates (x) of a first-time ultrasonic transmitter for transmitting a first-time positioning signal to the cloud based on the ID of the transmitting unit₁,y₁,z₁) Relative coordinates (x) of a second ultrasonic transmitter for transmitting a second positioning signal₂,y₂,z₂) Relative coordinates (x) of a third ultrasonic transmitter for transmitting a third locating signal₃,y₃,z₃) Relative coordinates (x) of the primary ultrasound transmitter transmitting the primary locating signal₀,y₀,z₀) (ii) a Based on respective delay times t₀,t₁,t₂,t₃And respective relative coordinates (x)₀,y₀,z₀)、(x₁,y₁,z₁)、(x₂,y₂,z₂)、(x₃,y₃,z₃) Calculating relative coordinates (x) of intelligent terminal by using TDOA algorithm_c,y_c,z_c). The intelligent terminal will relative coordinate (x)_c,y_c,z_c) And sending the relative coordinates to a cloud end, wherein the cloud end corresponds the relative coordinates to an indoor map, and shares the relative map to an intelligent terminal in an indoor environment.

3. A third positioning strategy:

in the square hatched area 60, a third positioning strategy of mutually mashup of weak ultrasonic positioning signals emitted by the plurality of ultrasonic emitting units is performed. The square shaded area 60 is a complex environment where there is a plurality of weak localization SIGNAL interferences, the SIGNAL-to-NOISE RATIO (SNR) of each ultrasound localization SIGNAL is low, there are many errors, and the estimation of the SIGNAL arrival time using the CDMA technique has a large error. In the embodiment of the invention, an ultrasonic emission group is created and positioned by utilizing a super-resolution method through the existing ultrasonic positioning system equipment.

And a comparison is made. When there are 3 j signals satisfying the above area judgment condition for an arbitrary i signal

i≠j,i∈[1,k],j∈[1,k]I.e., the signal strength is comparable, the intelligent terminal is in the square shaded area 60 and determines to employ the third positioning strategy.

Step two, at this time, the phase-locked loop (PLL) is used to calculate the frequency calibration signal S_f,kDoppler frequency shift F_D,f,kWherein k represents the kth ultrasound transmission unit;

step three: for corresponding frequency calibration signal S_f,kAnd performing frequency offset correction.

Step four: an ultrasound transmit group is created. The ultrasonic emission group comprises frequency calibration signal emitters of 4 ultrasonic emission units as shown in FIG. 1, and the positioning signal of the ultrasonic emission group is frequency calibration signal corrected by frequency offset

Step five: estimating the time of arrival of the positioning signals of the ultrasonic emission group at the intelligent terminal by using a super-resolution method, such as a MUSIC-CC method (Multiple Signal classification algorithm);

step six: based on the TDOA positioning principle, the accurate positioning of the intelligent terminal is realized.

The third positioning strategy is explained below by way of example.

Assume that the smart terminal is in the square shaded area 60. The intelligent terminal receives all the ultrasonic positioning signals and frequency calibration signals of the 1 st, 2 nd, 3 rd and 4 th ultrasonic transmitting units, but the signal intensity is low.

And a comparison is made. When there are four frequenciesRate calibration signal S_f,1、S_f,2、S_f,3、S_f,4The judgment condition is met,

i≠j,i∈[1,4],j∈[1,4]and if the signal strength is equivalent, the intelligent terminal is in the square shaded area 60, and the third positioning strategy is determined to be adopted.

Step two: at this time, the intelligent terminal calculates the frequency calibration signal S by using a phase-locked loop (pll)_f,1、S_f,2、S_f,3、S_f,4Doppler frequency shift F_D,f,1、F_D,f,2、F_D,f,3、F_D,f,4(ii) a Step three: frequency offset correction is carried out on the frequency calibration signals of the 1 st, 2 nd, 3 th and 4 th ultrasonic transmitting units;

step four: an ultrasound transmit group is created. The ultrasonic transmitting group consists of frequency calibration signal transmitters of 1 st, 2 nd, 3 th and 4 th ultrasonic transmitting units, and the positioning signal of the ultrasonic transmitting group is the frequency calibration signal after frequency deviation correction

Step five: the intelligent terminal respectively estimates the first positioning signals based on the MUSIC-CC super-resolution algorithm

First delay time t of reaching intelligent terminal₁Second positioning signal

Second delay time t of reaching the intelligent terminal₂Third positioning signal

Third delay time t of reaching the intelligent terminal₃Fourth positioning signal

Third delay time t of reaching the intelligent terminal₄；

Step six: the intelligent terminal acquires relative coordinates (x) of a first main ultrasonic transmitter for transmitting a first positioning signal to the cloud end₁,y₁,z₁) Relative coordinates (x) of a second primary ultrasound transmitter transmitting a second locating signal₂,y₂,z₂) Relative coordinates (x) of a third primary ultrasound transmitter transmitting a third locating signal₃,y₃,z₃) And a fourth master ultrasound transmitter relative coordinate (x) transmitting a fourth locating signal₄,y₄,z₄) (ii) a Based on respective delay times t₁、t₂、t₃、t₄And respective relative coordinates (x)₁,y₁,z₁)、(x₂,y₂,z₂)、(x₃,y₃,z₃)、(x₄,y₄,z₄) Calculating the relative coordinates (x) of the intelligent terminal by using the TDOA algorithm_c,y_c,z_c). The intelligent terminal will relative coordinate (x)_c,y_c,z_c) And sending the relative coordinates to a cloud end, wherein the cloud end corresponds the relative coordinates to an indoor map, and shares the relative map to an intelligent terminal in an indoor environment.

Based on the above description, the embodiment of the invention also provides an ultrasonic positioning method. The method is applied to an ultrasonic positioning system, and the ultrasonic positioning system comprises: a plurality of ultrasound transmission units and intelligent terminals arranged at respective fixed positions; the method comprises the following steps: the intelligent terminal is enabled to compare the intensity of the ultrasonic positioning signals received from the ultrasonic transmitting units; enabling the intelligent terminal to determine to execute one of the following positioning strategies based on the comparison result: the intensity of the ultrasonic positioning signal transmitted by one ultrasonic transmitting unit is obviously stronger than that of the ultrasonic positioning signals transmitted by other ultrasonic transmitting units; a second positioning strategy that at least two ultrasonic transmitting units transmit strong ultrasonic positioning signals; and the weak ultrasonic positioning signals transmitted by the at least two ultrasonic transmitting units are mutually mashup. In one embodiment, the number of the ultrasound transmission units is 4, and the arrangement points of the 4 ultrasound transmission units constitute a square. Preferably, the ultrasonic positioning signal comprises a primary ultrasonic positioning signal, a secondary ultrasonic positioning signal and a frequency calibration signal; the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter is arranged at the geometric center of the at least three secondary ultrasound transmitters, and frequency calibration signal transmitters are arranged at the periphery of the primary ultrasound transmitter; the main ultrasonic transmitter is used for transmitting the main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting the frequency calibration signal; the secondary ultrasonic transmitter is used for transmitting the secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency.

Fig. 6 is a flow chart of a first positioning strategy according to the present invention. As shown in fig. 6, the method includes: step 601: calculating the Doppler frequency offset of the main ultrasonic positioning signal transmitted by the ultrasonic transmitting unit which is obviously stronger than the intensity of other ultrasonic positioning signals; step 602: performing frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal which are transmitted by the ultrasonic transmitting unit and have the intensity which is obviously stronger than that of other ultrasonic positioning signals by using the Doppler frequency offset; step 603: selecting three secondary ultrasonic positioning signals from the secondary ultrasonic positioning signals after the frequency offset correction according to the sequence of the signal-to-noise ratio from large to small; step 604: and calculating the coordinates of the intelligent terminal based on the frequency offset corrected main ultrasonic positioning signal and the selected three secondary ultrasonic positioning signals.

As shown in fig. 7, the method includes: step 701: calculating respective Doppler frequency offsets of frequency calibration signals transmitted by at least two ultrasonic transmitting units for transmitting strong ultrasonic positioning signals; step 702: respectively carrying out frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal transmitted by the at least two ultrasonic transmitting units by using respective Doppler frequency offsets; step 703: comparing the signal-to-noise ratios of the main ultrasonic positioning signals of the at least two ultrasonic transmitting units after the frequency offset correction, and selecting the ultrasonic transmitting unit corresponding to the main ultrasonic positioning signal with the largest signal-to-noise ratio as a target ultrasonic transmitting unit; step 704: selecting three secondary ultrasonic positioning signals from the secondary ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit according to the sequence of the signal-to-noise ratio from large to small; step 705: and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signal and the selected three secondary ultrasonic positioning signals after the frequency offset correction of the target ultrasonic transmitting unit.

Fig. 8 is a flow chart of a third positioning strategy according to the present invention. As shown in fig. 8, the method includes:

step 801: calculating respective Doppler frequency offsets of the frequency calibration signals transmitted by all the ultrasonic transmitting units; step 802: respectively carrying out frequency offset correction on the frequency calibration signals transmitted by all the ultrasonic transmitting units by utilizing the respective Doppler frequency offsets; step 803: and calculating the coordinates of the intelligent terminal based on the frequency calibration signals which are corrected by the frequency offset and transmitted by all the ultrasonic transmitting units.

The embodiment of the present invention further provides an ultrasonic positioning apparatus, which includes a processor, a memory, and a computer program stored on the memory and executable on the processor, and when the computer program is executed by the processor, the steps of the ultrasonic positioning method as described in any one of the above are implemented. It should be noted that not all steps and modules in the above flows and structures are necessary, and some steps or modules may be omitted according to actual needs. The execution order of the steps is not fixed and can be adjusted as required. The division of each module is only for convenience of describing adopted functional division, and in actual implementation, one module may be divided into multiple modules, and the functions of multiple modules may also be implemented by the same module, and these modules may be located in the same device or in different devices. The hardware modules in the various embodiments may be implemented mechanically or electronically. For example, a hardware module may include a specially designed permanent circuit or logic device (e.g., a special purpose processor such as an FPGA or ASIC) for performing specific operations. A hardware module may also include programmable logic devices or circuits (e.g., including a general-purpose processor or other programmable processor) that are temporarily configured by software to perform certain operations. The implementation of the hardware module in a mechanical manner, or in a dedicated permanent circuit, or in a temporarily configured circuit (e.g., configured by software), may be determined based on cost and time considerations. The present invention also provides a machine-readable storage medium storing instructions for causing a machine to perform a method as described herein. Specifically, a system or an apparatus equipped with a storage medium on which a software program code that realizes the functions of any of the embodiments described above is stored may be provided, and a computer (or a CPU or MPU) of the system or the apparatus is caused to read out and execute the program code stored in the storage medium. Further, part or all of the actual operations may be performed by an operating system or the like operating on the computer by instructions based on the program code. The functions of any of the above-described embodiments may also be implemented by writing the program code read out from the storage medium to a memory provided in an expansion board inserted into the computer or to a memory provided in an expansion unit connected to the computer, and then causing a CPU or the like mounted on the expansion board or the expansion unit to perform part or all of the actual operations based on the instructions of the program code. Examples of the storage medium for supplying the program code include floppy disks, hard disks, magneto-optical disks, optical disks (e.g., CD-ROMs, CD-R, CD-RWs, DVD-ROMs, DVD-RAMs, DVD-RWs, DVD + RWs), magnetic tapes, nonvolatile memory cards, and ROMs. Alternatively, the program code may be downloaded from a server computer or the cloud by a communication network. The above-listed detailed description is only a specific description of a possible embodiment of the present invention and is not intended to limit the scope of the present invention, and equivalent embodiments or modifications such as combinations, divisions or repetitions of the features without departing from the technical spirit of the present invention are included in the scope of the present invention.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for estimating doppler frequency offset of an ultrasonic locating signal, comprising:

2. The system of claim 1, wherein the number of the ultrasound transmitting units is 4, and the arrangement points of the 4 ultrasound transmitting units form a square.

3. The system for Doppler frequency offset estimation of ultrasonic locating signals according to claim 1,

the intelligent terminal is used for comparing the strength of the frequency calibration signals received from the ultrasonic transmitting units and determining to execute one of the following positioning strategies based on the comparison result: a first positioning strategy in which the intensity of the frequency calibration signal transmitted by one ultrasound transmitting unit is significantly stronger than the intensity of the frequency calibration signals transmitted by the other ultrasound transmitting units; a second positioning strategy that at least two ultrasonic transmitting units transmit strong frequency calibration signals; and a third positioning strategy for mutual mixing of the weak frequency calibration signals transmitted by the at least two ultrasonic transmitting units.

4. The system for Doppler frequency offset estimation of ultrasonic locating signals according to claim 3,

the intelligent terminal is used for:

and when the amplitude of the frequency calibration signal transmitted by each ultrasonic transmitting unit is smaller than a preset fourth threshold, or the difference value of the amplitudes of the frequency calibration signals transmitted by any two ultrasonic transmitting units is smaller than a preset fifth threshold, determining to execute a third positioning strategy.

5. The system for Doppler frequency offset estimation of ultrasonic locating signals according to any one of claims 1 to 4,

and the intelligent terminal is used for performing frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal, and calculating the coordinates of the intelligent terminal based on the main ultrasonic positioning signal after the frequency offset correction and the secondary ultrasonic positioning signal after the frequency offset correction.

6. A Doppler frequency offset estimation method of ultrasonic positioning signals is characterized by being suitable for performing Doppler frequency offset estimation on the ultrasonic positioning signals transmitted by an ultrasonic transmitting unit, wherein the ultrasonic transmitting unit comprises a main transmitting module, a secondary transmitting module and a controller; the main transmitting module comprises a main ultrasonic transmitter and a frequency calibration signal transmitter; the secondary transmitting module comprises at least three secondary ultrasonic transmitters; a primary ultrasound transmitter is arranged at the geometric center of the at least three secondary ultrasound transmitters, and frequency calibration signal transmitters are arranged at the periphery of the primary ultrasound transmitter; the main ultrasonic emitter is used for emitting a main ultrasonic positioning signal; the frequency calibration signal transmitter is used for transmitting a frequency calibration signal; the secondary ultrasonic emitter is used for emitting a secondary ultrasonic positioning signal; the controller is used for controlling the main ultrasonic transmitter, the frequency calibration signal transmitter and the secondary ultrasonic transmitter to simultaneously transmit according to preset frequency; wherein the primary and secondary ultrasonic locating signals are modulated onto a first carrier having a first center frequency; modulating a frequency calibration signal onto a second carrier wave with a second center frequency, wherein the second center frequency is greater than the first center frequency, the first carrier wave and the second carrier wave are not overlapped, and the frequency calibration signal is a narrow-band signal; the method comprises the following steps:

7. The method of estimating Doppler frequency offset of an ultrasonic locating signal of claim 6, further comprising:

and performing frequency offset correction on the main ultrasonic positioning signal and the secondary ultrasonic positioning signal based on the Doppler frequency offset of the main ultrasonic positioning signal and the secondary ultrasonic positioning signal, and calculating the coordinates of the intelligent terminal based on the frequency offset corrected main ultrasonic positioning signal and the frequency offset corrected secondary ultrasonic positioning signal.

8. The method of estimating Doppler frequency offset of an ultrasonic locating signal according to claim 6,

the bandwidth of the first carrier wave is 3KHZ, and the frequency band of the first carrier wave is 17KHz-20 KHz;

and the bandwidth interval of the second carrier wave is [200Hz,500Hz ].

9. The method of estimating Doppler frequency offset of an ultrasonic locating signal according to claim 6,

the number of the second carriers is multiple, a guard interval is arranged between adjacent second carriers, and the bandwidth range of the guard interval is [200Hz, 400Hz ].

10. An apparatus for doppler frequency offset estimation of an ultrasonic locating signal, comprising a processor, a memory and a computer program stored on the memory and executable on the processor, the computer program, when executed by the processor, implementing the steps of the method for doppler frequency offset estimation of an ultrasonic locating signal according to any one of claims 6 to 9.

11. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method of doppler frequency offset estimation of ultrasound localization signals of any of claims 6 to 9.