CN112147579B - Ultrasonic positioning system based on composite ultrasonic signal - Google Patents
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/18—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using ultrasonic, sonic, or infrasonic waves
- G01S5/30—Determining absolute distances from a plurality of spaced points of known location
Abstract
The invention discloses an ultrasonic positioning system based on a composite ultrasonic signal, which comprises: the device comprises a mobile transmitting beacon and a plurality of fixed receiving beacons, wherein the number of the fixed receiving beacons is not less than 3; the mobile transmitting beacon is used for synchronously transmitting a radio signal and a composite ultrasonic signal, and the composite ultrasonic signal comprises a broadband ranging signal and a carrier coding signal; the device is also used for receiving the distance returned by the fixed receiving beacon and calculating the position of the device by a filtering algorithm based on the measurement confidence and the last positioning result; each fixed receiving beacon is used for receiving a radio signal and a composite ultrasonic signal, calculating the flight time of the ultrasonic by utilizing a cross-correlation algorithm, and calculating the compensating sound velocity by utilizing temperature and humidity compensation, thereby calculating the distance between the fixed receiving beacon and the mobile transmitting beacon; the range is transmitted back over the air to the mobile transmitting beacon.
Description
Technical Field
The invention relates to the field of ultrasonic positioning, in particular to an ultrasonic positioning system based on a composite ultrasonic signal.
Background
Compared with other base station positioning systems, ultrasonic waves can provide real-time centimeter-level positioning due to the principle, and the positioning mode has the greatest advantage. However, at present, no mature and stable ultrasonic positioning product which can be applied in a large scale exists. The existing ultrasonic positioning system often faces the problems of unstable positioning precision, low positioning frequency, short measuring distance, poor anti-interference capability, unstable system and the like. Especially in positioning in a large scene, factors such as multiple propagation paths in a complex environment, a time-varying propagation process, noise of a self transceiving circuit and the like cause signal deformation, signal to noise ratio reduction, multiple paths of fading and the like, which are reflected in the solution of a ranging and positioning algorithm, thereby influencing the positioning result of the system. The ultrasonic ranging method is mainly characterized in that the ultrasonic signal form is too single, the contained information amount is too small, and meanwhile, the ranging algorithm is too simple in structure and cannot resist complex time-varying environments.
Disclosure of Invention
The invention aims to overcome the technical defects and provides an indoor positioning system based on a composite ultrasonic signal, which has the four technical characteristics of high precision, high robustness, high frequency and high concurrency, realizes centimeter-level positioning in a complex environment through an algorithm and temperature compensation, and supports simultaneous positioning of multiple beacons.
In order to achieve the above object, the present invention provides an ultrasonic positioning system based on composite ultrasonic signals, the system comprising: the device comprises a mobile transmitting beacon and a plurality of fixed receiving beacons, wherein the number of the fixed receiving beacons is not less than 3;
the mobile transmitting beacon is used for synchronously transmitting a radio signal and a composite ultrasonic signal, and the composite ultrasonic signal comprises a broadband ranging signal and a carrier coding signal; the device is also used for receiving the distance returned by the fixed receiving beacon and calculating the position of the device by a filtering algorithm based on the measurement confidence and the last positioning result;
each fixed receiving beacon is used for receiving a radio signal and a composite ultrasonic signal, calculating the flight time of the ultrasonic by utilizing a cross-correlation algorithm, and calculating the compensating sound velocity by utilizing temperature and humidity compensation, thereby calculating the distance between the fixed receiving beacon and the mobile transmitting beacon; the range is transmitted back over the air to the mobile transmitting beacon.
As an improvement of the above system, the mobile transmit beacon comprises: the device comprises a signal generation module, a first radio module, an ultrasonic transducer, a positioning module, a first wireless communication module and a first temperature measurement module;
the signal generation module is used for generating a broadband ranging signal, generating a unique identification code of a frame according to the hardware number of the beacon and the current time, and obtaining a carrier coded signal through CDMA coding and IQ modulation; synthesizing the broadband ranging signal and the carrier coded signal into a composite ultrasonic signal, and outputting the composite ultrasonic signal to an ultrasonic transducer; and is also used for synchronously sending a radio signal containing the identification code to the radio module;
the ultrasonic transducer is used for transmitting the composite ultrasonic signal;
the radio module is used for transmitting radio signals and receiving radio signals containing ranging information returned by each fixed receiving module;
the positioning module is used for calculating self position information according to the received 3 or more distance measuring information;
the temperature measuring module is used for measuring the temperature of the temperature measuring module and sending the temperature through the wireless communication module.
As an improvement of the above system, the wideband ranging signal is a chirp signal, a pseudo random signal, a dual-frequency differential signal or a single-frequency pulse signal.
As an improvement of the above system, the specific implementation process of the positioning module is as follows:
converting each ranging data into positioning information in a three-dimensional space;
when 3 or more pieces of ranging information are received, a mathematical model is established by using a space geometric relation, and then a nonlinear solver is used for calculating to obtain the estimation of the target position;
and inputting the current estimation result and the result of the previous moment into a Kalman filter to obtain the optimal estimation and the variance of the current position, wherein the variance is the confidence coefficient of the current positioning result.
As an improvement of the above system, the fixed reception beacon comprises: the system comprises a second radio module, an omnidirectional pickup, a sampling module, a signal matching module, a signal processing module, a second wireless communication module and a second temperature measuring module;
the second wireless module is used for receiving a wireless signal and outputting the wireless signal to the signal processing module;
the omnidirectional sound pickup is used for receiving the mixed composite ultrasonic signal and outputting the mixed composite ultrasonic signal to the sampling module;
the sampling module is used for amplifying and filtering the aliasing composite ultrasonic signals, sampling the analog signals by using AD (analog-to-digital) with a sampling rate of 1M, and sending the sampled aliasing composite ultrasonic signals to the signal processing module;
the signal matching module is used for separating the mixed composite ultrasonic signals by using the radio signals to obtain single-frame composite ultrasonic signals corresponding to all the received radio signals;
the signal processing module is used for processing a radio signal, a composite ultrasonic signal, the temperature of the signal processing module and the temperature of a mobile transmitting beacon to obtain the distance measurement information of a local mobile transmitting beacon;
the second wireless communication module is used for sending the received temperature of the mobile transmitting beacon to the signal processing module;
and the second temperature measuring module is used for measuring the temperature of the second temperature measuring module and sending the measured temperature to the signal processing module.
As an improvement of the above system, the specific implementation process of the signal matching module includes:
step S1) generating a composite ultrasonic signal corresponding to each code according to the code information in the currently received radio signal, and using the composite ultrasonic signal as a template signal, thereby generating a plurality of template signals;
step S2) carrying out matched filtering on the plurality of template signals and the received aliasing compound ultrasonic signals to obtain a plurality of corresponding matching functions;
step S3), taking the peak value of the matching function as the matching degree, when all the matching degrees do not exceed a given threshold value, namely the residual signals do not contain any effective information, turning to step S5), otherwise, taking the signal with the highest matching degree as the main signal in the current signal, enhancing the main signal and eliminating the interference of other non-main signals to obtain a group of single-frame composite ultrasonic signals, and entering step S4);
step S4) removing the template signal corresponding to the main signal from the plurality of template signals, and turning to step S2);
step S5) outputs a plurality of independent sets of single-frame composite ultrasonic signals.
As an improvement of the above system, the signal processing module includes: the device comprises a broadband ranging signal intercepting unit, a self-adaptive filter, a cross-correlation calculation time delay unit, a sound velocity compensation unit and a distance calculation unit;
the intercepting broadband ranging signal unit is used for intercepting a broadband ranging signal in a single-frame composite ultrasonic signal and sending the intercepted broadband ranging signal to the adaptive filter;
the adaptive filter is used for processing the broadband ranging signal by utilizing an LMS adaptive filtering algorithm and sending the processed broadband ranging signal to the cross-correlation calculation time delay unit;
the cross-correlation calculation time delay unit is used for taking the time of radio reception as the transmission time of the ranging signal, carrying out cross-correlation operation on the ranging signal transmitted at the moment and the received ranging signal, carrying out envelope detection on the result, finding a value exceeding a certain threshold value or a maximum value on the relevant envelope as ultrasonic signal time delay, and outputting the ultrasonic signal time delay to the distance calculation unit;
the sound velocity compensation unit is used for averaging the temperature of the received mobile transmitting beacon and the temperature measured by the mobile transmitting beacon to obtain an average temperature, and calculating a compensation sound velocity c by using the average temperature:
wherein gamma is a gas insulation index and a dimensionless coefficient, R is a universal gas constant, T is an average temperature, and mu is a gas molar mass;
and the distance calculation unit is used for multiplying the ultrasonic signal time delay by the compensated sound velocity to serve as the ranging information between the beacon and the mobile transmitting beacon.
The invention has the advantages that:
the system has the four technical characteristics of high precision, high robustness, high frequency and high concurrency, and centimeter-level positioning in a complex environment is realized through a positioning algorithm and temperature compensation, and simultaneous positioning of multiple beacons is supported.
Drawings
FIG. 1 is a positioning flow chart of the present invention;
FIG. 2 is a schematic diagram of a composite ultrasonic signal;
fig. 3 is a block diagram of a mobile transmitting beacon of the present invention;
fig. 4 is a signal transmission flow diagram of a mobile transmission beacon of the present invention;
FIG. 5 is a schematic diagram of signal modulation;
FIG. 6 is a flow chart of the positioning of a mobile transmitting beacon of the present invention;
fig. 7 is a schematic illustration of the positioning of mobile transmitting beacons of the present invention;
FIG. 8 is a block diagram of a fixed-receiver beacon of the present invention;
fig. 9 is a signal reception flow chart of a fixed reception beacon according to the present invention;
FIG. 10 is a schematic illustration of a stationary beacon of the present invention receiving multiple composite ultrasonic signals;
FIG. 11 is a schematic diagram of the present invention for decomposing an aliased composite ultrasonic signal into a plurality of single-frame composite ultrasonic signals;
FIG. 12 is a schematic of the cross-correlation algorithm of the present invention.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.
The technical scheme of the invention is as follows: firstly, arranging a plurality of fixed receiving beacons in a scene in advance, synchronously transmitting a radio signal and a composite ultrasonic signal through a mobile transmitting beacon, and starting timing after the fixed receiving beacon receives the radio signal until the ultrasonic signal is received. And obtaining the flight time of the ultrasonic wave by using a cross-correlation algorithm, compensating the sound velocity by using a temperature and humidity compensation and difference average method, and multiplying the sound velocity by the time to obtain the distance between the fixed receiving beacon and the mobile transmitting beacon. The ranging results are then transmitted back over the radio to the mobile (transmitting) beacon. And (3) carrying out triangular positioning on the mobile (transmitting) beacon according to the received measuring distance, and calculating the position of the label by a filtering algorithm by virtue of the measuring confidence coefficient and the last positioning result. As shown in fig. 1.
As shown in fig. 2, the composite ultrasonic signal designed by the present invention is composed of two parts, one part is a wideband ranging signal, and the other part is a coded signal containing information such as an ID number and a time number. The broadband signal can be a chirp signal, a pseudo-random signal, a rectangular pulse signal or other ranging signals, the signal bandwidth is large, the autocorrelation result is close to the impulse response, and the accuracy and the stability of ranging can be ensured. The coded signals are used for distinguishing signals sent by different time instants and different beacons, and the coding can adopt frequency modulation and phase modulation modes. Considering that the bandwidth of the ultrasonic probe is narrow, signals are easy to generate aliasing if arriving at the same time, and cannot be distinguished. Under the condition of not increasing bandwidth, the problem is solved by means of CDMA technology, the stability of the system is improved, the error rate is reduced, and the anti-multipath capability is improved.
The invention provides an ultrasonic positioning system based on a composite ultrasonic signal, which comprises: the device comprises a mobile transmitting beacon and a plurality of fixed receiving beacons, wherein the number of the fixed receiving beacons is not less than 3; the number of the mobile transmitting beacons can be 1 or more, and the simultaneous positioning of the plurality of mobile transmitting beacons can be realized simultaneously.
As shown in fig. 3, the mobile transmitting beacon includes a signal generating module, a first radio module, an ultrasonic transducer, a positioning module, a first wireless communication module and a first temperature measuring module;
the signal transmission process of the mobile transmission beacon is shown in fig. 4, and the signal generation module selects a suitable wideband ranging signal, such as a Chirp (Chirp) signal, a pseudo random signal, a dual-frequency differential signal, a single-frequency pulse signal, and the like. The chirp signal and the pseudo-random signal are wider in bandwidth, and the ranging is more stable. And generating a unique identification code of the frame according to the hardware number of the label and the current time, and then obtaining a carrier coded signal through CDMA coding and IQ modulation. And synthesizing the broadband signal and the carrier coded signal into a complete signal, outputting the complete signal to an ultrasonic transducer, and sending an ultrasonic signal. The radio signals containing the identification codes are synchronously transmitted by the first radio module.
The signal encoding includes: start bit, ID number, sequence number, and check bit, as shown in table 1:
TABLE 1
| Start bit | ID number | Sequence number | Check bit |
Spread spectrum modulation uses Code Division Multiple Access (CDMA) techniques to spread the data obtained by signal coding using pseudo-random codes, which greatly broadens the spectrum of the signal. Each transmitting end modulates the transmitted signal with different, mutually orthogonal address codes. At the receiving end, the orthogonality of the code patterns is utilized, and corresponding signals are selected from the mixed signals through matched filtering, multi-signal detection, signal enhancement and the like.
As shown in fig. 5, signal modulation typically includes amplitude modulation, frequency modulation, and phase modulation. The error rate of the amplitude-modulated signal is relatively high in consideration of the decay of the ultrasonic waves in the air. Ultrasonic transducers are generally narrow in bandwidth and are not well suited for frequency modulation. Compared with the prior art, the phase modulation is more suitable for an ultrasonic carrier system, particularly IQ modulation, the frequency spectrum utilization rate is high, and the modulated communication frequency can reach 4 KByte/s. Two paths of carriers in IQ modulation are orthogonal with each other, have the same frequency and 90-degree phase difference, and generally use sin and cos signals. The coded signals are input from the I path and the Q path and multiplied by the two paths of carrier signals to obtain modulated coded signals.
As shown in fig. 6, the positioning module converts the ranging data between beacons into positioning information in a three-dimensional space. The fixed beacon sends out the ranging result through a radio signal, and the mobile beacon receives and unpacks the position of the fixed beacon and the distance from the fixed beacon. When 3 or more fixed beacon ranging information is received, triangulation positioning can be carried out, otherwise, the waiting is continued. The so-called triangulation is to use 3 or more positioning beacons to detect the target position at different positions, use a space geometric relationship to establish a mathematical model, and then use a non-linear solver, such as gradient descent, Newton iteration, steepest descent, etc., to calculate and obtain the estimation of the target position. And inputting the current estimation result and the result of the previous moment into a Kalman filter, so as to obtain the optimal estimation and the variance of the current position. The variance can be considered as the degree of reliability, i.e. confidence, of the current localization result.
As shown in fig. 7, in a scenario with four fixed receiving beacons and one mobile transmitting beacon, the positioning formula of the mobile transmitting beacon is as follows:
as shown in fig. 8, the fixed receiving beacon includes a second radio module, an omnidirectional microphone, a sampling module, a signal receiving module, a signal processing module, a second wireless communication module, and a second temperature measuring module.
The signal receiving flow of the fixed receiving beacon is as shown in fig. 9, after the omnidirectional pickup collects the ultrasonic signal, the signal is amplified and filtered in the sampling module, and the analog signal is collected by using the AD of 1M sampling rate. Considering the case that a plurality of mobile beacons simultaneously transmit ultrasonic signals, the positions of the mobile beacons are different, and the time of arrival of a certain fixed beacon is different. At this time, the ultrasonic signal received by the fixed beacon is superposed by a plurality of ultrasonic signals with different time delays.
The mobile transmitting beacon sends the same number information through two channels of radio and ultrasonic. This number is uniquely determined with respect to the time and the ID of the transmitting tag. The radio signal must arrive before the ultrasonic signal. At the receiving end, it is possible to receive the radio signals transmitted by a plurality of mobile transmitting beacons simultaneously, and then receive the ultrasonic signals formed by mixing a plurality of ultrasonic signals. As shown in fig. 10.
As shown in fig. 11, in order to separate a group of aliased ultrasonic signals into a plurality of groups of independent ultrasonic signals, multiple signal detection and identification are required, and the specific processing procedure of the signal matching module includes:
step S1) generating a composite ultrasonic signal corresponding to each code according to the code information in the currently received radio signal, and using the composite ultrasonic signal as a template signal, thereby generating a plurality of template signals;
step S2) carrying out matched filtering on the plurality of template signals and the received aliasing compound ultrasonic signals to obtain a plurality of corresponding matching functions;
step S3), taking the peak value of the matching function as the matching degree, when all the matching degrees do not exceed a given threshold value, namely the residual signals do not contain any effective information, turning to step S5), otherwise, taking the signal with the highest matching degree as the main signal in the current signal, enhancing the main signal and eliminating the interference of other non-main signals to obtain a group of single-frame composite ultrasonic signals, and entering step S4);
step S4) removing the template signal corresponding to the main signal from the plurality of template signals, and turning to step S2);
step S5) outputs a plurality of independent sets of single-frame composite ultrasonic signals.
After the separated single-frame composite ultrasonic signal is obtained, a broadband ranging signal in front of the coded signal is intercepted, and the signal-to-noise ratio of the signal is improved by utilizing an LMS adaptive filter. And then, solving the ultrasonic flight time delay by utilizing a cross-correlation operation, envelope detection and peak searching algorithm.
And performing cross-correlation operation, namely performing cross-correlation operation on the transmitted broadband ranging signal and the received ranging signal, and performing envelope detection on a result. Finding the time delay exceeding a certain threshold or the maximum value on the relevant envelope is the ultrasonic signal time delay (as shown in fig. 12), and multiplying the time delay by the sound velocity to obtain the distance.
When calculating the distance, the speed of sound is generally considered to be 340 m/s. In practice, the speed of sound is not constant, but depends on the temperature, humidity and pressure of the air, wherein the temperature is the most influential factor. In order to obtain a more accurate distance measurement, the temperature of the air needs to be compensated. In the temperature compensation, the mobile (transmitting) beacon transmits the temperature value measured by the mobile (transmitting) beacon to the fixed (receiving) beacon by radio. The measured temperature of the fixed (receiving) beacon receiving the mobile (transmitting) beacon is averaged with the self-measured temperature to obtain an average temperature. The average temperature is used for compensating the sound velocity, and the specific formula is as follows:
wherein gamma is a gas insulation index and a dimensionless coefficient, R is a general gas constant, T is the temperature under an absolute temperature scale, and mu is the gas molar mass.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (4)
1. An ultrasonic positioning system based on composite ultrasonic signals, the system comprising: the device comprises a mobile transmitting beacon and a plurality of fixed receiving beacons, wherein the number of the fixed receiving beacons is not less than 3;
the mobile transmitting beacon is used for synchronously transmitting a radio signal and a composite ultrasonic signal, and the composite ultrasonic signal comprises a broadband ranging signal and a carrier coding signal; the device is also used for receiving the distance returned by the fixed receiving beacon and calculating the position of the device by a filtering algorithm based on the measurement confidence and the last positioning result;
each fixed receiving beacon is used for receiving a radio signal and a composite ultrasonic signal, calculating the flight time of the ultrasonic by utilizing a cross-correlation algorithm, and calculating the compensating sound velocity by utilizing temperature and humidity compensation, thereby calculating the distance between the fixed receiving beacon and the mobile transmitting beacon; transmitting the range back over the air to the mobile transmitting beacon;
the mobile transmit beacon comprises: the device comprises a signal generation module, a first radio module, an ultrasonic transducer, a positioning module, a first wireless communication module and a first temperature measurement module;
the signal generation module is used for generating a broadband ranging signal, generating a unique identification code of a frame according to the hardware number of the beacon and the current time, and obtaining a carrier coded signal through CDMA coding and IQ modulation; synthesizing the broadband ranging signal and the carrier coded signal into a composite ultrasonic signal, and outputting the composite ultrasonic signal to an ultrasonic transducer; and is also used for synchronously sending a radio signal containing the identification code to the radio module;
the ultrasonic transducer is used for transmitting the composite ultrasonic signal;
the radio module is used for transmitting radio signals and receiving radio signals containing ranging information returned by each fixed receiving module;
the positioning module is used for calculating self position information according to the received 3 or more distance measuring information;
the temperature measuring module is used for measuring the temperature of the temperature measuring module and sending the temperature through the wireless communication module;
the fixed receive beacon comprises: the system comprises a second radio module, an omnidirectional pickup, a sampling module, a signal matching module, a signal processing module, a second wireless communication module and a second temperature measuring module;
the second wireless module is used for receiving a wireless signal and outputting the wireless signal to the signal processing module;
the omnidirectional sound pickup is used for receiving the mixed composite ultrasonic signal and outputting the mixed composite ultrasonic signal to the sampling module;
the sampling module is used for amplifying and filtering the aliasing composite ultrasonic signals, sampling the analog signals by using AD (analog-to-digital) with a sampling rate of 1M, and sending the sampled aliasing composite ultrasonic signals to the signal processing module;
the signal matching module is used for separating the mixed composite ultrasonic signals by using the radio signals to obtain single-frame composite ultrasonic signals corresponding to all the received radio signals;
the signal processing module is used for processing a radio signal, a composite ultrasonic signal, the temperature of the signal processing module and the temperature of a mobile transmitting beacon to obtain the distance measurement information of a local mobile transmitting beacon;
the second wireless communication module is used for sending the received temperature of the mobile transmitting beacon to the signal processing module;
the second temperature measuring module is used for measuring the temperature of the second temperature measuring module and sending the measured temperature to the signal processing module;
the specific processing procedure of the signal matching module comprises the following steps:
step S1) generating a composite ultrasonic signal corresponding to each code according to the code information in the currently received radio signal, and using the composite ultrasonic signal as a template signal, thereby generating a plurality of template signals;
step S2) carrying out matched filtering on the plurality of template signals and the received aliasing compound ultrasonic signals to obtain a plurality of corresponding matching functions;
step S3), taking the peak value of the matching function as the matching degree, when all the matching degrees do not exceed a given threshold value, namely the residual signals do not contain any effective information, turning to step S5), otherwise, taking the signal with the highest matching degree as the main signal in the current signal, enhancing the main signal and eliminating the interference of other non-main signals to obtain a group of single-frame composite ultrasonic signals, and entering step S4);
step S4) removing the template signal corresponding to the main signal from the plurality of template signals, and turning to step S2);
step S5) outputs a plurality of independent sets of single-frame composite ultrasonic signals.
2. The ultrasonic positioning system based on the composite ultrasonic signal of claim 1, wherein the broadband ranging signal is a chirp signal, a pseudo-random signal, a dual-frequency differential signal or a single-frequency pulse signal.
3. The ultrasonic positioning system based on the composite ultrasonic signal as claimed in claim 2, wherein the positioning module is implemented by the following steps:
converting each ranging data into positioning information in a three-dimensional space;
when 3 or more pieces of ranging information are received, a mathematical model is established by using a space geometric relation, and then a nonlinear solver is used for calculating to obtain the estimation of the target position;
and inputting the current estimation result and the result of the previous moment into a Kalman filter to obtain the optimal estimation and the variance of the current position, wherein the variance is the confidence coefficient of the current positioning result.
4. The composite ultrasonic signal-based ultrasonic positioning system of claim 1, wherein the signal processing module comprises: the device comprises a broadband ranging signal intercepting unit, a self-adaptive filter, a cross-correlation calculation time delay unit, a sound velocity compensation unit and a distance calculation unit;
the intercepting broadband ranging signal unit is used for intercepting a broadband ranging signal in a single-frame composite ultrasonic signal and sending the intercepted broadband ranging signal to the adaptive filter;
the adaptive filter is used for processing the broadband ranging signal by utilizing an LMS adaptive filtering algorithm and sending the processed broadband ranging signal to the cross-correlation calculation time delay unit;
the cross-correlation calculation time delay unit is used for taking the radio receiving time as the transmitting time of the ranging signal, carrying out cross-correlation operation on the ranging signal transmitted by the transmitting time and the received ranging signal, carrying out envelope detection on the result, finding a value exceeding a certain threshold value or a maximum value on the related envelope as the time delay of the ultrasonic signal, and outputting the time delay to the distance calculation unit;
the sound velocity compensation unit is used for averaging the temperature of the received mobile transmitting beacon and the temperature measured by the mobile transmitting beacon to obtain an average temperature, and calculating a compensation sound velocity c by using the average temperature:
wherein gamma is a gas insulation index and a dimensionless coefficient, R is a universal gas constant, T is an average temperature, and mu is a gas molar mass;
and the distance calculation unit is used for multiplying the ultrasonic signal time delay by the compensated sound velocity to serve as the ranging information between the fixed receiving beacon and the mobile transmitting beacon which the ultrasonic signal time delay belongs to.
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| CN113820695A (en) * | 2021-09-17 | 2021-12-21 | 深圳市睿联技术股份有限公司 | Ranging method and apparatus, terminal system, and computer-readable storage medium |
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