CN111025355A

CN111025355A - A tower-type indoor positioning system and method based on GPS signal

Info

Publication number: CN111025355A
Application number: CN201910982169.4A
Authority: CN
Inventors: 马建晓; 韩佳乐; 方祥; 田润崧; 李巧娜; 李果
Original assignee: Nanyang Normal University
Current assignee: Henan Rongchuang Xinhe Technology Co ltd
Priority date: 2019-10-16
Filing date: 2019-10-16
Publication date: 2020-04-17
Anticipated expiration: 2039-10-16
Also published as: CN111025355B

Abstract

The invention provides a tower type indoor positioning system and method based on GPS signals, comprising the following steps: the GPS signal receiver, the antenna is a Cassegrain reflector antenna device; the first amplification unit is used for amplifying the signal passing through the GPS signal receiver for the first time; the processing host unit carries out comprehensive processing on the signals subjected to primary amplification and interacts with the pseudo-fixed point base station auxiliary device data; the pseudo-fixed-point base station auxiliary device comprises a plurality of pseudo-reference stations which are uniformly distributed around the circumferential direction of the processing host unit, the pseudo-reference stations are connected with the position of the processing host unit through connecting rods, and the connecting rods are telescopic rods; the second amplifying unit is used for carrying out secondary amplification on the signal processed by the host unit and transmitting the signal to the transmitter; and the transmitter is used for diffusing and distributing the signal indoors on the premise of not influencing the performance of the indoor inherent equipment. The invention can improve the indoor positioning precision by using the only positioning equipment and reduce the influence on the indoor equipment.

Description

Tower type indoor positioning system and method based on GPS signals

Technical Field

The invention relates to the field of GPS positioning, in particular to a tower type indoor positioning system and method based on GPS signals.

Background

The GPS is a short for Global Positioning System (GPS), is mainly applied to planar Positioning navigation, and is composed of 24 GPS satellites with a Global coverage rate as high as 98%. However, under the influence of factors such as weather, buildings, noise and the like, some uncontrollable deviation occurs in the transmission process of the GPS signal, the precision of the GPS signal is also influenced, when the GPS signal penetrates through, spreads and is transmitted to the indoor environment, the signal received by the intelligent equipment is very weak, the generated deviation is also very large, and even the satellite signal cannot be received.

The traditional pseudo satellite positioning method is based on a differential GPS positioning method and mainly comprises a fixed monitoring station with a known position, which receives GPS signals in real time and determines pseudo range errors, the pseudo range errors are provided to a user as correction numbers, and then the user corrects the self-measured pseudo range by the pseudo range errors through intelligent equipment. Thus, the positioning precision within a range of hundreds of kilometers near the monitoring station can be improved to about 5m by adopting proper equipment. However, no matter how the differential GPS improves the navigation accuracy, reliability and integrity, the defects caused by the non-ideal geometry of the satellite constellation cannot be overcome.

Currently, the mainstream indoor positioning technologies mainly include Wi-Fi fingerprint technology, geomagnetic technology, bluetooth technology, infrared technology, radio frequency identification technology, ultra wide band technology, and the like, and these technologies often need support of more hardware devices. Although some technologies achieve indoor high-precision positioning, the installation of equipment is complicated due to different complexity of internal structures of different buildings, the number of equipment is large, the workload of files is large, and the maintenance is inconvenient, so that the indoor high-precision positioning method cannot be widely applied to large-scale buildings.

Indoor positioning technique based on UWB ultra wide band, its positioning accuracy can reach the decimetre level, and the ultra wide band radio has extremely strong penetrability, can be better pierce through the material to building structure. But also because of this property, the technology can have an impact on the performance of the equipment inherent in the room, for example, the hospital's associated therapeutic equipment, which ultra-wideband radio will likely malfunction.

Disclosure of Invention

An object of the present invention is to provide a tower-type indoor positioning system and method based on GPS signals, which improves the accuracy of indoor positioning with a single positioning device, and reduces the influence on the indoor device.

In particular, the present invention provides a tower-type indoor positioning system based on GPS signals, comprising:

the GPS signal receiver is positioned outdoors, and the antenna main body is a Cassegrain reflector antenna device consisting of a main reflector, an auxiliary reflector and a rear feed source;

the first amplification unit is used for carrying out primary amplification on the signal passing through the GPS signal receiver;

the processing host unit is used for carrying out comprehensive processing on the signals subjected to primary amplification and interacting with the pseudo-fixed point base station auxiliary device;

the pseudo-fixed point base station auxiliary device comprises a plurality of pseudo-reference stations which are uniformly distributed around the circumferential direction of the processing host unit, the pseudo-reference stations are connected with the position of the processing host unit through connecting rods, and the connecting rods are telescopic rods;

the second amplification unit is used for carrying out secondary amplification on the signal passing through the processing host unit and transmitting the signal to the transmitter;

and the transmitter is used for diffusing and distributing the signal indoors on the premise of not influencing the performance of the indoor inherent equipment.

Preferably, the three pseudo-reference sites are uniformly distributed in the circumferential direction of the processing host unit, and the three pseudo-reference sites and the processing host unit are located on the same plane.

Preferably, the pseudo reference station is rotatable about the processing host unit to adjust the relative position.

Preferably, the processing host unit includes: the device comprises a host, a receiving unit, a frequency hopping processing unit, a signal processing unit, an anti-interference unit, a monitoring unit and a display screen.

Preferably, the maximum telescopic length of the connecting rod is 5 m.

According to another aspect of the invention, a tower type indoor positioning method based on GPS signals is also disclosed, which comprises the following steps:

s1: the GPS signal receiver receives signals through the Cassegrain reflector antenna device, primarily amplifies the signals through the preamplifier, and obtains low-frequency signals through the receiver host;

s2: amplifying the signal passing through the GPS signal receiver for the first time;

s3: the processing host unit performs comprehensive processing on the signals subjected to primary amplification;

s4: the processing host unit carries out data interaction with a plurality of pseudo-reference stations of the pseudo-fixed point base station auxiliary device to form a pseudo-satellite correction system in a range and generate a new GPS signal;

s5: carrying out secondary amplification on the new GPS signal and transmitting the new GPS signal to a transmitter;

s6: the signal is diffused and distributed indoors on the premise of not influencing the performance of the indoor inherent equipment.

Preferably, the processing main unit in S3 performs integrated processing using a plurality of auxiliary function units, including: the device comprises a receiving unit, a frequency hopping processing unit, a signal processing unit, an anti-interference unit and a monitoring unit.

The tower-type positioning system is combined with the pseudo-satellite correcting system, and the pseudo-satellite correcting system consists of a plurality of pseudo-reference stations and a processing host unit, so that a weak GPS signal can be processed by amplification, de-spreading, modulation and the like, and then passes through the pseudo-satellite correcting system to form a new GPS signal suitable for indoor, thereby improving the indoor positioning precision.

Furthermore, the tower positioning system is also provided with a transmitter, and the new GPS signals after measurement and correction are diffused and distributed indoors through the transmitter. Since the attenuation constant becomes larger and the penetration depth decreases as the wavelength of the signal decreases (i.e., higher frequency signals), the signal dispersion of the transmitter of the present invention can be achieved without affecting the inherent device performance in the room.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a simplified system block diagram of a tower-type indoor positioning system and method according to the present invention;

FIG. 2 is a front view of an external device configuration of a tower-type indoor positioning system according to the present invention;

FIG. 3 is a top view of an external device configuration of a tower-type indoor positioning system according to the present invention;

FIG. 4 is an antenna structure view of the Cassegrain reflector of the present invention;

FIG. 5 is a general schematic diagram of a receiver host unit of the GPS signal receiver of the present invention;

FIG. 6 is a signal path schematic of a receiver host unit of the GPS signal receiver of the present invention;

fig. 7 is a diagram of the present invention processing a frequency hopping spread spectrum output waveform in a host unit.

The symbols in the drawings have the following meanings:

1-a cassegrain reflector antenna arrangement; 101-a sub-reflector; 102-a main reflector; 103-a feed source; 2-a first amplification unit; 3-processing the host unit; 4-a connecting rod; 5-pseudo reference site; 6-a second amplification unit; 7-transmitter.

Detailed Description

The invention is mainly aimed at: firstly, the existing indoor positioning technology can influence the performance of indoor equipment while ensuring the precision diffusion process; secondly, a large amount of hardware equipment is often required to be installed to support the implementation of the related technology due to the complex structure inside the building. A system and a realization method for finishing indoor accurate positioning by means of single equipment on the premise of not influencing indoor inherent equipment are researched.

As shown in fig. 1, the present invention designs a tower-type device for receiving, demodulating, modulating, analyzing, converting, amplifying, correcting and diffusing GPS signals, and mainly achieves the purpose of indoor accurate positioning by means of a single device without affecting the inherent indoor devices through several functions. These large blocks function as: a GPS signal receiver, a first amplification unit 2, a processing host unit 3, a second amplification unit 6, and a transmitter 7.

As shown in fig. 2,3 and 4, the GPS signal receiver is located outdoors for receiving GPS signals. The GPS signal receiver comprises an antenna, a host and a power supply. The antenna body is a Cassegrain reflector antenna device 1 which mainly comprises a main reflector 102, a secondary reflector 101 and a feed source 103. The primary reflector 102 is a parabolic cone and the secondary reflector 101 is a hyperbolic cone. In this embodiment, the feed source 103 is a rear feed source, which can shorten the length of the feed line, reduce noise caused by the transmission line, and convert the very weak electromagnetic wave of the GPS satellite signal into corresponding current. The preamplifier and the post-feed source are hermetically mounted together. The antenna and the preamplifier are sealed into a whole so as to ensure the normal work of the antenna and reduce the signal loss. The receiver main unit has: frequency converter, intermediate frequency receiving amplifier, signal channel, memory, microprocessor, display.

As shown in fig. 5, the GPS signal receiver located outdoors receives and converts a signal efficiently by the cassegrain reflector antenna device 1. According to the principle of the cassegrain reflector antenna, the smaller its eccentricity, the greater the magnification, and usually the magnification M > 3. After passing through the antenna and the preamplifier, the weak electromagnetic pen of the GPS is converted into corresponding current, and then the signal current is amplified. And then the amplified signal is subjected to frequency conversion, despreading and demodulation through a receiver host machine to obtain a navigation message of the received signal. The frequency converter and the intermediate frequency amplifier in the receiver host machine enable the receiver channel to obtain stable high gain and enable the radio frequency signal of the L frequency band to be changed into a low frequency signal.

As shown in the signal channel analysis diagram of fig. 6, the C/a code generator and the P code generator are used to perform despreading and demodulation processing on the low-frequency signal, so as to obtain multiple sets of navigation message D code pseudo code measurement data and carrier phase measurement data. And calculating the time of the GPS signal from the satellite to the receiving antenna in real time, and calculating the three-dimensional position, the three-dimensional speed and the time of the monitoring station. All of the data is stored in the memory of the GPS signal receiver. And finishing data output under the analysis and processing of the microprocessor, displaying the data processed by the microprocessor on a display screen, and observing and controlling the data through a display. Therefore, the GPS signal receiver can be used for carrying out frequency conversion amplification on a received signal, carrying out signal de-spreading modulation, carrying out measurement on a bit code and a carrier phase, carrying out processes such as self-checking, measurement, calculation and the like in a microprocessor, and also carrying out data observation and operation through a display.

The first amplification unit 2 amplifies the signal passing through the GPS signal receiver once for subsequent processing.

The processing host unit 3 performs comprehensive processing on the signal subjected to primary amplification and interacts with the pseudo fixed point base station auxiliary device data. The processing host unit 3 and the pseudo-fixed point base station auxiliary device jointly form a pseudo-satellite correction system. The pseudo fixed point base station assist apparatus has a plurality of pseudo reference stations 5. The processing host unit 3 is the center of the orthotic system. A plurality of pseudo-reference stations 5 are arranged uniformly around the circumference thereof with the processing host unit 3 bit center. In the present embodiment, there are three pseudo reference sites 5, which are angularly offset from each other by 120 °. The pseudo-reference station 5 is connected to the location of the processing master unit 3 by a connecting rod 4. Since the connecting rod 4 is a telescopic rod. The linear distance between the pseudo reference station 5 and the processing master unit 3 is adjustable. The maximum telescopic length of the single connecting rod 4 is 5 meters. Also, the pseudo reference station 5 can also rotate around the processing host unit 3. Therefore, the pseudo reference station 5 can capture signal sources of different point locations, receive different GPS signals in real time, determine a pseudo-range error, and send information to the processing host unit 3 to complete data interaction, thereby measuring and correcting the GPS signals.

Assuming that the propagation time is Ti and the ideal velocity is the speed of light c, the data transmission distance Di can be expressed as: di ═ c × Ti (i ═ 1,2, 3). In addition, the error rate and the base station sensitivity are calculated by combining a WCDMA algorithm. Wherein the radio frequency bandwidth is equal to the chip rate, i.e. 3.84MHz, and a prescribed BER (0.1%) of the bit error rate can be obtained for QPSK modulated signals with a rate of 12.2kbit/s at an Eb/No value of 5 dB. It can be calculated that:

KTBRF(dBm)＝ 10log(1.381×10-23W/Hz/K×290K×3.84MHz×1000mW/W)＝-108dBm

Gp(dB)＝BRF/Rb＝25dB

then, the base station sensitivity: (dBm) NF-108+5-25 NF-128dB

In addition, in order to achieve a dynamic range of 60dB, FDMA, frequency offset, is used to offset the pseudolite signal by approximately 10-20 MHz from the nominal 1575.42MHz, which isolates 25dB of the normal code.

The processing host unit 3 carries out comprehensive processing on the signals and is completed by the host, the receiving unit, the frequency modulation processing unit, the signal processing unit, the anti-interference unit, the monitoring unit and the display screen which form the processing host unit in an auxiliary mode. The processing host unit 3 comprehensively analyzes, processes and monitors data transmitted by the GPS signal receiver and data transmitted by the pseudo-fixed point base station auxiliary device.

Because noise interference is generated in the transmission processing process, an anti-interference unit is added in the processing process to improve the anti-interference performance of the anti-interference unit, and the anti-interference performance is expressed by a processing gain Gp as follows:

the processing gain of the spread spectrum system determines the strength of the anti-interference capability of the system. According to Shannon's theorem, the ratio of the noise power ratio of the input and output signals of the system can be converted into the system spread spectrum bandwidth (B) while keeping the information capacity unchanged_RF) And information bandwidth (B)_b) The ratio of the amount of the water to the amount of the water,or to pseudo code rate (R)_c) And information rate (R)_b) The ratio of. Expressed mathematically as:

wherein R is the transmission rate of the signal, B_RFFor the rf bandwidth of the signal, if there are no additional parameters, the ratio of gp (db): 10lg [ PN code length]The interference resistance of the device is improved through the above processing.

Fig. 7 is a frequency hopping spread spectrum output waveform. For the frequency hopping processing unit, a hybrid spread spectrum technology is adopted, namely direct sequence spread spectrum, frequency hopping spread spectrum, time hopping spread spectrum and linear modulation. Wherein the direct sequence spread spectrum technology and the frequency hopping spread spectrum technology are mainly applied. For direct sequence spread spectrum techniques, the synchronized data signal may be a bit or a binary channel coded symbol, and chips are formed by modulo-2 addition and then phase-shifted modulated. The received spread spectrum signal for a single user may be expressed as:

where m (t) is a data sequence and p (t) is a PN (pseudo noise sequence) spreading sequence. For the frequency hopping spread spectrum technology, the carrier frequency is changed according to the pattern produced by a code sequence by discrete increment, after the digital information and the binary pseudo code sequence are processed by the modulo-2 addition operation, the output frequency of the radio frequency carrier oscillator is controlled discretely, the frequency of the transmitting signal jumps along with the change of the pseudo code, as shown in fig. 7, in the process of transmitting to the receiving unit, the receiving unit is supposed to be synchronized, the received signal passes through the broadband filter, and then multiplied by the PN sequence p (t) produced locally, if p (t) is plus or minus 1, there are:

p^2(t)＝1

obtaining a de-spread signal through multiplication:

S₁t＝A_m(t)cos(2πf_ct+θ)

due to S₁(T) is a BPSK signal, and accordinglyAnd demodulating a data sequence m (t). The anti-interference capability of the system is enhanced through spread spectrum, and the sensitivity formula of the spread spectrum system is as follows:

spread spectrum system sensitivity equation 1:

Sin(dBm)＝NF(dB)+KTB(dBm)+Eb/No(dB)-Gp(dB)

spread spectrum system sensitivity equation 2:

Sin(dBm)＝NF(dB)+KTB(dBm)+SNR(dB)--->SNR＝Sout/Nout(dB)

wherein NF is a noise coefficient, K, T is a boltzmann constant and a kelvin temperature (here, 290K), B is a spread spectrum bandwidth, Eb is a signal energy per bit, N0 is a noise power spectrum density (note different) ═ F × KT, F is a noise coefficient, and Gp is a spread spectrum gain ═ B/R (R ═ user data baud rate), it can be concluded that the codec is effective to reduce Eb/N0, improve system sensitivity, enlarge a radius of coverage, and improve interference rejection.

In the information processing process, the GPS accuracy factor is mainly analyzed, wherein the value range of the position accuracy factor (PDOP) is as follows: 0.5-99.9, which is the root-opening number value of the sum of the squares of errors such as latitude, longitude and elevation, so that the following values are provided:

HDOP²+VDOP²＝PDOP²

the HDOP is a horizontal component precision factor, the VDOP is a vertical component precision factor, and the clock error precision factor TDOP and the geometric precision factor GDOP have the relation:

PDOP²+TDOP²＝GDOP²

the method comprises the following steps of resolving the codes, improving the sensitivity and the real sensitivity, designing an LNA and an input matching circuit with key points at the first stage, matching the LNA input by the lowest noise coefficient, and finding a proper GamaS according to a matching method including a Gt gain circle, an NF noise circle and a stable circle, wherein the matching steps are taken as the matching steps, and in addition, the consideration of the sensitivity is added again to divide the received signal power into a plurality of parts in a refining mode:

patent: signal power received by the antenna, psig: the matched output signal power of the antenna signal, i.e. the signal power before LNA, Psig _ deflect: does not completely match the power reflected back from the LNA, Psig _ LNA: the relationship between the received signal power of the LNA and the received signal power of the LNA is as follows:

psignal [ attenuation factor ] Psig _ LNA + Psig _ reflex

The signal that can be effectively decoded for the system is Psig _ LNA, and the way to increase sensitivity is: the attenuation factor of the signal power from the antenna is reduced, and the reflected power of the LNA input system is reduced.

Therefore, the processing host unit 3 performs data exchange with the plurality of pseudo reference sites 5 of the pseudo-fixed-point base station assist device to form a pseudo-satellite correction system within a range, and generates a new GPS signal. The new GPS signal is then amplified a second time by the second amplification unit 6 and passed to the transmitter 7. The transmitter 7 spreads and distributes the signal indoors without affecting the performance of the equipment inherent in the indoor.

The signal is transmitted and diffused through the transmitter 7, and in the process, the penetration depth of the signal is described as follows according to the Lambert-Beer law to ensure that the signal does not affect the performance of indoor inherent equipment:

wherein

Referred to as light transmittance, equal to T%,

the Lambert-Beer law is related to the signal attenuation constant, which is found α by calculating the attenuation constant, and thus is influenced by the signal wavelength lambda, and thus, as the signal wavelength decreases (i.e., higher frequency signals), the attenuation constant becomes larger and the penetration depth decreases.

In summary, since the GPS signal receiver is combined with the pseudolite correction system, which is composed of a plurality of pseudo reference stations 5 and a processing host unit 3, a weak GPS signal can be processed by amplification, despreading, modulation, and the like, and then the weak GPS signal is processed by the pseudolite correction system to form a new GPS signal suitable for indoor use, thereby improving the accuracy of indoor positioning. The new GPS signals after measurement and correction are diffused and distributed indoors by the transmitter 7. Since the attenuation constant becomes larger and the penetration depth decreases as the wavelength of the signal decreases (i.e., higher frequency signal), the signal dispersion of the transmitter 7 of the present invention can be achieved without affecting the indoor inherent device performance.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. a tower type indoor positioning system based on GPS signal, is characterized in that, comprises:

The GPS signal receiver is located outdoors, and the main body of the antenna is a Cassegrain reflector antenna device composed of a main reflector, a sub-reflector and a rear feedback source;

a first amplifying unit, used to amplify the signal passing through the GPS signal receiver once;

The processing host unit is used to comprehensively process the once amplified signal and perform data exchange with the auxiliary device of the pseudo-fixed-point base station;

A pseudo-fixed-point base station auxiliary device, which includes a plurality of pseudo-reference sites evenly arranged around the circumference of the processing host unit, the pseudo-reference sites are connected with the location of the processing host unit through a connecting rod, and the connecting rod is a telescopic rod;

a second amplifying unit, configured to amplify the signal passing through the processing host unit twice, and transmit it to the transmitter;

Transmitters are used to spread and distribute signals indoors without affecting the performance of inherent indoor equipment.

2 . The tower-type indoor positioning system according to claim 1 , wherein three pseudo-reference sites are evenly distributed in the circumferential direction of the processing host unit, and the three pseudo-reference sites are located on the same plane as the processing host unit. 3 . .

3. The tower-type indoor positioning system according to claim 1 or 2, wherein the pseudo-reference site can be rotated around the processing host unit to adjust the relative position.

4 . The tower-type indoor positioning system according to claim 1 , wherein the processing host unit comprises: a host, a receiving unit, a frequency hopping processing unit, a signal processing unit, an anti-jamming unit, a monitoring unit, and a display screen. 5 .

5. The tower-type indoor positioning system according to claim 1 or 2, wherein the maximum telescopic length of the connecting rod is 5m.

6. a tower type indoor positioning method based on GPS signal, is characterized in that, comprises:

S1: The GPS signal receiver receives the signal through the Cassegrain reflector antenna device, amplifies the signal through the preamplifier, and obtains the low-frequency signal through the receiver host;

S2: amplify the signal passing through the GPS signal receiver once;

S3: The processing host unit comprehensively processes the once amplified signal;

S4: The processing host unit exchanges data with multiple pseudo-reference sites of the pseudo-fixed-point base station auxiliary device, forms a pseudolite correction system within the range, and generates a new GPS signal;

S5: Amplify the new GPS signal twice and transmit it to the transmitter;

S6: Diffuse and distribute signals indoors without affecting the performance of inherent indoor equipment.

7. The tower-type indoor positioning method according to claim 6, wherein the processing host unit in S3 utilizes a plurality of auxiliary function units to perform comprehensive processing, including: a receiving unit, a frequency hopping processing unit, a signal processing unit, a Interference unit, monitoring unit.