CN102841364A - GPS (global position system) velocity measurement implementation method and GPS velocity meter - Google Patents

Abstract

The invention discloses a GPS (global position system) velocity measurement implementation method and a GPS velocity meter. A host computer finishes the setting of a motion scene and other control parameters according to a velocity measurement requirement of a user and transmits the set parameters to a GPS velocity meter by a serial port; and the GPS velocity meter is composed of a base-band signal processing unit, an AD (analog/digital) unit and a radio frequency unit. The base-band signal processing unit is based on a DSP (digital signal processor) and FPGA (field programmable gate array) software radio platform, a module simulates user motion state and track according to the set parameters transmitted from the host computer, then a GPS middle-frequency digital signal is generated via navigation message encoding, spread spectrum modulation and carrier wave modulation, is converted into a middle-frequency analog signal by the AD unit, and then is converted into a GPS analog radio signal by the radio frequency unit; a GPS receiver receives the analog signal in real time so as to realize receiver velocity measurement; a receiver velocity measurement result is compared with an analog user speed by using host computer software, a velocity measurement statistics file or report form is generated, and thus, the estimation of the receiver velocity measurement precision is realized finally, and a velocity measurement standard is provided for the GPS receiver.

Description

GPS test the speed implementation method and GPS knotmeter

Technical field

The present invention relates to the gps satellite navigation field, be specifically related to a kind of GPS test the speed implementation method and GPS knotmeter.

Background technology

GPS is widely used in fields such as aviation and marine navigation, automobile navigation and scheduling, geodetic surveying, marine charting, agricultural, military affairs owing to have characteristics such as round-the-clock, high precision, robotization and high benefit.GPS of USA is owing to develop early, and GPS has occupied most markets that satellite navigation is used, and portion surpasses 95%.Along with the development of GPS chip, present GPS receiver development is rapid, and receiver is that indexs such as volume, power consumption, sensitivity, precision have all had very big lifting.Though; The GPS receiver has been used for all trades and professions; In traffic administrations such as vehicle, shipping, brought into play huge effect especially, still, testing the speed of GPS receiver but do not have unified standard; Each tame unit is only demarcated from the index that tests the speed of grinding receiver with the standard of oneself, and this demarcates for testing the speed of GPS receiver and has brought difficulty.

Summary of the invention

Technical matters to be solved by this invention provides a kind of GPS test the speed implementation method and GPS knotmeter, and it can provide the standard of testing the speed for the GPS receiver.

Inventive concept of the present invention is: according to user's requirement of testing the speed, host computer is accomplished moving scene and is provided with other controlled variable, and issues the GPS knotmeter through serial ports; The GPS knotmeter is to be made up of baseband signal processing unit, AD unit and radio frequency unit.Wherein, Baseband signal processing unit is based on the DSP+FPGA Software Radio platform; This module is provided with parameter according to what host computer transmitted, and analog subscriber motion state and track generate the GPS digital intermediate frequency signal after navigation message coding, band spectrum modulation and carrier modulation; The GPS digital intermediate frequency signal is analog intermediate frequency signal after the conversion of AD unit, is the GPS analog radio-frequency signal again after the radio frequency unit conversion; This simulating signal that the GPS receiver receives in real time realizes that receiver tests the speed; The result that tests the speed compares through the user velocity of upper computer software and simulation receiver; And generation rate accuracy statistics file or form; Thereby the assessment of the receipts that finally achieve a butt joint machine rate accuracy is for the GPS receiver provides the velocity survey standard.

For addressing the above problem, the present invention realizes through following technical scheme:

A kind of GPS implementation method that tests the speed comprises the steps:

1. the DSP processing module of GPS knotmeter is according to the user movement scene of host computer setting, and simulation also generates subscriber simulation movement locus constantly; Navigation message according to host computer is sent extracts ephemeris parameter, accomplishes the coding of gps navigation message; Calculate the positional information of satellite according to the ephemeris parameter that extracts; And the subscriber simulation movement locus constantly of combination generation; Whether the prediction gps satellite is visible, and then calculates the original carrier phase place and initial pseudo-code phase of whole visible satellites at the satellite-signal delivery time;

2. the FPGA processing module of GPS knotmeter is assigned to corresponding signal with every visible satellite and generates passage; Each passage generates corresponding carrier wave and pseudo-code signal according to the frequency information of assigned visible satellite again; The carrier wave and the pseudo-code that at last each passage are generated are modulated on the synchronous navigation message, generate the GPS digital intermediate frequency signal;

3. the D/A converter module of GPS knotmeter changes the GPS digital intermediate frequency signal that 3. step generates into the GPS analog intermediate frequency signal; This GPS analog intermediate frequency signal is converted to the standard radio frequency frequency of GPS through the up-conversion module, and exports to the GPS receiver through emitting antenna or radio-frequency cable;

4. GPS receiver reception GPS knotmeter is the radiofrequency signal that 4. step launches, and carries out velocity calculated, and is dealt into the result that tests the speed on the host computer;

5. host computer receives that the GPS receiver returns the user's analog rate that result and GPS knotmeter feed back that tests the speed, and both are compared and add up; To compare at last and form the assessment file that tests the speed with statistics and store, the final completion GPS receiver test the speed result's assessment and demarcation.

Above-mentioned steps 1. described in the user movement scene set of host computer comprise motion morphology and the motor pattern of setting the user.

Above-mentioned motion morphology is straight line, curve or circle; Above-mentioned motor pattern at the uniform velocity, even quicken or become to quicken.

As the improvement of such scheme, also record the velocity error parameter σ of GPS receiver in the 6. said assessment file that tests the speed of step, promptly

$\mathrm{\σ}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(v_i-u_i)}^2}{n}}---\left(1\right)$

In the formula, v _iIt is i user's analog rate value of GPS knotmeter feedback constantly; u _iIt is the structured value that tests the speed that i moment GPS receiver returns; N is an observation frequency.

A kind of GPS knotmeter, mainly by power module, and the DSP processing module that links to each other with power module, FPGA processing module, D/A converter module and up-conversion module are formed; The FPGA processing module is connected with host computer; DSP processing module and FPGA processing module interconnect; The output terminal of FPGA processing module connects the up-conversion module via D/A converter module; Be connected to emitting antenna or radio-frequency cable on the up-conversion module; Wherein,

The DSP processing module, according to the user movement scene that host computer is set, simulation also generates subscriber simulation movement locus constantly; Navigation message according to host computer is sent extracts ephemeris parameter, accomplishes the coding of gps navigation message; Calculate the positional information of satellite according to the ephemeris parameter that extracts; And the subscriber simulation movement locus constantly of combination generation; Whether the prediction gps satellite is visible, and then calculates the original carrier phase place and initial pseudo-code phase of whole visible satellites at the satellite-signal delivery time;

The FPGA processing module is assigned to corresponding signal with every visible satellite and generates passage; Each passage generates corresponding carrier wave and pseudo-code signal according to the frequency information of assigned visible satellite again; The carrier wave and the pseudo-code that at last each passage are generated are modulated on the synchronous navigation message, generate the GPS digital intermediate frequency signal;

D/A converter module is sent in the up-conversion module after changing the GPS digital intermediate frequency signal that generates into the GPS analog intermediate frequency signal;

The up-conversion module is converted to the standard radio frequency frequency of GPS with the GPS analog intermediate frequency signal, and exports to the GPS receiver through emitting antenna or radio-frequency cable.

In the such scheme, above-mentioned FPGA processing module is connected with host computer through serial communication modular.

Compared with prior art, the present invention has following characteristics:

1, the simulation of GPS knotmeter produces the various moving scenes of user; And generate the radiofrequency signal that the GPS receiver antenna receives in real time according to simulation time; The GPS receiver receives the simulating signal that the GPS knotmeter generates, and accomplishes user's real-time speed and measures, and the user velocity of GPS knotmeter simulation and the result that tests the speed of GPS receiver are unified in statistics and assessment on the host computer; And deposit comparison result and assessment result with the form of form or file, so that realize the demarcation of testing the speed of GPS receiver.

2, the GPS knotmeter can be simulated multiple user movement scene, can demarcate the speed of user under the different motion situation; Compare with the common GPS simulator; GPS knotmeter in the present invention's design not only can be realized GPS simulator all functions; Can also be according to the user movement pattern of host computer setting; Produce corresponding moving scene; And postpone the radiofrequency signal that receives of generation receiver antenna after NCO generations, carrier wave NCO generations, information coding, signal modulation, AD and the up-conversion of calculating, satellite position and speed calculation, sign indicating number via satellite launch time, and after the GPS receiver receives this signal, the calculating of completion user's real-time speed.

Description of drawings

Fig. 1 is a kind of GPS of the present invention implementation method application example figure that tests the speed.

Fig. 2 is a kind of GPS knotmeter.

Embodiment

Referring to Fig. 1, a kind of GPS velocity-measuring system mainly is made up of host computer, GPS knotmeter and GPS receiver to be measured.Wherein host computer interconnects through serial ports and GPS knotmeter; The output terminal of GPS knotmeter is connected with the input end of GPS receiver; The output terminal of GPS receiver connects host computer.Host computer is accomplished moving scene through upper computer software and is provided with other controlled variable, and issues the GPS knotmeter through serial ports; Accomplish the generation of GPS radiofrequency signal after these parameters of GPS knotmeter reception, the GPS radiofrequency signal of generation is input to the GPS receiver through antenna or radio-frequency cable; The GPS receiver receives this signal, accomplishes testing the speed of receiver, and is dealt into the result that tests the speed on the host computer through serial ports; Host computer also receives the user's analog rate from the GPS knotmeter simultaneously; These two groups of data are deposited with the mode of form or file; Through the comparison to two groups of data, the method for adding up with mass data obtains the mean square deviation that the GPS receiver tests the speed, thereby accomplishes the demarcation that the GPS receiver is tested the speed.

Above-mentioned GPS knotmeter is mainly by power module, and the DSP processing module that links to each other with power module, FPGA processing module, D/A converter module and up-conversion module are formed.The FPGA processing module is connected with host computer through serial communication modular; DSP processing module and FPGA processing module interconnect; The output terminal of FPGA processing module connects the up-conversion module via D/A converter module; Be connected to emitting antenna or radio-frequency cable on the up-conversion module.As shown in Figure 2.

1. DSP processing module

The DSP processing module is accomplished various information processings, the signal calculated controlled variable.The user movement that DSP processing module reception host computer sends is provided with parameter, the motion state of analog subscriber and track; Navigation message according to host computer is sent extracts ephemeris parameter and star clock parameter information; Calculate position, the speed of institute's analog satellite according to ephemeris parameter, and judge the observability of satellite, and combine user's position, speed, temporal information, set up satellite information.And then extrapolate satellite, and calculate the signal condition (code phase and carrier phase) of whole satellite-signal delivery times to essential informations such as user's pseudorange and pseudorange rate of change; According to ephemeris parameter and the star clock information extracted, carry out navigation data again and calculate, squeeze into the text markers, generate the navigation information of satellite; Calculate satellite-signal various analog simulation signal parameters of each satellite of x time and control information; Set up the error model of all kinds of error sources,, generate corresponding error simulation signal by error model according to all kinds of error sources; According to the user movement trajectory parameters that host computer provides, carry out high dynamic NCO and carrier wave NCO simulation.

2. FPGA processing module

The FPGA processing module is accomplished signal Processing, functions such as sequential control, the intermediate-freuqncy signal of synthetic numeral.Because of the visible gps satellite number in GPS user any point on earth is 8-12; So; FPGA processing module inside is 12 passages altogether; Can simulate 12 satellites simultaneously, but the asterisk of each passage correspondence is fixing, the DSP processing module can be sent to each passage of FPGA processing module in the starting stage defend asterisk.Corresponding code table is selected according to the asterisk of receiving of defending in FPGA processing module inner passage, again according to the initial control word of receiving, selects corresponding code phase and carrier phase as initial, begins to simulate.Under the control of tfi module, upgrade control word and textual information then, at last through the synthetic digital medium-frequency signal that generates of direct sequence according to certain frequency.Communication between DSP processing module and the FPGA processing module uses the EMIF mode of DSP to realize.

Signal Processing evaluation work in the GPS knotmeter mainly is responsible for realization by FPGA, realizes that specifically function comprises pseudo-code and carrier generator design, and the intermediate-freuqncy signal modulation is carried out in high dynamic NCO and carrier wave NCO simulation, and system sequence control is with synchronously.In addition, the FPGA processing module still is the transfer of each intermodular data communication in the GPS knotmeter, is responsible for realizing the mutual and buffer memory of related data, to realize the data communication between sub-systems.

The DSP processing module can (comprise the knotmeter function to each passage sendaisle information of FPGA processing module in the starting stage; Analog satellite number, channel switch state etc.), FPGA processing module inner passage is according to the asterisk of receiving of defending; Select corresponding pseudo-code and carrier generator; According to initial chip phase and the carrier phase received, select the starting point in this code table and the carrier wave again, begin to carry out NCO and add up.Pseudo-code that generates and carrier modulation form digital medium-frequency signal on synchronous navigation message data.

3. D/A converter module

Be sent in the up-conversion module after changing the GPS digital intermediate frequency signal that generates into the GPS analog intermediate frequency signal.

4. up-conversion module

In the GPS knotmeter, the accurate emission and the transmission that produce signal are important indicators.Consider that the GPS knotmeter has the characteristics of multi channel signals transmission, the design of intermediate frequency, radio circuit is a very the key link to the realization of the parameter indexs such as parameter of making an uproar mutually.The digital intermediate frequency modulation system is the analog if signal of BPSK, and signal bandwidth is 2.046MHz.Radiofrequency signal port output L1 (1.57542GHz) rf frequency signal, the radio frequency that can be used as the GPS receiver is imported.The design demand of system satisfies signal amplitude (dummy source amplitude output signal precision, accuracy, variation range), make an uproar index, frequency stability mutually, index requests such as signal bandwidth.

GPS knotmeter analog signal parameter and navigation message are sent in the buffer zone on the integrated circuit board through serial ports; DSP reads these data from buffer area, produce corresponding C/A sign indicating number, and accomplishes and select star and to the passage control of FPGA processing module etc.; The control of bit rate and code phase, digital carrier modulation, multichannel digital signal synthesize and can in the FPGA processing module, accomplish; Promptly obtain the GPSL1 radiofrequency signal that carrier frequency is 1575.42MHz after up-conversion, filtering and the gain control such as the modulation of signal process analog if signal, radiofrequency signal modulation.

5. serial communication modular

The serial communication control module is accomplished communicating by letter between upper computer software and the GPS knotmeter baseband portion; The parameters that upper computer software produces is according to certain communication protocol; Form with frame format sends to GPS knotmeter baseband portion through serial ports RS232 interface; Load mode is a bulk transfer, promptly is used for a kind of load mode of data of conveying capacity.

Communication control module mainly contains two effects: the one, according to the moving scene that the user sets, distribute feed signals status information parameter and various control command parameter to GPS knotmeter digital processes; The 2nd, information data such as reading speed from signal GPS knotmeter baseband portion and GPS receiver shows in upper computer software in real time respectively.

6. power module

The secondary power supply of total system is provided, provides each module hardware chip required voltage.

7. host computer and software

Host computer is according to GPS receiver marks for measuring velocity provisioning request; Host computer is provided with the user trajectory scene; The motor pattern that relates to the user is can be at the uniform velocity, even acceleration that quicken, even, become several scenes such as acceleration; The user movement form can be straight line, curve with circle, and be handed down to the GPS knotmeter parameter is set through serial ports.

GPS knotmeter upper computer software provides the good man-machine interaction interface, can make the user define the working environment of receiver user more easily, and upper computer software is divided into scene and generates software, User Interface and the assessment file that tests the speed.Scene generation software passes through computing machine according to the user and imports starting condition such as user's initial position coordinate, satellite ephemeris file, user movement track, atmospheric envelope delay model; Computing machine solves the model parameter of simplification according to these conditions; And these parameters are saved as document scene; Send the GPS knotmeter to according to certain communication transport protocols, thereby control hyperchannel GPS knotmeter produces the corresponding digital intermediate-freuqncy signal.

The User Interface major function provides the interactive interface between user and the computing machine; The data that feed back from the GPS knotmeter through this interface; Like user's analog rate, the speed of real-time demonstration GPS receiver, each passage satellite-signal status information etc. on User Interface.Therefore, the user can accomplish the management of hardware platform and control, realizes the management to software emulation and test assignment, visual and test result.

The assessment file that tests the speed is mainly added up and is assessed the speed result of GPS knotmeter analog rate and the output of GPS receiver, and it not only can simply write down the result of comparison and statistics, but also can further write down the velocity error σ of GPS receiver, promptly

$\mathrm{\σ}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(v_i-u_i)}^2}{n}}---\left(1\right)$

In the formula, v _iIt is i user's analog rate value of GPS knotmeter feedback constantly; u _iIt is the structured value that tests the speed that i moment GPS receiver returns; N is an observation frequency.

The GPS that above-mentioned GPS velocity-measuring system the is realized implementation method that tests the speed comprises the steps:

1. the DSP processing module of GPS knotmeter is according to the user movement scene of host computer setting, and simulation also generates subscriber simulation movement locus constantly; Navigation message according to host computer is sent extracts ephemeris parameter, accomplishes the coding of gps navigation message; Calculate the positional information of satellite according to the ephemeris parameter that extracts; And the subscriber simulation movement locus constantly of combination generation; Whether the prediction gps satellite is visible, and then calculates the original carrier phase place and initial pseudo-code phase of whole visible satellites at the satellite-signal delivery time;

3. the FPGA processing module of GPS knotmeter is assigned to corresponding signal with every visible satellite and generates passage; Each passage generates corresponding carrier wave and pseudo-code signal according to the frequency information of assigned visible satellite again; The carrier wave and the pseudo-code that at last each passage are generated are modulated on the synchronous navigation message, generate the GPS digital intermediate frequency signal;

4. the D/A converter module of GPS knotmeter changes the GPS digital intermediate frequency signal that 3. step generates into the GPS analog intermediate frequency signal; This GPS analog intermediate frequency signal is converted to the standard radio frequency frequency of GPS through the up-conversion module, and exports to the GPS receiver through emitting antenna or radio-frequency cable;

5. GPS receiver reception GPS knotmeter is the radiofrequency signal that 4. step launches, and carries out velocity calculated, and is dealt into the result that tests the speed on the host computer;

6. host computer receives that the GPS receiver returns the user's analog rate that result and GPS knotmeter feed back that tests the speed, and both are compared and add up; To compare at last and form the assessment file that tests the speed with statistics and store, the final completion GPS receiver test the speed result's assessment and demarcation.

Claims (6)

1. GPS implementation method that tests the speed is characterized in that comprising the steps:

1. the DSP processing module of GPS knotmeter is according to the user movement scene of host computer setting, and simulation also generates subscriber simulation movement locus constantly; Navigation message according to host computer is sent extracts ephemeris parameter, accomplishes the coding of gps navigation message; Calculate the positional information of satellite according to the ephemeris parameter that extracts; And the subscriber simulation movement locus constantly of combination generation; Whether the prediction gps satellite is visible, and then calculates the original carrier phase place and initial pseudo-code phase of whole visible satellites at the satellite-signal delivery time;

2. the FPGA processing module of GPS knotmeter is assigned to corresponding signal with every visible satellite and generates passage; Each passage generates corresponding carrier wave and pseudo-code signal according to the frequency information of assigned visible satellite again; The carrier wave and the pseudo-code that at last each passage are generated are modulated on the synchronous navigation message, generate the GPS digital intermediate frequency signal;

3. the D/A converter module of GPS knotmeter changes the GPS digital intermediate frequency signal that 3. step generates into the GPS analog intermediate frequency signal; This GPS analog intermediate frequency signal is converted to the standard radio frequency frequency of GPS through the up-conversion module, and exports to the GPS receiver through emitting antenna or radio-frequency cable;

4. GPS receiver reception GPS knotmeter is the radiofrequency signal that 4. step launches, and carries out velocity calculated, and is dealt into the result that tests the speed on the host computer;

5. host computer receives that the GPS receiver returns the user's analog rate that result and GPS knotmeter feed back that tests the speed, and both are compared and add up; To compare at last and form the assessment file that tests the speed with statistics and store, the final completion GPS receiver test the speed result's assessment and demarcation.

2. a kind of GPS according to claim 1 implementation method that tests the speed is characterized in that, step 1. described in the user movement scene set of host computer comprise motion morphology and the motor pattern of setting the user.

3. a kind of GPS according to claim 2 implementation method that tests the speed is characterized in that said motion morphology is straight line, curve or circle; Said motor pattern at the uniform velocity, even quicken or become to quicken.

4. a kind of GPS according to claim 1 implementation method that tests the speed is characterized in that, also further records the velocity error parameter σ of GPS receiver in the 6. said assessment file that tests the speed of step, promptly

$\mathrm{\σ}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(v_i-u_i)}^2}{n}}---\left(1\right)$

In the formula, v _iIt is i user's analog rate value of GPS knotmeter feedback constantly; u _iIt is the structured value that tests the speed that i moment GPS receiver returns; N is an observation frequency.

5. GPS knotmeter is characterized in that: mainly by power module, and the DSP processing module that links to each other with power module, FPGA processing module, D/A converter module and up-conversion module are formed; The FPGA processing module is connected with host computer; DSP processing module and FPGA processing module interconnect; The output terminal of FPGA processing module connects the up-conversion module via D/A converter module; Be connected to emitting antenna or radio-frequency cable on the up-conversion module; Wherein,

The DSP processing module, according to the user movement scene that host computer is set, simulation also generates subscriber simulation movement locus constantly; Navigation message according to host computer is sent extracts ephemeris parameter, accomplishes the coding of gps navigation message; Calculate the positional information of satellite according to the ephemeris parameter that extracts; And the subscriber simulation movement locus constantly of combination generation; Whether the prediction gps satellite is visible, and then calculates the original carrier phase place and initial pseudo-code phase of whole visible satellites at the satellite-signal delivery time;

The FPGA processing module is assigned to corresponding signal with every visible satellite and generates passage; Each passage generates corresponding carrier wave and pseudo-code signal according to the frequency information of assigned visible satellite again; The carrier wave and the pseudo-code that at last each passage are generated are modulated on the synchronous navigation message, generate the GPS digital intermediate frequency signal;

D/A converter module is sent in the up-conversion module after changing the GPS digital intermediate frequency signal that generates into the GPS analog intermediate frequency signal;

The up-conversion module is converted to the standard radio frequency frequency of GPS with the GPS analog intermediate frequency signal, and exports to the GPS receiver through emitting antenna or radio-frequency cable.

6. a kind of GPS knotmeter according to claim 5, it is characterized in that: the FPGA processing module is connected with host computer through serial communication modular.

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