CN101975956A - CAPS (China Area Position System) satellite analog signal generator - Google Patents

Abstract

The invention discloses a CAPS (China Area Position System) satellite analog signal generator, mainly comprising an upper computer, a baseband signal processing module, a digital to analog converter, a power divider, three radio frequency modules and an output part, wherein the baseband signal processing module is mainly internally provided with a DSP (Digital Signal Processor) information processing module and an FPGA (Field Programmable Gata Array) signal processing module connected with the DSP information processing module; the upper computer is connected with the DSP information processing module of the baseband signal processing module through a serial port, the FPGA signal processing module of the baseband signal processing module is connected to the power divider through the digital to analog converter, three output end of the power divider are respectively connected with the three radio frequency modules, and the output ends of the three radio frequency modules are connected with the output parts. The invention can be used for simulating high-precision satellite navigation signals and signals received by the antennas of receivers in actual environments.

Description

CAPS Satellite Simulation signal generator

Technical field

The present invention relates to CAPS satellite navigation field, be specifically related to a kind of CAPS Satellite Simulation signal generator.

Background technology

Satellite signal simulator is the critical equipment of satellite navigation system and receiver (especially high dynamic receiver) development, owing to relate to military purposes, the technical literature that the satellite navigation signal simulator research field is abroad published seldom, and the receiver type of sports of the satellite signal simulator of import has strict restriction.And CAPS (regional positioning system) system is the regional navigation positioning system of Chinese independent research, and its space segment is that 6 commercial geosynchronous satellites and 1 inclined plane satellite are formed, the GDOP of constellation at regional about 20.Therefore for can be for the development of the ground system in the CAPS satellite navigation system, build and test provides reliable, stable, an accurate and easy-to-use emulation and test environment and provides the indoor test environment for CAPS three frequency receivers, the signal reception of test CAPS three frequency receivers, positioning performance, catch, index such as tracking sensitivity, need a CAPS satellite navigation signal simulator of development with independent intellectual property right.

Summary of the invention

Technical matters to be solved by this invention provides a kind of CAPS Satellite Simulation signal generator, and it can simulate the received signal of receiver antenna under high-precision satellite navigation signals and the actual environment.

For addressing the above problem, the CAPS Satellite Simulation signal generator that the present invention is designed mainly is made of host computer, baseband signal processing module, digital to analog converter, power splitter, 3 radio-frequency modules and output block; Wherein the inside of baseband signal processing module mainly is made of DSP message processing module and the FPGA signal processing module that is attached thereto; Linking to each other with the DSP message processing module of baseband signal processing module of host computer through serial ports, the FPGA signal processing module of baseband signal processing module is connected to power splitter through digital to analog converter, 3 output terminals of power splitter link to each other with 3 radio-frequency modules respectively, and the output terminal of 3 radio-frequency modules is connected with output block; Host computer finishes mainly that text parameter extraction, scene generate, the satellite channel state of simulation, satellite starry sky distribute, simulated time defines, receiver location and speed and analog position are compared with the receiver positioning result; The DSP message processing module of baseband signal processing module is finished the calculating of user trajectory, the navigation message decoding, the phantom atom clock calculates, the real-time calculating of satellite position, and the calculating of propagation delay, yardage controlled oscillator and carrier number controlled oscillator calculate and monitor with run time behaviour that the FPGA message processing module is finished each passage jointly and proofread and correct; The FPGA message processing module of baseband signal processing module is finished high dynamic yardage controlled oscillator and the simulation of carrier number controlled oscillator, carries out the intermediate-freuqncy signal modulation, system sequence control and synchronous; The baseband signal that above-mentioned baseband signal processing module generated is divided into 3 the tunnel to baseband signal by power splitter after the digital to analog converter conversion, this 3 road signal is exported by output block after 3 radio-frequency modules upconvert to three frequencies of GAPS.

The described output block of such scheme both can be combiner and the antenna that links to each other with combiner, also can be 3 radio-frequency cables.

Because the CAPS ephemeris upgrades frequent, can not deposit text for a long time in the DSP message processing module, therefore, the used ephemeris information of simulator is to regroup according to the CAPS text of particular moment to form, and form is identical with CAPS message processing module text.The described host computer of such scheme extracts correlation parameter according to the CAPS text, and the parameter of being extracted is transferred to by the FPGA message processing module carries out regrouping of text in the DSP message processing module.

The movement locus of host computer analog receiver comprises dead point, uniform motion, circular motion, uniform acceleration motion or varying accelerated motion and can be according to the User Defined movement locus.By setting the movement locus of receiver, can define interior, definite receiver location and speed down in simulated time.

In order to obtain more accurate GAPS Satellite Simulation signal, also establish ionospheric error model, tropospheric error model, multipath error model, satellite ephemeris error model, phantom atom clock error model and/or earth rotation effect errors model in the above-mentioned baseband signal processing module, the DSP message processing module generates the parameter of revising and changing the satellite-signal state according to the above-mentioned error model error of calculation.

Because this simulator is at CAPS three phase code combination dynamic receiver application frequently, one of great advantage of three combinations frequently is to eliminate ionospheric first-order effects, and CAPS ionosphere first-order error is than big 3 orders of magnitude of high-order error, therefore, the described ionospheric error model of such scheme is an ionosphere first-order error model.

Because the polarization characteristic of CAPS satellite-signal has determined that CAPS multipath error ratio is more serious, the present invention simulates CAPS multipath error from amplitude, phase place and the relative time delay of the relative direct wave of multi-path signal.

The present invention is directed to the CAPS satellite navigation system, structure is based on the high dynamic satellite signal simulator of CAPS three frequencies of DSP (digital signal processing)+FPGA (field programmable gate array), it is different from general signal generator, not only to simulate high-precision satellite navigation signals, more main is to simulate special time, the signal of all satellite constellation emissions that the receiver of locality is received, it is the output signal of simulator, it is exactly the received signal of receiver antenna under the actual environment, this has comprised satellite ephemeris information, also include the CAPS receiver and (be commonly referred to pseudorange to the distance of each satellite, it comprises the troposphere, ionosphere, multipath, the pseudorange of earth rotation effect equal error) information, at one time under the benchmark, according to the distance of satellite to the receiver of being simulated, signal has been done corresponding delay, this simulating signal that receives receiver can realize the location, and the receiver track position of being simulated in positioning result and the simulator is consistent.The present invention can provide reliable, stable, an accurate and easy-to-use emulation and a test environment for the development of the ground system in the CAPS satellite navigation system, construction and test; For the CAPS receiver provides the indoor test environment, the signal reception of test CAPS receiver, positioning performance is caught, index such as tracking sensitivity.

Description of drawings

Fig. 1 is the principle schematic of a kind of CAPS Satellite Simulation of the present invention signal generator;

Fig. 2 is the process flow diagram of the DSP message processing module of CAPS Satellite Simulation signal generator.

Embodiment

The principle schematic of a kind of CAPS Satellite Simulation of the present invention signal generator as shown in Figure 1, its hardware components mainly is made of host computer, baseband signal processing module, digital to analog converter, power splitter, 3 radio-frequency modules and output block; Wherein the inside of baseband signal processing module mainly is made of DSP message processing module and the FPGA signal processing module that is attached thereto; Linking to each other with the DSP message processing module of baseband signal processing module of host computer through serial ports, the FPGA signal processing module of baseband signal processing module is connected to power splitter through digital to analog converter, 3 output terminals of power splitter link to each other with 3 radio-frequency modules respectively, and the output terminal of 3 radio-frequency modules is connected with output block.

Host computer finishes mainly that text parameter extraction, scene generate, the satellite channel state of simulation, satellite starry sky distribute, simulated time defines, receiver location and speed and analog position are compared with the receiver positioning result; The DSP message processing module of baseband signal processing module is finished the calculating of user trajectory, the navigation message decoding, the phantom atom clock calculates, the real-time calculating of satellite position, and the calculating of propagation delay, yardage controlled oscillator and carrier number controlled oscillator calculate and monitor with run time behaviour that the FPGA message processing module is finished each passage jointly and proofread and correct; The FPGA message processing module of baseband signal processing module is finished high dynamic yardage controlled oscillator and the simulation of carrier number controlled oscillator, carries out the intermediate-freuqncy signal modulation, system sequence control and synchronous; The baseband signal that above-mentioned baseband signal processing module generated is divided into 3 the tunnel to baseband signal by power splitter after the digital to analog converter conversion, this 3 road signal is exported by output block after 3 radio-frequency modules upconvert to three frequencies of GAPS.

Host computer of the present invention is divided into following 10 functional modules from function: i.e. initialization module, selftest module, communication control module, scene maker functional module, visible starlike attitude display module, stellar map display module, satellite power control module, receiver locating information module, simulator satellite-signal NMEA form output module and analog position-receiver positioning result data analysis module.Initialization module is finished the setting of simulator initiation parameter.Selftest module powers up or after the user sends the self check order, sends the self check exclusive data to simulator at simulator, and simulator is being accepted self-checking command, and beginning hardware each several part is checked, send computing machine with check result, is judged the duty of simulator by computing machine.Communication control module is finished communicating by letter between computing machine and the simulator, sends the movement locus that navigation information, receiver initial position message and initial velocity, user are provided with to simulator, receives the status information that simulator sends.Scene maker functional module generates required document scene of real time modelling and simulation preview.As seen starlike attitude display module sends to the position of the satellite-signal of host computer in the DSP message processing module, calculates the information such as the elevation angle, position angle, pseudorange of each visible star in real time.The stellar map display module calculates the elevation angle, the position angle of every relative receiver of satellite, and shows by figure.The satellite power control module can be controlled the signal power of each visible star with this to each satellite-signal passage of the random opening/closing of each visible star in simulation process.Receiver locating information module calculates the position of receiver in real time according to the initial parameter that is provided with in the DSP message processing module, receive and be converted to longitude, latitude and height in real time from serial ports, and calculates the speed of sky, northeast three directions.Simulator satellite-signal NMEA form output module goes out information such as the visible satellite elevation angle, position angle, pseudorange according to the position calculation of every visible satellite, and the information of each visible satellite in the simulator is shown and be stored as file according to standard N MEA0183 form.Analog position-receiver positioning result data analysis module relatively shows respectively from the movement locus (position of satellite) of the satellite of simulator setting with from the movement locus that receiver receives, thereby verifies the performance of receiver.Two serial ports are accepted the data of simulator and receiver simultaneously, and the demonstration that contrasts in real time, draws.

Include the imitative software of number in the host computer, the imitative work of each item number that it is used to finish simulator realizes that the mutual and observation data of simulator and receiver shows control.Major function comprises: realize the logic control of system start-up and replacement, realize the setting of initial parameter, emulation initial time and coordinate, finish the setting of simulated environment; According to the characteristics of motion and the characteristics of receiver, set up corresponding motion model respectively, generate the movement locus of receiver, extract dynamic parameter; In the preferred embodiment of the present invention, the movement locus of the receiver of host computer simulation comprises dead point, uniform motion, circular motion, uniform acceleration motion or varying accelerated motion and can be according to the User Defined movement locus.By setting the movement locus of receiver, can define interior, definite receiver location and speed down in simulated time.Realize the preservation of standard document scene and track preview function of receiver movement locus; By two serial ports designs, extract the receiver locating information, compare the analyzing and positioning performance with the customer position information of simulator simulation; Extraction and demonstration at every observation data of simulator comprise satellite constellation figure, user movement trajectory diagram, positioning result comparison chart, satellite real-time status hum pattern, pseudorange information, power control chart etc.Because the CAPS ephemeris upgrades frequent, can not deposit text for a long time in the DSP message processing module, therefore, the used ephemeris information of simulator is to regroup according to the CAPS text of particular moment to form, and form is identical with CAPS message processing module text.The described host computer of such scheme extracts correlation parameter according to the CAPS text, and the parameter of being extracted is transferred to by the FPGA message processing module carries out regrouping of text in the DSP message processing module.

Baseband signal processing module of the present invention adopts the scheme of DSP+FPGA.The floating type TMS320C6713B of the Ti company that selects for use of DSP message processing module wherein, frequency of operation can reach 300MHz, supreme command processing power 2400MIPS.The FPGA message processing module has been selected the Virtex-5 of Xilinx company for use, and its inside comprises nearly 330,000 logical blocks, and six Clock management modules (CMT) reach 1,200 user I/O, 550MHz integration module storer.Need to store because the DSP message processing module can produce lot of data in calculating process, the present invention has also selected the external memory space of SDRAM for use.For stored routine, also selected the FLASH storage space of 2Mb capacity for use.

The process flow diagram of DSP message processing module as shown in Figure 2, it mainly is responsible for most evaluation work in the simulating signal generative process, comprise the calculating of user trajectory, the navigation message decoding, the phantom atom clock calculates, the real-time calculating of satellite position, and the run time behaviour that the calculating of propagation delay, sign indicating number NCO (digital controlled oscillator) and carrier wave NCO calculate, finish each passage jointly with FPGA monitors and correction.Because the DSP message processing module enters duty prior to the FPGA message processing module, so the DSP message processing module also needs the FPGA message processing module is controlled.Major function has:

(1) parameter setting and user trajectory are calculated

The height of high dynamic satellite signal simulator dynamically refers to the dynamically high of receiver, so be mainly reflected in the calculating of user trajectory on the simulation link.The simulation of satellite-signal at first needs to set simulates the zero hour movement locus during this period of time of simulation duration and receiver.By serial ports these setting datas are sent into the DSP message processing module with host computer, the DSP message processing module calculates again then.

Needing definite parameter to comprise simulates the zero hour, the simulation duration, the initial position of receiver, the initial velocity of receiver and the acceleration of receiver (during rectilinear motion), the DSP message processing module calculates receiver locations all within the simulated time section with certain frequency (as 50Hz) in view of the above, deposits among the SDRAM.

(2) CAPS navigation message decoding

The base unit of CAPS navigation message is bit (20ms), and 30 bits constitute a word (0.6s), and 10 words constitute a subframe (6s), and 5 subframes constitute a frame, and 2 frames constitute a superframe, and 4 superframes constitute one page.The CAPS navigation message mainly comprises information such as virtual clock, ephemeris, barometric leveling.Wherein virtual clock information 30s upgrades once; Ephemeris information was reported once in 1 minute, upgraded once in 6 minutes; The barometric leveling data were upgraded once in 4 minutes, broadcast the air pressure and the temperature of 116 survey stations at every turn, 4 satellites intersected in 4 minutes broadcasts the air pressure and the temperature of 29 survey stations, the user caught the signal of 4 satellites simultaneously or caught a satellite-signal in continuous 4 minutes at one minute, can obtain the air pressure and the temperature information of all 116 survey stations.

At first store one section scale-of-two navigation message (as 2 hours) in the DSP message processing module, DPS decodes according to CAPS navigation message form, obtains satellite ephemeris information, phantom atom clock information and barometric leveling information.And with the decoding ephemeris parameter respectively divided by different coefficients, by depositing in the array after the bit extraction.

The data storage of navigation message is a two-dimensional array: first time of the act, the second behavioral data bit.The text that generates deposits among the SDRAM, and per 1 hour navigation message approximately will take the storage space of 5.4MB.

Extract the position and the velocity information of satellite according to navigation message, and, calculate information such as satellite-signal propagation delay and Doppler shift in conjunction with user trajectory and speed.

(3) various time-delay calculation

Also establish ionosphere first-order error model, tropospheric error model, multipath error model, satellite ephemeris error model, phantom atom clock error model and/or earth rotation effect equal error model in the baseband signal processing module, the DSP message processing module generates the parameter of revising and changing the satellite-signal state according to the above-mentioned error model error of calculation.

(4) high dynamic N CO simulation

In DSP message processing module calculation process, calculate carrier phase and the code phase that arrives the satellite-signal of receiver front end every 1ms by the real-time computing technique of pseudorange, obtain carrier phase difference Δ t between each millisecond thus _CWith code phase difference Δ t _P, and calculate carrier Control word and sign indicating number control word thus.Control word is DSP and issues the accumulated value that FPGA sends into NCO.If the FPGA frequency of operation is f (MHz), the NCO degree of depth is K, and then the carrier Control word is N _CARRIER=(Δ t _CGN)/(1000gf), the sign indicating number control word is N _CODE=(Δ t _PGN)/(1000gf).N=2 wherein ^K

The processing speed that is limited to the DSP message processing module is limited, and according to cycle of C/A sign indicating number, adopts every 1ms to send the disposal route of new control word to the FPGA message processing module.During this period, the DSP message processing module is finished the instant calculating of pseudorange, is converted into carrier phase and code phase, is transformed into carrier Control word and sign indicating number control word again, sends to the FPGA message processing module in interrupt handling routine.

Signal Processing evaluation work of the present invention mainly is responsible for realization by the FPGA message processing module, and the specific implementation function comprises pseudo-code and carrier generator design, and the intermediate-freuqncy signal modulation is carried out in high dynamically yard NCO and carrier wave NCO simulation, system sequence control and synchronous.In addition, the FPGA message processing module still is the transfer of each intermodular data communication in the whole simulation system, is responsible for realizing the mutual and buffer memory of related data, to realize the data communication between a subsystem.

The DSP message processing module can (comprise the simulator function to each passage sendaisle information of FPGA message processing module in the starting stage, analog satellite number, channel switch state etc.), the FPGA 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.

(1) starting stage

The FPGA message processing module does not really enter workflow when system start-up, must finish necessary initial calculation at the DSP message processing module, after the FPGA message processing module sends initialize signal, just enters normal operating conditions.The DSP message processing module can send to each passage of FPGA message processing module in the starting stage and defend asterisk.Asterisk is defended according to what receive in FPGA message processing module inner passage, selects corresponding short smart code table, again according to the initial chip of receiving, selects in the smart code table of this weak point a certain as initial, begins to add up.

(2) the short smart sign indicating number of CAPS generates

In CAPS satellite signal simulator generator, the short smart sign indicating number that generates for the FPGA message processing module has 3 requirements:

A) produce pairing sign indicating number sequence according to the selected asterisk of defending, and change the star function.

B) can carry out initial setting up and control to the base sign indicating number sequence number (1～10230) in sign indicating number cycle epoch, the chip phase of base sign indicating number.

C) Ma basic bit rate is controllable, is used for the influence of the Doppler frequency that the relative motion of analog satellite and receiver carrier brings.

The x time of satellite-signal can be represented with the sequence number (0～19) in sign indicating number cycle epoch in the sequence number (0～29) of the sequence number (0～9) of word in the subframe numbers of navigation message, the subframe, word meta, the position, the base sign indicating number sequence number (0～10229) in sign indicating number cycle epoch, the chip phase of base sign indicating number.All there is strict synchronized relation the subframe of navigation message, word, position with short smart sign indicating number base sign indicating number.So in the simulator design, be necessary the chip phase of short smart sign indicating number base sign indicating number sequence number (0～10229), base sign indicating number is carried out initial setting up and control.The chip phase of short smart sign indicating number base sign indicating number and the setting of basic bit rate and control can realize by sign indicating number NCO (employing direct digital frequency synthesis technology), the frequency control word that changes sign indicating number NCO just can change basic bit rate, the chip phase of the corresponding short smart sign indicating number base sign indicating number of the phase place of sign indicating number NCO.

(3) the dynamic pseudo-code based on sign indicating number NCO designs

The realization of sign indicating number NCO has several modes, and how main consideration can realize fast.Code phase is subjected to first phase, natural speed (10.23MHz) and Doppler's influence.For the influence that prevents to overflow, sign indicating number NCO is defined as the signless integer register (calculating according to index request) of 36bit in the FPGA message processing module processing procedure.Therefore it always has 2 ³⁶Individual state, a complete sign indicating number cycle is 1ms.

The dynamically simulation of pseudo-code, the design by sign indicating number NCO produces the bit rate clock that comprises dynamic perfromance, pseudo-code module pseudo-code generation module interface is carried out read operation produce dynamic pseudo-code.Sign indicating number NCO control word is made of initial code phase positions control word and dynamic code frequency control word.In the code phase totalizer, the initial code phase positions control word as the initial value that adds up, with the totalizer input of sign indicating number NCO frequency word increment as each sampling instant, is added up in sign indicating number NCO logic.When register accumulated value 〉=2 ³⁶The time, the code phase totalizer produces and once overflows, and whole chip count device adds 1, and expression is through a complete pseudo-code chip period.Read a chip by the pseudo-code interface module this moment, realizes the high dynamically generation of pseudo-code.

On overall, the function of sign indicating number NCO module is exactly to realize the transformation of user movement information to pseudo-code frequency dynamic information.Have multidate informations such as speed and acceleration in order to make into living short smart sign indicating number, adopt sign indicating number NCO mode to carry out chip count and complete cycle phase count.The frequency control word of sign indicating number NCO and phase control words are calculated in DSP and are passed to FPGA by bus in real time.

(4) design of carrier wave NCO

With respect to sign indicating number NCO, the realization of carrier wave NCO relatively can be more simpler, is the restriction of 10230 code elements because there is not the cycle, and the result of final output is the cosine and the sinusoidal phase value of directly mapping.The status word sum of carrier wave NCO is designed to 2 power, though because the wavelength of carrier wave is shorter, the power of NCO status word sum time can be too high, and for example 2 ¹⁰, respective distances resolution is: 19cm/1000=0.2mm.But in the treatment scheme of FPGA,, need not event memory, also do not have the restriction on the speed, handle a status word and add up to 2 owing to be real-time output ¹⁰With 2 ³⁶The shared resource of NCO be very nearly the same, so still taked 2 ³⁶The carrier wave NCO of total status word, range resolution can reach 7.2cm/2 in theory like this ³⁶=1.047 * 10 ^-10Mm.

The state correspondence of carrier wave NCO output also has 2 ³⁶Kind.

(5) signal modulation

In CAPS band spectrum modulation and intermediate frequency carrier generation module, from the pseudo-code code stream under the bit rate clock control of Doppler simulation circuit, finish the band spectrum modulation of data, the output data streams with navigation message.To export simultaneously by the dynamic digital carrier wave that carrier wave NCO control produces down simultaneously,, finally generate digital intermediate frequency signal in the outside carrier modulation that realizes of FPGA message processing module.

In order to realize the band spectrum modulation of data, need to guarantee Frame speed and corresponding spread-spectrum code rate strict synchronism.In the data transmission module by epoch counter design come pseudo-code counting, and provide information update time of information data, thereby can guarantee the correct modulation of data.Epoch, the design of counter mainly comprised following content:

The communication data sub-frame count: allowed band 0～299 (data bit number in the corresponding subframe), unit period is 1 frame text length (containing Doppler);

The pseudo-code cycle count: allowed band 0～19 (sequence number in pseudo-code cycle epoch in data bit of corresponding navigation message), unit period is a 1bit navigation message length (containing Doppler);

The pseudo-code chip count: allowed band 0～10229 (the pseudo-code base sign indicating number sequence number in corresponding pseudo-code cycle epoch), unit period is 1 chip period (containing Doppler).

Above-mentioned count content and pseudo-code NCO phase value combine, and the x time information of communication data just can be provided.Wherein, utilize the pseudo-code cycle count to produce navigation message framing clock, the data bit of navigation message output synchronously.By the renewal of pseudo-code cycle count synchronous communication data, and carry out band spectrum modulation with pseudo-code, carrier wave.

(6) the NCO simulated data is proofreaied and correct in real time

The present invention is when real time execution, and As time goes on the control word quantization error, the simulation that adds up of sign indicating number NCO and carrier wave NCO will produce certain error.Simulate for high dynamic signal, this error is accumulation rapidly, and simulation precision is brought than mistake.Therefore the data closed loop that has designed between FPGA---DSP is proofreaied and correct in real time.Concrete principle and process are as follows:

A) FPGA is according to the real-time NCO accumulated value of counter generation epoch, and chip phase value, sign indicating number cycle count value and navigation message bit count value deposit in the fixing registers group;

B) each system break is come temporarily, as the passback data data in the above-mentioned register is sent to the DSP message processing module by bus.

C) independently calculate current simulated time DSP message processing module inside, will resolve into navigation message counting, ms counting, chip count and code phase simultaneously the time, corresponding one by one with FPGA message processing module passback data.

D) relatively FPGA message processing module and DSP message processing module ring corresponding counter and code phase, if the error between the two has reached certain value, then proofread and correct this error, finely tune the sign indicating number NCO and the carrier wave NCO frequency word that interrupt sending next time.

Radio-frequency module of the present invention is mainly used in the generation of finishing up-conversion local oscillator and output power, be converted to 3 road CAPS intermediate-freuqncy signals radiofrequency signal, this 3 road sign standard of 3 road sign standards by upconversion process the frequency of radiofrequency signal is respectively 3826.02MHz, 3979.47MHz and 4143.15MHz, and signal is amplified in advance.Radio-frequency module is that output power is adjustable.

Output block of the present invention both can be that combiner reaches the antenna that links to each other with combiner, and this moment, 3 road signals were launched by 1 surface antenna after synthesizing 1 road signal by combiner; Output block of the present invention can also be 3 radio-frequency cables, and this moment, 3 road signals were respectively by these 3 radio-frequency cable outputs.

The present invention also includes power module, and this power module is used to provide the secondary power supply of total system, and provides each module hardware chip required voltage.

The satellite-signal that the CAPS receiver is received at current time, be a little earlier a certain moment from satellites transmits.To different satellites, the distance between time delay between the signal transmitting and receiving and satellite and the receiver, radio wave refration influence etc. is closely related.Be subjected to the influence of propagation delay, Doppler effect and each error component, when the signal of satellites transmits arrived receiver, the carrier frequency that receiver is measured, sign indicating number state and satellites transmits moment state were compared certain variation have all been taken place.How simulating this variable quantity, is one of main task of CAPS satellite signal simulator generator.The DSP message processing module has been born most calculating.

1, CAPS system coordinate system

In order to determine satellite and the position of receiver in three dimensions, need a specific coordinate system, CAPS adopts the ITRF2000 ITRF.Like this, ephemeris uses body-fixed coordinate system more convenient, because the receiver positioning result generally all makes land used be admittedly, needn't carry out coordinate transform like this.In addition, and select ITRF2000 ITRF self precision height for use; Highly versatile helps coordinate system and refines and improve, and to name this coordinate be the CAPS-03 terrestrial coordinate system.

2, CAPS satellite signal simulator parameter is analyzed

The arrival receiver front end that CAPS simulator operate as normal will be simulated can be expressed as (is the example explanation with one the tunnel) through the satellite-signal of down coversion:

$\mathrm{Signal}\left(t\right)=A_{\mathrm{noise}}+\underset{j}{\mathrm{\Σ}}{A}_j{C}_j(t-{\mathrm{\τ}}_{\mathrm{CODEj}})D_j(t-{\mathrm{\τ}}_{\mathrm{CODEj}})\cos (2\mathrm{\π}{f}_{\mathrm{IF}}\·t_j-2\mathrm{\π}{f}_{L1}\·{\mathrm{\τ}}_{\mathrm{cj}})$ ①

By formula 1. as can be known, determining simulated time t, after corresponding short smart sign indicating number and the navigation message, most critical is exactly the time delay τ that will obtain the signal arrival receiver of every satellites transmits.Time delay comprises carrier wave time delay and sign indicating number time delay.Obtain the time delay of satellite, must at first obtain following data to receiver:

A) position of receiver

B) position of satellite

C) satellite is to the delay of receiver, comprises that spatial transmission postpones, and signal is by ionospheric delay, and signal is by tropospheric delay, or the like

Wherein the position of receiver promptly calculates before the simulator loop computation according to preset parameters, and the acquisition to other two parameters is elaborated below.

3, the real-time calculating of CAPS satellite position

3.1, navigation message decoding

When the CAPS simulator was worked at every turn, the ephemeris parameter of employing was not what fix, but according to the different time, selected to read in corresponding navigation text file.Navigation message is the interior text of a period of time that CAPS land station notes, for the CAPS simulator provides necessary parameter.Provided a typical navigation message file below to a satellite storage organization and corresponding parameters explanation.

CAPS text structure:

telegraphID insertTime telegraphtype frame1count frame1type frame1effectlen

584404 2009-2-2423:00:01 3 2759 1 300

frame1effectdata satelliteno

EB90AC76382008000080ECED785DC008020000203977000D513200800008112D4918020D3AA03

The explanation of CAPS message format:

" telegraphID " message numbering; " insertTime " text generation time; " telegraphtype " text type; " frame1count " item is a frame number; " frame1type " frame type; " frame1effectlen " frame length; " frame1effectdata " item is a telegraph text content; " satelliteno " satellite numbering.300 texts are the satellite numberings with 75 sexadecimal numeric representations, last " 3,4,5 ".

3.2, ephemeris parameter calculates

3.2.1, virtual clock calculates

CAPS uses the quadravalence power function as virtual clock time model, four of transmission pattern parameter (a in text _T4, a _T3, a _T2, a _T1, a _T0).The value that the user corrects according to the virtual clock time of these four calculation of parameter:

τ _clk＝a _t3·(t-t _t0) ⁴+a _t3·(t-t _t0) ³+a _t2·(t-t _t0) ²+a _t1·(t-t _t0) ¹+a _t0+0.1245s ②

Wherein, t represents the current time, and tt0 representation model starting point all is the time of CAPST constantly

3.2.2, satellite position calculation

In the CAPS system, satellite ephemeris adopts " heart solid " coordinate system (ECEF), is specially the ITRF2000 ITRF.

According to toe ephemeris parameter constantly, can calculate satellite position coordinates and speed at any time and be:

In the formula, the implication of parametric t in the formula: current time toe; The co-ordinates of satellite that following formula resolves uses the ITRF2000 frame of reference.

4, the troposphere time-delay is calculated

Tropospheric delay is generally made a general reference non ionized atmosphere to electromagnetic refraction, and non ionized atmosphere comprises troposphere and stratosphere, because the major part of refraction occurs in the troposphere, so be called tropospheric refraction.Is the troposphere from ground upward to 40km, and the troposphere is a nondispersive medium, when the CAPS signal passes the troposphere, propagates the phase velocity and the group velocity that are associated with signal and has been postponed on an equal basis for free space is propagated.This delay changes with the tropospheric refraction rate, and the refractive index size depends on local temperature, pressure and relative humidity.As not revising, the troposphere is about several meters magnitudes in the delay of zenith direction, and during 5 ° at the elevation angle, delay can reach tens meters magnitudes.

Refractive index can be expressed as dried component and wet component sum.Dried component is caused by dry air, accounts for about 90% of tropospheric delay error, and can predict very exactly.Wet component is caused that by water vapor distributing has uncertainty in atmosphere, difficult prediction.Two kinds of components extend to tropospheric differing heights, and dried component extends to the 40km height, and wet component extends to height about 10km.

Receiver adopts following formula correction usually in order to simplify calculating

$\left\{\begin{array}{c}\mathrm{\&Delta;}{\mathrm{\&rho;}}_{\mathrm{trop}}^{\&prime;}=\frac{K_d^{\&prime;}}{\sin {({\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">E</figure-callout>}}^2+6.25)}^{1/2}}+\frac{K_W^{\&prime;}}{\sin {({\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">E</figure-callout>}}^2+2.25)}^{1/2}}\\ K_d^{\&prime;}=1.552\&times;{10}^{-5}\frac{p_0}{T_k}(h_d-h_u)\\ K_W^{\&prime;}=7.46512\&times;{10}^{-2}\frac{e}{{T_k}^2}(h_w-h_u)\\ h_d=40136+148.72(T_k-273.16)\\ h_W=11000\end{array}\right.$ ③

At present, utilize model correction, the user can revise 90%～95% tropospheric error near ground, in the high-altitude such as airborne user this reduce than regular meeting.Owing to dried component is more easily predicted the difficult prediction of the component that wets, so desirable coefficient η _d=1.07, η _w=1.10, the revised residual error of user is kept between 5%～10%.

5, the ionosphere time-delay is calculated

Ionosphere delay is relevant with wave frequency, and CAPS is that the C-band frequency is higher, and ionospheric error only is 1/7～1/10 of L-band delay.But ionospheric error remains one of maximum error source of hi-Fix.

Because CAPS satellite-signal analog generator is at CAPS three phase code combination dynamic receiver application frequently, one of great advantage of three combinations frequently is to eliminate ionospheric first-order effects, and CAPS ionosphere first-order error is than big 3 orders of magnitude of high-order error, therefore, the ionospheric first-order error of emphasis simulation CAPS.Top ionosphere analogy method has also no longer adapted to CAPS, and this is because of 8 parameters that do not have the Klobuchar model in the present navigation message of CAPS.Then first-order error simulation in CAPS ionosphere is as follows:

The influence that propagate the signal in the radio frequency territory in ionosphere mainly characterizes with chromatic dispersion.Describing signal ionosphere phase delay and group delay expression formula is

$\mathrm{\&Delta;}{\mathrm{\&rho;}}_p=-\frac{40.3}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}\mathrm{TEC}$ ④

$\mathrm{\&Delta;}{\mathrm{\&rho;}}_g=\frac{40.3}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}\mathrm{TEC}$ ⑤

Usually represent electronics sum with TEC, promptly along the electromagnetic wave propagation path

$\mathrm{TEC}={\&Integral;}_{P_u}^{P_s}{n}_e\mathrm{dl}$ ⑥

In the formula, P _uPosition for the user; P _sPosition for satellite.

The unit of TEC is electron number/rice 2, and it changes with factors vary such as time of one day, customer location, satellite elevation angle, season, ionization flux, magnetic acitvity, solar activitys, and is wherein particularly close with the correlativity of solar activity intensity.The nominal range of TEC is between 1016-1019.Above-mentioned delay expression has only reflected that satellite in zenith direction (elevation angle is 90 °) path delay vertically upward, for other elevations angle, need multiply by an inclination factor, its inclination factor expression formula:

$K=[1-{\left(\frac{R_e\cos \mathrm{\&theta;}}{R_e+\mathrm{hI}}\right)}^2]$ ⑦

Wherein, R _eBe the distance of user to the earth's core, θ is the Horizon elevation angle of satellite, and hI is that the height from the face of land is passed through a little in ionosphere.

After considering this inclination factor, single order formula in path delay in ionosphere becomes

$\mathrm{\&Delta;}{\mathrm{\&rho;}}_p=-K\frac{40.3}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}\mathrm{TEC}$ ⑧

$\mathrm{\&Delta;}{\mathrm{\&rho;}}_g=K\frac{40.3}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HSA00000297863200011.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}\mathrm{TEC}$ ⑨

If user's position range, according to the value that the forecast of TEC can be consulted TEC, changing in one day according to TEC is that one-period becomes process slowly again, can adopt the method for fitting of a polynomial to set TEC.If method estimation ionospheric error Δ ρ ' above adopting _Ion, when receiver adopts three frequency phase code combinations, will influence Δ ρ to institute ionosphere _IonAll eliminate, the positioning result of receiver no longer comprises the ionosphere influence, and this just can not reflect the actual location situation.Therefore, simulator will suitably be adjusted the value of TEC, makes in the target travel zone, has:

Δρ _ion≈0.999Δρ′ _ion ⑩

6, CAPS multipath error

Satellite-signal through around can produce mirror signal and diffuse scattering signal after the reflected by objects, that is, and multi-path signal.Signal after reflection, its polarization characteristic can change.The CAPS satellite-signal is a signals having linear polarisation, and the linear polarization mode that each satellite adopts is also different, the satellite-signal that has be vertical polarization (as, on the 4143.15MHz frequency, Chinastar 1, Asian Pacific 1 satellite, No. two, Asia and Asia-Pacific 1A are vertical polarization), the satellite that has be the horizontal polarization signal (as, prosperous promise is a horizontal polarization No. one on the 4143.15MHz frequency), for normal all CAPS satellite-signals, the CAPS receiving terminal antenna employing circular polarized antenna (left-handed or right-handed polarized antenna) of receiving.Therefore, CAPS compares the polarization loss that 3dB is arranged with GPS.

Polarization characteristic and reflection coefficient after the research signal reflex, all significant for analyzing multiple footpath signal to GNSS pseudorange and the influence of carrier phase measurement precision.With the 4143.15MHz of CAPS and the L1=1575.42MHz frequency band signals of GPS is main analytic target.The specific inductive capacity and the conductivity of water intaking are respectively 81.5 and 5.4263.That is: ε=ε _r-j60* σ * c/ ω, ε _r=81.5, σ=5.4263, ω=1575.42MHz or 4143.15MHz, the c=3.8e9 light velocity.For line polarization wave, the reflection coefficient of level (HH) polarization and vertical (VV) polarization can be calculated by the Fresnel reflection coefficient formula

$R_{\mathrm{HH}}(\mathrm{\&theta;},\mathrm{\&epsiv;})=\frac{\sin \left(\mathrm{\&theta;}\right)-\sqrt{\mathrm{\&epsiv;}-{\cos }^2\left(\mathrm{\&theta;}\right)}}{\sin \left(\mathrm{\&theta;}\right)+\sqrt{\mathrm{\&epsiv;}-{\cos }^2\left(\mathrm{\&theta;}\right)}}$

$R_{\mathrm{VV}}(\mathrm{\&theta;},\mathrm{\&epsiv;})=\frac{\mathrm{\&epsiv;}\sin \left(\mathrm{\&theta;}\right)-\sqrt{\mathrm{\&epsiv;}-{\cos }^2\left(\mathrm{\&theta;}\right)}}{\mathrm{\&epsiv;}\sin \left(\mathrm{\&theta;}\right)+\sqrt{\mathrm{\&epsiv;}-{\cos }^2\left(\mathrm{\&theta;}\right)}}$

In the formula, θ is the satellite-signal incident angle.

Signals having linear polarisation is different with circularly polarized signal, and polarization characteristic after the linear polarization signal reflex changes very little, vertically polarized wave particularly, and the polarization characteristic of itself is occupied an leading position.But, the horizontal polarization signal incident angle during less than 10 ° because transmitting signal can produce polarization current at big ground surface during at ground proximity, polarization current decays electric field signal rapidly because of being subjected to the earth impedance influences to produce heat energy, therefore, also just caused reflection coefficient very little, that is, the reflected signal energy is very weak.

For GPS, what antenna adopted is the right-handed circular polarization antenna, and multi-path signal generally is the left-hand circular polarization signal, the big high attenuation of meeting after multipath signal receives through the right-handed circular polarization antenna, and multi-path signal mainly is that the lower satellite-signal reflection of incident angle causes.CAPS difference, its satellite-signal itself are the linear polarization signals, and antenna adopts circular polarisation to receive, and received signal itself just has the loss of 3dB, and simultaneously, the firing angle that receives that antenna does not have the polarization loss is 0 °-90 ° a multi-path signal.In a word, CAPS is influenced by multipath to compare with GPS to want big many.Therefore, multipath error model of the present invention includes the caused error of amplitude, phase place and relative time delay of the relative direct wave of multi-path signal, i.e. the present invention simulates CAPS multipath error from amplitude, phase place and the relative time delay of the relative direct wave of multi-path signal.

The intermediate-freuqncy signal mathematic(al) representation of simulation can be expressed as (is example with a satellite)

$\mathrm{Signal}\left(t\right)=A_{\mathrm{noise}}+\underset{i=0}{\overset{M}{\mathrm{\&Sigma;}}}{\mathrm{\&alpha;}}_i\mathrm{AC}(t-{\mathrm{\&tau;}}_i)D(t-{\mathrm{\&tau;}}_i)\cos (2\mathrm{\&pi;}{f}_{\mathrm{IF}}\&CenterDot;t-{\mathrm{\&phi;}}_i)$

Wherein, i=0 represents that this signal is the satellite direct signal, and other is a M-1 multi-path signal; A represents carrier amplitude; α _iExpression signal reflex coefficient, α ₀=1 corresponding direct signal; D (t) expression navigation data information; C (t-τ _i) expression different delay the CAPS pseudo-random code; f _IFThe IF-FRE (having supposed that here direct signal has identical frequency with multi-path signal) of expression satellite-signal; φ _i(t) phase place of i signal of expression.Therefore, the simulation multipath mainly is amplitude, phase place and the relative time delay of the relative direct signal of simulating multi-path signal.

7, earth rotation error

At electric wave signal in the transmission time, because of the earth certainly then a kind of relativistic effect that causes the Sagnac effect.Compare the CAPS satellite orbit with GPS higher, and the influence of this effect is bigger.

In the agreement coordinate system that connects firmly with the earth, if the instantaneous position of satellite is according to the instantaneous calculating of signal broadcast, so also should consider the correction of earth rotation, because when satellite-signal propagates into the research station, the above-mentioned instantaneous position of the relative satellite of agreement terrestrial coordinate system that connects firmly mutually with the earth has produced rotation (around the Z axle).If get the rotational velocity that ω is the earth, then the anglec of rotation is

$\mathrm{\&Delta;\&alpha;}=\mathrm{\&omega;\&Delta;}{\mathrm{\&tau;}}_i^j$

In the formula,

Propagate into the time delay of research station for satellite-signal.Cause that thus the variation (Δ x, Δ y, Δ z) of satellite in above-mentioned coordinate system is

$\left[\begin{array}{c}\mathrm{\&Delta;x}\\ \mathrm{\&Delta;y}\\ \mathrm{\&Delta;z}\end{array}\right]=\left[\begin{array}{ccc}0& \sin \mathrm{\&Delta;\&alpha;}& 0\\ -\sin \mathrm{\&Delta;\&alpha;}& 0& 0\\ 0& 0& 0\end{array}\right]\left[\begin{array}{c}{x}^j\\ y^j\\ z^j\end{array}\right]$

Wherein, (x ^j, y ^j, z ^j) be the instantaneous coordinate of satellite.

Because rotation angle Δ α is very little, so following formula can be reduced to

$\left[\begin{array}{c}\mathrm{\&Delta;x}\\ \mathrm{\&Delta;y}\\ \mathrm{\&Delta;z}\end{array}\right]=\left[\begin{array}{ccc}0& \mathrm{\&Delta;\&alpha;}& 0\\ -\mathrm{\&Delta;\&alpha;}& 0& 0\\ 0& 0& 0\end{array}\right]\left[\begin{array}{c}{x}^j\\ y^j\\ z^j\end{array}\right]$

Because the time delay error that the Sagnac effect causes is:

$\mathrm{\&Delta;}{\mathrm{\&tau;}}_{\mathrm{Sagnac}}=\frac{\sqrt{{\left(\mathrm{\&Delta;x}\right)}^2+{\left(\mathrm{\&Delta;y}\right)}^2+{\left(\mathrm{\&Delta;z}\right)}^2}}{c}$

8, the real-time calculating of pseudorange

The CAPS system receives the navigation signal that satellite is transmitted by receiver user, measures by the signal transmission time Δ t of satellite to receiver _i(i represents satellite PRN number), the distance that just can calculate user to an i satellite is (wherein c is the electric wave transmission speed):

ρ _i＝c·Δt _i

The measured identical pseudo-code of CAPS subscriber equipment is produced respectively by land station and user, they all with separately clock synchronization, the local pseudo-code of receiver user and satellite are transmitted the pseudo-code of coming and are being moved before reaching maximal correlation always.Timing by local pseudo-code is compared with the timing of the clock of receiver, just can measure the time of arrival of signal, thereby obtains the distance of user to satellite.

In fact, because the influence of various errors, the range finding orientation problem is many more than above-mentioned principle complexity.What the user recorded is to comprise various error effects in interior distance, is referred to as pseudorange.The pseudorange that arrives receiver from i satellite is defined as follows:

ρ _i(n)＝c·[t _R(n)-t _Ti(n)]

In the formula, t _R(n) expression and the CAPS receiver clock n corresponding time of reception of epoch (s); t _Ti(n) expression is transmitted (s) constantly based on i satellite.

From formula

In as can be seen, the unit of pseudorange can be a distance, also can convert to time is unit.In the simulation process of simulator, the time of receiver comes out according to calculation of parameter, is known quantity.And send constantly to be unknown, need to calculate with respect to some receivers satellite-signal constantly.

When calculating satellite position, at first need calculate the moment on the star by following formula, below this formula is overwritten in:

t _k＝t-t _oe

It should be noted that the t here is the simulator moment, t _OeBe ephemeris constantly, the mistiming t that calculates by this formula _kDo not consider the influence of satellite transmission time and error, thus just thus the satellite position that calculates of formula be inaccurate.

In the CAPS satellite simulator generator course of work, because receiver receives that the moment of signal is not the moment that satellite-signal sends, thus can not simply apply mechanically following formula, need be to formula

Revise.Consider the propagation delay of satellite and receiver, suppose the satellite-signal that i satellite sends, through t _rAfter time, arrive receiver constantly at t.Then the time of sending of i the satellite-signal that receives constantly at t for receiver, following formula is modified to:

Δt _k＝t-t _r-t _oe

When just beginning to calculate, because the position of satellite is a unknown quantity, so can not determine t at the very start _r, in design, begin to get t averaging time that the CAPS satellite-signal arrives ground _r=0.125s.Use formula

Replace

Obtain (t-Δ t _k) position (x of i satellite constantly _Svi, y _Svi, z _Svi), by t receiver location (x constantly _u, y _u, z _u), can calculate t more accurately _r

$t_r=\frac{\sqrt{{(x_{\mathrm{svi}}-x_u)}^2+{(y_{\mathrm{svi}}-y_u)}^2+{(z_{\mathrm{svi}}-z_u)}^2}}{c}$

The t that obtain this moment _rMay still certain gap be arranged from actual value.In order to make result of calculation, need carry out interative computation and obtain new t as much as possible near actual value _rContrast the t that calculates for twice _rValue, the t that comes out up to twice iterative computation _rDifference less than 1 * 10 ^-10Till the s, promptly Dui Ying distance error is promptly thought to have obtained the correct relative propagation delay less than 3cm.

Pseudorange also comprises other error components except the relative position propagation delay.According to satellite constantly, satellite position and receiver location, having aforesaid Model Calculation to go out the range error that virtual clock error, troposphere cause is Δ ρ _TropError delay Δ τ with the ionosphere generation _Ion, then the range error that causes of ionosphere is Δ ρ _Ion=c Δ τ _Ion

Because in many error sources, having only ionospheric error is different to carrier phase and code phase, other are all just the same.Finally obtain real-time code delay

τ _CODE＝Δτ _P-i _clk+Δτ _Sagnac+Δρ _trop/c+Δτ _ion

Carrier phase postpones in real time

τ _c＝Δτ _P-i _clk+Δτ _Sagnac+Δρ _trop/c-Δτ _ion

Claims (7)

1.CAPS the Satellite Simulation signal generator is characterized in that:

Mainly constitute by host computer, baseband signal processing module, digital to analog converter, power splitter, 3 radio-frequency modules and output block; Wherein the inside of baseband signal processing module mainly is made of DSP message processing module and the FPGA signal processing module that is attached thereto; Linking to each other with the DSP message processing module of baseband signal processing module of host computer through serial ports, the FPGA signal processing module of baseband signal processing module is connected to power splitter through digital to analog converter, 3 output terminals of power splitter link to each other with 3 radio-frequency modules respectively, and the output terminal of 3 radio-frequency modules is connected with output block;

Host computer finishes mainly that text parameter extraction, scene generate, the satellite channel state of simulation, satellite starry sky distribute, simulated time defines, receiver location and speed and analog position are compared with the receiver positioning result; The DSP message processing module of baseband signal processing module is finished the calculating of user trajectory, the navigation message decoding, the phantom atom clock calculates, the real-time calculating of satellite position, and the calculating of propagation delay, yardage controlled oscillator and carrier number controlled oscillator calculate and monitor with run time behaviour that the FPGA message processing module is finished each passage jointly and proofread and correct; The FPGA message processing module of baseband signal processing module is finished high dynamic yardage controlled oscillator and the simulation of carrier number controlled oscillator, carries out the intermediate-freuqncy signal modulation, system sequence control and synchronous; The baseband signal that above-mentioned baseband signal processing module generated is divided into 3 the tunnel to baseband signal by power splitter after the digital to analog converter conversion, this 3 road signal is exported by output block after 3 radio-frequency modules upconvert to three frequencies of GAPS.

2. CAPS Satellite Simulation signal generator according to claim 1 is characterized in that: described output block is that combiner reaches antenna or 3 radio-frequency cables that link to each other with combiner.

3. according to claim 1 and 2 described CAPS Satellite Simulation signal generators, it is characterized in that: host computer is according to the CAPS text, extract correlation parameter, the parameter of being extracted is transferred to by the FPGA message processing module carries out regrouping of text in the DSP message processing module.

4. according to claim 1 and 2 described CAPS Satellite Simulation signal generators, it is characterized in that: the movement locus of host computer analog receiver comprises dead point, uniform motion, circular motion, uniform acceleration motion or varying accelerated motion.

5. according to claim 1 and 2 described CAPS Satellite Simulation signal generators, it is characterized in that: also establish ionospheric error model, tropospheric error model, multipath error model, satellite ephemeris error model, phantom atom clock error model and/or earth rotation effect errors model in the baseband signal processing module, the DSP message processing module generates the parameter of revising and changing the satellite-signal state according to the above-mentioned error model error of calculation.

6. CAPS Satellite Simulation signal generator according to claim 5 is characterized in that: described ionospheric error model is an ionosphere first-order error model.

7. CAPS Satellite Simulation signal generator according to claim 5 is characterized in that: the multipath error model includes the caused error of amplitude, phase place and relative time delay of the relative direct wave of multi-path signal.

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