CN102313892B - GPS (Global Position System) and GLONASS (Global Orbiting Navigation Satellite System) multichannel parallel signal tracking method and module - Google Patents

Abstract

The invention discloses GPS (Global Position System) and GLONASS (Global Orbiting Navigation Satellite System) multichannel parallel signal tracking method and module, wherein the module comprises a carrier digital control oscillator, a code digital control oscillator, a carrier cycle counter, a C/A (Coarse/Acquisition) code generator, a signal source selector, a carrier mixer, a code mixer, an adder and a rejecter, a code phase counter, a code toggle counter and an epoch counter.

Description

GPS and GLONASS multichannel parallel signal method for tracing and tracing module

Technical field

The present invention relates to satellite-signal tracing system, mainly refer to a kind of GPS and GLONASS multichannel parallel signal method for tracing and tracing module.

Background technology

Known GPS adopts CDMA signals, and GLONASS adopts and divides multi-address signal equally.Traditional satellite-signal tracing system can only receive GPS or GLONASS signal, can not receive GPS and GLONASS signal simultaneously.

Summary of the invention

Object of the present invention is just to provide a kind of GPS and GLONASS multichannel parallel signal method for tracing and tracing module, by antenna compatibility, decoding, carrier separation mixing, programming Control channel, realize a receiver and can receive GPS and GLONASS multi-channel signal simultaneously, overcome preferably the deficiency that prior art exists.

Realizing method of the present invention is: catch with tracking satellite signal and comprise the steps:

CHx_SATCNTL register is programmed to select GPS gold code (RPN numbering) or the GLONASS code wanted, the tracking arm that will be also correlator is selected type of coding simultaneously, generally at acquisition mode, fix on following the trail of arm " Dithering " pattern (" Early " and " Late " pattern do not stop to switch) search at two phase unwrappings immediately, once then find satellite just to switch to tracking pattern;

To CHx_SIGSEL register programme for correlator select input signal and for arrowband converter (if GLONASS) select centre frequency;

The numerical value that CHx_CARR_INCR_LO register is programmed into this register is for being the frequency that married operation in the correlator of 12 channels is selected local oscillator, come 2 bit digitized signals of input to mix down to base band from radio-frequency front-end, the nominal frequency that the numerical value being programmed equals local oscillator adds the compensate for estimated value of Doppler displacement, adds the compensate for estimated value of user clock frequency drift;

The numerical value that CHx_CODE_INCR_LO register is programmed into this register is the twice of C/A coding nominal code check (2.046MHz or 1.022MHz), if needed, adds a small amount of compensation of Doppler displacement and user clock frequency;

Remove the replacement of following the trail of channel by programming writes suitable numerical value to RESET CONTROL register.This operation can start associated process;

Obtain cumulative data data to the reading of cumulative data register, to continuous the reading the cycle that can be added to increase correlation integral several times of same tracking channel;

Determine GNSS signal whether found be by correlation integral result and a threshold, if determine that signal finds that just to jump to signal and draws in algorithm.The cumulative data that is noted that the signal of homophase and the signal of vertical phase all will be considered, because the uncertain and input GNSS signal homophase of local carrier numerically-controlled oscillator during this time;

If GNSS signal does not have the found reprogramming that just needs to change carrier wave numerically-controlled oscillator, coded digital control oscillator frequency or gold code are attempted again.Typical way is first to keep the frequency of two numerically-controlled oscillators constant, stir gold code phase place until 2046 or 1022 possible positions be all covered to, if signal does not find, that just marginally changes the frequency of carrier wave numerically-controlled oscillator and then the phase place of gold code is scanned, and stirring of gold code phase place is to realize by the programming to CHx_C0DE_SLEW register;

Once the found encoding phase alignment of GNSS signal, carrier phase alignment and Doppler and user all the time deviation compensation are also very coarse, encoding phase alignment accuracy can be half code bit, the digital control oscillator signal of carrier wave and not homophase of input signal, and the error of frequency also can reach continuous attempt time step value.

Realizing tracing module of the present invention is: comprise that carrier wave numerically-controlled oscillator, coded digital control oscillator, carrier wave cycle counter, C/A code generator, signal source selector switch, carrier wave mixer, coding mixer, cumulative sum abandon, encoding phase counter, coding are stirred counter, epoch counter;

The beneficial effect that the present invention has: adopt compatible antenna, relatively independent channel, different decoding processes, and believe channel receiving signal by programming Control, realized a receiver and can receive GPS and GLONASS multi-channel signal simultaneously.

Accompanying drawing explanation

Fig. 1 is integration carrier phase figure of the present invention, shows integration carrier phase equation is what how to be pulled to out.

Fig. 2 is the structural drawing of time mark generator of the present invention.

Fig. 3 is time marker figure of the present invention.

Fig. 4 empties sequential under more new model of the present invention.

Fig. 5 is tracing module schematic diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the invention will be further described:

The present invention includes method and tracing module two parts.

Method part:

The software sequences (Software Sequence For Acquisition) of acquiring satellite

The frequency spectrum of satellite-signal is the gold code of band spectrum modulation.

This has caused satellite-signal very faint In the view of GNSS recipient, has been submerged in noise so that can only just can be detected by relevant.So relevant in order to do to the received signal, must select a this locality to generate, type of coding, the coding duplicate that code check and phase place are all mated.

Then this model is taken advantage of with regard to carrying out position with the data stream of input, and the result obtaining is carried out integration and recovered this signal on code length.The process of signal capture is exactly simple coupling receiver setting and real signal value in fact.But actual conditions are more complex, satellite carrier signal frequency can be because of the Doppler effect of satellite motion generation by a small amount of skew, user's clock can drift about randomly, and (in most cases) some satellites signal to noise ratio (S/N ratio) very undesirable.So just require software must be " wideband " to can find signal, be again simultaneously " narrow frequency " to reduce noise, cause the greatest differences of program under different application environment.At all tracking channels, signal processing software needs following active sequences:

1. pair CHx_SATCNTL register programmes to select GPS gold code (RPN numbering) or the GLONASS code wanted, will be also the tracking arm selection type of coding of correlator simultaneously.Generally at acquisition mode, preferably fix on following the trail of arm " Dithering " pattern (" Early " and " Late " pattern do not stop to switch) search at two phase unwrappings immediately, once then find satellite just to switch to tracking pattern

2. pair CHx_SIGSEL register is programmed for correlator selection input signal and is arrowband converter (if GLONASS) selection centre frequency

3. to be programmed into the numerical value of this register be for being the frequency that married operation in the correlator of 12 channels is selected local oscillator to pair CHx_CARR_INCR_LO register, comes 2 bit digitized signals of input to mix down to base band from radio-frequency front-end.The nominal frequency that the numerical value being programmed equals local oscillator adds the compensate for estimated value of Doppler displacement, adds the compensate for estimated value of user clock frequency drift.

4. pair CHx_CODE_INCR_LO register is programmed into the twice that the numerical value of this register is C/A coding nominal code check (2.046MHz or 1.022MHz).If needed, add a small amount of compensation of Doppler displacement and user clock frequency.

5. remove the replacement of following the trail of channel by programming writes suitable numerical value to RESET_CONTROL register.This operation can start associated process.

6. obtain cumulative data data from reading cumulative data register.To continuous the reading the cycle that can be added to increase correlation integral several times of same tracking channel.

7. determine GNSS signal whether found be by correlation integral result and a threshold.If determine that signal finds that just to jump to signal and draws in algorithm.The cumulative data that is noted that the signal of homophase and the signal of vertical phase all will be considered, because the uncertain and input GNSS signal homophase of local carrier numerically-controlled oscillator during this time.

8., if GNSS signal does not have the found reprogramming that just needs to change carrier wave numerically-controlled oscillator, coded digital control oscillator frequency or gold code are attempted again.Typical way is first to keep the frequency of two numerically-controlled oscillators constant, stir gold code phase place until 2046 or 1022 possible positions be all covered to, if signal does not find, that just marginally changes the frequency of carrier wave numerically-controlled oscillator and then the phase place of gold code is scanned.Stirring of gold code phase place is to realize by the programming to CHx_CODE_SLEW register.

9. once, the found encoding phase alignment of GNSS signal, carrier phase alignment and Doppler and user all the time deviation compensation are also very coarse.Encoding phase alignment accuracy can be half code bit, the digital control oscillator signal of carrier wave and not homophase of input signal, and the error of frequency also can reach continuous attempt time step value.

Signal processing software next step must adopt one to draw in algorithm to improve these alignment operation.There are a lot of suitable algorithms available, such as continuous a small amount of stepping is until error is negligible, as analog PLL, or carrys out evaluated error with more complicated signal processing and then jump to good many data group.Then signal draws in algorithm and can write CHx_CARR_INCR_LOl register programming the value more accurately of carrier wave numerically-controlled oscillator.The correction that gold code is less than to half code bit cannot realize by the programming of the CHx_CODE_SLEW register in code generator, and should guide coded digital control oscillator at leisure gold code phase place to be adjusted to correct numerical value by CHX_CODE_INCR_LO register is set.

Signal tracing (Signal Tracking)

Because satellite box has an inhomogeneous movement for recipient, so the GNSS signal of input can show a Doppler displacement changing in time domain, user clock skew simultaneously is also tended to change in time domain.Net result is exactly, unless coding and carrier wave numerically-controlled oscillator are proofreaied and correct dynamically, GNSS signal will be lost.This has caused two servo loops essential: maintenance locking to gold code phase place, another keeps the locking to carrier wave.This can be realized by following method.

The raw data that guides these two servo loops is cumulative data, and these data are exported once with every millisecond of frequency once by following the trail of channel.The cumulative data of following the trail of arm is used in gold code circulation; Some approximation methods are with " deducting in advance hysteresis " (' early minus late ") gold code carries out a kind ofly without boot cycle, and other use a kind of shake replacing half code bit after and between the coding that shifts to an earlier date of half code bit to encode.In ZVM2060IP, chattering frequency Shi Mei road 20ms (20 coding epoch) shifts to an earlier date code since one after resetting,

This coding is chosen by CHx_CNTL register.Gold code circulation comes closed by upgrade regularly coded digital control oscillator frequency with CHx_CODE_INCR_LO register.

The cumulative data of punctual arm is used to carrier phase circulation (also may being used although follow the trail of the jitter mode of arm).A kind of method is the phase place that changes carrier wave numerically-controlled oscillator to keep all correlation energy all at homophase correlator arm and not at all at vertical phase correlator arm.Carrier phase circulation comes closed by upgrade regularly the digital control oscillator frequency of carrier wave with CHx_CARR_INCR_LO register.

Data demodulates (Data Demodulation)

C/A coding and space communication instrument (SV) data are modulated at 50 bauds.This modulation system is that C/A coding and SV data are asked to XOR.The fragrance of that C/A coding of new data bit and difference before this means every 20 milliseconds (namely 20C/A encodes epoch), if will be reversed (mobile 180 degree).At punctual arm, once signal is correctly followed the trail of, such data bit transmission can change the symbol of cumulative data.Data demodulates just realizes through the following two-step:

1. locator data position transmission time, to pick out the beginning of which C/A coding epoch of corresponding new bit.This just allows counter initialization epoch (by CHx_1MS_EPOCH and CHx_20MS_EPOCH register) of ZVM2060IP, with from 0 to 19 and data bit homophase counting coding epoch.In the new circulation of each 1ms counter epoch, 20ms counter epoch can increase.

2. the symbol that records cumulative data at the data bit period of each 20ms at punctual arm, reduces the impact of signal noise by filtering.Notice that demodulating process exists the ambiguous situation of symbol because cannot from which data bit of signal judgement itself be 0 that be 1.This ambiguous situation can solve in next step after complete navigation information is resolved.

Pseudo range measurement (Pseudorange Measurement)

Measurement data register provides compute pseudo-ranges needed raw data, and this raw data is a sampling, at a 20ms or 1ms counter epoch, and the moment of the TIC signal setting of C/A encoding phase counter and coded digital control oscillator phase.According to definition, pseudorange is expressed as chronomere, equals satellite and adds user clock deviation to recipient's signal propagation delay.User clock deviation be first estimated (if cold start-up that be exactly to guess blindly mostly, but to consume more recurrence time) then as the secondary product of navigation results be calculated come.The local solar time (t1) that pseudorange equals subscriber signal deducts the actual time (t2) that GNSS signal transmits.

By the data of demodulation, software just can addressing space vehicle navigation information (Space Vehicle Navigation Message), and it has comprised the GNSS system time information of transmitting current subframe.It equals time t2.

Temporal information in navigation information allows the receiver time (data bit period) under the resolution of 20ms to be initialised, if but precision is known about to many resolution that just can reach, such as being less than the code bit of C/A coding-more a little bit smaller than 1ms.Because the travel-time of light from satellite to receiver is in the scope of 60-80ms, the improvement that local zone time is guessed for the first time can reduce the recursive calculation time below.

Labelled to the TIC moment by usage data, and epoch counter values, code generator phase place, and encoded clock phase place, measuring SV signal is possible in the time of local solar time.This has just provided the value of the required t1 of pseudo range measurement, and pseudorange just can be calculated by t1-t2 like this.

The error representing in set of time is the initial user limit value of deviate and various counter phase all the time.Once a navigation results is found, just can very accurately know clocking error, it can be used in its computation of pseudoranges in the future.Because receiver clock is along with time drift, clock jitter is along with the time changes, so they must be followed the trail of with navigation software.

Control ZVM2060IP

Ensuing trifle has been described the typical method of controlling ZVM2060IP.They comprise signal capture and tracking, the generation of carrier phase measurement and time marker.

Search operation (Search Operation)

Want executive signal to catch, the searched until signal of carrier frequency and encoding phase space requirement is detected.The carrier swing relatively peak excursion of its nominal value adds that by maximum carrier doppler displacement maximum receiver clock error determines.Maximum encoding phase is by code length (fixing) decision.In general, before moving to next carrier frequency, all encoding phase grids all can searchedly arrive, and then just travel frequency grid is searched for encoding phase again.

The programming of carrier wave numerically-controlled oscillator

Following register:

CHx_CARRIER_DCO_INCR

Be programmed by relevant data successively according to searched frequency grid.Carrier wave numerically-controlled oscillator is programmed in when channel is released (activation) and comes into force.If channel is activated, to the write operation of CHx_CARRIER_DCO_INCR come into force (the of short duration time delay of a maximum 175ns can occur, to allow the synchronous of the write operation of processor to chip) at once.

The programming of coded digital control oscillator

Following register

CHx_CODE_DCO_INCR

Use successively relevant data programing according to the coding frequency shift (FS) of estimating.Coded digital control oscillator is programmed in when channel is released (activation) and comes into force.If channel is activated, to the write operation of CHx_CODE_DCO_INCR come into force (the of short duration time delay of a maximum 175ns can occur, to allow the synchronous of the write operation of processor to chip) at once.

Code generator programming

To each channel, CHx_SATCNTL register root is according to being programmed as follows:

1. SOURCESEL position is set and selects input signal source

2. arrange TRACK_SEL position arrange follow the trail of arm be encoded to " shift to an earlier date " or " backwardness " (with respect to " on time " arm).

3. G2_LOAD position is set and selects the PRN coding requiring.

4. according to the encoding phase deviation of expecting, CHx_CODE_SLEW register is programmed.Stir operation meeting comes into force in the time that CHx_RSTB is released.First DUMP operation can generate cumulative data and relevant CHx_NEW_ACCUM_DATA mode bit is set for channel.

5. discharge the CHx_RSTB position of RESET_CONTROL to activate channel.

When encoded clock disabled (being used for stirring encoding phase) " integration " and " abandon " module keeps resetting.Only have when stirring and just can start cumulative correlated results after having operated.

Satellite of multichannel search can be by using coding value of stirring of MULTI channel address and suitable difference.

Read cumulative data

Each " abandon " operate corresponding CHx_NEW_ACCUM_DATA mode bit and can in ACCUM_STATUS_A register, be set up.The mapped all continuous addresses of status register and all accumulator register (CHx_1_TRACK, CHx_Q_TRACK, CHx_1_PROMPT, CHx_Q_PROMPT).If needed, interrupt at each ACCUM_INT, these register datas can be read as a continuous block.Or status register can be by training in rotation.Accumulator register is write covering protection now, so very fast-response of system in the time that new data come into force.Whether need to process cumulative operation in each DUMP operation and depend on concrete application.Reading the order of these register datas can select, but it is desirable to CHx_Q_PROMPT register is finally read, the CHx_NEW_ACCUM_DATA position because this can reset.

The CHx_MISSED_ACCUM position of ACCUM_STATUS_B indicates new cumulative data to lose.These register-bit can only be removed by writing CHx_ACCUM_RESET or reactivating channel.Search for other encoding phases, be correlated with when being desirably in next encoding phase, such as after a whole code bit, CODE_SLEW will be programmed and write 2 (unit is half code bit).Stirring operation meeting carries out at next DUMP.The effect of CODE_SLEW is relevant with current encoding phase.Repeat CODE_SLEW, register will be re-write, even the size of stirring is the same.Once satellite-signal is detected (having reached dependent thresholds), the tracking circulation of coding and carrier wave just can have been closed.The parameter of following the trail of circulation must be integrated in software to adapt to concrete application.

Data bit sync data bit sync algorithm should find the moment of data bit transmission.Processor calculates and then this numerical value is write to 1MS_EPOCH counter one millisecond of current epoch.Under perfect condition, epoch counter access should occur in the accumulator register write operation of each DUMP after.

Or epoch, counter can leave that it turns round voluntarily, deviation by software each it add up in reading register epoch.If attention integration operation is passed through bit border, integral result can be very little.

Read measurement data

In each TIC moment, measurement data all can be latched in measurement data register:

CHx_EPOCH，

CHx_CODE_PHASE，

CHx_CARRIER_DCO_PHASE，

CHx_CARRIER_CYCLE_HIGH，

CHx_CARRIER_CYCLE_LOW，

CHx_CODE_DCO_PHASE.

ACCUM_STATUS_B or MEAS_STATUS_A register must be ask (whether occurring to check a TIC) at an enterprising road wheel of frequency that is greater than TIC frequency, otherwise measurement data can be lost.ACCUM_INT or MEAS_INT event can be used for starting this operation.Both reading of measurement data can be also poll by interrupting starting.In each MEAS_INT, have no progeny and read ACCUM_STATUS_B or MEAS_STATUS_A register for the strick precaution microprocessor that interrupts starting, if TIC position is set up, and then just read measurement data.For polling method, ACCUM_STATUS_A register is always had no progeny and is read in ACCUM_INT.ACCUM_STATUS_B register is had no progeny and is read to guarantee not have cumulative data to be lost and to check TIC position (and several mode bit) in each ACCUM_INT in addition.Software inspection TIC position determines that new measurement data can be read.

Prepattern (Preset Mode)

A PRESET/UPDATEB position high position for register, each channel can be programmed into prepattern.

When TIC event occurs, satellite coding, epoch numerical value and stir number and be loaded, a new phase place is programmed and writes coded digital control oscillator, the numerical value before in this phase place and oscillator is irrelevant.Before the TIC time, channel is according to the running that arranges before it.

Prepattern multi-carrier digital control oscillator and carrier cycle counter do not affect.

Once prepattern actuated, it should be allowed to move to end.The running process requiring is as follows:

1. register is selected prepattern, writes suitable new setting simultaneously

2. load coding and the digital control oscillator increment numerical value of carrier wave.Attention: can affect current measurement so these come into force.

3. load following register

CHx_CODE_DCO_PHASE，

CHx_CODE_SLEW and

CHx_EPOCH_COUNT_LOAD.

The last loading of CHx_EPOCH_COUNT_LOAD is very important, because it can activate the initialize operation of next TIC

Interrupt (Interrupts)

Having the INTOUT cycle of interrupt source: an INTOUT. acquiescence is 505.05s.This cycle can reset by PROG_ACCUM_INT register or by the INTERRUPT_PERIOD position that changes SYSTEM_SETUP register.

The TIC cycle of acquiescence is 99.9999ms.It can reconfigure by PROG_TIC_HIGH and PROG_TIC_LOW register.

The signalling channel time delay that hardware signal processing is introduced

When expecting to produce an accurate clock reference or add time mark to location, position from GNSS signal, the time delay of receiver must take in.Signalling channel time delay comprises two parts, and one is analog channel time delay, along with temperature and component tolerances variation, and a digital communication channel delay, if oscillator drift variation can be ignored, it is exactly constant.

The valuation of digital delay is simpler, and it consists of the following components:

1. the time from (SMPCLK) SIGN of front end and the sampled edge of MAG position to sampling latch resampling (than from SMPCLK to the few 175ns of front end propagation delay).

2. add the associative operation required time (175ns) of correlator on identical SIGN and MAG position.

3. add and in totalizer, be used for the time delay of latch sampled data.

4. deduct the time between associative operation and accumulator latch phase place (75ns) TIC clock phase before.

Be set to the group delay parameter in wave filter by the simulation time delay of radio-frequency transmitter, for C/A encode loan used or 1 in the scope of 2ms, so be submerged in digital delay.But it can measured and correction.

Integration carrier phase measurement

The hardware that correlator is followed the trail of channel allows to be sampled in each TIC moment by the measured value as a measurement data part of CHx_CARRIER_CYCLE_HIGH/_LOW and CHx_CARRIER_DCO_PHASE register.The crossing numerical value of forward zero of the carrier wave numerically-controlled oscillator that CHx_CARRIER_CYCLE_HIGH/_LOW register has comprised 20 bits: these can be more one than the numerical value in the whole cycle in past (4 at _ HIGH, and 16 at _ LOW register).

CHx_CARRIER_DCO_PHASE register has comprised cycle decimal or phase place, and the resolution of 10 provides the increment of 2/2046 radian.

Obtain the integration carrier phase in several TIC cycles, required do be exactly each TIC moment read CHx_CARRIER_CYCLE_HIGH and _ LOW register and read value is sued for peace.When carrier cycle measurement is to send to mutually next forward zero from a forward zero to intersect, this can provide one than the numerical value of complete carrier cycle high 1.

Last carrier cycle decimal must be added on this numerical value, and the carrier cycle decimal starting must be subtracted.Two numerical value are to be all read from CHx_CARR_DCO_PHASE register.Total phase place variation can be calculated as follows:

Integration carrier phase=2 π * Σ Numbersin Carrier Cycle Counter+final Carrier DCO phase-Initial Carrier DCO phase

Fig. 1 has shown this equation is what how to be pulled to out

This integration carrier phase can be with " delta " distance (to the change of distance of each satellite) connects.When using with together with the orbit parameter of satellite, " delta " distance can provide the traverse measurement value of receiver between an anchor point, and this measured value is with respect in anchor point, so can be used for them to do smoothly.It also can directly provide velocity amplitude simultaneously." delta " and distance be comprise noise and also most of numerical value depend on the motion of satellite, so determining of speed must be used the data from the TIC of abundant separation.Level and smooth all for position " delta " apart from being all comprised in the input of Navigation Filter.This wave filter can be carried out one " delta " consecutive mean of distance and distance.

Rise time mark (TMARK)

Time marker (Time Mark) generator be designed to each second provide one can be with given time base (such as receiver time base, GPS, GLONASS UTC Universal Time Coordinated lock unit or UTC Universal Time Coordinated) synchronous time marker output signal.Time marker generates after certain programmable time delay relevant with TIC.

The structure (referring to Fig. 2) of selecting has provided lower energy consumption so only relate to clock at the minimum hardware of high-frequency drive.

Give an example, for lock in time mark to UTC Universal Time Coordinated (UTC), software can have following operating process (referring to Fig. 3):

1. catching once in a while measurement data (in arbitrary TIC moment) is used for

2. resolve the UTC Universal Time Coordinated (t0) of measuring the moment.Noticing that resolution can only be accurate to the hardware transmission speed in receiver, is generally several milliseconds, unless these time delays were calibrated and UTC Universal Time Coordinated resolution is corrected according to calibration result.

3.Compute on which 100ms TIC, tm, to take the next sample of measurement data such that: calculate in which 100 milliseconds of TIC moment next measurement data is sampled to meet:

UTCTIMEMARK-tm＝δ1+δ2

Here UTC TIME MARK=and UTC Universal Time Coordinated synchronous expected time mark second

δ 1=kx (time between TICs), here k=INTEGER and δ 1 > navigation results computation delay.

δ 2=time marker and 100ms TIC mark " tr " between time deviation (having the resolution of 50ns)

δ 2 < (time between the TIC moment)

4. catch measurement data at moment tm.Calculate Nav result at moment tm.Transmit Nav result in the UTC moment.By known oscillator drift, the 25ns time delay that time marker maker unit adds and the propagation delay of calibrating, calculate DOWNCOUNT, and the numerical value of the input reciprocal counter able to programme of programming is with time marker time delay δ 2.

5. before tr event occurs, to reciprocal counter, programming writes DOWN COUNT value.

6. after the tr time, in 2000ms, export ARINC DATA (following ARINC743).

7. then location tm+1 returns to step 4.

The budget of UTC Universal Time Coordinated (UTC) error

Following error budget all and the generation of time marker (Time Mark) have relation:

Total error=TDOP+ clock resolution+oscillator drift residual error.

+ calculate and introduce error.

The time delay that the transmission of+time marker produces by device/circuit..

+: the transmission delay in hardware, from antenna to correlator to measurement data sampling thief.

Representative value is wherein:

1.TDOP: when selecting availability (SA) to open, estimated value is 177ns (2 δ number)

2. clock resolution: 50ns (in 21 reciprocal counters able to programme).

3. oscillator drift residual error:

(a) come to calculate the temperature variation on the TCXO starting since last oscillator drift:

(i) TCXO maximum slope is ± 1ppm/ ℃

(ii) maximum temperature variation is 5 ℃/minute

(iii) so once there is at most a second in oscillator drift calculating per second in UTC Universal Time Coordinated mark.

Such as:

Using 5 ℃/min of 1ppm/ ℃ of x x 1sec=83ns as temperature step change or 41.5ns (being rounded to 50ns) as linear gradient

(b) because maximum error is total oscillator drift error=(a)+(b) >>100ns. of 50ns (roughly conjecture) in drift valuation

4. calculate and introduce error: be retained this error and level off to 0 so be assumed to be abundant useful position.

5. the time delay that time marker transmission produces by device/circuit: this can carry out calibration and compensation by the feedback with reciprocal counter according to the output of GPS receiver, can have residual error, because:

(a) clock resolution=50ns

(b) delay of feedback correction=25ns (estimated value)

6. the transmission delay in hardware: so these are all the chief components of time marker (Time Mark) timing error by estimating in the scope of several milliseconds.When whole hardware design completes, an algorithm for estimating can be contained in software to improve total degree of accuracy.

The time delay of total error=177ns+50ns+100ns+0+75ns+ hardware

The time delay of total error=402ns+ hardware.

Tracing module part:

As shown in the figure, the present invention is the tracing module of 60 channel parallel correlators, and it can be used for catching and following the trail of GPS C/A coding or GPS L2 or GLONASS signal.

Tracing module (Tracking Modules):

By 60 numberings, the identical signal tracing channel from CH1 to CH60 forms tracing module, and each possesses the cellular construction shown in Figure 10.These unit produce and are used for the data of tracking satellite signal.These data do not possess the covering protection of writing mechanism.More information is referring to " controlling ZVM2060IP " chapter.

Each tracking channel can independently be programmed, so that they are operated under renewal (Update) or preset (Preset) pattern.More new model is general mode of operation.Prepattern is a special pattern, under this pattern, can be delayed to next TIC to the write operation of certain register, to reach the object of SYN register and preset coded digital control oscillator phase.Concrete information is with reference to " prepattern " trifle of " controlling ZVM2060IP " chapter of 13 pages.

Carrier wave numerically-controlled oscillator (Carrier DCO):

The digital control oscillator synchronization of carrier wave is in SMPCLK clock frequency, is used for synchronous local digital oscillator signal, and this signal is used to the input signal of mixer module to be downconverted to base band.It must depart from nominal value to allow certain Doppler shift and reference frequency error.

In the time using together with GP2015/GP2010, the nominal frequency of this signal is 1405396825MHz (resolution is 4257475mHz), sets by the CHx_CARRIER_DCO_INCR register that loads 26 bits.So high resolution is in order to guarantee that numerically-controlled oscillator can keep homophase with satellite-signal within one sufficiently long period.The phase place of carrier wave numerically-controlled oscillator cannot directly arrange, and must indirectly arrange by changing its frequency.

The output of carrier wave numerically-controlled oscillator is the sine wave of fourth class eight-phase, and its sequence in one-period is as shown in table 2.

Terminal arm sequence

ILO -1+1+2+2+1-1-2-2

QLO +2+2+1-1-2-2-1+1

The output of table 2. carrier wave numerically-controlled oscillator

Because the clock of DCO generally all wants specific output frequency low 8 times, so not every phase place all can generate at one-period.If the typical clock frequency of 5.714MHz and the output frequency of 1.405MHz, so each cycle only has about four phase places.These phase places can slide along with passage of time the whole cycle to cover all values.

Coded digital control oscillator (Code DCO):

Coded digital control oscillator and carrier wave numerically-controlled oscillator are similar.It is also synchronized with SMPCLK clock frequency, and synchronous corresponding crystal oscillator makes it in the frequency that doubles desired code check, drive code generator.The output frequency of nominal is 2046MHz, gives the code check of GPS 1023MHz or 1022MHz, gives the code check of GLONASS 511MHz.This is that CHx_CODE_DCO_INCR register by loading 25 bits is set.

In the time using together with GP2015/GP2010 front end, crystal oscillator frequency resolution is set to 8514949mHz, and similarly, so high resolution is in order to keep numerically-controlled oscillator and satellite-signal to keep homophase.Under prepattern, the phase place of coded digital control oscillator can only be accurately set to the phase place of satellite-signal.In new model more, it can only by regulate not holding any government official post's frequency come and satellite-signal maintenance phase place consistent.

Carrier cycle counter (Carrier Cycle Counter):

Carrier cycle counting appliance, for the length of 20 bits, is used for calculating the digital control cycle oscillator of carrier wave between the TIC moment.Basic navigational system is not need this, but can be used to measure between the TIC moment and the variation (delta-change) of each satellite distance." delta-change " can be used to the pseudorange of smoothly encoding.More particularly, will be read in the digital control oscillator phase of each TIC moment carrier wave, to provide the fraction part of periodicity or " delta-change ".

GPS C/A, GPS L2and GLONASS coding maker (Code Generators) C/A coding maker is GPS satellite (1-32), terrestrial transmitters (pseudo satellite, pseudolite, 33-37), INMARSAT-GIC satellite (201-210) or GLONASS satellite generate the gold code (Gold code) of selecting.

The selection of gold code is 10 bits by CHx_SATCNTL register being write to the AD HOC that " register is introduced in detail " chapter lists, or is that low level is selected GLONASS coding by GPS_NGLON is set.Generate two outputs to provide a PROMPT signal and a TRACKING signal simultaneously.TRACKING signal can be set to four one in pattern: EARLY (putting forward previous half code bit than PROMPT signal), LATE (falling behind one and half code bits), FIXEDW (525ns in advance) or FIXEDN (falling behind 525ns).

In the ending of each coded sequence (GPS pattern is 1023, and GLONASS pattern is 511), a DUMP signal can be generated, and is used for the required cumulative data of latch signal Trancking Software.Each channel is independent latch, because satellite-signal is not homophase each other received time.

The feature of GLONASS is, each satellite-signal uses identical PRN gold code, and on frequency domain these signal distinguishings come (1598MHz is to 1616MHz).Navstar GPS is the carrier signal (L1=1575.42MHz) that uses same frequency, and modulation is with different PRN gold codes.Special arrowband converter can be transformed into GPS frequency range GLONASS signal, then forms the signal needing with demodulation GLONASS signal at each channel.Because possess such ability, so GZVM2060IP can decode efficiently to GLONASS group of stars signal.

The present invention comprises a C/A code generator (by the GPS_NGLON position zero of CHx_SATCNTL is chosen), is used for GLONASS signal to decode.

In the present invention, there are 12 channels (49 to 60) to comprise GPS L2 code generator (choosing by GPSL2_M and GPSL2_C position that CHx_SIGSEL register is set), are used for GPS L2 signal to decode.

Signal source is selected multiplexer (Source Selector Multiplexor):

Signal source selector switch is a multiplexer.It determines to use two input signals (referring to the form of CHx_SIG_SEL register) of which 16 1 groups.

Carrier wave mixer (Carrier Mixers):

Carrier wave mixer obtains baseband signal the signal multiplication of input signal and the generation of local carrier numerically-controlled oscillator.The digital control oscillator phase of carrier wave of I and Q is all sent to suitable mixer.The mixing of local carrier numerically-controlled oscillator and input signal is created in interval+1, the baseband signal of value in-1 ,+2 ,-2 ,+3 ,-3 ,+6 and-6.

Coding mixer (Code Mixers):

Coding mixer obtains four independently correlated results PROMPT and the TRACKING code multiplied of the baseband I & Q signal from the output of carrier wave mixer and local replica generation.Correlated results can be sent to " cumulative sum abandons " module carries out integration.

Cumulative sum abandons " (Accumulate andDump):

Cumulative sum abandons " module coding carries out integration to the output of mixer (nominal is 1ms) in a code period.Each channel has four independently 16 bit accumulators.The result of these totalizers has represented the correlativity of in whole integral process i/q signal and PROMPT and TRACKING coding.Because these registers do not possess the covering protection of writing mechanism, data wherein must just be read before next ' DUMP ' operation.

Encoding phase counter (Code Phase Counter):

Encoding phase counter calculates the number of the subluxation of generate coding, then in each TIC moment, this numerical value is stored in to CHx_CODE_PHASE register.

Coding is stirred counter (Code Slew Counter):

Coding is stirred counter and is used for stirring with the unit of half code bit in the scope of the scope that the is coded in 0-2047 generating.In new model more, after stirring and occurring in next DUMP operation.Under prepattern, it occurs in the next TIC moment.All fluctuation operations are all relevant with current encoding phase.When need to stirring operation, all want odd encoder to stir counter at every turn and carry out write operation.

In the process of stirring, the totalizer of respective channel is disabled, so that first result is effective.When one stir operation while being written into channel disabled, stir so and will when channel is activated, occur.

Counter epoch (Epoch Counter):

Epoch, counter continued to calculate the code period in one second interval.This is expressed as an expression with 5 words of the integral time (0-19) of 1ms position unit, adds 6 words that comprise the counting (0-49) take 20ms as unit.Epoch counter can be loaded in advance with synchronization of data streams from satellite.Epoch, the value of counter more can be sent to counter under new model at once, or under prepattern, was transmitted in the next TIC moment.

Epoch, the numerical value of counter was latching to CHx_EPOCH register in each TIC moment.Its instantaneous value can be checked from CHx_EPOCH_CHECK register in addition.

Fig. 1 word annotation:

1.Reading at TICo (reading in the TICo moment): CHx_CARR_DCO_PHASE ₀=PH ₀

2.Reading at TIC ₁(at TIC ₁moment reads): CHx_CARR_DCO_PHASE ₁=PH ₁

CHx_CARR_CYCLE ₁＝K ₁+1

3.Reading at TIC ₂(at TIC ₂moment reads): CHx_CARR_DCO_PHASE ₂=PH ₂

CHx_CARR_CYCLE ₂＝K ₂+1

ΔY1＝2πK1+(2π-PH0)+PH1

＝2π(K1+1)-PH0+PH1

＝2π(CHX_CARR_CYCLE1-CHX_CARR_DC0_PHASE0/1204+

CHX_CARR_DC0_PHASE1/1024)；

$\mathrm{\&Sigma;\&Delta;<figure-callout\; id="1"\; label="Y"\; filenames="HSB00000520184500031.png"\; state="\{\{state\}\}">Y</figure-callout>}1=2\mathrm{\&pi;}(\underset{i=1}{\overset{\mathrm{LAST}}{\mathrm{\&Sigma;}}}\mathrm{CHX}\_\mathrm{CARR}\_\mathrm{CYCLE}1-\mathrm{CHX}\_\mathrm{CARR}\_\mathrm{DCO}\_\mathrm{<figure-callout\; id="0"\; label="PHASE"\; filenames="HSB00000520184500031.png"\; state="\{\{state\}\}">PHASE</figure-callout>}0/1024-$

$\mathrm{CHX}\_\mathrm{CARR}\_\mathrm{DCO}\_\mathrm{PHASELAST}/1024);$

NOTE：The carrier cycle counter counter value is stored at every

TIC and the counter is reset

(note: the numeral of carrier cycle counter was stored in each TIC moment, unison counter resets)

Fig. 2 word annotation:

40Mhz MASTER CLOCK (40Mhz major clock);

20-bit counter (20-digit counter);

CNTL (control);

CONTROL LOGIC (steering logic);

21-BIT PROGRAMMABLE DOWN (countdown able to programme of 21-position);

MARKFBx (FBx mark);

1SEC.TIMEMARK (1 second time marking);

EXTERNAL LINE DRIVERS (outside line driving);

Fig. 3 word annotation:

NAV SOLUTION COMPUTATION DELAY (navigation results computing relay);

TIME BETWEEN TICs IS CONSTANT (time interval between the TIC moment is constant);

OUTPUT UTC TIME MARK (output universal time mark);

Fig. 4 word annotation:

1023CHIPS (1023);

DUMP (emptying);

C/ACODE CHIP NO (C/A bits of coded numbering);

T1:Load 4into CHx_SLEW register=2*5chip delay (T1: write 5=2*5 position to CHx_SLEW and postpone);

Fig. 5 word annotation:

ADC (digital-to-analog conversion);

MUX (multichannel final election device);

SIG MAG (signal intensity);

TEST (test);

NA PROW BAND CONVERTER (base band rectifier able to programme navigates);

SELECT SOURCE & SELCET MODE (selecting signal source & preference pattern);

SOURCE SELECTOR (signal source selection);

CARRIER DCO (carrier wave DCO);

CARRIER CYCLE COUNTER (carrier cycle counter);

32-BIT ACCUMULATE & DUMP Q_TARCKING (the cumulative & in 32-position empties Q_ and follows the trail of);

32-BITACCUMULATE & DUMP Q_TARCKING (the cumulative & in 32-position empties Q_ prompting);

CODE SLEW (bits of coded slip);

C/A, L2, GLO CODE GENERATOR (C/A, L2, GLO code generator);

CODE PHASE COUNTER (encoding phase counter);

CODE DCO (encoding D CO);

EPOCHCOUNTER (counter epoch);

32-BITACCUMULATE & DUMP I_TARCKING (the cumulative & in 32-position empties I_ and follows the trail of);

32-BIT ACCUMULATE & DUMP I_TARCKING (the cumulative & in 32-position empties I_ prompting);

IN and OUTDATA BUSes (input/output bus);

Claims (3)

1. GPS and a GLONASS multichannel parallel signal method for tracing, is characterized in that comprising that A. catches with tracking satellite signal to provide pseudorange; B. process pseudorange and be then encapsulated as to draw navigation information the form that is applicable to user; Wherein

A comprises the following steps:

CHx_SATCNTL register is programmed to select GPS gold code (RPN numbering) or the GLONASS code wanted, the tracking arm that will be also correlator is selected type of coding simultaneously, generally at acquisition mode, fix on following the trail of arm " Dithering " pattern, " Early " and " Late " and pattern do not stop switch, immediately two phase unwrapping search, once then find satellite just to switch to tracking pattern;

CHx_SIGSEL register is programmed and select input signal and for arrowband converter, if GLONASS selects centre frequency for correlator;

CHx_CARR_INCR_LO register is programmed, the numerical value that is programmed into this register is for being the frequency that married operation in the correlator of 12 channels is selected local oscillator, come 2 bit digitized signals of input to mix down to base band from radio-frequency front-end, the nominal frequency that the numerical value being programmed equals local oscillator adds the compensate for estimated value of Doppler displacement, adds the compensate for estimated value of user clock frequency drift;

To the programming of CHx_CODE_INCR_LO register, the numerical value that is programmed into this register is C/A coding nominal code check, and the twice of 2.046MHz or 1.022MHz, if needed, is added a small amount of compensation of Doppler displacement and user clock frequency;

Remove the replacement of following the trail of channel, by RESET_CONTROL register, programming writes suitable numerical value, this operation can start associated process;

Obtain cumulative data, data are to the reading of cumulative data register, to continuous the reading the cycle that can be added to increase correlation integral several times of same tracking channel;

Determine that whether GNSS signal is found, by correlation integral result and a threshold, if determine that signal finds that just to jump to signal and draws in algorithm, the cumulative data that is noted that the signal of homophase and the signal of vertical phase all will be considered, because the uncertain and input GNSS signal homophase of local carrier numerically-controlled oscillator during this time;

If GNSS signal does not have the found reprogramming that just needs to change carrier wave numerically-controlled oscillator, coded digital control oscillator frequency or gold code are attempted again, typical way is first to keep the frequency of two numerically-controlled oscillators constant, stir gold code phase place until 2046 or 1022 possible positions be all covered to, if signal does not find, that just marginally changes the frequency of carrier wave numerically-controlled oscillator and then the phase place of gold code is scanned, stirring of gold code phase place is to realize by the programming to CHx_CODE_SLEW register,

Once the found encoding phase alignment of GNSS signal, carrier phase alignment and Doppler and user all the time deviation compensation are also very coarse, encoding phase alignment accuracy can only be half code bit, the digital control oscillator signal of carrier wave and not homophase of input signal, and the error of frequency also can reach continuous attempt time step value.

2. GPS as claimed in claim 1 and GLONASS multichannel parallel signal method for tracing, it is characterized in that described method also comprises signal tracing (SIGNAL TRACKING), data demodulates (DATA DEMODULATION), pseudo range measurement (PSEUDORANGE MEASUREMENT), control correlator, search operation (SEARCH OPERATION), the programming of carrier wave numerically-controlled oscillator, the programming of coded digital control oscillator, code generator programming, read cumulative data, search for other encoding phases, data bit sync, read measurement data, prepattern (PRESET MODE), interrupt (INTERRUPTS), the signalling channel time delay that hardware signal processing is introduced, integration carrier phase measurement, rise time mark (TMARK), the budget of UTC Universal Time Coordinated (UTC) error, deposit.

3. GPS as claimed in claim 2 and GLONASS multichannel parallel signal method for tracing, it is characterized in that described signal tracing comprises: because satellite box has an inhomogeneous movement for recipient, so the GNSS signal of input can show a Doppler displacement changing in time domain, user clock skew simultaneously is also tended to change in time domain, net result is exactly, unless coding and carrier wave numerically-controlled oscillator are proofreaied and correct dynamically, otherwise GNSS signal will be lost, this has caused two servo loops essential: maintenance locking to gold code phase place, another keeps the locking to carrier wave, can realize by following method, the raw data that guides these two servo loops is cumulative data, these data are exported once with every millisecond of frequency once by following the trail of channel, the cumulative data of following the trail of arm is used in gold code circulation, some approximation methods are with " deducting in advance hysteresis " (' EARLY MINUS LATE ') gold code carries out a kind of without boot cycle, other use a kind of shake replacing half code bit after and between the coding that shifts to an earlier date of half code bit to encode, after resetting, shift to an earlier date code since one, this coding is chosen by CHX_CNTL register, and gold code circulation comes closed by upgrade regularly coded digital control oscillator frequency with CHX_CODE_INCR_LO register, the cumulative data of punctual arm is used to carrier phase circulation, although following the trail of the jitter mode of arm is also used, method is the phase place that changes carrier wave numerically-controlled oscillator to keep all correlation energy all at homophase correlator arm and not at all at a vertical phase correlator arm, carrier phase circulation is closed by upgrade regularly the digital control oscillator frequency of carrier wave with CHX_CARR_INCR_LO register.

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