WO2014017338A1

WO2014017338A1 - Satellite positioning signal receiving method and device

Info

Publication number: WO2014017338A1
Application number: PCT/JP2013/069305
Authority: WO
Inventors: 潔谷島; 裕昭前田
Original assignee: ライトハウステクノロジー・アンド・コンサルティング株式会社
Priority date: 2012-07-25
Filing date: 2013-07-16
Publication date: 2014-01-30
Also published as: KR20150038293A; TW201411169A; AU2013294159A1; JP5965765B2; TWI596363B; PH12015500155A1; PH12015500155B1; AU2013294159B2; SG11201500577XA; JP2014025744A

Abstract

Provided are a satellite positioning receiving method and device which achieve a reduction in calculation processing amount required to decode message information included in a second signal. A satellite positioning receiving device of a satellite positioning system including one or more positioning satellites that each transmit a first signal and a second signal of different frequencies, the satellite positioning receiving device being characterized by, on the basis of a frequency and phase information acquired when the reception of the first signal is started or continuously performed, performing conversion processing to the frequency of the second signal and phase information relating thereto.

Description

Satellite positioning signal receiving method and apparatus

The present invention relates to a signal reception technique for receiving satellite positioning signals transmitted from a satellite positioning system represented by Global Positioning System (GPS), and more specifically to receiving two types of signals of different frequencies. Method and apparatus

Satellite positioning systems rely on passive measurement of satellite positioning signals broadcast by multiple satellites. The on-board clock is used to generate a regular, usually continuous series of events often referred to as "epochs", with random epochs repeated at regular epoch intervals. By receiving a spread-coded radio wave by the receiving device, the phase difference between the spreading code generated at the time timing of the receiving device and the spreading code of the received signal is measured, and the distance between the positioning satellite and the receiving device is calculated. It can be measured.

An example of such a satellite positioning system is the Global Positioning System (GPS). In general, GPS operates using multiple frequencies, designated L1, L2, and L5, etc., centered at 1575.42 MHz, 1227.6 MHz, and 1176.45 MHz, respectively. Each of these signals is modulated by a respective spread signal. As can be easily understood by those skilled in the art, a CA (Coarse Acquisition) code signal emitted by a GPS satellite navigation system is transmitted at a frequency of 1575.42 MHz (referred to as L1 band) and a spreading code rate of 1.023 MHz. (Chip rate). Furthermore, these signals overlap data called navigation messages, and the data transmission rate is 50 bps. A signal with a spreading code rate of 1.023 MHz and a data transmission rate of 50 bps is generally called "L1 C / A signal". FIG. 8 shows the signal structure of the L1 C / A signal.

In addition, as an example of a satellite positioning system, Quasi Zenith Satellite System (QZSS) developed in Japan can be mentioned (Non-Patent Document 1). QZSS, like GPS, is being developed with the intention to operate using multiple frequencies such as L1, L2 and L5 centered at 1575.42 MHz, 1227.6 MHz and 1176.45 MHz respectively . Also, in QZSS, the frequency of E6 centered on 1278.75 MHz is also used, and the "LEX signal" is transmitted at this frequency.

In position determination by a satellite positioning system such as GPS, radio waves transmitted from positioning satellites are received by a ground receiver, and between the satellite and the receiver based on radio wave propagation time from the satellite to the receiver. Measure the distance. Here, with respect to the radio wave transmitted from the positioning satellite, orbit information indicating the position of the positioning satellite itself and clock information that means a deviation of time of the satellite itself are superimposed.

The receiver can know the position and time of the satellite by demodulating the orbit information and the clock information transmitted from the positioning satellite. Then, the reception device determines the position of the reception device itself, for example, in the manner of trilateration using the measurement values of the distances between the plurality of satellites and the reception device, the position of the satellite, and the time.

FIG. 9 shows the configuration of a satellite positioning system having a conventional satellite positioning receiver. The receiving device 902 that performs passive measurement continuously receives satellite positioning signals from the plurality of positioning satellites 901a to 901d of the satellite positioning system 900, and performs positioning and the like. The satellite positioning reception apparatus 902 performs preprocessing on the signal input from the reception antenna unit 9021 in the front end unit 9022, converts it into a digital signal in the ADC unit 9023, and sends it to the data processing unit 9024.

FIG. 10 shows a block configuration of a data processing unit of a conventional receiving apparatus. The data processing unit 1000 has one or more reception channels (channel 1 to channel n in the figure), and one satellite positioning for each reception channel with respect to satellite positioning signals transmitted from a plurality of satellites Signals are allocated to perform continuous reception processing. Continuous reception processing refers to processing the target satellite positioning signal in a state in which the message contained in the signal can be decoded while continuing tracking, and in some cases, ranging (satellite Measurement of the distance between the

Here, in order for each reception channel to perform continuous reception processing, it is necessary to know the frequency of the satellite positioning signal and the phase of the spreading code. However, in general, since the frequency of the satellite positioning signal and the phase of the spreading code fluctuate, it can not be acquired without searching for these when starting reception.

Further, with respect to the frequency of the satellite positioning signal, the frequency is unknown because there is also a Doppler effect caused by the relative velocity between the satellite and the receiver and the influence of the frequency error of the internal transmitter of the receiver. In order to shift to a state in which each reception channel can be continuously received, the frequency of the satellite positioning signal plus the frequency due to the Doppler effect (Doppler frequency) and the frequency error of the internal transmitter of the receiving apparatus, Need to explore.

Furthermore, as for the spreading code, since the satellite positioning signal is spread by the repeated spreading code, the same spreading code sequence is matched in phase and the satellite positioning signal is received if it is not correlated with the satellite positioning signal. You can not do it. On the other hand, the code rate of the spreading code is usually on the order of MHz, and it is difficult for the onboard clock of the receiver to operate stably with that accuracy over the long term, and satellites always transmit satellite positioning signals It is impossible for the clock and the time to match. Therefore, it is almost impossible to know the phase of the spreading code in advance. Therefore, it is also necessary to search the phase of the spreading code.

Therefore, in order for the reception channel to start continuous reception of one satellite positioning signal, it is necessary to search for the frequency as well as the phase of the spreading code in advance. A series of processes of this search is called "capture process" or "capture". As a result of the acquisition process, it is possible to acquire the frequency for starting the tracking process and the phase of the spreading code.

In acquisition processing, basically, all frequencies (about ± 5 kHz in the case of L1 C / A signal) where satellite positioning signals may exist and phases of all spreading codes (in the case of L1 C / A signal) , 1023 chips). The frequency interval for searching is determined according to the characteristics of the satellite positioning signal, and in the case of L1 C / A signal, it is generally set to about 500 Hz. Also, the phase of the spreading code to be searched needs to be searched for the number of chips of the spreading code. That is, as the length of the spreading code and the number of chips increase, the amount of calculation processing required for the acquisition process as a whole increases.

The reception channel is controlled to maintain the reception state while updating the frequency of the satellite positioning signal and the phase of the spread code after acquiring the frequency for starting tracking by acquisition and the phase of the spread code. Specifically, using a general tracking circuit 1100 as shown in FIG. 11, each of the frequency and the phase of the spreading code is separated by the synchronization circuit described later based on the satellite positioning signal continuously received. Control to keep the reception state.

First, with regard to frequency, it is common to use a phase lock loop (PLL) 1101. The PLL is a processing circuit that receives a periodic signal and performs stable signal reception processing by feedback control. In the receiver for satellite positioning, the frequency acquired by acquisition can be used as an initial value, and the successively updated frequency f _L1 can be acquired as an output for the input satellite positioning signal.

Next, as to the phase of the spreading code, it is general to use a delay lock circuit (DLL) 1104. Similarly to the PLL, the DLL is a processing circuit which receives a periodic signal and performs stable signal reception processing by feedback control. In the satellite positioning reception apparatus, the phase of the spread code acquired by acquisition can be set as an initial value, and the phase φ _L1 of the spread code sequentially updated can be acquired as an output for the input positioning signal.

As described above, a series of processes in which the satellite positioning signal to be received is input, the frequency and the phase of the spreading code are used to synchronize in each synchronization circuit are called "tracking process" or "tracking". The tracking process is performed at a specific cycle based on the characteristics of the satellite positioning signal, and each time the tracking process is performed, the updated frequency and the phase of the spreading code can be acquired. Also, from the tracking circuit, a message included in the satellite positioning signal is obtained as an output.

Next, in the receiving channel being tracked, it is possible to decode the message contained in the satellite positioning signal. The decryption of the message is performed by the "decryption unit". In addition, it is possible to measure the distance between the satellite and the receiver in the reception channel in which tracking is performed. This is called "ranging" and is performed by the "ranging unit". The principle of ranging is to read the propagation time from the time difference between the spread code transmitted at a known time on the satellite side and the spread code (generated at the receiver side) whose phase is matched by tracking, It is a mechanism that measures the distance by applying the speed of light. Specifically, it is as follows.

The time on the positioning satellite is managed by a precise satellite clock, and the timing at which the spreading code is transmitted is precisely in line with the satellite clock. On the other hand, in the satellite positioning signal receiver, if the satellite positioning signal is tracked and the message is deciphered, the accurate time of the moment when the signal is transmitted

You can know In addition, while the satellite positioning signal receiving device is tracking the satellite positioning signal from the positioning satellite, the satellite positioning signal receiving device generates the same spreading code as the positioning satellite with the matched phase. Since the satellite positioning signal has a spreading code repeated at a constant period (for example, 1 ms in the case of L1 C / A signal), the phase of the spreading code synchronized with the satellite positioning signal

The value of {circumflex over (L1) C / A signal] means the transmission time of the signal at time _{Tu at} the moment of reception with an accuracy finer than 1 ms.

Therefore, the satellite positioning signal reception device is the time when the satellite positioning signal was transmitted from the satellite

And the phase of the spreading code

And the propagation time from the positioning satellite to the satellite positioning signal receiver can be known.
In practice, the on-board clock in the receiver is not as accurate as the positioning satellite's clock. That is, the difference between the positioning satellite and the satellite positioning signal receiver is an apparent propagation time including an error. However, this is not a big problem because the propagation time is measured with the same error for all positioning satellites (described later). Therefore, the distance measured on the receiving device side is usually called "pseudo distance". The calculation procedure of the pseudo distance is shown in FIG.

FIG. 12 is a flow chart showing an example of a procedure for calculating a conventional pseudorange based on an L1 C / A signal. The meaning of each variable in FIG. 12 is as follows.

In FIG. 12, the calculation of the pseudorange starts with the state in which the target k-th reception channel is tracking the satellite positioning signal (S1201).

Is the phase of the spreading code of the satellite of the kth reception channel, but since it is possible to obtain the frequency of the spreading code and the frequency updated each time by tracking, the phase of the spreading code obtained by tracking as it is

(S1202). In the case of the L1 C / A signal, the phase of the spreading code can take a value of 0 or more and less than 1023.

next,

If you do not know (No in S1203)

If the message has already been decoded, the time at which the satellite transmitted the signal can be calculated from the time information included in the message (S1204). For example, in the case of a message of the L1 C / A signal, time information expressed in seconds within a week is included every 6 seconds.
In the message there is described in the message the content of knowing the transmission start time of the signal containing the message. Therefore, if the message including the time information is decoded even once, the L1 C / A signal being continuously received can know the time when it was transmitted from the satellite, and it can be updated one after another It is possible. This time

And put.

next,

(S1203: Yes),

But not the first tracking, already

Is set (Yes in S1205), the process proceeds to S1207, but in the case of the first tracking (No in S1205), the process proceeds to S1206, and the reception channel tracked in the first is used as a reference in the receiving apparatus. clock

Set to the appropriate value. For example, assuming that the reception channel tracked first is the kth reception channel,

The setting is

The value obtained by adding an appropriate value (e.g., 100 ms) may be used as a reference, and thereafter, the clock in the receiver operates based on this. The appropriate value used here corresponds to a common error for expressing the pseudoranges between the satellites and the receiver, and basically any value may be used.

As mentioned above

When it is determined, on the basis of the speed of light C, the pseudo distance d ^k in the L1 C / A signal can be calculated by the following equation (S1207).

As described above, the “positioning operation unit” can calculate the position of the receiving device based on the result of distance measurement (pseudo distance) obtained in each reception channel. This is an outline of the "positioning" process. In order to perform positioning, satellite positioning signals from four or more positioning satellites are usually required. By obtaining pseudoranges with at least four positioning satellites, the error due to the "appropriate value" used in setting the clock in the receiving apparatus is eliminated.

Now, the satellite positioning signal broadcasted by the satellite positioning system is not intended for ranging itself, but corrects / reinforces the distance between the satellite obtained by ranging and the receiver and the positioning position of the receiver. There is a signal that has a function. This is called "reinforcement signal", and the information contained in the reinforcement signal is called "reinforcement information". The reinforcement information in the reinforcement signal is generally included in the message part.

Then, in order to decipher the reinforcement information from the reinforcement signal by a general method, the receiver assigns one reception channel to the reinforcement signal by the same method as the case of performing to the distance measurement signal, and It is necessary to perform capture processing and tracking processing and decoding processing.

However, the frequency band in which the reinforcement signal is broadcast and the spreading code of the reinforcement signal are often different from the frequency band and spreading code of the signal generally used for ranging. Compared to the processing power and resources of the receiver that handles only signals used for ranging, the receiver that handles reinforcement signals requires more processing power and resources. Also, in the case of the LEX signal, which is more specific, in order to decipher the message including the reinforcement signal included in the LEX signal short code, first, the signal spread by the long code of 2.5575 MCps · 410 ms length is received It is necessary to This is much longer than the signal spread by the 1.023 MHz 1 ms long spreading code of the L1 C / A signal usually used for ranging. Therefore, there has been a problem that, if the reception processing of the LEX signal and tracking processing are performed in the receiving apparatus assuming handling of L1 C / A, parts and processing increase and a large cost increase is caused.

The present invention is a satellite positioning reception device of a satellite positioning system including one or more positioning satellites transmitting a first signal and a second signal different in frequency, the satellite positioning reception device comprising It is characterized in that conversion processing is performed on frequency and phase information of the second signal based on frequency and phase information acquired when signal reception is started or performed continuously.

Further, the present invention is characterized in that message information included in the second signal is decoded based on frequency and phase information of the converted second signal.

Further, the second signal is continuously tracked on the basis of frequency and phase information of the converted second signal.

In addition, measuring the distance between the positioning satellite and the satellite positioning reception device based on frequency and phase information of the first signal or frequency and phase information of the converted second signal. It features.

Further, the present invention is a satellite positioning signal receiving method in a satellite positioning system including a positioning satellite for transmitting a first signal and a second signal different in frequency and a satellite positioning receiving device, wherein the satellite positioning receiving device is And converting the frequency and phase information of the second signal on the basis of the frequency and phase information acquired when the reception of the first signal is started or continuously performed.

The satellite positioning signal receiving method and apparatus according to the present invention can reduce the amount of operation processing and reduce the cost required for operation processing components in the acquisition processing and tracking processing of satellite positioning signals of two different frequencies, etc. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining schematic structure of a satellite positioning system which has a satellite positioning signal receiver concerning one Embodiment of this invention. It is an explanatory view explaining a block configuration of a satellite positioning signal receiving device concerning one embodiment of the present invention. It is a flowchart explaining the processing flow in the satellite positioning signal receiver concerning one embodiment of the present invention. It is explanatory drawing explaining the relationship of the L1 C / A signal and LEX signal in the satellite positioning system concerning one Embodiment of this invention. It is explanatory drawing explaining schematic structure of a satellite positioning system which has a satellite positioning signal receiver concerning other embodiment of this invention. It is explanatory drawing explaining the block configuration of the satellite positioning signal receiver concerning other embodiment of this invention. It is an explanatory view explaining a signal generation circuit in a satellite positioning system concerning one embodiment of the present invention. It is explanatory drawing explaining the signal structure of the conventional L1 C / A signal. It is explanatory drawing explaining the structure of the satellite positioning system which has the conventional satellite positioning reception apparatus. It is explanatory drawing explaining the block configuration of the data processing part of the conventional receiver. It is explanatory drawing explaining the block configuration of the conventional tracking circuit. It is a flowchart explaining the calculation procedure of the conventional pseudo | simulation distance.

Hereinafter, a mode for carrying out a satellite positioning signal receiving method and apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a satellite positioning system having a satellite positioning signal receiving apparatus according to an embodiment of the present invention. In one embodiment of the present invention, LEX signals are handled, and QZSS (Quasi-Zenith Satellite System) transmitting LEX signals is adopted as a model of the satellite positioning system.

In FIG. 1, L1 C / A signals and LEX signals broadcast from positioning satellites 101a to 101d of QZSS system 100 propagate in space and the atmosphere, and reach satellite positioning receiver 102. The L1 C / A signal and LEX signal that have arrived at the receiving device 102 convert their respective carrier frequencies into manageable frequencies (intermediate frequencies) in the front end unit 1022 (referred to as down conversion or down conversion). The intermediate frequency differs depending on the design concept of the receiver, and in the present specification, the intermediate frequency of the L1 C / A signal is conveniently used.

And the intermediate frequency of the LEX signal

I assume. Thereafter, the down-converted signals are respectively quantized by the

ADC units

1023 a and 1023 b and sent to the data processing unit 1024 for reception processing.

Next, FIG. 2 shows a detailed configuration of the data processing unit 1024 in FIG.

In FIG. 2, in general, the positioning reception apparatus receives signals from a plurality of positioning satellites, and thus a plurality of reception channels exist in the data processing unit, but in the present specification, the convenience of understanding and explanation of the invention Therefore, the explanation of the operation in one reception channel is kept. Also, as an example, the embodiment will be described in which the message of the LEX signal is decrypted.

In FIG. 2, the data processing unit 200 exemplarily illustrates an L1 capturing unit 201 that captures L1 C / A signals, an L1 tracking unit 202 that tracks L1 C / A signals, and an L1 C / A signal. L1 decoding unit 203 for decoding the L1 C / A signal, the L1-E6 conversion processing unit 204 for converting the phase of the spread code and the frequency of the L1 C / A signal to the phase of the LEX signal, and the phase of the spread code It comprises an E6 decryption unit 205 that performs decryption.
In the case of a satellite positioning receiver of a plurality of reception channels, these components are included as components of one reception channel, and in some cases, a "ranging unit" and one "positioning operation unit" in each channel It is also possible to adopt a configuration comprising In this case, the “ranging unit” and the “positioning operation unit” can adopt a configuration common to the data processing unit of a general reception device.

FIG. 3 shows a processing flow in the data processing unit 200.

In the data processing unit 200, first, the process is started in S301, and after acquiring the initial value f _L1 of the frequency of the satellite positioning signal and the initial value φ _L1 of the phase of the spreading code in S302, acquisition processing for the L1 C / A signal Is performed (S303). In the acquisition processing, correlation calculation with the input satellite positioning signal is performed based on the acquired f _L1 and φ _L1 , and the success or failure of acquisition is determined based on the magnitude of the correlation value (S304). As long as acquisition of f _L1 and φ _L1 used in tracking is not successful (Yes in S304), the process returns to S303 and a supplementary process is performed. During the supplementary process, by changing gradually f _L1 and phi _L1, and the highest frequency of the f _L1 and phi _L1 when the correlation value is obtained by capturing successful time and spread code phase used in subsequent tracking The initial values of the frequency and the phase of the spreading code are used (S305).

Note that an algorithm used in capture, such as a method of gradually changing f _L1 and φ _L1 and a determination criterion of success or failure of capture, can adopt a capture algorithm conventionally used. As a result of the acquisition process, it is possible to acquire the frequency f _L1 for tracking the L1 C / A signal and the phase φ _{L1 of the} spreading code.

Then, when the frequency and the phase of the spread code to be used first in the tracking are determined by the above-described L1 C / A signal acquisition, the acquisition is temporarily ended, and the L1 C / A signal is subsequently tracked (S305). ). First, tracking processing is performed with f _L1 obtained by acquisition as the frequency of the satellite positioning signal and φ _L1 as the phase of the spreading code of the satellite positioning signal.

The algorithm used for tracking can adopt a known tracking algorithm that has been used conventionally. By the tracking process using the L1 C / A signal as input, the phases of the frequency and the spreading code are sequentially updated, and become new f _L1 and φ _L1 .

The frequency at which the signal tracking is performed is specifically an intermediate frequency to which a Doppler frequency is added. The Doppler frequency is a value determined by the relative velocity of the positioning satellite and the satellite positioning receiver and the frequency to be transmitted. That is, even if signals are transmitted from the same positioning satellite, the frequencies to be transmitted are different between the L1 C / A signal and the LEX signal, so that the Doppler frequency also has different values.

In addition, in the tracking process of the L1 C / A signal, the tracking process (S306) is continued on the assumption that the reception state is correct as long as no abnormality occurs in the reception state (Yes in S306). If the tracking process of the L1 C / A signal is not continued correctly due to some cause (No in S306), the process returns to the capture process (S303), and repeats the process of tracking again when the capture process is completed.
While the tracking process of the L1 C / A signal is continued, the decoding unit decodes the message of the L1 C / A signal (S307).

Subsequently, while the tracking of the L1 C / A signal is continued, if the time information is acquired even once (S309), L1− based on the time information and f _L1 and φ _L1 (S308). E6 conversion processing is performed (S310). In addition, while tracking is continuing, it is sufficient if time information can be acquired once.

The following two processes are performed in the L1-E6 conversion process.
(Processing A) Conversion process of L1 C / A signal frequency to LEX signal frequency (Processing B) conversion process of L1 C / A signal spreading code phase to LEX signal spreading code phase

The term "spread code of LEX signal" refers to a short code of 4 ms cycle in which the message of LEX signal is CSK modulated, and long code reception is not performed as in the prior art. Is a feature of the present invention.

The conversion from the frequency of the L1 C / A signal to the frequency of the LEX signal (the process A) is performed based on the following equation (2).

However,

It is.

The above equation (2) shows that the frequency f _{E6 of the} LEX signal is the frequency f _L1 of L1 C / A, the center frequency f _IFL1 of the L1 C / A signal, the intermediate frequency f _IFE6 of the LEX signal, and L1 C / the center frequency L ₁ of the a signal, indicating that can be calculated using the center frequency E ₆ of the LEX signal.
Here, L ₁ is a known value (1575.42 MHz), and E ₆ is a known value (1278.75 MHz). Known values specific to the design concept of the receiver can be used for f _IFL1 and f _IFE6 .
Since f _L1 is the frequency of the L1 C / A signal, the frequency f _L1 used in tracking may be used as it is.

As described above, the conversion process from the frequency of the L1 C / A signal to the frequency of the LEX signal is performed based on the above equation (2).

Further, the conversion from the phase of the spreading code of the L1 C / A signal to the phase of the spreading code of the LEX signal (the process B) is performed based on the following equation (3).

However, k is taken as any one of 0, 1, 2, 3

It is.

In the above (3), the phase φ _E6 of the spreading code of the LEX signal is the phase φ _L1 of the spreading code of the L1 C / A signal, the chip rate R _L1 of the spreading code of the L1 C / A signal, and the spreading of the L1 signal It is shown that calculation is possible using the code period T _L1 and the chip rate R _E6 of the spreading code of the LEX signal.
Here, R _L1 is a known value (1.023 MCps), T _L1 is a known value (0.001 sec), and R _E6 is a known value (2.5575 MCps). Since φ _L1 is the phase of the spreading code of the L1 C / A signal, the phase φ _L1 of the spreading code used in tracking can be used as it is.

In addition, k is a value which changes with the spreading code period of two signals, and in the case of L1 C / A and LEX, it is an integer which takes the value of [0, 3]. That is, k is updated every 0 ms as 0, 1, 2, 3, 0, 1, 2, 3, 0,. The value of k is determined after time information is obtained by message decryption of the L1 C / A signal. Specifically, this will be described with reference to the relationship between the L1 C / A signal and the LEX signal shown in FIG.

In FIG. 4, the time at which the currently received satellite positioning signal is transmitted is t _x [sec]. t _X is the number of times the spreading code has been repeated based on the time information contained in the message at a rate of once every 6 seconds by message decoding after tracking processing of the L1 C / A signal It can be determined from the phase φ _L1 of the spreading code of the L 1 C / A signal.

Next, a time when the spreading code of the L1 C / A signal and the spreading code of the LEX signal start simultaneously is defined as t ₀ [sec]. The L1 C / A signal and the LEX signal simultaneously start transmitting signals relative to the beginning of the week. Spreading code period T _E6 of LEX signal is 4 ms, L1 for C / A spreading code period T _L1 of the signal is 1 ms, week beginning after the exactly every 4 ms, spreading code L1 C / A signal The spreading codes of the LEX signal and the LEX signal start simultaneously. That is, the spreading code of the L1 C / A signal and the spreading code of the LEX signal are always simultaneously started at times that are multiples of 4 ms with reference to the start of the week. In FIG. 4, when looking at the nearest point before t _X , the spreading code of the L1 C / A signal and the spreading code of the LEX signal start at the same time by 1 cycle of the spreading code of the L1 C / A signal. Time is present. That is, before t _X , the nearest time to be a multiple of 4 ms is t ₀ .

The value of k represented by the above equation (3) is the number of periods of the spreading code of the L1 C / A signal included between t _X and t ₀ . That is, based on the time at which the spreading code of the L1 C / A signal and the spreading code of the LEX signal are simultaneously started, k is updated every 1 ms from k = 0.

As described above, the phase of the spreading code of the L1 C / A signal is converted to the phase of the spreading code of the LEX signal.

When the L1-E6 conversion process is completed in S310, the process proceeds to S311, where the LEX message is decrypted.

Refer again to FIG. The frequency of the LEX signal and the phase of the spreading code calculated by the L1-E6 conversion processing unit 204 are passed to the E6 decoding unit 205, and used by the E6 decoding unit 205 to decode the message included in the LEX signal.
In FIG. 2, the signal flow from the L1 tracking unit 202 through the L1-E6 conversion processing unit 204 to the E6 decoding unit 205 is represented by dotted lines in that the data processing unit is delivered between blocks. It means that it is not the input satellite positioning signals, but the phase of the frequency and spreading code calculated based on them, and the time information based on the message decoded by the decoding unit.

The E6 decoding unit 205 decodes the message included in the signal based on the converted frequency of the LEX signal and the phase of the spreading code. In order to actually decipher the message of the LEX signal, it is necessary to know the start time of the LEX spreading code every 4 ms, but in this case, the L1-E6 conversion processing unit 204 calculates the phase of the spreading code of the LEX signal. This corresponds to the spreading code simultaneous start time t ₀ used in this case. t ₀ can be expressed by the following equation using the phase φ _E6 of the spreading code of the converted LEX signal.

That is, the start time (= spread code simultaneous start time) t ₀ of the LEX spreading code is the transmission time t _{X of the} signal currently being received, the phase φ _E6 of the spread code of the converted LEX signal, and It can be calculated using the chip rate R _E6 of the spreading code.

After all, the short message decryption of LEX signals, which for messages LEX signal 4ms each from t _0, the frequency components are removed superimposed on the LEX signal based on the frequency of the converted LEX signals, are CSK modulation By decoding the code, the message of the LEX signal can be deciphered.

As described above, it is possible to directly decode the message included in the LEX signal based on the frequency of the converted LEX signal and the phase of the spreading code.

As more advanced processing, it is also possible to newly assign one reception channel to the LEX signal based on the converted frequency of the LEX signal and the phase of the spreading code, and start tracking of the long code of the LEX signal. In this case, there is an advantage that the long code acquisition processing of the LEX signal can be omitted, which is necessary to start tracking of the long code of the conventional LEX signal according to the prior art.

In this case, the message included in the short code of the LEX signal is decoded while continuing the tracking process of the long code of the LEX signal.

One feature of the present invention is that the processing included in the LEX signal is omitted from the frequency and the phase of the spread code acquired by the capture processing and tracking processing of the L1 C / A signal, omitting the capture processing and tracking processing of the LEX signal. It is in the point of deciphering information. Although the transmitting frequency is different, because the L1 C / A signal and the LEX signal are transmitted from the same satellite, it is utilized that the spreading codes of the two issues are transmitted periodically at the same timing. ing.

In the best mode for carrying out the invention described above, the L1 C / A signal is continuously received, and the frequency of the LEX signal and the phase of the spreading code are determined from the frequency and the phase of the spreading code. It is preferable to decipher the reinforcement information included in the LEX signal.

In the embodiment described above, the configuration in which the E6 decoding unit is provided in the data processing unit has been described, but the present invention is not limited to this. For example, as shown in FIG. It is also possible to set up the E6 decoding unit 5025 as an external system. That is, it is conceivable to pass the frequency of the LEX signal and the phase of the spreading code to the E6 decoding unit 5025 in another system as the output of the data processing unit 5024. In this case, the satellite positioning signal output from the ADC unit 5023b and the frequency of the converted LEX signal and the phase of the spreading code are output as the receiving apparatus, and separately passed to the E6 decoding unit (dedicated machine) 5025.
In this case, as shown in the data processing unit 600 illustrated in FIG. 6 as a detailed block diagram of the data processing unit 5024, the data processing unit 600 simply receives the L1 C / A signal. The E6 signal does not have to be input.

In the above description, the L1 C / A signal and the LEX signal are handled as two different signals, but the present invention is not limited to the combination of the L1 C / A signal and the LEX signal, In the case of satellite positioning signals of two different frequencies transmitted from the same positioning satellite, similarly, relative to acquisition processing and tracking processing based on satellite positioning signals requiring relatively light processing capability for acquisition processing and tracking processing It is possible to obtain information on satellite positioning signals that require extremely heavy processing power.

Also, due to the difference between the L1 band in which the L1 C / A signal is carried and the frequency in the E6 band in which the LEX signal is carried, two signals exist above the earth when propagating through space and the atmosphere. Under the influence of the ionosphere, in general, the propagation distance has a difference between signals of two frequencies (this is called "ionosphere delay error"). Since the ionospheric delay error also affects the phase of the spreading code of the L1 C / A signal and the phase of the spreading code of the LEX signal, the phase of the spreading code of the L1 C / A signal to the phase of the spreading code of the LEX signal It is further preferred to take into account the ionospheric delay error that occurs between the two frequencies during conversion.
The difference due to the ionospheric delay error can be predicted according to an academic model, such as, for example, a ROCHATTER model. Therefore, in this case, the conversion from the phase of the diffusion code of the L1 C / A signal to the phase of the diffusion code of the LEX signal represented by the above equation (3) is the diffusion code of the L1 C / A signal due to the ionospheric delay error. including a term in which [psi _K representing the phase difference between the spreading codes and LEX signals, can be expressed as follows.

However,

It is.

Also, in the above embodiment, after the L1 C / A signal and the LEX signal are input to the receiving device, they are respectively ADC converted in the ADC unit and input to the data processing unit. The difference between the phase of the spreading code of the L1 C / A signal and the phase of the spreading code of the LEX signal may occur due to the influence of the difference between
Therefore, when converting the phase of the spreading code of the L1 C / A signal to the phase of the spreading code of the LEX signal, it is more preferable in consideration of an error caused between the two frequencies.

In this case, it is possible to predict several values for the error component, perform conversion taking each into consideration, and obtain a plurality of results. As a specific processing procedure, the conversion from the phase of the spreading code of the L1 C / A signal to the phase of the spreading code of the LEX signal expressed by the above equation (3) is performed by converting the L1 C / A signal It can be improved as in the following equation, including ψ _n which is a term representing the phase difference between the spreading code and the spreading code of the LEX signal.

However,

In addition, when several values to be an error component are predicted, and conversion taking into consideration each is performed, the phase and LEX of the diffusion code of the L1 C / A signal in consideration of the above-mentioned ionospheric delay error The difference from the phase of the spreading code of the signal may be included.

Finally, an example of a signal generation circuit in the satellite positioning system according to an embodiment of the present invention will be described. FIG. 7 shows a LEX signal generation circuit used in the satellite positioning system according to an embodiment of the present invention.

The signal generation circuit 700 relates to the LEX signal broadcast in the 1278.75 MHz band (E6 band) of the Quasi-Zenith Satellite System (QZSS) as an example, but the LEX signal is used as a reinforcement signal.
The LEX signal is generated from the spreading code generator 701 and a spreading code of 2.5575 Mcps called “short code” called “short code” which is CSK code-modulated by the CSK modulator 702 by a 4 ms long 8-bit (= 256 ways) message A 410 ms long, 2.5575 Mcps spreading code called a "long code" alternated at intervals of 5.115 Mcps, superimposed on the square wave generated by generator 701 and superimposed on the square wave generated by square wave generator 703 To be selected and transmitted superimposed on the carrier frequency of 1278.75 MHz generated by the carrier generator 705.
CSK modulation is an abbreviation of code shift keying, and is one of modulation schemes in which the phase of a spread code is changed according to the value of data.

[Known technology etc.]
In the context of the present invention, the contents of all articles and documents filed concurrently with or separately from the present specification and freely available to the public are hereby incorporated by reference.

[combination]
These features are mutually exclusive with respect to all of the constituent elements described in the specification (including claims, examples, abstracts, and drawings) and / or all steps of all methods or processes disclosed. It can be combined in any combination except the combination which is the target.

[One example of features]
Each of the features recited in the specification (including the claims, examples, abstracts and drawings) serve an alternative for the same purpose, an equivalent purpose or a similar purpose, unless explicitly denied Can be substituted for Thus, unless expressly stated to the contrary, each of the disclosed features is only an example of a generic series of identical or equivalent features.

The present invention is not limited to any specific configuration of the above-described embodiment. The present invention comprises all novel features or combinations thereof described in this specification (including claims, examples, abstracts and figures), or all novel methods or process steps described, or It can be extended to their combination.

100 satellite positioning system 101a to 101d positioning satellite 102 positioning positioning receiver 1021 receiving antenna unit 1022

front end unit

1023a, 1023b ADC unit 1024 data processing unit

Claims

A satellite positioning reception device of a satellite positioning system including one or more positioning satellites transmitting a first signal and a second signal different in frequency, the satellite positioning reception device receiving the first signal A satellite positioning receiving apparatus characterized in that conversion processing is performed to frequency and phase information of the second signal based on frequency and phase information acquired when starting or continuously performing.
The satellite positioning receiver according to claim 1, wherein the message information included in the second signal is decoded based on frequency and phase information of the converted second signal.
The satellite positioning receiving device according to claim 1, wherein tracking of the second signal is continuously performed based on frequency and phase information of the converted second signal.
Measuring a distance between the positioning satellite and the satellite positioning reception apparatus based on frequency and phase information of the first signal or frequency and phase information of the converted second signal; The satellite positioning receiving device according to any one of claims 1 to 3.
The satellite positioning receiving device according to any one of claims 1 to 4, wherein the first signal is a C / A signal in an L1 frequency band (1575.42 MHz band).
The satellite positioning reception device according to any one of claims 1 to 5, wherein the second signal is a LEX signal in an E6 frequency band (1278.75 MHz band).
The satellite positioning receiving apparatus according to any one of claims 1 to 6, wherein, when converting the frequency and phase information of the second signal, the frequency of the first signal and the frequency of the second signal. A satellite positioning receiving apparatus characterized in that the conversion processing is performed based on an ionospheric delay error component generated by a difference from a frequency.
The satellite positioning reception device according to any one of claims 1 to 7, wherein, when converting the frequency and phase information of the second signal, the phase information of the first signal and the second signal. A satellite positioning receiving apparatus characterized in that the conversion processing is performed after setting a plurality of candidates for the phase information of the second signal based on the error included in the phase information of.
A satellite positioning signal receiving method in a satellite positioning system including a positioning satellite transmitting a first signal and a second signal different in frequency and a satellite positioning receiving device, wherein the satellite positioning receiving device is the first signal. A satellite positioning signal reception method characterized in that it is converted into frequency and phase information of the second signal based on frequency and phase information acquired when starting or continuing reception of the second signal.
The method according to claim 7, wherein the message information contained in the second signal is decoded based on frequency and phase information of the converted second signal.
The method according to claim 7, characterized in that reception of the second signal is performed continuously on the basis of frequency and phase information of the converted second signal.
Measuring a distance between the positioning satellite and the satellite positioning reception apparatus based on frequency and phase information of the first signal or frequency and phase information of the converted second signal; The method according to any one of claims 7-9.
The method according to any one of claims 7 to 10, wherein the first signal is a C / A signal in an L1 frequency band (1575.42 MHz band).
The method according to any one of claims 7 to 11, wherein the second signal is a LEX signal in an E6 frequency band (1278.75 MHz band).