JP3104132B2 - Positioning signal receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Pos
The present invention relates to a positioning signal receiver suitable for being applied to a receiver of a positioning system using a satellite called a “positioning system”.

[0002]

2. Description of the Related Art Conventionally, various receivers of a positioning system using a satellite called GPS have been developed. Positioning by the receiver is performed by receiving positioning signals transmitted from a plurality of (about 24) satellites orbiting the earth, demodulating information included in the positioning signals from each satellite, and demodulating the information. The information is analyzed to determine the current position. In this case, the information contained in the positioning signal transmitted from each satellite includes time data of the satellite, orbit data for calculating the position of the satellite, and the like. The positioning signal containing these information is spread spectrum modulated. At the same time, the signal is transmitted after being subjected to quadrature phase modulation (two-phase PSK modulation) by two carriers. The frequencies of these two carrier waves are the same for all satellites (1227.6 MHz and 1575.42 MHz), and the codes used for spread spectrum modulation are different for each satellite.

At the time of positioning, positioning signals from at least three satellites are received at the same time, and information contained in the received positioning signals from the three satellites is demodulated. Analysis is performed to perform position measurement. For this reason, a GPS receiver is provided with a plurality of channel receivers, and each receiver captures a positioning signal from another satellite one by one.

[0004] Processing for capturing a plurality of satellites at the same time includes a case where a plurality of receiving circuits are provided and a plurality of receiving circuits are configured to form a receiving section of a plurality of channels, and one to several receiving circuits. In some cases, the satellites to be captured are switched in a time-division manner, and a process of capturing a plurality of satellites at the same time is performed to virtually configure a receiving unit of a plurality of channels.

[0005]

By the way, in order to improve the positioning accuracy, it is necessary to receive positioning signals from not only three satellites but also more satellites at the same time and use them for analysis. For this reason, in the GPS receiver, it is necessary to increase the number of channels of the receiving unit so that more satellites can be captured at the same time. GPS receivers capable of receiving transmitted positioning signals at the same time have been developed.

[0006] However, the number of satellites located above each point on the earth is usually about 5 to 8 satellites. Improvement of positioning accuracy by increasing the number of reception channels is limited to about 8 channels. However, even if the number of receiving channels is further increased, the positioning accuracy and the like cannot be improved.

On the other hand, in such a GPS receiver, accurate positioning can be performed for the first time after a positioning signal from a satellite is captured by a receiving unit of each channel, but it takes time until the positioning signal is captured. As a result, there is an inconvenience that it takes time from the start of reception by the receiver to the positioning of the current position. That is, the positioning signal transmitted from each satellite has a fixed frequency defined when transmitting from the satellite, but is actually received by the receiver due to the Doppler effect due to the relative speed between the satellite and the receiver. There are fluctuations in the frequency,
It takes time to accurately capture the positioning signals from each satellite.

In addition, since a positioning signal from another satellite is captured for each receiving unit of each channel, if capturing of a positioning signal fails in any of the receiving units, the receiving unit of this channel re-captures the positioning signal. Until successful, information from the satellite received on that channel cannot be used for positioning, and during that time positioning may not be possible and the positioning rate may decrease.

The present invention has been made in consideration of the above points, and has as its object to improve the positioning rate and reduce the time required for positioning.

[0010]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a first method for demodulating information by receiving positioning signals transmitted from different satellites for each positioning signal.
And a second receiver for receiving and processing a positioning signal from a satellite having a high elevation angle among the positioning signals transmitted from the respective positions to demodulate information.

According to the present invention, a positioning signal from a satellite having a high elevation angle among a plurality of positioning signals received and demodulated by the first receiving unit is also received and demodulated by the second receiving unit. As a result, the same positioning signal is received twice, so that the positioning rate can be improved and the positioning time can be shortened.

[0012]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In this embodiment, the present invention is applied to a receiver of a positioning system using an artificial satellite called GPS, and FIG. 1 shows a configuration of the receiver 10. This receiver 10
An antenna 11 for receiving a positioning signal from a satellite (this positioning signal is a spread spectrum signal) is provided. The antenna 11 is connected to an amplifier 12, and the reception signal amplified by the amplifier 12 is passed through a band-pass filter 13. The mixer 14 mixes the oscillation output of the oscillator 15 with the received signal to form a first intermediate frequency signal.
Then, the first intermediate frequency signal output from the mixer 14 is transmitted to the mixer 1 via the bandpass filter 16 and the amplifier 17.
8 and the oscillation output of the oscillator 19 is mixed with the first intermediate frequency signal to form a second intermediate frequency signal.

The second intermediate frequency signal output from the mixer 18 is transmitted to the demodulation unit 10 having 12 channels.
1, 102, 103 ‥‥ 112. Each demodulation unit 1
01 to 112 have the same configuration, and each demodulation unit demodulates a positioning signal from one satellite. That is, the second
An intermediate frequency signal is supplied to a PN code demodulator 21 and a PN code (pseudo random code) generated by a PN code generator 22
Is multiplied by the second intermediate frequency signal by the PN code demodulator 21 to despread the spectrum. In this case, the PN code differs depending on the satellite to be captured, and the setting of the PN code generated by the PN code generator 22 (that is, the setting of which satellite is captured) is performed under the control of the arithmetic processing unit 27 described later. Will be The P-phase signal having the same phase as the PN code generated on the transmitting side (ie, the satellite side) of the signal received on each channel.
When the N code is generated, it is determined that the demodulated signal has the highest correlation value and accurate demodulation has been performed, and the demodulated signal is supplied to the mixer 24 via the band pass filter 23. It should be noted that the phase data obtained when the demodulation has been performed correctly is supplied to an arithmetic processing unit 27 described later.

The mixer 24 mixes the signal subjected to the spectrum despreading process with the frequency signal output from the voltage controlled oscillator 25, and performs frequency correction. This frequency correction is for correcting the frequency fluctuation due to the Doppler effect determined by the relative speed between the satellite and the positioning point (that is, the position of the receiver). The oscillation frequency of the voltage controlled oscillator 25 is
It is controlled by an arithmetic processing unit 27 described later.

The signal frequency-corrected by the mixer 24 is supplied to a PSK demodulator 26 to demodulate data (orbit data of a satellite or the like) included in the received signal. And
The demodulated data is supplied to the arithmetic processing unit 27. Although FIG. 1 shows only the configuration of the demodulation unit 101 of channel number 1, the demodulation units 102 to 112 of other channels are shown.
Has the same configuration. The selection of which satellite the signals are captured by the demodulation units 101 to 112 of each channel is controlled by the arithmetic processing unit 27.

The arithmetic processing unit 27 is constituted by a microcomputer. The arithmetic processing unit 27 is supplied with demodulated data from the demodulation units 101 to 112 of all channels, and the orbit of each captured satellite indicated by the demodulated data. And the propagation time of the signal from each satellite (determined by the phase of the PN code generated at the time of spectrum despreading), the current position is calculated by an operation using the determined data, and the calculated current position is calculated. Is supplied to the display unit 28.

The display section 28 displays the supplied current position in a predetermined manner (for example, display of latitude, longitude, and altitude). Alternatively, in the case of a receiver for a navigation device, the current position and a map of the vicinity thereof are displayed on the display unit 28.
To display.

FIG. 2 shows an example of an actual reception state. For example, positioning signals from, for example, four GPS satellites 1, 2, 3, and 4 are received by the antenna 11 and received by the receiver 10 for receiving processing. Suppose you did. In this case, each satellite 1-4 at a certain time
Is calculated based on the received orbit data and the like, the distance between each of the satellites 1 to 4 and the positioning point (current position) is obtained from the detected propagation delay, and the position data and the distance of these satellites are obtained. The position of the positioning point is obtained by solving a quaternary simultaneous equation derived from the data.

Next, each demodulation unit 101 of the receiver 10 of the present embodiment.
The process of selecting a satellite to be captured in to 112 will be described with reference to the flowchart of FIG.

The process of selecting a satellite to be captured is performed under the control of the arithmetic processing unit 27,
A total of eight channels from the demodulation unit 101 to the demodulation unit 108 of channel number 8 capture another satellite one channel at a time. That is, in the case of the GPS positioning system, there is a possibility that up to eight positioning satellites may exist above each positioning point, and up to eight satellites may be used.
The channel demodulation units 101 to 108 individually capture (Step S11). The positioning of the current position by the arithmetic processing unit 27 is performed by the demodulation units 101 to 101 of the eight channels.
At 108, it becomes possible when at least three satellites have been acquired.

Next, the demodulation units 101 to 10 of eight channels
The arithmetic processing unit 27 determines the satellite located at the position with the highest elevation angle among the maximum eight satellites captured in step 8. That is, for example, in the reception state shown in FIG.
The angles θ ₁ , θ ₂ , θ ₃ , θ ₄ formed by the line connecting the lines ₂ , ₃ , ₄ and the horizontal line are determined, and the satellite having the largest angle is determined. Then, a signal from a satellite determined to have the largest elevation angle is transmitted to a demodulation unit 10 of channel number 9.
9 is captured (step S12).

Next, the satellite having the second highest elevation angle is determined, and the signal from this satellite is captured by the demodulation unit 110 of channel number 10 (step S13). further,
The satellite having the third highest elevation angle is determined, and a signal from this satellite is captured by the demodulation unit 111 of the channel number 11 (step S14). Furthermore, the satellite having the fourth highest elevation angle is determined, and a signal from this satellite is captured by the demodulation unit 112 of the channel number 12 (step S15).

The processing shown in the flowchart of FIG. 3 shows the order of channel assignment under the control of the arithmetic processing unit 27, and does not show the order in which satellites are captured by each demodulation unit. Therefore, from step S11 to S
Channel allocation up to 15 is performed in order when allocation in each step becomes possible (orbit of each satellite can be determined if accurate time data is known, and satellite with a high elevation angle can be determined). It does not move to the next step after the signal from the satellite can be captured by the demodulation unit of the channel.

Also, as time elapses and the positioning point moves,
Satellites with high elevation angles change sequentially, but for satellites captured by demodulators 109 to 112 of channel numbers 9 to 12, when the order of the satellites with high elevation angles changes, the satellites to be captured change accordingly. You can do it.

In this example, in the processing shown in the flowchart of FIG. 3, the arithmetic processing unit 27 performs positioning of the current position based on signals from satellites captured on channel 12. In this case, for the signals captured and demodulated by the demodulation units 109 to 112 of the channel numbers 9 to 12,
If the demodulation units 101 to 108 of channel numbers 1 to 8 are correctly acquired, the same four satellites will be acquired twice, but they are used for positioning in the arithmetic processing unit 27. As data to be used, data demodulated by any demodulation unit is used for data of the same satellite. That is,
For example, the same satellites as the four satellites captured by the positioning units 101 to 104 of channel numbers 1 to 4 are channel numbers 9 to
When the signals are captured by the twelve positioning units 109 to 112, the data demodulated by the positioning units 109 to 112 of the channel numbers 9 to 12 may not be used for positioning.

Here, demodulation units 1 of channel numbers 1 to 8
01 to 108 (hereinafter, referred to as a first group of demodulators) and demodulators 109 to 1 of channel numbers 9 to 12
12 (hereinafter referred to as a second group of demodulators), the possibility of acquiring a satellite by both demodulators is the same, but the same is obtained by changing the acquisition process. There is a difference in the possibility of capturing even signals from satellites.

A specific processing example in the case where the acquisition process is changed by the demodulation units of each group will be described below. In a search process for locking to a signal from a satellite when a satellite is not acquired in each demodulation unit, The following processing can be performed.

As a factor for capturing a signal from a satellite in the demodulation unit, a frequency correction signal output from the voltage controlled oscillator 25 for locking to the frequency of the received signal subjected to the Doppler effect corresponds to the received signal. And the case where the phase of the PN code generated by the PN code generator 22 becomes the phase corresponding to the received signal and the spectrum despreading can be accurately performed. Change the processing until the factor can be captured.

First, the case where the change state of the frequency correction signal output from the voltage controlled oscillator 25 is changed between the first group of demodulators and the second group of demodulators will be described. range to change the frequency of the frequency correction signal is from f ₁ to f ₂ (f _1, f ₂ is any frequency) is. In this case, the demodulator of the first group, to vary the oscillation frequency of the voltage controlled oscillator 25 from the frequency f ₁ to f _2. Then, in the demodulator of the second group, it causes changes the oscillation frequency of the voltage controlled oscillator 25 from the frequency f ₂ to f ₁ (i.e. changes in the direction opposite to the first group).

Instead of reversing the direction of change, the range in which the frequency changes may be divided. That is, in the first group of demodulators, the voltage controlled oscillator 25
Oscillation frequency between frequencies f ₁ and f ₃ (this frequency f ₃
At a frequency substantially intermediate between the frequencies f ₁ and f ₂ ). In the second group of demodulators, the voltage controlled oscillator 2
The oscillation frequency of 5 vary between a frequency f ₂ and f _3.

Next, the process of changing the phase at which the PN code generator 22 generates the PN code for spectrum despreading between the first group of demodulators and the second group of demodulators will be described. Regarding the phase for generating the PN code,
The direction in which the phase is changed by the first group of demodulators and the direction in which the phase is changed by the second group of demodulators can be reversed. Alternatively, the direction in which the phase is changed in each group may be the same, and the initial phase at the start of the search may be set to a phase inverted from each other.

As described above, the direction in which the frequency and phase change,
By changing the range or the like in groups, there is a higher possibility that the satellite can be acquired earlier than when one satellite is acquired by only one demodulator. Therefore, for example, the time required to capture four satellites required for performing three-dimensional positioning can be shortened, and after the receiver is turned on and reception is started, the display unit is started. The time until the positioning position is displayed at 28 can be reduced.

Further, in a state where signals from four or more satellites have been captured, the number of satellites temporarily captured due to some factor (for example, when a vehicle equipped with a receiver enters a tunnel). When the number of satellites becomes less than four and the satellite can be captured again, the time until the same satellite can be captured again can be shortened, and the time during which positioning can be performed is lengthened (that is, the positioning rate is reduced). Higher).

When a signal from a satellite once captured cannot be captured for some reason and is to be re-captured, a different process from the first capture may be performed.

That is, for example, when the signal captured by the demodulation unit of any channel in the first group is interrupted,
In the demodulation unit of this channel, the generation phase of the PN code generated by the PN code generator 22 and the frequency of the frequency correction signal generated by the voltage control oscillator 25 are maintained as they are, and the state in which the demodulation unit is able to capture An interpolation process for continuing the same process is performed.

In the second group of demodulators, the demodulators of the channels for demodulating the signals from the satellites that cannot be captured change the frequency of the frequency correction signal generated by the voltage controlled oscillator 25, and Search for the signal from. Alternatively, P generated by the PN code generator 22
A search for searching for a signal from a satellite is performed by changing the generation phase of the N code.

[0038] By doing so, there is a high possibility that a satellite whose reception has been temporarily interrupted can be quickly reacquired.
That is, when the signal from the same satellite can be received again, and the condition at this time is the same as immediately before the reception is interrupted, the first
Can be immediately captured by the demodulation unit of the second group, and when some condition changes, it can be captured by the demodulation unit of the second group, and the time until re-acquisition is shortened as compared with the case of capturing by the demodulation unit of one channel. And the positioning rate can be improved.

In the above description, the case where the correction of the frequency and the generation phase of the PN code are changed has been described. The first group of demodulators and the second group of demodulators may be changed. For example, P
The level of the threshold for judging that demodulation could be performed by the N-code demodulator 21 may be changed in each group so that signals from satellites can be captured in a short time.

In this example, up to four satellites having a high elevation angle are captured by the demodulation unit of the second group. However, from among the satellites captured by the demodulation unit of the first group, another method is used. A satellite to be captured by the second group of demodulators may be selected. For example, the number of satellites used for positioning of the current position is usually four, and the satellites using received data for positioning
May be selected as satellites to be captured by the demodulation units of the group.

Next, another example of processing when capturing a signal from a satellite using the GPS receiver 10 shown in FIG. 1 will be described.
This will be described with reference to the flowchart of FIG.

Also in this example, as a demodulation unit for capturing a signal from a satellite, the eight-channel demodulation units 101 to 108 of channel number 1 to channel number 8 are used as a first group of demodulation units, and channel number 9 to channel number 12 are used. And the demodulation units 109 to 112 of the four channels as a second group of demodulation units,
The first group of demodulation units 101 to 108 individually capture up to eight satellites that can be captured at the position at that time. Then, when the process of capturing is started, it is determined whether or not the capturing has been completed in each channel. That is, as shown in the flowchart of FIG. 4, it is determined whether the satellite assigned to the demodulation unit 101 of the channel number 1 has been captured (step S21). If this satellite cannot be acquired, the demodulators 109 to 112 of the second group of four channels are used.
Then, the demodulation unit 101 of the channel number 1 performs a process of simultaneously capturing the same satellite as the satellite being searched. In this case, similar to the processing according to the flowchart of FIG. 3 described above, demodulation processing (change in frequency, change in phase, etc.) is performed in a different state for each channel (step S2).
2).

When the corresponding satellite can be captured by any one of the channels in the capturing process using the total of five channels, the capturing state (PN
(Code phase and frequency) to the demodulation unit 10 of channel number 1
1 and the signal from the corresponding satellite is captured by the demodulation unit 101 of the channel number 1 (however, if the demodulation unit 101 of the channel number 1 is able to capture the earliest, there is no need to move this captured channel). .

Next, it is determined whether or not the satellite assigned to the demodulation unit 102 of channel number 2 has been captured (step S23). If this satellite cannot be acquired, the demodulators 109 to 112 of the second group of four channels are used.
Then, the demodulation unit 102 of the channel number 2 performs a process of simultaneously capturing the same satellite as the satellite being searched. Also in this case, demodulation processing (change in frequency, change in phase, etc.) is performed in different states for each channel (step S24).

When the corresponding satellite can be captured by any one of the channels in the capturing process using the total of five channels, the capturing state (PN
Code phase and frequency) to the demodulator 10 of channel number 2
2 and the signal from the corresponding satellite is captured by the demodulation unit 102 of channel number 2 (however, if the demodulation unit 102 of channel number 2 is able to capture the earliest, there is no need to move this captured channel). .

Hereinafter, similarly, the demodulation section 103 for channel number 3, the demodulation section 104 for channel number 4, the demodulation section 105 for channel number 5, and the demodulation section 1 for channel number 6
06, the demodulation unit 107 for channel number 7 and the demodulation unit 108 for channel number 8 determine whether satellites assigned to each channel have been captured (steps S25 and S2).
7, S29, S31, S33, S35), when it is determined that the signals cannot be captured by the respective channels, the capturing processes are performed simultaneously by the demodulators 109 to 112 of the four channels constituting the second group (steps S26, S28). , S3
0, S32, S34, S36), and when the capture is completed, the process proceeds to the next step.

By performing the process of capturing up to eight satellites in this manner, the time required for capturing satellites in each channel of the first group is reduced, and the time required for positioning is reduced. Can be. Further, when all eight channels have been captured, the processing of the flowchart of FIG. 4 is further performed, so that the satellite currently being captured by any of the channels in the first group cannot be captured temporarily. And the positioning rate can be improved.

In each of the capturing processes so far, the first group of demodulators of eight channels and the second group of demodulators of four channels are divided into a second group of demodulators. Is used to improve the capture rate. However, the capture rate may be improved by sequentially and effectively using the demodulation units of all 12 channels.

That is, for example, as shown in the flowchart of FIG.
Using the demodulation units 101 to 112 of all the channels, a search process for capturing simultaneously is performed (step S41).
At this time, the capture processing state is changed in 12 channels.

Then, it is determined whether or not the satellite having the highest elevation angle has been captured (step S42). If the corresponding satellite has been captured on any channel, the captured state (PN code phase, Frequency) is set by the demodulation section 101 of channel number 1
The signal from the corresponding satellite is captured by the demodulation unit 101 (step S43). However, if the demodulation unit 101 of channel number 1 has been able to capture the earliest, there is no need to move this captured channel.

Next, a search process is performed to simultaneously capture the satellite located at the position having the second highest elevation angle using the demodulators 102 to 112 of the remaining 11 channels (step S44). At this time, the capture processing state is changed in 11 channels.

Then, it is determined whether or not the satellite having the second highest elevation angle has been captured (step S45). If the corresponding satellite has been captured on any channel, the captured state (phase of the PN code) in that channel is determined. , Frequency) are set in the demodulation unit 102 of channel number 2 and the demodulation unit 102 of channel number 2 captures a signal from the corresponding satellite (step S46). However, if the demodulation unit 102 of the channel number 2 is able to capture the earliest, the process of moving the captured channel is not necessary.

Thereafter, a centralized search is performed in the same manner using all the remaining demodulators (steps S47, S50, S5).
3, S56, S59, S62), and in each stage, it is determined whether or not the corresponding satellite has been captured (step S48, S48).
(S51, S54, S57, S60, S63) When the corresponding satellite can be acquired, the acquisition of the satellite is demodulated into channel number 3, channel number 4, channel number 5, channel number 6, channel number 7, and channel number 8. Parts 103, 104, 105, 106, 107, 10
8 are performed (steps S49 and S5).
2, S55, S58, S61, S64).

By performing the processing in this manner, the processing until eight satellites can be captured is performed by effectively utilizing all 12 channels, and signals from up to eight satellites are captured in a short time. This makes it possible to shorten the time required for positioning, reduce the time during which positioning cannot be performed, and improve the positioning rate.

In each of the above-described processes, 12
The use condition of each channel is set on the assumption that up to eight satellites are always captured using the demodulation unit prepared for the channel. The number of satellites having the number may be other numbers, and an optimal configuration may be adopted according to the purpose of use of the receiver.

In the above-described embodiment, the 12-channel demodulator is constituted by 12 actual circuits. However, one to several demodulators are used in a time-division manner.
It may be configured to function as a demodulation unit for 12 channels or the like.

In the above-described embodiment, the GPS
However, it is needless to say that the present invention can also be applied to receivers for other positioning systems.

[0058]

According to the present invention, a positioning signal from a satellite having a high elevation angle among a plurality of positioning signals received and demodulated by the first receiving unit is also received by the second receiving unit and demodulated. Since the same positioning signal is received twice, the positioning rate can be improved and the positioning time can be shortened.

In this case, the first receiving unit and the second receiving unit use the first receiving unit and the second receiving unit for despreading the positioning signal transmitted from the same satellite. By searching for positioning signals from satellites with different phases of pseudo-random code generation, the time required for accurate demodulation of positioning signals during search can be reduced, and the time required for positioning can be reduced. This can be shortened, and re-acquisition can be quickly performed when the acquired positioning signal is temporarily lost.

The first receiving unit and the second receiving unit differ in the level of the threshold value for judging that the positioning signal transmitted from the same satellite can be demodulated by despreading. By searching for the positioning signal from, even if the signal cannot be obtained by the first receiving unit for some reason,
It is backed up by the received data obtained by the second receiving unit, and the possibility that positioning cannot be performed is reduced, and the positioning rate can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a signal reception state according to an example of an embodiment;

FIG. 3 is a flowchart illustrating a channel assignment process according to an example of the embodiment;

FIG. 4 is a flowchart showing processing (intensive search processing) according to an example of another embodiment of the present invention.

FIG. 5 is a flowchart showing processing (search processing using all channels) according to another example of the present invention.

[Explanation of symbols]

10 GPS receiver, 11 antenna, 21 PN code demodulator, 22 PN code generator, 24 mixer, 25
Voltage controlled oscillator (VCO), 26 PSK demodulator, 27
Arithmetic processing unit, 28 display unit, 101 channel 1 demodulation unit, 102 channel 2 demodulation unit, 103 channel 3 demodulation unit, 104 channel 4 demodulation unit, 10
5 demodulator for channel 5, 106 demodulator for channel 6, 107 demodulator for channel 7, 108 demodulator for channel 8, 109 demodulator for channel 9, 11
0 Channel 10 demodulator, 111 Channel 11
Demodulation section, 112 channel 12 demodulation section

Continuation of the front page (56) References JP-A-3-170890 (JP, A) JP-A-61-219881 (JP, A) JP-A-2-103487 (JP, A) JP-A-8-62319 (JP) , A) JP-A-62-298787 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 21/00-21/36 G01C 23/00-25/00 G01S 5/00 -5/14 G08G 1/00-9/02

Claims (3)

(57) [Claims] 1. A method for receiving a plurality of positioning signals transmitted by being spread with pseudo-random codes different for respective satellites from different satellites, and transmitting information included in the received positioning signals to the spread code. In the positioning signal receiver that despreads and demodulates with the same pseudo-random code and analyzes the demodulated information to determine the current position, it receives the positioning signals from each satellite individually for each positioning signal A first receiving unit that obtains the information from each of the satellites by performing processing and demodulation processing, and a plurality of satellites are selected from the satellites received by the first receiving unit in descending order of elevation angle A second receiving unit that individually receives and demodulates the information to obtain the information from the selected satellite; and, among the information obtained by the first and second receiving units, which are necessary for positioning. Use sensitive information A positioning signal receiver, comprising: an arithmetic processing unit for positioning the current position. 2. A positioning signal transmitted from the same satellite, the first receiving unit and the second receiving unit differ in the generation phase of a pseudo-random code for despreading from the satellite. 2. A search for a positioning signal is performed.
The positioning signal receiver as described. 3. A method in which the first receiving unit and the second receiving unit differ in the level of a threshold value for judging that they can be demodulated by despreading with respect to a positioning signal transmitted from the same satellite. 2. The positioning signal receiver according to claim 1, wherein a search for a positioning signal from the GPS is performed.