JP2002156439A - Satellite receiver for monitoring multipath signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive satellite receiver for monitoring multipath signals of simple device constitution. SOLUTION: Correlating processing is executed according to a multipath non-suppressing system relatively susceptible to multipath effects (Fig. (2)(a)), and correlating processing is executed according to a multipath suppressing system, relatively unsusceptible to multipath effects (Fig. (2)(b)). By comparing and collating the results of the correlating processing according to the multipath non-suppressing system and the results of the correlating processing according to the multipath suppressing system, for example, subtracting one from the other, it is possible to perform detection, evaluation, etc., on the degree of multipath effects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a GPS (Global Pos
GNSS (GlobalNaviga)
and a system in which a receiver on the earth receives satellite signals from positioning satellites in orbit around the earth and performs positioning. More specifically, the present invention is used in monitoring a phenomenon in which a plurality of satellite signal propagation paths from a positioning satellite to a receiver occur, that is, in the occurrence of multipath, or measuring or evaluating the degree (multipath error). The present invention relates to a multipath signal monitoring satellite receiver.

[0002]

2. Description of the Related Art One of the causes of deterioration of positioning accuracy in GNSS is multipath due to reflection of a satellite signal by an obstacle. When multipath occurs,
The interference of the delayed wave with the direct wave degrades the quality of the received satellite signal and, consequently, the accuracy of positioning based on the received satellite signal. The appearance of the multipath differs depending on the reception environment, including the position of an antenna for receiving a satellite signal (positional relationship with an obstacle) and the like.

[0003] Therefore, hardware for monitoring the occurrence of multipath and measuring and evaluating multipath errors is required.
Software has been developed for some time. For example, NovA
The tel website (http://www.novatel.ca/) is a MAT (Mu
ltipath Assesment Tool). This software is software that can be executed on a personal computer basis, and is a delay lock loop for multipath evaluation (MEDLL: Multipath Estimat).
ing Delay Lock Loop) By processing the output of a multipath meter equipped with a receiver, information indicating the presence / absence and degree of multipath occurrence (multipath power, phase, delay, etc.) is related to the occurrence of multipath. This information is provided to the user together with the obtained information (elevation angle / azimuth of the positioning satellite, C / No of the satellite signal, etc.).

[0004] Conventional multipath signal monitoring satellite receivers, such as MEDLL receivers, are all based on the idea of detecting the presence / absence and degree of multipath from disturbances in the correlation waveform. Here, the correlation waveform means the difference between the spread phase of the received satellite signal (the phase of the spread code relating to the received satellite signal) and the phase of the despread code on the horizontal axis, and the correlation value between the received satellite signal and the despread code. Is plotted on the vertical axis. Ideally, in the vicinity of the correlation peak, FIG.
A triangular waveform shown in FIG. In FIG. 3, a point indicated by “○” is a correlation peak, and when the phase difference of the despread code with respect to the received satellite signal is 0, the correlation value thus becomes a peak. When the phase difference deviates from 0, the correlation value becomes lower than its peak. Further, when multipath occurs on the propagation path of the satellite signal, the waveform is distorted.

Therefore, a conventional multipath signal monitoring satellite receiver generates a large number of despread codes having different mutual phase differences, and obtains a correlation value between each of them and a received satellite signal. Correlation values are obtained at many sample points (phases). The phase difference between the multiple despreading codes to be generated is made sufficiently small so that the triangles near the correlation peak are captured using the despreading codes and the correlation waveform can be estimated from the correlation values of those many sample points. . For example,
The mutual phase difference between a large number of despreading codes in a multipath signal monitoring satellite receiver is E and L in a normal receiver.
Compared with the phase difference p. Here, the normal receiver is a receiver used for positioning, not for multipath monitoring. In a positioning receiver,
As shown in FIGS. 3A and 3A, various techniques for accurately capturing and tracking a correlation peak using a despreading code such as E or L are employed. Delay for phase despreading code E (Late) Phase despreading code L
Is set to about one chip or smaller.

A multipath signal monitoring satellite receiver obtains a correlation value between each of a large number of despread codes having such a small phase interval and a received satellite signal. If the number of points for detecting the correlation value is sufficiently large, a waveform as shown in FIGS. 3A and 3B can be obtained by connecting the obtained correlation values “●”. By detecting that the correlation waveform is distorted relative to an ideal triangle near the correlation peak, it is possible to determine the presence or absence of multipath. Further, by detecting and evaluating the degree of distortion, the degree of the multipath error can be known.

[0007]

However, in order to implement the conventional method, the correlation values must be sampled at a number of points as indicated by "●" in FIGS. 3 (1) and 3 (b). . If a large number of correlators are operated in parallel in order to obtain correlation values at a large number of sample points in a relatively short time, a large number of correlators are required, so that the receiver becomes expensive and bloated. SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is not necessary to detect correlation values for a large number of points, and therefore, a multipath signal monitoring satellite having a low-cost and simple configuration. Providing a receiver is one of its purposes.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to (1) a method for receiving a satellite signal on a terrestrial earth by transmitting a spread spectrum signal from a positioning satellite in an orbit around the earth. A system that receives and despreads the spectrum and determines the position of the receiver based on the information obtained through it, monitors the occurrence of multipath in the satellite signal propagation from the positioning satellite to the receiver, or measures the degree Or a multipath signal monitoring satellite receiver used for evaluation, wherein (2) a correlation means for performing spectrum despreading of the satellite signal by correlation processing between a receiving means for receiving the satellite signal and a predetermined despreading code. And (3) the correlation processing means performs a correlation processing on a set of despread codes having a relatively large phase difference. A multipath non-suppression type correlation processing means to be used; and a multipath suppression type correlation processing means for performing correlation processing using another set of despreading codes having a relatively small phase difference. The information obtained through the correlation processing by the non-suppression type correlation processing unit and the multipath suppression type correlation processing unit is compared with each other,
There is provided a means for outputting the information obtained thereby as information indicating the result of monitoring, measurement or evaluation related to multipath.

One of the basic ideas in the present invention is based on the conventional idea that a correlation value is detected at many points, a correlation waveform is obtained, and distortion of the correlation waveform is detected. And comparing the resulting correlation values, and in particular, detecting the effect of multipath by comparing correlation values that are seen to be relatively strongly affected by multipath and correlation values that are not. There is a shift to thinking. In the present invention, as described above, this basic idea is realized by providing a plurality of types of correlation processing means, that is, a multipath non-suppression method correlation processing means and a multipath suppression method correlation processing means.

Here, a sequence of information (for example, a code phase, a code pseudorange, a difference of a code pseudorange with respect to a carrier pseudorange, etc.) obtained through the correlation processing by the multipath non-suppression type correlation processing means is represented by y1 (t), Let the effect of the appearing multipath be β1 (t). Similarly,
The sequence of information obtained through the correlation processing by the multipath suppression type correlation processing means is represented by y2 (t), and the effect of the multipath appearing on the sequence is represented by β2 (t). At this time, y1 (t) and y2 (t) are

Y1 (t) = α (t) + β1 (t) y2 (t) = α (t) + β2 (t) In these equations, α (t) is an information sequence to be obtained when no multipath occurs, that is, a “true value”, and is a term common to both equations.

The following equation is obtained: y1 (t) -y2 (t) = β1 (t) -β2 (t).

[0011] The right side of this equation is the influence of the multipath included in the information sequence obtained by the multipath non-suppression type correlation processing means and the multipath effect included in the information sequence obtained by the multipath suppression type correlation processing means. The difference from the influence of the path is shown. On the other hand, a set of despreading codes used in the correlation processing by the multipath non-suppression type correlation processing means has a phase difference p1 such as E and L shown in FIG. A pair of despreading codes which are relatively large and are used in the correlation processing by the multipath suppression type correlation processing means include, for example, E and L shown in FIGS. The phase difference p2 is relatively small (that is, p1> p2). Further, as is known in the art, the influence of the distortion of the correlation waveform caused by the multipath is such that the smaller the mutual phase difference of the despreading code used for the correlation processing is, the smaller the information sequence obtained by the correlation processing becomes. Hard to appear.

Therefore, the information obtained by the process of comparing the information sequences obtained from both correlation processing means, for example, the left side y1 (t) -y2 (t) of the above-mentioned equation is (indirectly) affected by the multipath. This is information that can be correlated. That is, through the process of mutually comparing the information sequences obtained from both correlation processing means, it is possible to realize detection of the presence or absence of multipath, quantitative detection and evaluation of multipath error, and the like. Since the number of points for sampling the correlation value is reduced, the number of correlators can be reduced as compared with the related art shown in FIGS. 3A and 3B.
It will be excellent in terms of cost reduction and simplification. Further, the multipath non-suppression type correlation processing means and the multipath suppression type correlation processing means can be realized by time-sharing use of a common correlation processing means. In such a case, the number of correlators is further reduced. be able to.

According to the knowledge of the inventor, the multipath error is likely to appear when the elevation angle of the positioning satellite is relatively low. Thus, in a preferred embodiment of the present invention, each visible satellite is given a ranking in ascending order of elevation,
Observation satellite indicating means for providing each visible satellite to the reception and correlation processing according to the assigned order is provided. The visible satellite here is a satellite located at a position that can be seen from a multipath signal monitoring satellite receiver among positioning satellites. The elevation angle can be derived based on information indicating the orbit of each positioning satellite, information indicating the position of the multipath signal monitoring satellite receiver, and information indicating the current time. In this way, by preferentially receiving an object having a low elevation angle as a target of reception and correlation processing, the effect of multipath can be detected, measured, and evaluated in a relatively short time. Since the influence of multipath can be detected in a short time, intermittent operation can be performed by stopping power supply to each circuit in the receiver or stopping the clock or lowering the frequency, and the effect of reducing power consumption in the receiver can be obtained. .

Further, the present invention provides a configuration in which a measurement schedule (setting information on which positioning satellites are to be sequentially received and subjected to correlation processing, etc.) is given from a user, and multipath monitoring / measurement is performed accordingly. Can also be implemented. This method also contributes to a reduction in the time required for multipath monitoring / measurement and the like, and can provide an effect of intermittent operation and, consequently, reduction in power consumption of the receiver.

In the example shown in FIG. 3B, two despreading codes E and L are used in each correlation processing means, however, this is only an example for explanation. In practicing the present invention, three or more despreading codes may be used as one set. Although the content of each despreading code used in each correlation processing means has not been particularly described, the multipath non-suppression type correlation processing means and the corresponding multipath suppression type correlation processing means are transmitted from the same positioning satellite. Since these are means for processing the satellite signals obtained, the contents of the despreading code sequences used in them are all the same (only the phase is different).

Further, while the above description has been directed to the processing for one positioning satellite, the present invention is embodied as a receiver that simultaneously captures a plurality of positioning satellites and performs monitoring, measurement, and the like related to multipath. Is preferred. When the present invention is implemented as such a receiver, a plurality of pairs of multipath non-suppression type correlation processing means and multipath suppression type correlation processing means are provided, and a pair of satellite signals to be processed by each pair is provided for each pair. The despreading code of the corresponding sequence content is used.

Further, in a normal or positioning receiver, first, the spread code of the received satellite signal from the positioning satellite is captured with the phase difference between E and L set to be wide, and once the capture is successful, A technique of narrowing the phase difference between E and L to achieve accurate tracking has been conventionally employed. The present invention executes multipath monitoring or the like based on information obtained from both correlation processing means simultaneously or in succession, and performs variable control of a phase difference at the time of transition from acquisition to tracking of a received satellite signal. Note that this is not the case, i.e. different in nature from conventional operation in a normal receiver. In addition, with a normal receiver, acquisition and
A process of determining a positioning satellite to be tracked may be employed. On the other hand, the preferred embodiment of the present invention also determines the measurement order according to the elevation angle of the positioning satellite. However, while the order of selection in a normal receiver is the order of high elevation for the purpose of maintaining and maintaining the positioning accuracy, the order in the preferred embodiment of the present invention is the order of low elevation for the purpose of grasping the degree of multipath influence. Is different in both its purpose and procedure.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the reference numerals shown in FIG. 3B are also used in the following description.

FIG. 1 shows the configuration of a multipath signal monitoring satellite receiver 10 according to an embodiment of the present invention. The multipath signal monitoring satellite receiver 10 shown in FIG. 1 includes a signal processing device 14 for despreading a spectrum of a satellite signal received from a positioning satellite by a satellite reception antenna 12 and demodulating navigation data. As illustrated in FIG. 2, the signal processing device 14 includes 2n correlation processing units 14-ij (i = 1, 2).
2,... N; j = a, b; n = natural numbers). Among these, the correlation processing unit 14-ia corresponds to FIG.
This is a unit for performing a correlation process in accordance with the method shown in FIG.
ib is a unit that performs a correlation process according to the method shown in FIGS. 3B and 3B, that is, multipath suppression. Further, the correlation processing unit 14-ia and the correlation processing unit 14-ib form a pair, and the same positioning satellite is assigned to both. In FIG. 2, the unit related to the multipath non-suppression scheme and the unit related to the multipath suppression scheme are illustrated as separate units. However, these units are actually shared by a single unit in a time-sharing manner. Can also be realized.

The signal processing device 14 includes the observation satellite pointing device 1
When the observation satellite instruction data V2 is received from the observation satellite instruction data 6, the first satellite number n1 of the maximum n satellite numbers included in the observation satellite instruction data V2 is correlated with the correlation processing unit 14-1j.
The positioning satellite is assigned to each correlation processing unit 14-ij, such as the second satellite number n2 to 14-2j, and so on. Each correlation processing unit 14-ij converts a despreading code, which is a data sequence corresponding to a positioning satellite assigned to itself, into at least a leading phase (E) and a lagging phase (L).
Generate as street. Although not shown, each of the correlation processing units 14-ij includes, in addition to a code generator for generating E and L despreading codes, a control member for sequentially changing the phase of the E and L despreading codes, and their despreading. A correlator (group) for detecting a correlation value between the code and the received satellite signal is built in. Each correlation processing unit 14-ij detects a correlation value between each of the E and L despread codes and the received satellite signal while sequentially changing the phase of the despread code, thereby forming a spread phase, ie, a triangle ( The position of the peak or the valley is detected as a code phase. At this time, the received satellite signal is despread in spectrum, and becomes a state in which navigation data can be demodulated. FIG. 3 (2) shows a state in which the despreading codes of E and L are synchronized with the correlation peak phase and the code phase is detected. Each correlation processing unit 14-
Since the details of the internal configuration of ij can be appropriately designed in accordance with the common sense in the art, a detailed description thereof will be omitted here.

A correlation processing unit 14-ia that performs correlation processing according to the multipath non-suppression method, and a correlation processing unit 14-ia that performs correlation processing according to the multipath suppression method.
3 (2) (a) and (b), the phase difference between the E and L despread codes is different from each other, and the phase difference p1 in the former is larger than that in the latter. That is, it is larger than the phase difference p2. In general, as the phase difference between the E and L despread codes is larger, the influence of multipath, that is, the distortion of the correlation waveform is more likely to become apparent, so that the code phase obtained as a result of the code phase synchronization control in the correlation processing unit 14-ia includes , The effect of multipath appears more remarkably than the code phase obtained as a result of the code phase synchronization control in the correlation processing unit 14-ib. Signal processing device 1
4 supplies the information obtained in the correlation processing unit 14-ia, for example, the code phase as observation data V3 to the observation data processing device 18, and the information obtained in the correlation processing unit 14-ib, for example, the code phase as the observation data V4. The data is supplied to the observation data processing device 18.

The observation data processing device 18 measures or estimates the effect of multipath for each positioning satellite by comparing these observation data V3 and V4 for each positioning satellite. For example, if the observation data V3 and V4 include a carrier phase (a phase of a carrier component in a received satellite signal; obtained through oscillation phase control of a local oscillator in each correlation processing unit) and a code phase, the observation data processing is performed. The device 18 supplies the fluctuation of the pseudo distance obtained from the code phase to the pseudo distance to each positioning satellite obtained based on the carrier phase to the input / output device 20 as information M indicating the degree of influence of the multipath. The input / output device 20 is, for example,
It is an interface to the user terminal device 22 having a display function, and combines the degree of influence information M supplied from the observation data processing device 18 with the observation satellite data V6 supplied from the observation satellite instruction device 16 to output data V7
To the user terminal device 22.

The observation satellite data V6 is data indicating elevation angle, azimuth angle, C / No, etc. of the positioning satellite, that is, data including data relating to the occurrence of multipath. In order to obtain the observation satellite data V6, etc., each correlation processing unit 14-ij in the signal processing device 14 demodulates navigation data from the received satellite signal that has undergone spectrum despreading, and among the data included in the navigation data, Data indicating the orbit (calendar) of each positioning satellite is extracted, and the extracted data is supplied to the observation satellite indicating device 16 as demodulated data V1 together with information such as the received signal strength. The observation satellite indicating device 16 calculates the observation satellite based on the demodulated data V1, current time information obtained from a clock or the like (not shown), and current position information given or initialized from time to time by a user as described later. The data V6 is derived. The observation satellite data V6 is created for each visible satellite, or at least for the visible satellite currently being used for multipath impact detection.

The observation satellite indicating data V2 is created by the observation satellite indicating device 16 so that each visible satellite is processed according to the measurement schedule given by the user or is processed in the order of low elevation angles. Signal processing device 1
4 is supplied.

For example, when the user operates the user terminal device 22, (1) the satellite number of the positioning satellite to be subjected to the multipath influence measurement, and (2) (outline) the multipath signal monitoring satellite receiver 10. When the setting data V8 including information such as the current position and (3) the time at which the multipath influence is measured is input, the setting data V8 is supplied to the observation satellite pointing device 16 as the setting data V5 by the input / output device 20. .
Among the information included in the setting data V8, the satellite number and the measurement time are information that gives a measurement schedule. Therefore, the observation satellite instruction device 16 generates the observation satellite instruction data V2 according to the information, and when the measurement time comes. The signal is supplied to the signal processing device 14 accordingly. The receiver position is used for generating the observation satellite data V6 based on the demodulated data V1 as described above and for generating the observation satellite instruction data V2 at the time of selecting the low elevation angle order described below. When a member (not shown) is performing the positioning operation in the signal processing device 14 or based on the output thereof, the result of the positioning operation can be used for the receiver position instead of the user input.

If the user has not input the setting data V8 by operating the user terminal device 22, or if the setting data V8 input by the user does not include information on the measurement schedule, the observation satellite instruction is issued. The device 16 obtains the elevation angle of each visible satellite at the measurement time, and generates the observation satellite instruction data V2 so that the measurement of the multipath influence and the reception / correlation processing therefor are executed in order from the visible satellite having the lower elevation angle. . The orbit (calendar) data in the demodulated data V1 and the multipath signal monitoring satellite receiver 10 determine which positioning satellite is a visible satellite at an arbitrary measurement time and how many elevation angles of the visible satellite are.
Can be determined and derived from the (approximate) position and the measurement time. Also, the orbit (calendar) of the information
Data that has been stored or collected in advance can be used, and the receiver (approximate) position that has been input by the user before or recently as the setting data V8 or that obtained by positioning can be used. The measurement time is a time previously input as a measurement schedule by the user or a time determined by initial settings. Here, it is considered that the influence of multipath is more likely to be manifested on a visible satellite whose elevation angle is relatively low. Therefore, the observation satellite indicating device 16 is configured to measure the observation satellites in order from the plurality of visible satellites in general in order from a relatively low elevation angle among the plurality of visible satellites and to perform reception / correlation processing therefor when the measurement time comes. The instruction data V2 is generated and supplied to the signal processing device 14.

As the information M, a positioning error may be derived instead of the fluctuation of the pseudo distance. For example, the observation data processing device 18 performs the positioning calculation based on the observation data V3 related to the multipath non-suppression method, and also performs the positioning calculation based on the observation data V4 related to the multipath suppression method. (For example, a difference in position) is set as information M. Thereby, the user can know the estimated value of the deterioration amount of the positioning accuracy due to the multipath. Alternatively, the estimation of satellites by or via the observation satellite indicating device 16 may be stopped, and all visible satellites or positioning satellites may be set as observation targets. Even in that case, it is possible to narrow down the output (display) from the user terminal device 22 to some satellites.

As described above, according to the present embodiment, the number of correlation value sample points per positioning satellite can be reduced. Therefore, the correlation of the correlators constituting each correlation processing unit 14-ij in the signal processing device 14 can be reduced. Since the number can be reduced, the configuration of the signal processing device 14 and thus the multipath signal monitoring satellite receiver 10 can be simplified and the price can be reduced. In addition, when the processing is performed in order from the positioning satellite having the low elevation angle, the multipath error can be detected and evaluated relatively early, so that the operation time of the signal processing device 14 is short. Therefore, the intermittent operation is sufficient, so that the power consumption of the power supply can be suppressed. Similarly, when processing is performed in accordance with the measurement schedule input from the user terminal device 22, the operation may be intermittent, so that power consumption of the power supply can be suppressed. Generally speaking, the configuration of the multipath signal monitoring satellite receiver 10 according to the present embodiment is small, simple, low-cost, and power-saving, and the accuracy of multipath error detection and the like is relatively high. It can be suitably used for applications such as optimizing the position of the antenna in consideration of the degree of multipath influence.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of a multipath signal monitoring satellite receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a functional configuration of a signal processing device according to the present embodiment.

FIG. 3 is a diagram showing a problem of the prior art and a principle of the present invention. In particular, FIG. 3 (1) (a) shows the phase difference between E and L in a normal, ie, positioning receiver, and the time of satellite acquisition. FIG. 3 (1) (b) is a diagram showing a relationship with a correlation peak, and FIG. 3 (1) (b) is a diagram showing a relationship between correlation value sample points in a conventional multipath signal monitoring receiver, and FIG. 3 (2).
FIG. 3A is a diagram showing the relationship between the phase difference between E and L and the correlation peak at the time of satellite acquisition according to the multipath non-suppression method of the present invention, and FIGS. FIG. 9 is a diagram illustrating a relationship between a phase difference between E and L and a correlation peak at the time of satellite acquisition according to the suppression method.

[Explanation of symbols]

Reference Signs List 10 satellite receiver for monitoring multipath signal, 12 satellite receiving antenna, 14 signal processor, 14-1a, 14-
1b, 14-2a, 14-2b, ..., 14-na, 14-
nb correlation processing unit, 16 observation satellite pointing device, 1
8 Observation data processing device, 20 input / output device, 22 user terminal device, E Lead phase despreading code, L Delay phase despreading code, p1, p2 Phase difference between E and L.

Claims (4)

[Claims] 1. A receiver on the earth receives and despreads a satellite signal that is spread and transmitted by a positioning satellite in an orbit around the earth, and the position of the receiver is determined based on information obtained through the spread. In the system that asks for
A multipath signal monitoring satellite receiver used to monitor the occurrence of multipath in satellite signal propagation from a positioning satellite to a receiver or to measure or evaluate the degree thereof, and a receiving means for receiving a satellite signal And a correlation processing means for performing spectrum despreading of the satellite signal by correlation processing with a predetermined despreading code, wherein the pair of the correlation processing means has a relatively large phase difference. Multipath non-suppression type correlation processing means for using the despreading code for correlation processing, and multipath suppression type correlation processing means for performing correlation processing using another set of despreading codes having a relatively small phase difference. Further, the information obtained through the correlation processing by the multipath non-suppression type correlation processing means and the multipath suppression type correlation processing means are compared with each other. And, monitoring Multipath the information obtained thereby, multipath signal monitoring satellite receiver, characterized in that it comprises a means for outputting as information indicating the result of measurement or evaluation. 2. The multipath signal monitoring satellite receiver according to claim 1, wherein the multipath non-suppression type correlation processing means and the multipath suppression type correlation processing means are realized by time sharing of a common correlation processing means. A satellite receiver for monitoring a multipath signal. 3. The multipath signal monitoring satellite receiver according to claim 1, wherein each of the positioning satellites is located at a position visible to the multipath signal monitoring satellite receiver. Information indicating the orbit of the satellite, information indicating the position of the satellite receiver for monitoring the multipath signal, and information indicating the current time are assigned ranks in ascending order of elevation angle, and each visible satellite is assigned according to the assigned rank. A multipath signal monitoring satellite receiver comprising observation satellite instruction means for receiving and correlating. 4. A receiver on the earth receives and despreads a satellite signal that is spread and transmitted by a positioning satellite in orbit around the earth, and the position of the receiver is determined based on information obtained through the spread. In the system that asks for
A multipath signal monitoring satellite receiver used to monitor the occurrence of multipath in satellite signal propagation from a positioning satellite to a receiver or to measure or evaluate the degree thereof, and a receiving means for receiving a satellite signal And a correlation processing means for performing spectrum despreading of the satellite signal by correlation processing with a predetermined despreading code, wherein a position visible from the multipath signal monitoring satellite receiver among the positioning satellites is provided. Of the visible satellites, which are satellites located in the order of the elevation angles derived from information indicating the orbit of each positioning satellite, information indicating the position of the multipath signal monitoring satellite receiver, and information indicating the current time, in ascending order of elevation. And an observation satellite indicating means for subjecting each visible satellite to the reception and correlation processing in accordance with the assigned order. Monitoring satellite receiver.