WO2015129243A1 - Satellite positioning-use radio wave interference detection mechanism, satellite positioning-use radio wave interference detection method, and augmentary information transmission system provided with satellite positioning-use radio wave interference detection mechanism - Google Patents

Abstract

Provided is a satellite positioning-use radio wave interference detection mechanism that can determine with a high degree of accuracy whether there is radio wave interference with a GPS signal, without increasing processing load. The satellite positioning-use radio wave interference detection mechanism comprises: a signal-to-noise ratio acquisition means that acquires a signal-to-noise ratio for a received GPS signal; a rate of change calculation means that calculates a time rate of change within a prescribed period of time with respect to the signal-to-noise ratio; and a determination means that determines whether there is radio wave interference with the received GPS signal, on the basis of the calculated time rate of change.

Description

Radio interference detection mechanism for satellite positioning, radio interference detection method for satellite positioning, and reinforcement information transmission system provided with radio interference detection mechanism for satellite positioning

The present invention relates to a system and method for determining the presence or absence of radio wave interference in a global positioning system (GPS) signal.

The navigation of modern aircraft is supported by navigation assistance systems using ground radio facilities and satellites. In recent years, navigation assistance systems using satellites can realize high-precision, high-reliability navigation on a global scale regardless of the landform or form (land / sea) on the ground. Introduction has been actively done. In addition, a ground-based augmentation system (GBAS) has been introduced to support precision approach and landing at airports where the highest safety performance is required for aircraft navigation. GBAS is a system that provides positioning augmentation information to satellite-navigating aircraft using positioning satellites such as GPS and GLONASS (GLObal NAvigation Satellite System).

GBAS creates reinforcement information on the ground system, and sends correction information by DGPS (Differential GPS), integrity information, FAS (Final Approach Segment) and TAP (Terminal Area Path) route information, etc. to the aircraft via VHF signals. To do. By using the reinforcement information received by the devices on the aircraft, navigation safety and accuracy that cannot be obtained by GPS alone are guaranteed.

However, a GPS signal transmitted from a GPS satellite with an output power of 50W is affected by the medium that passes through while propagating to the positioning reference station, and when the positioning reference station receives it, the received power is about ^10-16W . The signal is weak. Therefore, when a positioning reference station that receives this radio wave interferes with radio waves from other radio wave sources, the waveform of the positioning signal is distorted, and normal reception processing is hindered, so that positioning calculation cannot be performed. In this case, GBAS cannot create highly accurate and highly reliable reinforcement information.

Therefore, GBAS detects the presence or absence of radio wave interference, and determines whether the reinforcement information created in the state of radio wave interference affects the safe navigation of the aircraft. If there is a possibility that reinforcement information that hinders safe navigation due to radio wave interference is generated, transmission of the reinforcement information to the aircraft is stopped.

There are two main methods for determining the presence or absence of radio wave interference and thus the reliability of GPS signals. One is a method using a pseudorange error, and the other is a method using a carrier power to noise power ratio.

In Japanese Patent Laid-Open No. 2011-242296, after correcting the influence of the ionosphere for the calculated pseudorange, a predetermined threshold value is set from the average value and standard deviation regarding the correction result, and this threshold value is used for GPS satellites. A technique for determining the presence or absence of a failure is disclosed.

JP 2012-58185 discloses a carrier threshold value calculated using carrier power to noise power ratio, detection failure probability, false alarm probability and lower limit probability in the frequency distribution table of carrier power to noise power ratio, A technique for determining the reliability of a GPS signal based on the above is disclosed.

JP 2011-242296 A JP 2012-058185 A

When determining the presence or absence of radio wave interference with the error based on the pseudo distance output by a GPS receiver, etc., the amount of calculation required for setting and determining the threshold is large, and the load on the computer is a problem. In addition, the pseudo-range error is not necessarily generated only by radio wave interference, but may be caused by various causes such as the state of the radio wave propagation process (ionosphere, troposphere) and the state of the receiver or GPS satellite (failure, etc.). When determining the presence or absence of radio wave interference using the carrier power to noise power ratio, it is necessary to change the threshold depending on the type of interference wave to be detected, but the technology described in Patent Document 2 does not describe such content at all .

The present invention provides a radio interference detection mechanism for satellite positioning, a radio interference detection method for satellite positioning, and a radio interference detection mechanism for satellite positioning capable of accurately determining the presence or absence of radio wave interference to a GPS signal without increasing the processing load. An object of the present invention is to provide a supplementary information transmission system.

In order to achieve the above object, a radio interference detection mechanism for satellite positioning according to the present invention includes a signal-to-noise ratio acquisition unit that acquires a signal-to-noise ratio of a received GPS signal, and the acquired signal-to-noise ratio. A rate-of-change calculating unit that calculates a rate of change in time within a predetermined time; and a determining unit that determines whether or not there is radio wave interference with the received GPS signal based on the calculated rate of change of time.

In order to achieve the above object, a reinforcement information transmission system according to the present invention includes a reinforcement information generation means for generating reinforcement information using the received GPS signal, a radio interference detection mechanism for satellite positioning, and no radio interference. Control means for transmitting the generated reinforcement information to the moving body when it is determined that the generated reinforcement information is transmitted, and not transmitting the generated reinforcement information when it is determined that there is radio wave interference.

In order to achieve the above object, a radio interference detection method for satellite positioning according to the present invention acquires a signal-to-noise ratio of a received GPS signal, and a rate of time change of the acquired signal-to-noise ratio within a predetermined time. When the calculated time change rate is included in the predetermined range, it is determined that there is no radio wave interference with the GPS signal, and the calculated time change rate is not included in the predetermined range. Determines that there is radio wave interference to the GPS signal.

According to the above-described aspect of the present invention, the presence or absence of radio wave interference with a GPS signal can be determined with high accuracy without increasing the processing load.

It is a figure for demonstrating the concept of the various parameters used in the reinforcement information transmission system which concerns on 1st embodiment. It is a system configuration figure of the reinforcement information transmitting system concerning a first embodiment. 3 is a block configuration diagram of a radio wave interference detector 3 according to the first embodiment. FIG. It is an example of the data memorize | stored in C / No memory | storage part 3b which concerns on 1st embodiment. It is an example of the data memorize | stored in (sigma) memory | storage part 3c which concerns on 1st embodiment. It is a figure for demonstrating the difference of the change of C / No and Detect by the presence or absence of the radio wave interference by a pulse wave. It is an example of a detection probability distribution f (σ) stored in the f (σ) storage unit 3g according to the first embodiment. It is an operation | movement flowchart of the reinforcement information transmission system which concerns on 1st embodiment. It is an operation | movement flowchart of the reinforcement information transmission system which concerns on 1st embodiment. It is an operation | movement flowchart at the time of C / No determination of the reinforcement information transmission system which concerns on 1st embodiment. It is the figure which showed an example of the permission area | region when Thres. Changes with time. It is a figure for demonstrating the difference of the change of C / No and Detect by the presence or absence of the radio wave interference by a fixed wave. 1 is a system configuration diagram of a reinforcement information transmission system 10 according to an embodiment of the present invention. 2 is a block configuration diagram of a satellite positioning radio wave interference detection mechanism 30 according to an embodiment of the present invention. FIG.

Embodiments of the present invention will be described. A system configuration diagram of the reinforcement information transmission system is shown in FIG. 12, and a block configuration diagram of the satellite positioning radio wave interference detection mechanism is shown in FIG. In FIG. 12, the reinforcement information transmission system 10 includes reinforcement information generation means 20, satellite positioning radio wave interference detection mechanism 30, and control means 40.

The reinforcement information generation means 20 receives a positioning GPS signal transmitted from a GPS satellite, and generates reinforcement information using the received GPS signal. Here, the reinforcement information is information necessary to compensate for erroneous information included in the GPS signal and to calculate an accurate position of the moving body.

The satellite positioning radio wave interference detection mechanism 30 determines the presence or absence of radio wave interference with the received GPS signal. In FIG. 13, the satellite positioning radio wave interference detection mechanism 30 includes a signal-to-noise ratio acquisition unit 31, a change rate calculation unit 32, and a determination unit 33.

The signal-to-noise ratio acquisition unit 31 acquires the signal-to-noise ratio of the received GPS signal and outputs it to the change rate calculation unit 32.

The rate-of-change calculating means 32 calculates a time rate of change of the acquired signal-to-noise ratio within a predetermined time and outputs it to the determining means 33.

The determining means 33 determines the presence or absence of radio wave interference with the GPS signal based on the time rate of change of the input signal-to-noise ratio. For example, when the time change rate of the signal-to-noise ratio is not included in a predetermined range, the determination unit 33 according to the present embodiment determines that there is radio wave interference with the GPS signal. On the other hand, the determination means 33 determines that there is no radio wave interference to the GPS signal when the time change rate of the signal-to-noise ratio is within a predetermined range.

When the satellite positioning radio wave interference detection mechanism 30 determines that there is no radio wave interference, the control unit 40 transmits the reinforcement information generated by the reinforcement information generation unit 20 to the mobile body. On the other hand, when it is determined that there is radio wave interference, the control means 40 does not transmit the generated reinforcement information.

As described above, in the augmented information transmission system 10, the satellite positioning radio wave interference detection mechanism 30 determines the presence or absence of radio wave interference of the GPS signal based on the time change rate of the signal-to-noise ratio of the received GPS signal. Thereby, the presence or absence of the radio wave interference to the GPS signal can be detected with high accuracy without increasing the processing load.

Further, in the reinforcement information transmission system 10, the control means 40 does not transmit the reinforcement information when the satellite positioning radio wave interference detection mechanism 30 determines that there is radio wave interference. Thereby, it can suppress that the reinforcement information with low reliability is transmitted to a moving body.

[First embodiment]
[Description of configuration]
The concept of various parameters used in the system according to the first embodiment will be described with reference to FIG. In this system, the ratio C / No [of the signal power C [W] of the GPS signal received at the positioning reference station 2 to the measurement noise power No [W] is determined in order to determine the presence or absence of radio wave interference from a source of radio interference (not shown). dBHz] and pseudorange error σ [m] are used.

The pseudorange is defined as the GPS signal propagation time between the GPS satellite 1 and the positioning reference station 2 multiplied by the speed of light. However, the GPS signal is affected by the ionosphere and troposphere in the propagation process, so it differs from the distance measured when there is no influence from the ionosphere and troposphere. Further, the pseudo distance also changes depending on the elevation angle θ [deg.] When the GPS satellite 1 is viewed from the positioning reference station 2.

The difference between the distance measured when there is no influence from the ionosphere or troposphere and the actually measured pseudo distance is called pseudo distance error. Although the pseudorange error can be calculated using actually observed data, here, for simplicity, a theoretical calculation formula of the pseudorange error σ and the signal-to-noise ratio C / No is used. That is, when white noise is assumed, C / No and σ satisfy Equation 1.
1 set

Here, c, T _c , d, and T are the speed of light [m / s], the chip width [s], the chip length [s], and the averaging time [s], respectively. In this system, it is determined whether or not C / No and the above-mentioned σ each satisfy a predetermined condition. If the predetermined condition is satisfied, it is determined that there is no radio wave interference. Hereinafter, determination regarding C / No is referred to as C / No determination, and determination regarding σ is referred to as σ determination.

The reinforcement information transmission system according to this embodiment will be described. The system configuration diagram of this system is shown in FIG. This system includes a plurality of GPS satellites 1 constituting a GPS satellite group, a plurality of positioning reference stations 2 constituting a positioning reference station group, a radio wave interference detector 3, and a reinforcement information creator 4.

GPS signals used for GBAS are transmitted from multiple GPS satellites 1, respectively. The GPS satellite 1 transmits a GPS signal for positioning toward the ground while orbiting the earth. In this embodiment, four GPS satellites 1 (PRN # 1-PRN # 4) are provided. The GPS signal is a carrier wave composed of an RF sine wave signal, a ranging code including a PRN code, a C / A code and a P (Y) code, navigation data including a satellite health status, an ephemeris, an almanac, and a clock bias parameter, Consists of

The positioning reference station group includes a plurality of positioning reference stations 2 that receive GPS signals transmitted from each GPS satellite 1. In the present embodiment, each positioning reference station 2 receives GPS signals at a ΔT [s] period. In general, ΔT = 1 to 0.1 seconds. In the case of GBAS, since it is necessary to detect multipath as a non-common error, at least 3-4 positioning reference stations 2 are arranged. In this embodiment, four positioning reference stations 2 (2-1 to 2-4) are provided.

Each positioning reference station 2 transmits a carrier wave, a distance measurement code, and navigation data included in the received GPS signal to the reinforcement information creator 4. Each positioning reference station 2 calculates C / No from the signal power and noise power, and calculates σ from the calculated C / No using one equation. Assume that each positioning reference station 2 receives a GPS signal at time t, and C / No and σ at that time are C / No ^t and σ ^t , respectively. Each positioning reference station 2 transmits the calculated C / No ^t and σ ^t to the radio wave interference detector 3.

FIG. 3 shows a block diagram of the radio wave interference detector 3. The radio wave interference detector 3 includes a received signal input unit 3a, a C / No storage unit 3b, a σ storage unit 3c, a Detect ^t calculation unit 3d, a Thres. Input unit 3e, a C / No determination unit 3f, and an f (σ) storage unit. 3g, σ determination unit 3h, and radio wave interference determination unit 3i.

Receiving signal input unit 3a receives the transmitted C / No ^t and sigma ^t from the positioning reference station 2. Since the four positioning reference stations 2-1 to 2-4 receive GPS signals from the four GPS satellites PRN # 1 to PRN # 4, the received signal input unit 3a sets C / No ^t and σ ^t to 16 Receive one by one.

C / No storage section 3b stores every reception time to 16 C / No ^t received signal input unit 3a has received. As shown in FIG. 4A, the C / No storage section 3b C / No ^t of the GPS satellite PRN # 1-PRN # 4 at each measuring reference stations 2-1 to 2-4 are sequentially stored.

The σ storage unit 3c stores the 16 σ ^t received by the reception signal input unit 3a for each reception time. As shown in FIG. 4B, σ ^t of GPS satellites PRN # 1-PRN # 4 in each of the measurement reference stations 2-1 to 2-4 is sequentially stored in the σ storage unit 3c.

Detect ^t calculating section 3d calculates the time rate of change Detect ^t of C / No ^t in C / No storage section 3b on the stored C / No ^t and ^C / No ^t-ΔT from the time t. Detect ^t is calculated based on the backward difference formula (2 formulas) shown below. Detect ^t used when detecting a pulsed interference wave is particularly denoted as PW_Detect ^t .
2 sets

The Thres. Input unit 3e accepts an input of a threshold value Thres. Used for C / No determination. The threshold Thres. Is set according to the GBAS usage environment. For example, measure the C / No without radio wave interference for about one year, and calculate the difference calculated for the obtained C / No at the dt interval in Equation 2 at the satellite position (for example, elevation and azimuth at every 5 ° cell). The frequency distribution is determined by taking statistics for each observation satellite). Then, a false alarm probability value obtained from the GBAS availability requirement defined by the International Civil Aviation Organization (ICAO) is applied to this frequency distribution, and the obtained value is set as a threshold Thres. When performing take-off and landing support of the aircraft 5 by GBAS, it is desirable to set the threshold value Thres. To be smaller than that at the time of cruise.

The C / No determination unit 3f performs C / No determination for each C / No ^t using the PW_Detect ^t calculated by the Detect ^t calculation unit 3d and the threshold Thres. Received by the Thres. Input unit 3e. Thus, a pulsed interference wave is detected. The σ determination unit 3h according to the present embodiment detects a pulsed interference wave having a pulse width longer than ΔT.

Describe C / No judgment. As described above, the C / No of the GPS signal varies depending on the elevation angle θ when the GPS satellite 1 is viewed from the positioning reference station 2. Since θ and time t satisfy the relationship θ = ωt, C / No changes with time t. That is, C / No changes within a certain range as t changes regardless of the presence or absence of radio wave interference. When there is no radio wave interference or when the influence of radio wave interference included in the GPS signal is removed by some method, the change in C / No and Detect accompanying the change in t is shown by a broken line in FIG. Here, ω = 0.10 rad / s. When there is no radio wave interference, C / No and Detect change monotonously as t changes.

Next, consider the case where there is radio wave interference. In the present embodiment, it is assumed that the GPS signal interferes with a pulsed radio wave transmitted from a radio wave transmission source at around t = 440 s. The change in C / No and Detect accompanying the change in t is shown by a solid line in FIG. When there is interference with pulsed radio waves, C / No and Detect vary greatly.

In the C / No determination, it is determined whether or not PW_Detect ^t for each measurement point indicated by a black circle in FIG. 5 is included in the permitted area defined by the threshold value Thres. Here, the threshold value Thres. = 0.5 dBHz / sec. Determination is performed for each C / No ^t, to each signal on the basis of the determination result is set to 0 or 1 value as a flag. 0 if PW_Detect ^t is included in the permission region, set the If not included 1, then calculates the logical sum for all C / No ^t.

The f (σ) storage unit 3g stores the detection probability distribution f (σ) of the pseudorange error σ used for σ determination. In this embodiment, C / No is measured for a certain period in a state where there is no radio wave interference, or in which the influence of radio wave interference included in the GPS signal is removed by some method, and f ( σ) is stored. FIG. 6 shows f (σ). Note that f (σ) is normalized so as to satisfy Equation 3.
3 sets

The σ determination unit 3h performs σ determination for each σ ^t when the logical sum = 1 in the C / No determination in the C / No determination unit 3f.

The σ determination will be described. In the σ determination, a pseudorange error detection failure criterion defined by ICAO is used. First, the σ determination unit 3h calculates the pseudorange error threshold σ ₁ from the detection probability distribution f (σ) and a predetermined reference value. The σ determination unit 3h according to the present embodiment calculates a pseudo-range error threshold σ ₁ that satisfies Formula 4 with a predetermined reference value of 1 × 10 ⁻⁵ . That is, σ is σ ₁ so that the total area of hatched portions in FIG. 6 is 1 × 10 ⁻⁵ .
4 sets

Subsequently, the σ determination unit 3h determines the reliability of each | σ ^t | by comparing each | σ ^t | with σ ₁ . The σ determination unit 3h determines that there is reliability when | σ ^t | <σ ₁ and that there is no reliability when | σ ^t | ≧ σ ₁ .

The radio wave interference determination unit 3i determines whether the received GPS signal is reliable based on the determination result from the C / No determination unit 3f or the σ determination unit 3h, and transmits the determination result to the reinforcement information creator 4 . The radio wave interference determination unit 3i creates reinforcement information when the logical sum in the C / No determination is 0, or when the logical sum in the C / No determination is 1, but satisfies | σ ^t | <σ ₁ in the σ determination. Instruct vessel 4 to send reinforcement information to aircraft 5. On the other hand, if the logical sum is 1 in the C / No determination and satisfies | σ ^t | ≧ σ ₁ in the σ determination, the radio wave interference determination unit 3i transmits the reinforcement information to the aircraft 5 to the reinforcement information creator 4 Instruct not to.

In FIG. 2, the reinforcement information creator 4 transmits a reinforcement information signal to the aircraft 5 when receiving an instruction to transmit the reinforcement information from the radio wave interference determination unit 3i.

The aircraft 5 receives the reinforcement information from the reinforcement information creator 4 and the GPS signal from each GPS satellite 1, and calculates its precise position and altitude information.

[Description of operation]
Next, the operation procedure of the reinforcement information transmission system according to the present embodiment will be described with reference to FIGS.

The GPS satellite group PRN # 1 to PRN # 4 transmits a GPS signal composed of a carrier wave, a distance code, and navigation data to the positioning reference station group 2-1 to 2-4 with a period of ΔT seconds (S1).

Each positioning reference station 2 receives GPS signals from the GPS satellite groups PRN # 1 to PRN # 4 at time t (S2), and transmits a carrier wave, a distance code, and navigation data to the reinforcement information creator 4. Also, with each positioning reference station 2 calculates the ratio C / No ^t of noise during reception and the received signal power power, calculates a pseudo-range error sigma ^t based on Equation 1 (S3), the calculated C / No ^t and σ ^t are transmitted to the radio wave interference detector 3.

The reinforcement information creator 4 receives the carrier wave, distance code, and navigation data transmitted from each positioning reference station (S4), and creates reinforcement information (S5).

The radio wave interference detector 3 receives the C / No ^t and σ ^t transmitted from each positioning reference station 2 by the reception signal input unit 3a (S6), and stores them in the C / No storage unit 3b and the σ storage unit 3c, respectively ( S7). The C / No storage unit 3b and the σ storage unit 3c store data as shown in FIGS. 4A and 4B, respectively.

Next, the interference detector 3 acquires the C / No ^t and ^C / No ^t-ΔT from C / No storage section 3b (S8), the time of C / No based on the two equations in Detect ^t calculating section 3d A change rate PW_Detect ^t is calculated (S9). In order to detect an interference wave generated in a pulse shape, it is desirable to set the difference interval dt small. By setting the difference interval dt to be small, it is possible to grasp the detailed time change of C / No. Therefore, even when an interference wave is generated in a pulse shape, the time change of C / No can be captured. Here, dt = ΔT.

Subsequently, a threshold Thres. (> 0) used by the Thres. Input unit 3e for C / No determination is acquired (S10). Even when there is no radio wave interference, C / No fluctuates by about ± 2.5 dBHz from the average value C / No _∞ ^t, so the threshold Thres. Is preferably about 0.5 dBHz / s. The threshold value Thres. Is preferably input in advance before the detection of radio wave interference.

Then C / No determination unit 3f performs C / No determined using a C / No ^t and PW_Detect ^t (S11). Fig. 9 shows the operation procedure for C / No judgment. First, as shown in Equation 5, Hisuru and C / No, the C / No _∞ ^t -Thres. And ^{_{C / No ∞ t + Thres.}} , The magnitude of (S 111).
5 sets

If Formula 5 is satisfied, 0 is set in the flag (S112), and if not satisfied, 1 is set in the flag (S113). C / No decision is performed for each C / No ^t, 0 or 1 of the flag in each signal is set.

After performing the C / No determination process, the logical sum of the flags set for each signal is calculated (S12).

Next, it is determined whether the calculated logical sum is 0 or 1 (S13). When the logical sum is 0, all the signal flags are 0, so that it is considered that the signal is reliable without receiving radio wave interference. Therefore, the reinforcement information creator 4 is instructed to transmit the reinforcement information to the aircraft 5. On the other hand, when the logical sum is 1, at least one of the 16 signals stored in the C / No storage unit 3b is in a state where the flag “1” is set. Therefore, since there is a possibility of radio wave interference, σ determination is performed by the σ determination unit 3h.

In performing the σ determination, σ ₁ satisfying the four expressions is calculated from the detection probability distribution f (σ) stored in the f (σ) storage unit 3g and a predetermined reference value (S14). The calculated σ ₁ is transmitted to the σ determination unit 3h. Also, σ ^t is acquired from the σ storage unit 3c (S15).

The obtained σ ^t and σ ₁ are compared in size (S16) .If all | σ ^t | is less than σ ₁ , the GPS signal is reliable and the reinforcement information generator 4 sends the reinforcement information to the aircraft 5. Instruct to send. In this case, the operation can be continued without departing from the operation requirements of GBAS. On the other hand, if there is at least one | σ ^t | greater than σ ₁ among the 16 GPS signals that have been subjected to σ ^t determination, it must be subject to radio wave interference and not meet the ICAO pseudorange error detection failure probability criterion Therefore, it is considered that the GPS signal is not reliable. Therefore, the reinforcement information is not transmitted to the aircraft 5.

When the reinforcement information creator 4 receives the reinforcement information transmission instruction after the C / No determination (S17), or when the reinforcement information transmission instruction is received after the σ determination (S18), the reinforcement information creator 4 transmits the reinforcement information to the aircraft 5 (S19). .

[Description of effects]
C / No determination is performed before the created reinforcement information is transmitted to the aircraft 5, and the reliability of the data used for creating the reinforcement information is evaluated. As a result, transmission of reinforcement information created based on the GPS signal subjected to radio wave interference to the aircraft 5 is suppressed, and the aircraft 5 can achieve safer operation. In addition, after performing the C / No determination, reference is made to the pseudorange error detection failure probability criterion by ICAO. Thereby, even if it is determined that there is radio wave interference by the C / No determination, the reinforcement information can be used as long as the pseudorange error detection failure probability criterion is satisfied, and the aircraft 5 can be operated continuously.

When it is determined that there is radio wave interference in the C / No determination, a determination based on the pseudorange error detection failure probability criterion is performed. Thereby, the time required for the determination and the calculation load can be reduced, and the presence or absence of the reliability of the GPS signal can be quickly determined.

In the present embodiment, the threshold value Thres. Is a constant value, but as shown in FIG. 10, the threshold value Thres. (Permitted area) may be set to change over time. As a result, even if the level of safety required for GPS signals changes from moment to moment, it is possible to flexibly respond. The threshold Thres. Is increased during times when the level of safety required for GPS signals, such as when the aircraft 5 performs cruise flight, and the threshold Thres. Is decreased during times when high safety is required, such as during takeoff and landing. It is desirable to do.

In the present embodiment, the example in which the radio wave interference detector 3 is installed on the ground is shown, but it may be on the aircraft 5.

[Second Embodiment]
In the second embodiment, a reinforcement information transmission system for detecting the presence or absence of stationary radio wave interference will be described. The time change of C / No when there is no radio wave interference or when the influence of radio wave interference is removed by some method is shown by a broken line in FIG. On the other hand, the time change of C / No when receiving a steady radio wave interference is shown by a solid line in FIG. In this embodiment, it is assumed that the radio wave interferes with a radio wave having a stationary time of about 40 seconds from t = 430 to 510 seconds.

[Description of configuration]
When calculating Detect, in the first embodiment, Detect was calculated by referring to C / No one cycle before in order to detect a pulse-like change in C / No. In this embodiment, Detect is calculated from C / No several cycles before in order to detect a steady change in C / No. Here, as an example, reference is made to C / No five cycles ago.

In the present embodiment, calculates the Detect ^t based on a different processing from the first embodiment in Detect ^t calculating section 3d. Since the configuration other than the Detect ^t calculation unit 3d is the same as that of the first embodiment, the description thereof is omitted.

Detect ^t calculating section 3d calculates the Detect ^t based on the equation (6 type) of backward difference below. In this embodiment, dt = 5ΔT is used to refer to C / No five cycles before. Detect ^t used for detecting stationary interference waves is particularly denoted as CW_Detect ^t .
6 formulas

[Description of operation]
The radio wave interference detector 3 receives the C / No ^t and σ ^t transmitted from each positioning reference station 2 by the reception signal input unit 3a (S6), and stores them in the C / No storage unit 3b and the σ storage unit 3c, respectively ( S7). Data as shown in FIGS. 4A and 4B is stored in the C / No storage unit 3b and the σ storage unit 3c, respectively. Next, using the C / No ^t and ^{C / No t-5ΔT, Detect} t calculating section 3d calculates the CW_Detect ^t based on the equation (6) (S9).

Subsequently, the threshold Thres. (> 0) used by the Thres. Input unit 3e for C / No determination is acquired (S10), C / No determination is performed by the C / No determination unit 3f, and each signal is set to 0 or 1 The flag is set (S11). After flagging, it calculates a logical sum of the flags in the subject of each C / No ^t (S12). If the logical sum is 0, the reinforcement information creator 4 is instructed to transmit the reinforcement information to the aircraft 5. When the logical sum is 1, σ determination is performed by the σ determination unit 3h (S15). If all | σ ^t | is less than σ _{1 as} a result of the σ determination, it is considered that there is no interference with GBAS operation due to radio wave interference. To send. If at least one | σ ^t | ^{equal to} or greater than σ ₁ exists, the reinforcement information generator 4 is instructed not to transmit the reinforcement information to the aircraft 5 because it does not satisfy the GBAS safety requirements.

When the reinforcement information creator 4 receives the reinforcement information transmission instruction after the C / No determination (S17), or when the reinforcement information transmission instruction is received after the σ determination (S18), the reinforcement information creator 4 transmits the reinforcement information to the aircraft 5 (S19). .

[Description of effects]
By acquiring a long-term change in C / No with reference to C / No five cycles ago, it is possible to detect the presence or absence of steady interference. As a result, it is possible to suppress transmission of the reinforcement information created based on the GPS signal subjected to steady radio wave interference to the aircraft 5.

[Third embodiment]
In the first and second embodiments, Detect ^t is calculated for the purpose of detecting a single interference wave, and the threshold value Thres. Is set. In the present embodiment, it is assumed that both stationary interference waves and pulsed interference waves having different stationary times exist. However, it is assumed that the steady time is a maximum of nΔT seconds.

[Description of configuration]
In the present embodiment calculates the Detect ^t with C / No ^t and ^C / No ^t-iΔT. Here is a ^C / No ^t-iΔT is i cycles before the C / No ^t. In this embodiment Detect ^t calculating section 3d is first to calculate the Detect ^t based on a different processing from the second embodiment. Since the configuration other than the Detect ^t calculation unit 3d is the same as that of the first and second embodiments, the description thereof is omitted.

Detect ^t calculating section 3d calculates the Detect ^t based on equation (7 expression) of backward difference below. It shows the C / No ^t and ^C / No ^t-iΔT especially Detect ^t calculated using the CW (i) _Detect ^t. However, i = 1, 2,..., N.
7 sets

The Thres. Input unit 3e receives an input of the threshold value Thres. When the C / No determination unit 3f performs C / No determination. In the present embodiment, a threshold value Thres._i is set as the threshold value Thres. For each i.

C / No determination unit 3f performs C / No decision for each C / No ^t using CW (i) _Detect ^t and the threshold Thres._I. In this embodiment, C / No determination is performed on 16 × i GPS signals.

[Description of operation]
The radio wave interference detector 3 receives the C / No ^t and σ ^t transmitted from each positioning reference station 2 by the reception signal input unit 3a (S6), and stores them in the C / No storage unit 3b and the σ storage unit 3c, respectively ( S7). The data of FIGS. 4A and 4B are stored in the C / No storage unit 3b and the σ storage unit 3c, respectively.

Then using a C / No ^t and ^{C / No t-iΔT, Detect} t calculating section 3d calculates the CW (i) _Detect ^t from Equation 7 (S9).

Subsequently, the threshold Thres._i (> 0) used by the Thres. Input unit 3e for C / No determination is acquired (S10), and the C / No determination unit 3f performs C / No determination. A flag of 1 is set (S11). After flagging, it calculates a logical sum of the flags in the subject of each C / No ^t (S12). If the logical sum is 0, the reinforcement information creator 4 is instructed to transmit the reinforcement information to the aircraft 5. When the logical sum is 1, σ determination is performed by the σ determination unit 3h (S15). If all | σ ^t | is less than σ _{1 as} a result of the σ determination, it is considered that there is no interference with GBAS operation due to radio wave interference. To send. If there is at least one | σ ^t | greater than or ^{equal to} σ ₁ , the reinforcement information creator 4 is instructed not to transmit the reinforcement information to the aircraft 5.

When the reinforcement information creator 4 receives the reinforcement information transmission instruction after the C / No determination (S17), or when the reinforcement information transmission instruction is received after the σ determination (S18), the reinforcement information creator 4 transmits the reinforcement information to the aircraft 5 (S19). .

[Description of effects]
By performing C / No determination using all C / Nos up to i cycles before, it is possible to detect interference waves having various stationary times including pulses. As a result, it is possible to suppress the reinforcement information created based on the GPS signal that has received radio wave interference from the aircraft 5 from being transmitted.

Here, if there is no radio wave interference, or if the influence of radio wave interference included in the GPS signal is removed by some method, the frequency of interference radio wave appearance for each steady time is acquired, and the threshold Thres._i is set according to the frequency. It is desirable to set. For example, if the frequency of interference radio waves with a steady time of i seconds is high, but the frequency of interference radio waves with a stationary time of m (<n) seconds is low and does not affect the safe operation of GBAS, the threshold Thres Interference waves that affect GBAS operation can be detected with high probability by setting the threshold Thres._i smaller than ._m. As a result, it is possible to suppress transmission of reinforcement information created based on a GPS signal with low reliability to the aircraft 5.

Threshold value Thres._i is not a constant value and may change over time. When the intensity of the interference wave also changes with time, the threshold Thres._i is set in accordance with the dominant interference wave at each time. As a result, interference waves having various standing times that affect GBAS operation are detected with high probability, and transmission of reinforcement information with low reliability is suppressed.

As an application example other than GBAS of the present invention, it is possible to determine whether or not it is possible to transmit the reinforcement information of the GPS signal used when the mobile object is automatically driven. In this case, the cruise and takeoff / landing states of the aircraft correspond to parking and high-speed driving, respectively. When automatic control is performed while a moving object is moving at high speed on an expressway or the like, a serious accident may occur due to a deviation included in the position calculated based on the GPS signal. On the other hand, since the vehicle travels at a low speed when traveling in the city, even if some deviation is included in the position calculated based on the GPS signal, it is unlikely to lead to a serious accident. Therefore, by changing the threshold value Thres. According to the moving speed of the moving body and determining the reliability of the GPS signal, it is possible to suppress transmission of reinforcement information with low reliability to the moving body. As a result, a safer automatic traveling of the moving body can be performed.

The invention of the present application is not limited to the above-described embodiment, and any design change or the like within a range not departing from the gist of the invention is included in the invention. Moreover, although a part or all of said embodiment can be described also as the following additional remarks, it is not restricted to the following.

[Appendix 1]
Means for calculating a signal-to-noise ratio of a GPS signal received at a predetermined period;
Means for creating reinforcement information of the received GPS signal and transmitting it to a moving body;
Means for calculating a time change rate of a signal-to-noise ratio of the received GPS signal;
Means for controlling whether to transmit the reinforcement information to the mobile body based on the rate of time change;
A radio wave interference detection system for satellite positioning, characterized by comprising:

[Appendix 2]
Means for performing a first determination for determining whether the time change rate is included in a predetermined range;
The means according to claim 1, wherein when the rate of time change is not included in the predetermined range, the means capable of creating the reinforcement information and transmitting it to the mobile body does not transmit the reinforcement information to the mobile body. Radio interference detection system for satellite positioning.

[Appendix 3]
Means for receiving a GPS signal at a predetermined period, calculating a pseudorange error of the received GPS signal, means for storing a frequency distribution of the pseudorange error of the GPS signal;
Means for calculating a pseudo-range error threshold from the frequency distribution and a predetermined reference value;
A second determination means for comparing the magnitude of the pseudorange error and the pseudorange error threshold;
Means for performing a process of determining that the received GPS signal is subjected to radio wave interference when the pseudo distance error is equal to or greater than the pseudo distance error threshold;
The radio wave interference detection system for satellite positioning according to appendix 1, further comprising:

[Appendix 4]
5. The satellite positioning radio interference detection system according to appendix 4, wherein the second determination is performed when it is determined in the first determination that the GPS signal is subjected to radio interference.

[Appendix 5]
3. The satellite positioning radio wave interference detection system according to appendix 1 or 2, wherein the predetermined range is a range in which an influence of pulse radio wave interference can be ignored.

[Appendix 6]
The moving body is an aircraft;
6. The radio interference detection system for satellite positioning according to appendix 5, wherein the predetermined range is narrower when taking off and landing of the aircraft than when cruising.

[Appendix 7]
The satellite according to claim 1, further comprising means for calculating the rate of time change based on a signal-to-noise ratio of the received GPS signal and a signal-to-noise ratio of the GPS signal received one period before. Radio interference detection system for positioning.

[Appendix 8]
The satellite according to claim 1, further comprising means for calculating the rate of time change based on a signal-to-noise ratio of the received GPS signal and a signal-to-noise ratio of the GPS signal received a plurality of periods ago. Radio interference detection system for positioning.

[Appendix 9]
The apparatus further includes means for calculating the rate of time change based on the signal-to-noise ratio of the received GPS signal and the signal-to-noise ratio of each GPS signal received up to a plurality of periods ago, respectively. Radio interference detection system for satellite positioning as described.

[Appendix 10]
Calculating a signal-to-noise ratio of a GPS signal received at a predetermined period;
Calculating a time change rate of a signal-to-noise ratio of the received GPS signal using a signal-to-noise ratio of the received GPS signal;
Performing a first determination to determine whether the time change rate is included in a predetermined range;
A radio wave interference detection method for satellite positioning, comprising: instructing to stop transmission of reinforcement information of the received GPS signal when the time change rate is not included in the predetermined range.

The present invention can be widely applied to GBAS, an automatic traveling system for moving objects, and the like that calculate position information using GPS signals.

This application claims priority based on Japanese Patent Application No. 2014-036092 filed on February 27, 2014, the entire disclosure of which is incorporated herein.

1 GPS satellite 2 Positioning reference station 3 Radio interference detector 3a Received signal input unit 3b C / No storage unit 3c σ storage unit 3d Detect ^t calculation unit 3e Thres. Input unit 3f C / No determination unit 3g f (σ) storage unit 3h σ determination unit 3i Radio interference determination unit 4 Reinforcement information generator 5 Aircraft 10 Reinforcement information transmission system 20 Reinforcement information generation unit 30 Radio interference detection mechanism for satellite positioning 31 Signal-to-noise ratio acquisition unit 32 Change rate calculation unit 33 Determination unit 40 Control means

Claims (10)

1. A signal-to-noise ratio acquisition means for acquiring a signal-to-noise ratio of the received GPS signal;
   A rate-of-change calculating means for calculating a rate of time change within a predetermined time of the acquired signal-to-noise ratio;
   Determination means for determining the presence or absence of radio wave interference to the received GPS signal based on the calculated rate of time change,
   A radio wave interference detection mechanism for satellite positioning.
2. The radio interference detection mechanism for satellite positioning according to claim 1, wherein the predetermined time is shorter than a pulse width of the pulsed radio wave.
3. 2. The radio interference detection mechanism for satellite positioning according to claim 1, wherein the predetermined time is a length capable of detecting a stationary radio wave that interferes with the GPS signal.
4. The determination means determines that there is no radio wave interference to the GPS signal when the calculated time change rate is included in a predetermined range, and the calculated time change rate is not included in the predetermined range. The radio interference detection mechanism for satellite positioning according to any one of claims 1 to 3, wherein it is determined that there is radio wave interference to a GPS signal.
5. Reinforcement information generating means for generating reinforcement information using the received GPS signal;
   A radio wave interference detection mechanism for satellite positioning according to claim 4,
   When it is determined that there is no radio wave interference, the generated reinforcement information is transmitted to the mobile body, and when it is determined that there is radio wave interference, the control means that does not transmit the generated reinforcement information;
   A reinforcement information transmission system comprising:
6. A pseudorange error calculating means for calculating a pseudorange error σ using the received GPS signal;
   The control means further determines whether or not the calculated pseudorange error σ satisfies the pseudorange error detection failure probability criterion when it is determined that there is radio wave interference, and if generated, the generated pseudorange error σ Send reinforcement information to the mobile,
   The reinforcement information transmission system according to claim 5.
7. Σ threshold calculation means for calculating the pseudo distance error threshold σ ′ based on the frequency distribution of the pseudo distance error σ of the GPS signal when there is no radio wave interference and a predetermined reference value,
   The control means determines that the pseudorange error detection failure probability criterion is satisfied when | σ | <σ ′, and determines that the pseudorange error detection failure probability criterion is not satisfied when | σ | ≧ σ ′. To
   The reinforcement information transmission system according to claim 6.
8. The moving body is an aircraft;
   The predetermined range applied in the determination means at the time of takeoff and landing of the aircraft is set narrower than the predetermined range applied at the time of cruise of the aircraft.
   The reinforcement information transmission system according to any one of claims 5 to 7.
9. The reinforcement information transmission system according to claim 5, further comprising reception means for receiving the GPS signal.
10. Get the signal-to-noise ratio of the received GPS signal,
    Calculating a rate of time change within a predetermined time of the acquired signal-to-noise ratio;
    When the calculated time change rate is included in the predetermined range, it is determined that there is no radio wave interference to the GPS signal, and when the calculated time change rate is not included in the predetermined range, the GPS signal is determined. To determine that there is radio interference
    Radio interference detection method for satellite positioning.

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