GNSS receiver, reception method, and information processing terminal

Abstract

The present technology relates to: a GNSS receiver capable of continuously detecting an interference wave for a satellite signal even after a reception setting has been switched; a reception method; and an information processing terminal. A GNSS receiver according to one aspect of the present technology comprises: a first signal processing unit that receives satellite signals from a plurality of satellite systems and uses a variable-bandwidth IF filter to output a signal within a prescribed IF signal frequency band; and a second signal processing unit that, with respect to the signal output by the first signal processing unit, performs frequency conversion based on an oscillation signal generated by an oscillator having a variable oscillation frequency, and generates a baseband signal. An interference wave for a satellite signal is detected on the basis of the signal which has passed the IF filter, and after a reception setting is switched from a first setting used when there is no interference wave to a second setting used when there is an interference wave, the reception setting is temporarily returned to the first setting to detect an interference wave. The present technology can be applied to mobile devices such as smartphones.

Description

GNSS receiver, receiving method, and information processing terminal

[0001] The present technology relates to a GNSS receiver, a receiving method, and an information processing terminal, and in particular to a GNSS receiver, a receiving method, and an information processing terminal that are capable of continuing to detect interference waves against satellite signals even after switching reception settings.

[0002] The satellite signals received by GNSS (Global Navigation Satellite System) receivers installed in mobile devices such as smartphones are weaker (approximately -120 to 160 dBm) than signals from other wireless systems such as LTE. Therefore, if the transmitted waves of the wireless system interfere with the satellite signal band, or if unwanted radiation generated inside or outside the device interferes with the satellite signal band, the C / N0 of the satellite signal drops, degrading the positioning accuracy and rate.

[0003] In conventional GNSS receivers, when high-level interference waves are detected, the gain of the RF (high frequency) and IF (intermediate frequency) amplifiers in the RFFE (RF Front End) is reduced to prevent saturation of the ADC (Analog to Digital Converter).In addition, when the interference waves are narrowband electromagnetic waves such as CW (Continuous Wave), a notch filter is used to remove the interference waves within the receiving circuit.

[0004] Special Publication No. 2012-526460

[0005] In addition to interference caused by radio system transmission waves and unwanted radiation, there is also interference from signals sent with the purpose of intentionally disrupting the positioning of specific or unspecified GNSS receivers. As interference with satellite signals becomes more diverse, measures to combat these various types of interference are required.

[0006] The present technology has been developed in light of these circumstances, and makes it possible to continue detecting interference waves against satellite signals even after switching reception settings.

[0007] According to one aspect of the present technology, a GNSS receiver includes: a first signal processing unit that receives satellite signals from a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency to generate a baseband signal used for demodulating a navigation message; and a detection unit that detects interference with the satellite signal based on the signal after passing through the IF filter and switches reception settings including settings of the filter band and the oscillation frequency according to a state of the interference signal. The detection unit switches the reception setting from a first setting used when the interference signal is not present to a second setting used when the interference signal is present, and then temporarily switches the reception setting back to the first setting to detect the interference signal.

[0008] In one aspect of the present technology, interference with the satellite signal is detected based on the signal after passing through the IF filter, and a reception setting including the settings of the filter band and the oscillation frequency is switched according to the state of the interference. After the reception setting is switched from a first setting used when the interference signal is not present to a second setting used when the interference signal is present, the reception setting is temporarily returned to the first setting and the interference signal is detected.

[0009] FIG. 1 is a diagram illustrating a general configuration example of a GNSS receiver. FIG. 2 is a diagram illustrating frequency bands allocated to each satellite system. FIG. 3 is a diagram illustrating a general configuration example of a GNSS receiver compatible with the L1 band and the L5 band. FIG. 4 is a diagram illustrating an example of the relationship between the gain used in the AGC of the RFFE and the C / N0 of a satellite signal. FIG. 5 is a diagram illustrating a configuration example of a GNSS receiver. FIG. 6 is a diagram illustrating an example of the configuration of a GNSS receiver according to an embodiment of the present technology. FIG. 7 is a flowchart illustrating a flow of satellite signal reception processing illustrating an example of reception settings. FIG. 8 is a diagram illustrating an example of measurement of the C / N0 of a received signal and the acquisition state of ephemeris. FIG. 9 is a diagram illustrating another example of measurement of the C / N0 of a received signal and the acquisition state of ephemeris. FIG. 10 is a diagram illustrating an example of reception settings. FIG. 11 is a block diagram illustrating an example of the configuration of an information processing terminal.

[0010] Hereinafter, embodiments of the present technology will be described in the following order: 1. General configuration of a GNSS receiver 2. Overview of the present technology 3. GNSS receiver according to an embodiment of the present technology 4. Modified example

[0011] <<General Configuration of a GNSS Receiver>> <GNSS Receiver Compatible with L1 Band>> FIG. 1 is a diagram showing an example of a general configuration of a GNSS receiver.

[0012] The GNSS receiver 1 shown in Fig. 1 is a GNSS module compatible with the L1 band. At least part of the configuration shown in Fig. 1 is implemented on a single IC chip. The GNSS receiver 1 is installed in various information processing terminals, such as mobile devices such as smartphones and IoT devices for monitoring elderly people.

[0013] 1, the GNSS receiver 1 is composed of an antenna 11, an RF signal processing unit 12, a digital signal processing unit 13, acquisition and tracking units 14A to 14C, a CPU 15, and an I / O unit 16. The antenna 11 receives satellite signals in the L1 band. An RF signal is input from the antenna 11 to the RF signal processing unit 12.

[0014] FIG. 2 is a diagram showing frequency bands allocated to each satellite system.

[0015] As shown in Figure 2, the L1 band satellite systems GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C are allocated a frequency band with a center frequency of 1575.42 MHz. GPS / GAL in Figure 2 omits GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C. This is the same for other figures.

[0016] GLONASS L1, another L1-band satellite system, is assigned a frequency band centered at 1602 MHz, while BeiDou B1I is assigned a frequency band centered at 1561.098 MHz. The GNSS receiver 1 in Figure 1 receives satellite signals from all L1-band satellite systems and demodulates the navigation messages transmitted by each satellite system. The GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C satellite systems, the GLONASS L1 satellite system, and the BeiDou B1I satellite system are satellite systems that each use a different frequency band in the L1 band.

[0017] The RF signal processing unit 12 serving as an RFFE (RF Front End) is configured with an LNA (Low Noise Amplifier) ​​31, multipliers 32-1 and 32-2, a PLL (Phase Locked Loop) 33, LPFs (Low Pass Filters) 34-1 and 34-2, amplifiers 35-1 and 35-2, ADCs (Analog Digital Converters) 36-1 and 36-2, and a level detection unit 37. The level detection unit 37 may be provided outside the RF signal processing unit 12.

[0018] The LNA 31 amplifies and outputs the RF signal supplied from the antenna 11. The RF signal output from the LNA 31 is supplied to multipliers 32-1 and 32-2.

[0019] The multipliers 32-1 and 32-2 down-convert the RF signal by multiplying the RF signal supplied from the LNA 31 by the oscillation signal supplied from the PLL 33. The IF signal (I-phase component) generated in the multiplier 32-1 is supplied to the LPF 34-1, and the IF signal (Q-phase component) generated in the multiplier 32-2 is supplied to the LPF 34-2.

[0020] The PLL 33 generates an oscillation signal based on a reference clock signal generated by an internal oscillator. The PLL 33 generates a signal with an oscillation frequency LO1 corresponding to GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I, for example, a 1584 MHz signal. The oscillation signal generated by the PLL 33 is supplied to multipliers 32-1 and 32-2.

[0021] The LPF 34-1 passes the signal in a predetermined frequency band of the IF signal supplied from the multiplier 32-1 and outputs it to the amplifier 35-1. The LPF 34-2 passes the signal in a predetermined frequency band of the IF signal supplied from the multiplier 32-2 and outputs it to the amplifier 35-2.

[0022] The amplifier 35-1 amplifies the signal supplied from the LPF 34-1 and outputs the amplified signal to the ADC 36-1. The amplifier 35-2 amplifies the signal supplied from the LPF 34-2 and outputs the amplified signal to the ADC 36-2. The gains of the amplifiers 35-1 and 35-2 are controlled by a level detection unit 37.

[0023] The ADC 36-1 performs A / D conversion on the signal supplied from the amplifier 35-1 and outputs the A / D converted digital signal. The ADC 36-2 performs A / D conversion on the signal supplied from the amplifier 35-2 and outputs the A / D converted digital signal. The digital signals output from the ADCs 36-1 and 36-2 are supplied to the level detection unit 37 and the digital signal processing unit 13 at the subsequent stage.

[0024] The level detector 37 detects the levels of the digital signals output by the ADCs 36-1 and 36-2 and adjusts the gains of the LNA 31, amplifiers 35-1, and amplifiers 35-2 according to the levels of the digital signals so that the inputs of the ADCs 36-1 and 36-2 are not saturated.

[0025] The digital signal processing unit 13 serving as a DFE (Digital Front End) is made up of signal processing units 13A, 13B, and 13C. The signal processing unit 13A is a signal processing unit compatible with GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, and the signal processing unit 13B is a signal processing unit compatible with GLONASS L1. The signal processing unit 13C is a signal processing unit compatible with BeiDou B1I. The digital signals output from the ADCs 36-1 and 36-2 of the RF signal processing unit 12 are input to the signal processing units 13A, 13B, and 13C, respectively.

[0026] The signal processing unit 13A is made up of multipliers 51-1 and 51-2, an NCO (Numerical Controlled Oscillator) 52, decimation circuits 53-1 and 53-2, a noise filter 54, and a baseband AGC (Automatic Gain Control) 55.

[0027] The multiplier 51-1 performs frequency conversion by multiplying the digital signal of the I-phase component supplied from the ADC 36-1 of the RF signal processing unit 12 by the oscillation signal supplied from the NCO 52. The multiplier 51-2 performs frequency conversion by multiplying the digital signal of the Q-phase component supplied from the ADC 36-2 of the RF signal processing unit 12 by the oscillation signal supplied from the NCO 52. The baseband signal generated by the multiplier 51-1 through frequency conversion is supplied to a decimation unit 53-1, and the baseband signal generated by the multiplier 51-2 is supplied to a decimation unit 53-2.

[0028] The NCO 52 generates an oscillation signal of a predetermined frequency and outputs it to the multipliers 51-1 and 51-2. In the NCO 52 of the signal processing unit 13A, a signal of an oscillation frequency LO2 corresponding to GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C is generated, which has a frequency according to an offset from the oscillation frequency LO1 generated by the PLL 33.

[0029] The decimation 53-1 performs band limitation using an LPF and thinning processing to lower the sampling frequency on the baseband signal supplied from the multiplier 51-1, and outputs the processed baseband signal to the noise filter 54. The decimation 53-2 performs band limitation and thinning processing on the baseband signal supplied from the multiplier 51-2, and outputs the processed baseband signal to the noise filter 54.

[0030] The noise filter 54 removes noise from the baseband signals supplied from the decimation 53 - 1 and decimation 53 - 2 , and outputs the noise-removed baseband signals to the baseband AGC 55 .

[0031] The baseband AGC 55 adjusts the gain of the baseband signal supplied from the noise filter 54, and outputs the gain-adjusted baseband signal to the acquisition and tracking unit 14A.

[0032] The acquisition and tracking unit 14A performs synchronous acquisition (acquisition), which acquires the leading timing of the spreading code of the satellite signal included in the baseband signal supplied from the baseband AGC 55, and synchronous tracking (tracking), which tracks the phase of the spreading code of the acquired satellite signal and the phase change of the carrier wave. For example, in synchronous acquisition, the acquisition and tracking unit 14A detects the leading timing of the spreading code used to transmit the navigation message based on the correlation between the baseband signal and the spreading code. In synchronous tracking, the acquisition and tracking unit 14A uses the leading timing of the spreading code of the satellite signal detected in synchronous acquisition as the initial phase of the spreading code, and tracks the code phase change using a delay lock loop (DLL) or the like, while simultaneously tracking the carrier phase using a digital PLL or the like. In addition, the acquisition and tracking unit 14A detects information such as the type of spreading code, the phase of the spreading code, the carrier frequency, and the satellite identification information. The acquisition and tracking unit 14A performs demodulation processing, including spectrum despreading and demodulation, on the baseband signal based on the phase of the spreading code, the carrier frequency, etc., to obtain the navigation message. The GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C navigation message demodulated by the acquisition and tracking unit 14A is output to the CPU 15.

[0033] Signal processing units 13B and 13C also have a configuration similar to that of signal processing unit 13A. Furthermore, acquisition and tracking unit 14B, which is provided after signal processing unit 13B, and acquisition and tracking unit 14C, which is provided after signal processing unit 13C, each have the same functions as acquisition and tracking unit 14A. Descriptions that overlap with those described above will be omitted as appropriate. The same applies to the descriptions in and after FIG. 2.

[0034] The NCO 52 of the signal processing unit 13B generates a signal with an oscillation frequency LO3 corresponding to GLONASS L1, which has a frequency corresponding to the offset from the oscillation frequency LO1 generated by the PLL 33. The signal with the oscillation frequency LO3 is used to generate a baseband signal, and the same processing as that described above is performed on the baseband signal in each section of the signal processing unit 13B. The acquisition and tracking unit 14B demodulates the GLONASS L1 navigation message based on the baseband signal supplied from the signal processing unit 13B, and outputs the demodulated message to the CPU 15.

[0035] The NCO 52 of the signal processing unit 13C generates a signal with an oscillation frequency LO4 corresponding to BeiDou B1I, the signal having a frequency corresponding to the offset from the oscillation frequency LO1 generated by the PLL 33. The signal with the oscillation frequency LO4 is used to generate a baseband signal, and the same processing as that described above is performed on the baseband signal in each section of the signal processing unit 13C. The acquisition and tracking unit 14C demodulates the BeiDou B1I navigation message based on the baseband signal supplied from the signal processing unit 13C, and outputs the demodulated signal to the CPU 15.

[0036] The CPU 15 performs positioning calculations based on the information supplied from the acquisition and tracking units 14A, 14B, and 14C. The position information obtained by the positioning calculations is supplied to a processing unit external to the GNSS receiver 1 via the I / O 16.

[0037] <GNSS receiver compatible with L1 band + L5 band> Figure 3 shows a typical configuration example of a GNSS receiver compatible with the L1 band and L5 band. In recent years, GNSS receivers that support the L5 band (center frequency: 1176.45 MHz) in addition to the L1 band have become popular.

[0038] 3, the same components as those described above are denoted by the same reference numerals. An antenna 11A and an RF signal processing unit 12A correspond to the antenna 11 and RF signal processing unit 12 in FIG.

[0039] The antenna 11B receives satellite signals in the L5 band transmitted by GNSS satellites such as GPS, GALILEO, QZSS, and BeiDou. RF signals are input from the antenna 11B to the RF signal processing unit 12B.

[0040] In the RF signal processing unit 12B, down-conversion is performed using a signal with an oscillation frequency LO5 corresponding to the L5 band satellite signal generated by the PLL 33, and the IF signal is supplied to the signal processing unit 13D of the digital signal processing unit 13.

[0041] The signal processing unit 13D has a configuration similar to that of the signal processing unit 13A, etc. The NCO 52 of the signal processing unit 13D generates a signal with an oscillation frequency LO6 corresponding to the L5 band satellite signal. The signal with the oscillation frequency LO6 is used to generate a baseband signal, and the same processing as that described above is performed on the baseband signal in each section of the signal processing unit 13D. The acquisition and tracking unit 14D demodulates the L5 band GPS / GALILEO / QZSS / BeiDou navigation message based on the signal supplied from the signal processing unit 13D and outputs the demodulated message to the CPU 15.

[0042] <Influence of Interference Waves> A GNSS receiver configured as described above requires measures to prevent interference waves. Interference waves exist within the frequency band of the satellite signal or in frequency bands adjacent to the frequency band of the satellite signal, and include various interference components and electromagnetic waves that cause degradation of satellite signal characteristics, such as degradation of C / N0. Interference waves that interfere with satellite signals include various electromagnetic waves that interfere with or disrupt satellite signals. An effective measure to remove or reduce the influence of interference waves is to use an analog filter in front of the ADC in the RFFE (RF signal processing unit 12) to block interference waves.

[0043] The L5 band is a single continuous frequency band, so to eliminate interference signals in the L5 band, a single filter can be used with a passband that covers a single frequency band (e.g., 1176.45 MHz ±10 MHz) and a stopband that covers all other frequency bands.

[0044] In contrast, the L1 band includes three frequency bands: GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band, GLONASS L1 frequency band, and BeiDou B1I frequency band. The three frequency bands are distributed within a bandwidth of approximately 50 MHz. If one wideband filter is used to receive satellite signals from all satellite systems in the L1 band, interference signals for the L1 band will pass through the filter and be input to the ADC unattenuated.

[0045] It is possible to remove the interference signal using a digital filter in the DFE (digital signal processing unit 13), but in this case, it is necessary to reduce the AGC gain so that the signal level input to the ADC of the RFFE does not saturate. Also, to remove the interference signal using a digital filter, the number of bits in the ADC and DFE must be increased.

[0046] 4 is a diagram showing an example of the relationship between the gain used in the AGC of the RFFE and the C / N0 of the satellite signal, where the horizontal axis represents the gain used in the AGC and the vertical axis represents the C / N0 of the satellite signal.

[0047] An example of changes in the C / N0 of satellite signals for GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C is shown in Figure 4. For example, if there is a strong jamming wave within the frequency band of the satellite signal and the AGC gain is lowered to prevent the signal level at the ADC input from saturating, the C / N0 of the satellite signal will deteriorate as shown in Figure 4.

[0048] On the other hand, if a filter whose passband is the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I is used, three signal paths for frequency conversion, filtering, and ADC must be provided in the RFFE, as shown in Fig. 5. Signal processing unit 61A, signal processing unit 61B, and signal processing unit 61C of RF signal processing unit 12 shown in Fig. 5 constitute signal paths for frequency conversion, filtering, and ADC, respectively.

[0049] The adoption of the configuration shown in FIG. 5 is not preferable from the viewpoint of circuit size and power consumption in IoT products and the like that require low cost and low power operation.

[0050] <<Outline of the Present Technology>> A GNSS receiver according to an embodiment of the present technology is a receiver compatible with the L1 band. The GNSS receiver has the following configuration.

[0051] <Configuration 1> The receiver settings, including the IF filter bandwidth setting and the local frequency setting of the oscillator signal used to generate the baseband signal, are dynamically variable. The presence or absence of jamming signals within the IF filter bandwidth and in nearby frequency bands is detected based on the FFT results for signals that pass through the IF filter. The receiver settings used in a steady state when no jamming signals are present are a first setting, which includes a wide filter bandwidth that includes the frequency bands of all L1-band satellite signals (GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I) in its passband, and local frequencies (LO frequencies) corresponding to each satellite system. Jamming signals are detected periodically or aperiodically. The receiver settings used when jamming signals are present are a second setting, which includes a narrow filter bandwidth to attenuate jamming signals and LO frequencies corresponding to the satellite systems included in the passband. After the receiver settings are switched from the first setting to the second setting, jamming signals are detected by temporarily returning the receiver settings to the first setting. If the interference continues to exist, the second setting continues to be used. If the interference disappears, the receiving setting is returned to the first setting. The above series of operations continues.

[0052] <Configuration 2> The FFT execution period is variable. The FFT execution period when there is no jamming signal is set to a period shorter than the execution period when there is jamming signal. The FFT execution period during a cold start when there is jamming signal is set to a long period (first execution period) until a navigation message is acquired and positioning becomes possible. After positioning becomes possible, the FFT execution period is set to a period (second execution period) shorter than the first execution period.

[0053] <Configuration 3> When there is interference in a frequency band higher than the frequency band of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, a reception setting (second setting) is used that includes the filter band setting of the IF filter, which includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I in the passband and has a frequency band higher than the frequency band of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C as the stopband.

[0054] <Configuration 4> When interference is present in a frequency band lower than the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band, a reception setting (second setting) is used that includes an IF filter band setting that includes the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 frequency bands in the passband and has a frequency band lower than the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band as the stopband.

[0055] <Configuration 5> When interference signals are present in both higher and lower frequency bands than the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band, a reception setting (second setting) is used that includes an IF filter band setting that includes the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band in the passband and sets the rest as the stopband.

[0056] <Configuration 6> When interference is present in the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency bands, a reception setting (second setting) is used that includes a filter band setting for the IF filter that includes the GLONASS L1 or BeiDou B1I frequency band in the passband and sets the rest as the stopband.

[0057] <<GNSS Receiver According to an Embodiment of the Present Technology>> <Configuration of GNSS Receiver> Fig. 6 is a diagram showing an example configuration of a GNSS receiver according to an embodiment of the present technology. Of the configuration shown in Fig. 6, the same components as those shown in Fig. 1 are assigned the same reference numerals. Duplicate descriptions will be omitted as appropriate.

[0058] 6, the oscillation frequency LO1 of the oscillator provided in the PLL 33 of the RF signal processing unit 12 and the filter bandwidths of the LPFs 34-1 and 34-2 are variable. By changing the oscillation frequency LO1 and the filter bandwidths of the LPFs 34-1 and 34-2, the frequency band of the IF signal output to the subsequent stage is switched.

[0059] The multipliers 32-1, 32-2, PLL 33, LPFs 34-1, and 34-2 generate IF signals by performing frequency conversion on the satellite signals and function as IF filters that pass signals in a predetermined frequency band. The RF signal processing unit 12 functions as a first signal processing unit that receives satellite signals from multiple satellite systems in the L1 band and outputs signals in a predetermined frequency band of the IF signals using IF filters.

[0060] Furthermore, in the GNSS receiver 101, the oscillation frequencies LO2, LO3, and LO4 of the NCOs 52, which are oscillators provided in each of the signal processing units 13A, 13B, and 13C of the digital signal processing unit 13, are variable. The oscillation signals of the oscillation frequencies LO2, LO3, and LO4 are signals used to generate baseband signals of satellite signals to be received. The digital signal processing unit 13 performs frequency conversion on the signals output by the RF signal processing unit 12 based on the oscillation signals generated by the NCOs 52, whose oscillation frequency is variable, and functions as a second signal processing unit that generates baseband signals used to demodulate navigation messages.

[0061] In this way, in the GNSS receiver 101, reception settings including the filter band of the IF filter and the setting of the oscillation frequency of the oscillation signal used to generate the baseband signal are variable.

[0062] The configuration of the GNSS receiver 101 shown in Fig. 6 differs from the configuration of the GNSS receiver 1 shown in Fig. 1 in that it is provided with an FFT calculation unit 111 and an interference wave detection unit 112. The digital signals output from the ADCs 36-1 and 36-2 of the RF signal processing unit 12 are supplied to the FFT calculation unit 111.

[0063] The FFT calculation unit 111 performs FFT on the digital signals output from the ADC 36 - 1 and the ADC 36 - 2 , and outputs information indicating the results of the FFT to the interference wave detection unit 112 .

[0064] The interference detector 112 detects the presence or absence of interference based on the FFT result from the FFT calculator 111, and changes the reception settings according to the state of the interference. Specifically, the interference detector 112 outputs information indicating the oscillation frequency LO1 to the PLL 33, and outputs information indicating the filter bandwidth to the LPFs 34-1 and 34-2. The filter bandwidths of the LPFs 34-1 and 34-2 are specified by, for example, the cutoff frequency fc. The interference detector 112 also outputs information indicating the oscillation frequencies LO2, LO3, and LO4 to the NCOs 52 of the signal processors 13A, 13B, and 13C.

[0065] In this way, the GNSS receiver 101 has an FFT function that can observe the spectrum of the ADC output of the RF signal processing unit 12, and a function that can dynamically change the filter band of the IF filter and the LO frequency of the NCO 52.

[0066] <Examples of Reception Settings (for Configurations 1, 3, and 4)> Fig. 7 is a diagram showing examples of reception settings. The horizontal axes of A to C in Fig. 7 represent frequency.

[0067] Steady-State Setting Example: Figure 7A shows an example of reception settings in a steady state where there is no interference. In the steady state, as shown in Figure 7A, the center frequency (oscillation frequency LO1) of the IF filter band is set to 1584 MHz, and the cutoff frequency fc = 26 MHz is set as the bandwidth. Furthermore, the oscillation frequencies LO2, LO3, and LO4 of the NCOs 52 of the signal processing units 13A, 13B, and 13C are set to 8.58 MHz, -18 MHz, and 22.902 MHz, respectively. The oscillation frequencies of the NCOs 52 are expressed as offsets from the oscillation frequency LO1.

[0068] The filter band of the IF filter shown in A of Figure 7 is a wide filter band that includes the frequency bands of all L1-band satellite systems, including GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I, in its passband. Furthermore, by setting the oscillation frequencies LO2, LO3, and LO4, baseband signals of the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I satellite signals are generated.

[0069] - Example of settings when there is interference above GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C Figure 7B shows an example of reception settings when there is interference above GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C. Above GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C means a frequency band higher than the frequency band of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C.

[0070] In this case, as shown in Fig. 7B, the center frequency (oscillation frequency LO1) of the filter band of the IF filter is set to 1568 MHz, and the cutoff frequency fc = 10 MHz is set as the bandwidth. Furthermore, -7.42 MHz and 6.902 MHz are set as the oscillation frequencies LO2 and LO4 of the NCOs 52 of the signal processing units 13A and 13C, respectively. For example, the oscillation frequency LO3 is not set, and processing in the signal processing unit 13B is stopped.

[0071] The filter band of the IF filter shown in Figure 7B is a filter band that includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I in its passband. In addition, by setting the oscillation frequencies LO2 and LO4, baseband signals of the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I satellite signals are generated.

[0072] - Example of settings when there is interference below GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C Figure 7C shows an example of reception settings when there is interference below GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C. Below GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C means a frequency band lower than the frequency band of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C.

[0073] In this case, as shown in Fig. 7C, the center frequency (oscillation frequency LO1) of the filter band of the IF filter is set to 1591 MHz, and the cutoff frequency fc = 19 MHz is set as the bandwidth. Furthermore, the oscillation frequencies LO2 and LO3 of the NCOs 52 of the signal processing units 13A and 13B are set to 15.58 MHz and -11 MHz, respectively. For example, the oscillation frequency LO4 is not set, and processing in the signal processing unit 13C is stopped.

[0074] The filter band of the IF filter shown in Fig. 7C is a filter band that includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 in its passband. Furthermore, by setting the oscillation frequencies LO2 and LO3, baseband signals of the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 satellite signals are generated.

[0075] In this way, when there is an interference wave, the IF filter is set to a narrow filter band so that the frequency band of the interference wave is included in the stopband. This attenuates the interference wave signal and prevents the AGC from operating to lower the gain. If an interference wave is present within the filter band of the IF filter, the AGC will operate to lower the gain due to the interference wave signal, which would degrade the C / N0 ratio, but this can be avoided.

[0076] When a narrow filter bandwidth is set so that the frequency band of the jamming signal is included in the stopband, degradation of the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I satellite signals, or the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 satellite signals, can be avoided, and positioning can be performed based on these satellite signals. Using the setting B in Figure 7 makes it impossible to receive the GLONASS L1 satellite signal, and using the setting C in Figure 7 makes it impossible to receive the BeiDou B1I satellite signal. However, because the number of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C satellites is greater than the number of GLONASS L1 and BeiDou B1I satellites (Figure 2), the impact of not being able to receive the GLONASS L1 or BeiDou B1I satellite signals on positioning is limited.

[0077] Hereinafter, the reception setting shown in A of Figure 7, which uses a filter band that includes the frequency bands of all L1-band satellite systems (GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I) in its passband, will be referred to as the GPS / GAL+GLONASS+BeiDou reception setting. The reception setting shown in B of Figure 7, which uses a filter band that includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I in its passband, will be referred to as the GPS / GAL+BeiDou reception setting. The reception setting shown in C of Figure 7, which uses a filter band that includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 in its passband, will be referred to as the GPS / GAL+GLONASS reception setting. When there is no interference, the first setting, GPS / GAL + GLONASS + BeiDou reception setting, is used, and when there is interference, the second setting, GPS / GAL + BeiDou reception setting or GPS / GAL + GLONASS reception setting, is used.

[0078] Reception process flow Although the impact is limited, it is preferable to receive GLONASS L1 and BeiDou B1I satellite signals once the interference disappears. The GNSS receiver 101 repeatedly detects interference signals periodically or aperiodically, and once the interference disappears, the reception setting is restored to the GPS / GAL + GLONASS + BeiDou reception setting.

[0079] That is, when reception processing is being performed using the GPS / GAL+BeiDou reception setting or the GPS / GAL+GLONASS reception setting, the FFT calculation unit 111 repeatedly performs FFT to detect whether interference has disappeared. The interference detection unit 112 detects the presence or absence of interference based on the FFT results and switches the reception setting appropriately depending on the state of the interference. When interference has disappeared, the reception setting is switched from the GPS / GAL+BeiDou reception setting or the GPS / GAL+GLONASS reception setting to the GPS / GAL+GLONASS+BeiDou reception setting. On the other hand, when interference continues to exist, the GPS / GAL+BeiDou reception setting or the GPS / GAL+GLONASS reception setting continues to be used.

[0080] When reception processing is being performed using the GPS / GAL+BeiDou reception setting or the GPS / GAL+GLONASS reception setting, the FFT is performed with the reception setting temporarily returned to the GPS / GAL+GLONASS+BeiDou reception setting for a short period of time, such as a few milliseconds. While the reception setting is returned to the GPS / GAL+GLONASS+BeiDou reception setting, any interference waves will be affected, but if it is for only a few milliseconds, the effect on the C / N0 can be suppressed. While the reception setting is returned to the GPS / GAL+GLONASS+BeiDou reception setting, the digital signal may be blanked (processing stopped) in the digital signal processing unit 13 to suppress the effect.

[0081] FIG. 8 is a diagram showing the flow of satellite signal reception processing.

[0082] In step S1, initial settings are performed, and the settings of the RF signal processing unit 12 and the digital signal processing unit 13 are initialized.

[0083] In step S2, the interference wave detection unit 112 sets the GPS / GAL+GLONASS+BeiDou reception setting. Processing is performed in the RF signal processing unit 12 using an IF filter whose passband includes the frequency bands of all satellite systems in the L1 band. Furthermore, in the signal processing units 13A, 13B, and 13C, baseband signals for each of the satellite systems GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, GLONASS L1, and BeiDou B1I are generated based on the digital signal output by the RF signal processing unit 12.

[0084] In step S3, the level detection unit 37 detects the levels of the digital signals output by the ADCs 36-1 and 36-2.

[0085] In step S4, the level detector 37 adjusts the gain (RF gain) of the LNA 31 and the amplifiers 35-1 and 35-2 in accordance with the level of the digital signal.

[0086] In step S5, the FFT calculation unit 111 performs FFT on the digital signals output from the ADC 36-1 and ADC 36-2.

[0087] In step S6, the interference wave detector 112 detects the presence or absence of interference waves based on the FFT result, and checks the state of interference waves.

[0088] If it is confirmed in step S6 that there is no interference wave, the interference wave detection unit 112 sets a detection period for detecting the presence or absence of interference waves, i.e., an FFT execution period, in step S7. Information indicating the FFT execution period is supplied to the FFT calculation unit 111. In this way, the FFT execution period is appropriately switched by the interference wave detection unit 112 depending on the state of interference waves. For example, in a steady state where there is no interference wave, a short period such as a 3-second period is set. After the FFT execution period has been set, the processing from step S2 onwards is repeated when it is time to execute the FFT.

[0089] On the other hand, if it is confirmed in step S6 that there is an interference signal above GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, in step S8, the interference signal detection unit 112 sets the GPS / GAL+BeiDou reception setting. Processing is performed in the RF signal processing unit 12 using an IF filter whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I. Furthermore, in signal processing units 13A and 13C, baseband signals of the respective satellite systems, GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I, are generated based on the digital signal output by the RF signal processing unit 12.

[0090] The processes in steps S9 and S10 are similar to those in steps S3 and S4. The levels of the digital signals output by the ADCs 36-1 and 36-2 are detected in step S9, and the RF gain is adjusted in step S10.

[0091] After the gain is adjusted in step S10, the interference detector 112 sets the FFT execution period in step S7 when an interference signal is present. For example, when an interference signal is present, a period longer than the period in the steady state, such as a 12-second period, is set. After the FFT execution period is set, the processing from step S2 onward is repeated when the timing for FFT execution arrives.

[0092] If it is determined in step S6 that there is an interference signal below GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, the interference signal detection unit 112 sets the GPS / GAL+GLONASS reception setting in step S11. Processing is performed in the RF signal processing unit 12 using an IF filter whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1. Furthermore, in the signal processing units 13A and 13B, baseband signals of the respective satellite systems, GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1, are generated based on the digital signal output from the RF signal processing unit 12.

[0093] The processing in steps S12 and S13 is similar to the processing in steps S3 and S4. The levels of the digital signals output by the ADCs 36-1 and 36-2 are detected in step S12, and the RF gain is adjusted in step S13.

[0094] After the gain is adjusted in step S13, the interference detector 112 sets the FFT execution period in the presence of an interference wave in step S7. After the FFT execution period is set, the processing from step S2 onward is repeated when the FFT execution timing arrives.

[0095] Through this series of processes, the reception settings are temporarily switched to the steady-state settings when the FFT is executed, making it possible to continue detecting interference signals from satellite signals even after the reception settings have been switched to the settings for when interference signals are present.

[0096] Furthermore, it is possible to improve resistance to interference waves without increasing the circuit size and power consumption. For example, if the configuration of Figure 5 is used, the circuit size and power consumption will increase, but by adopting the above configuration, it is possible to prevent this.

[0097] <About the FFT execution cycle (Configuration 2)> The moment the reception settings are switched, the phase of the carrier wave in the received signal becomes discontinuous. Because the impact of the discontinuity is small during the acquisition stage, during tracking, the phase of the spreading code does not become discontinuous in code synchronization using a DLL or similar. However, in phase synchronization using a Digital PLL or similar, if the phase of the carrier wave in the received signal becomes discontinuous, synchronization is lost and it takes some time to resynchronize. This effect is manifested as a temporary interruption in the demodulation of the navigation message contained in the satellite signal, causing the satellite orbit information (ephemeris) in the navigation message to be inconsistent, making positioning impossible.

[0098] For example, in GPS L1C / A, navigation messages are sent every 30 seconds. Therefore, if the FFT execution period is set to 30 seconds or more, the response to jamming waves will be slower, but the necessary ephemeris will be ready by the time the next FFT is executed. On the other hand, if the FFT execution period is set too short, the response to jamming waves will be faster, but the time to first fix (TTFF) until the ephemeris is ready and positioning can be performed will be longer, or the ephemeris will not be ready and positioning will be impossible.

[0099] Figures 9 and 10 show examples of measurements of the C / N0 of the received signal and the state of ephemeris acquisition. Figures 9 and 10 show the measurement results when cold starts are repeated at 100-second intervals with jamming waves outside the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C bands. The upper rows of Figures 9 and 10 show the C / N0 of the received signal, and the thick horizontal lines in the lower rows indicate the state where ephemeris has been acquired. The horizontal axis represents time.

[0100] Figure 9 shows an example of measurements when the FFT execution period is set to 3 seconds, and Figure 10 shows the measurement results when the FFT execution period is set to 12 seconds. As shown in Figures 9 and 10, the difference in the FFT execution period does not appear very much in the C / N0 of the received signal, but it appears significantly in the ephemeris acquisition status. By lengthening the FFT execution period, it is possible to avoid the time it takes to acquire the ephemeris becoming abnormally long.

[0101] When the FFT execution period is set to 3 seconds, ephemeris data for the required number of satellites could be acquired within 60 seconds in only one of six cold starts, and ephemeris data could not be acquired in the remaining five, as shown in the bottom of Figure 9. On the other hand, when the FFT execution period is set to 12 seconds, ephemeris data for the required number of satellites could be acquired within 60 seconds in all six cold starts, as shown in the bottom of Figure 10.

[0102] The GNSS receiver 101 has a variable FFT execution period. During a cold start after the reception setting is switched from the GPS / GAL+GLONASS+BeiDou reception setting to the GPS / GAL+BeiDou reception setting or the GPS / GAL+GLONASS reception setting in response to the detection of an interference wave, a long FFT execution period (first execution period), such as 12 seconds or more, is set. After the necessary ephemeris is acquired and positioning becomes possible, a short FFT execution period (second execution period), such as 3 seconds or less, is set. In step S7 of FIG. 8 , the FFT execution period is set in this manner.

[0103] This makes it possible to avoid the long time required for positioning during a cold start, and once positioning becomes possible, it becomes possible to shorten the reaction time to interference waves.

[0104] The timing for switching the FFT execution period from the first execution period to the second execution period may be set to a timing other than when positioning becomes possible. For example, the FFT execution period may be switched when positioning is actually performed, or when necessary information from the navigation message has been acquired. The FFT execution period may also be switched when the number of satellites from which ephemeris has been acquired reaches a threshold number.

[0105] <<Modifications>> <Configuration 5>> FIG. 11 is a diagram showing an example of reception settings when there is interference in both the upper and lower frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C.

[0106] In this case, as shown in Figure 11, the center frequency (oscillation frequency LO1) of the filter band of the IF filter is set to 1575.42 MHz, and the cutoff frequency fc = 3 MHz is set as the bandwidth. Also, 0 MHz is set as the oscillation frequency LO2 of the NCO 52 of the signal processing unit 13A. For example, the oscillation frequencies LO3 and LO4 are not set, and processing in the signal processing units 13B and 13C is stopped.

[0107] The filter band of the IF filter shown in Figure 11 is a filter band that includes only the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C in its passband. Also, by setting the oscillation frequency LO2, baseband signals of the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C satellite signals are generated.

[0108] <Configuration 6> Fig. 12 is a diagram showing an example of reception settings when there is interference in the GPS L1 / GALILEO E1 / QZSS L1 frequency band. In this case, the reception setting shown in Fig. 12A or the reception setting shown in Fig. 12B is used.

[0109] For example, as shown in A of Fig. 12, 1561.098 MHz is set as the center frequency (oscillation frequency LO1) of the filter band of the IF filter, and a cutoff frequency fc = 3 MHz is set as the bandwidth. Also, 0 MHz is set as the oscillation frequency LO4 of the NCO 52 of the signal processing unit 13C. For example, the oscillation frequencies LO2 and LO3 are not set, and processing in the signal processing units 13A and 13B is stopped.

[0110] The filter band of the IF filter shown in A of Fig. 12 is a filter band that includes only the frequency band of BeiDou B1I in its passband. In addition, by setting the oscillation frequency LO4, a baseband signal of the BeiDou B1I satellite signal is generated.

[0111] 12B, the center frequency (oscillation frequency LO1) of the filter band of the IF filter is set to 1602 MHz, and the cutoff frequency fc = 5 MHz is set as the bandwidth. Also, the oscillation frequency LO3 of the NCO 52 of the signal processing unit 13B is set to 0 MHz. For example, the oscillation frequencies LO2 and LO4 are not set, and processing in the signal processing units 13A and 13C is stopped.

[0112] The filter band of the IF filter shown in Fig. 12B is a filter band that includes only the frequency band of GLONASS L1 in its passband. Also, by setting the oscillation frequency LO3, a baseband signal of the GLONASS L1 satellite signal is generated.

[0113] This makes it possible to perform positioning using only BeiDou B1I or only GLONASS L1.

[0114] <Other Examples> Example of Mounting a GNSS Receiver FIG. 13 is a block diagram showing an example of the configuration of an information processing terminal.

[0115] The information processing terminal 201 shown in Fig. 13 is a device equipped with the GNSS receiver 101. The information processing terminal 201 may be any of various devices such as a PC, a smartphone, an IoT device, or an in-vehicle device. In addition to the GNSS receiver 101, the information processing terminal 201 includes a wireless communication unit 211, a control unit 212, a display unit 213, an operation unit 214, and the like. Position information indicating the positioning result by the GNSS receiver 101 is supplied to the control unit 212.

[0116] The wireless communication unit 211 performs wireless communication such as LTE and wireless LAN with an external device. The wireless communication unit 211 transmits data supplied from the control unit 212 to the external device. The wireless communication unit 211 receives data transmitted from the external device and outputs the data to the control unit 212.

[0117] The control unit 212 executes programs and performs predetermined processes such as controlling the overall operation of the information processing terminal 201. For example, the control unit 212 outputs location information supplied from the GNSS receiver 101 to the wireless communication unit 211 and transmits it to an external server. Furthermore, the control unit 212 displays the current location on a map displayed by the display unit 213 based on the location information supplied from the GNSS receiver 101.

[0118] The display unit 213 is configured by an LCD, an organic EL display, etc. The display unit 213 displays a predetermined screen in accordance with the control of the control unit 212.

[0119] The operation unit 214 is composed of a touch panel provided over the display unit 213, buttons provided at predetermined positions on the housing of the information processing terminal 201, etc. The operation unit 214 detects a user operation and outputs information indicating the content of the user operation to the control unit 212.

[0120] Although the GNSS receiver 101 is described as a GNSS module that supports only the L1 band, it may also be configured as a GNSS module that supports the L5 band. In this case, the GNSS receiver 101 is provided with a signal processing unit that processes L5 band satellite signals, as described with reference to Fig. 3, in addition to the configuration shown in Fig. 6.

[0121] The above-described series of processes can be executed by hardware or software. When the series of processes is executed by software, the program constituting the software is installed in a computer incorporated in dedicated hardware or a general-purpose personal computer.

[0122] The program to be installed is provided by being recorded on removable media such as an optical disk (CD-ROM (Compact Disc-Read Only Memory), DVD (Digital Versatile Disc), etc.) or semiconductor memory. It may also be provided via wired or wireless transmission media such as a local area network, the Internet, or digital broadcasting. The program can be pre-installed in a ROM or memory unit.

[0123] The program executed by the computer may be a program that processes in chronological order according to the order described in this specification, or may be a program that processes in parallel or at the required timing, such as when called.

[0124] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0125] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0126] Example of configuration combinations The present technology can also be configured as follows.

[0127] (1) A GNSS receiver comprising: a first signal processing unit that receives satellite signals from a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency to generate a baseband signal used for demodulating a navigation message; and a detection unit that detects interference with the satellite signal based on the signal after passing through the IF filter and switches a reception setting including settings of the filter band and the oscillation frequency according to a state of the interference wave, wherein the detection unit switches the reception setting from a first setting used when the interference wave is not present to a second setting used when the interference wave is present, and then temporarily returns the reception setting to the first setting to detect the interference wave. (2) The GNSS receiver described in (1), wherein the detection unit switches the reception setting from the second setting to the first setting when the interference wave is eliminated. (3) The GNSS receiver according to (1) or (2), wherein the multiple satellite systems are L1-band satellite systems that use different frequency bands. (4) The GNSS receiver according to (3), wherein the first setting includes a filter band that includes all frequency bands of the multiple satellite systems in its passband and a setting of the oscillation frequency used for frequency conversion of signals in each frequency band. (5) The GNSS receiver according to (4), wherein the first setting includes a filter band that includes GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency bands, BeiDou B1I frequency band, and GLONASS L1 frequency band in its passband. (6) The GNSS receiver according to (4) or (5), wherein the second setting includes a filter band that has a narrower bandwidth than the filter band in the first setting and a setting of the oscillation frequency used for frequency conversion of signals in each frequency band included in the narrower bandwidth filter band.(7) The GNSS receiver according to (6), further comprising an FFT calculation unit that performs an FFT on the signal that has passed through the IF filter, wherein the detection unit detects the frequency band of the jamming wave based on the result of the FFT by the FFT calculation unit. (8) The GNSS receiver according to (7), wherein the detection unit uses the second setting as the reception setting, when the jamming wave is in a frequency band higher than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, the second setting including a filter band setting that includes in its passband the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I. (9) The GNSS receiver according to (7) or (8), wherein the detection unit uses, as the reception setting, the second setting including a filter band setting whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1 when the jamming wave is present in a frequency band lower than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C. (10) The GNSS receiver according to any of (7) to (9), wherein the detection unit uses, as the reception setting, the second setting including a filter band setting whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C when the jamming wave is present in a frequency band higher than and lower than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C. (11) The GNSS receiver according to any one of (7) to (10), wherein the detection unit uses the second setting as the reception setting, the second setting including a filter band setting that includes a BeiDou B1I frequency band or a GLONASS L1 frequency band in its passband, when the jamming signal is present in a GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency band. (12) The GNSS receiver according to any one of (7) to (11), wherein the FFT calculation unit switches an FFT execution cycle depending on whether the jamming signal is present or absent.(13) The GNSS receiver according to (12), wherein the FFT calculation unit performs the FFT at a shorter execution period when there is no jamming wave than when there is the jamming wave. (14) The GNSS receiver according to (13), wherein the FFT calculation unit performs the FFT at a first execution period until positioning becomes possible during a cold start in a state where there is the jamming wave, and performs the FFT at a second execution period shorter than the first execution period after positioning becomes possible. (15) A receiving method in which a GNSS receiver including: a first signal processing unit that receives satellite signals of a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency to generate a baseband signal used for demodulating a navigation message; and a detection unit that detects interference waves to the satellite signal based on the signal after passing through the IF filter and switches reception settings including the settings of the filter band and the oscillation frequency according to the state of the interference waves, switches the reception setting from a first setting used when the interference waves are not present to a second setting used when the interference waves are present, and then temporarily returns the reception setting to the first setting to detect the interference waves. (16) An information processing terminal including: a GNSS receiver comprising: a first signal processing unit that receives satellite signals of a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency, and generates a baseband signal used for demodulating a navigation message; a detection unit that detects interference with the satellite signal based on the signal after passing through the IF filter and switches reception settings including settings of the filter band and the oscillation frequency according to the state of the interference wave, wherein the detection unit switches the reception setting from a first setting used when the interference wave is not present to a second setting used when the interference wave is present, and then temporarily returns the reception setting to the first setting to detect the interference wave; and a control unit that performs predetermined processing based on the positioning result by the GNSS receiver.

[0128] 1 GNSS receiver, 11 antenna, 12 RF signal processing unit, 13 digital signal processing unit, 13A to 13C signal processing unit, 14A to 14C acquisition and tracking unit, 15 CPU, 16 I / O, 101 GNSS receiver, 111 FFT calculation unit, 112 jamming wave detection unit

Claims

1. A GNSS receiver comprising: a first signal processing unit that receives satellite signals from a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency, and generates a baseband signal used for demodulating a navigation message; and a detection unit that detects interference with the satellite signal based on the signal after passing through the IF filter, and switches reception settings including the settings of the filter band and the oscillation frequency according to the state of the interference wave, wherein the detection unit switches the reception setting from a first setting used when there is no interference wave to a second setting used when there is interference wave, and then temporarily returns the reception setting to the first setting to detect the interference wave.

2. The GNSS receiver according to claim 1, wherein the detection unit switches the reception setting from the second setting to the first setting when the interfering wave disappears.

3. The GNSS receiver according to claim 1, wherein the plurality of satellite systems are L1-band satellite systems that use different frequency bands.

4. The GNSS receiver according to claim 3, wherein the first setting includes a setting of the filter band that includes all frequency bands of the plurality of satellite systems in its passband, and a setting of the oscillation frequency used for frequency conversion of signals in each frequency band.

5. The GNSS receiver according to claim 4, wherein the first setting includes a setting of the filter band that includes the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency bands, the BeiDou B1I frequency band, and the GLONASS L1 frequency band in its passband.

6. The GNSS receiver according to claim 4, wherein the second setting includes a filter band narrower in bandwidth than the filter band in the first setting, and a setting of the oscillation frequency used for frequency conversion of signals in each frequency band included in the narrower filter band.

7. The GNSS receiver according to claim 6, further comprising an FFT calculation unit that performs an FFT on the signal after passing through the IF filter, and the detection unit detects the frequency band of the interference wave based on the result of the FFT by the FFT calculation unit.

8. The GNSS receiver according to claim 7, wherein, when the interfering signal is in a frequency band higher than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, the detection unit uses the second setting as the reception setting, which includes a filter band setting whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and BeiDou B1I.

9. The GNSS receiver according to claim 7, wherein, when the interfering signal is in a frequency band lower than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, the detection unit uses the second setting as the reception setting, which includes a filter band setting whose passband includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C and GLONASS L1.

10. The GNSS receiver according to claim 7, wherein when the interfering waves are present in a frequency band higher or lower than the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C, the detection unit uses the second setting as the reception setting, which includes a filter band setting that includes the frequency bands of GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C in its passband.

11. The GNSS receiver according to claim 7, wherein, when the jamming wave is present in the GPS L1 / GALILEO E1 / QZSS L1 / BeiDou B1C frequency bands, the detection unit uses the second setting as the reception setting, which includes a filter band setting whose passband includes the BeiDou B1I frequency band or the GLONASS L1 frequency band.

12. The GNSS receiver according to claim 7, wherein the FFT calculation unit switches the FFT execution cycle depending on whether the interfering signal is present or absent.

13. The GNSS receiver according to claim 12, wherein the FFT calculation unit performs FFT at a shorter execution cycle when there is no interference signal than when there is an interference signal.

14. The GNSS receiver according to claim 13, wherein, during a cold start in the presence of the interference wave, the FFT calculation unit performs FFT at a first execution period until positioning becomes possible, and after positioning becomes possible, performs FFT at a second execution period that is shorter than the first execution period.

15. A GNSS receiver comprising: a first signal processing unit that receives satellite signals from multiple satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; and a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency, and generates a baseband signal used to demodulate a navigation message; the GNSS receiver detects interference with the satellite signal based on the signal after passing through the IF filter; switches the reception setting from a first setting used when there is no interference to a second setting used when there is interference, and then temporarily returns the reception setting to the first setting to detect the interference, thereby switching the reception setting including the settings of the filter band and the oscillation frequency according to the state of the interference.

16. An information processing terminal comprising: a GNSS receiver comprising: a first signal processing unit that receives satellite signals from a plurality of satellite systems and outputs a signal in a predetermined frequency band of the IF signal using an IF filter with a variable filter band; a second signal processing unit that performs frequency conversion on the signal output by the first signal processing unit based on an oscillation signal generated by an oscillator with a variable oscillation frequency, and generates a baseband signal used for demodulating a navigation message; a detection unit that detects interference with the satellite signal based on the signal after passing through the IF filter, and switches reception settings including the settings of the filter band and the oscillation frequency according to the state of the interference wave, wherein the detection unit switches the reception setting from a first setting used when there is no interference wave to a second setting used when there is interference wave, and then temporarily returns the reception setting to the first setting to detect the interference wave; and a control unit that performs predetermined processing based on the positioning results obtained by the GNSS receiver.

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