QMBOC signal waveforms, modulation methods, devices, and computer equipment

Abstract

This application relates to a QMBOC signal waveform and modulation method. The method includes: constructing a first parameter and a second parameter based on the maximum frequency and initial frequency of a hyperbolic frequency-modulated signal; constructing an expression for the hyperbolic signal based on the first parameter and the second parameter; wherein the expression for the hyperbolic signal is a periodic function of frequency change over time; multiplying the spread spectrum signal with the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier; and performing QMBOC modulation on the navigation signal based on the periodic binary hyperbolic frequency-modulated subcarrier to obtain a QMBOC signal. This method can achieve better interference tracking performance to meet navigation performance requirements when the number of satellite navigation signals increases.

Description

Technical Field

[0001] This application relates to the field of navigation technology, and in particular to a QMBOC signal waveform and modulation method, apparatus and computer equipment. Background Technology

[0002] Currently, typical satellite navigation systems share similar signal architectures, transmitting either BPSK or BOC signals. BOC signals achieve spectral separation between military and civilian signals using binary sine and cosine subcarriers. However, this architecture also has limitations, such as high amplitude peaks in the autocorrelation function, which can lead to false lock-ups during acquisition and tracking, thus reducing the reception performance of satellite navigation signals. In the future, with the addition of low-Earth orbit (LEO) satellite navigation augmentation signals, the number of satellite navigation signals will further increase, inevitably bringing challenges in compatibility and anti-interference performance, and posing new requirements for satellite navigation augmentation signal architectures. Summary of the Invention

[0003] Therefore, it is necessary to provide a QMBOC signal waveform and modulation method to address the aforementioned technical problems.

[0004] A QMBOC signal waveform and modulation method, the method comprising:

[0005] Based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, construct the first parameter and the second parameter;

[0006] Based on the first parameter and the second parameter, an expression for the hyperbolic signal is constructed; wherein, the expression for the hyperbolic signal is a periodic function whose frequency changes with time;

[0007] Multiply the spread spectrum signal by the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier.

[0008] The navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier is subjected to QMBOC modulation to obtain the QMBOC signal.

[0009] In one embodiment, the method further includes: constructing a first parameter f0 and a second parameter m based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, respectively:

[0010]

[0011] Among them, f L f represents the initial frequency. H Indicates the maximum frequency.

[0012] In one embodiment, the method further includes: constructing an expression for the hyperbolic signal based on the first parameter and the second parameter as follows:

[0013]

[0014] Where s(t) represents the expression for the hyperbolic signal, and T represents the period.

[0015] In one embodiment, the time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is:

[0016]

[0017] Among them, signal BOC_HFM Here is the time-domain expression for the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier, where c(t) represents the spread spectrum signal, SC(t) represents the subcarrier signal, and sign(·) represents the sign function.

[0018] In one embodiment, the method further includes: performing QMBOC modulation on the navigation signal based on the periodic binary hyperbolic frequency-modulated subcarrier to obtain a QMBOC signal; the power spectral density function of the QMBOC signal is:

[0019]

[0020] Where Tc is the chip delay of the BOC(m,n) spreading code, T c = 1 / (n*1.023MHz), Ts2 is the BOC(m,n) subcarrier chip delay, T s2 = 1 / (2m*1.023MHz), where a*1.023MHz is the starting frequency of the hyperbolic FM subcarrier, b*1.023MHz is the single-sided bandwidth of the hyperbolic FM subcarrier, n*1.023MHz is the spreading code frequency of the BOC-HFM signal, T is the period of the binary hyperbolic FM subcarrier based on the periodic binary hyperbolic FM subcarrier signal, and γ is the power ratio of BOC(m,n).

[0021] A QMBOC signal waveform and modulation apparatus, the apparatus comprising:

[0022] The parameter setting module is used to construct the first and second parameters based on the maximum and initial frequencies of the hyperbolic frequency modulated signal.

[0023] The hyperbola expression construction module is used to construct an expression for a hyperbola signal based on the first parameter and the second parameter; wherein the expression for the hyperbola signal is a periodic function whose frequency changes with time;

[0024] The navigation signal generation module is used to multiply the spread spectrum signal with the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier.

[0025] The QMBOC signal modulation module is used to perform QMBOC modulation on the navigation signal based on the periodic binary hyperbola frequency-modulated subcarrier to obtain the QMBOC signal.

[0026] In one embodiment, the parameter setting module is further configured to construct the first parameter f0 and the second parameter m based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, respectively:

[0027]

[0028] Among them, f L f represents the initial frequency. H Indicates the maximum frequency.

[0029] In one embodiment, the hyperbola expression construction module is further configured to construct an expression for the hyperbola signal based on the first parameter and the second parameter as follows:

[0030]

[0031] Where s(t) represents the expression for the hyperbolic signal, and T represents the period.

[0032] In one embodiment, the time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is:

[0033]

[0034] Among them, signal BOC_HFM Here is the time-domain expression for the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier, where c(t) represents the spread spectrum signal, SC(t) represents the subcarrier signal, and sign(·) represents the sign function.

[0035] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program performing the following steps:

[0036] Based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, construct the first parameter and the second parameter;

[0037] Based on the first parameter and the second parameter, an expression for the hyperbolic signal is constructed; wherein, the expression for the hyperbolic signal is a periodic function whose frequency changes with time;

[0038] Multiply the spread spectrum signal by the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier.

[0039] The navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier is subjected to QMBOC modulation to obtain the QMBOC signal.

[0040] A computer-readable storage medium having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0041] Based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, construct the first parameter and the second parameter;

[0042] Based on the first parameter and the second parameter, an expression for the hyperbolic signal is constructed; wherein, the expression for the hyperbolic signal is a periodic function whose frequency changes with time;

[0043] Multiply the spread spectrum signal by the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier.

[0044] The navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier is subjected to QMBOC modulation to obtain the QMBOC signal.

[0045] The aforementioned QMBOC signal waveform, modulation method, apparatus, and computer equipment, firstly, compared with traditional BOC modulation, the navigation signal modulation method based on periodic binary hyperbolic frequency-modulated subcarrier has a binary subcarrier with a frequency that varies with time in each period. This changes the characteristics of the spreading code signal in the time and frequency domains, thereby giving the navigation signal better spectral characteristics. As the bandwidth increases, the main peak of the navigation signal becomes sharper, the side lobes decrease accordingly, and the interference tracking performance is better, so as to meet the navigation performance requirements when the number of satellite navigation signals increases. In addition, when performing QMBOC signal modulation, the subcarrier uses a periodic binary hyperbolic frequency-modulated waveform to replace the original BOC(1,1) while keeping the BOC(6,1) component unchanged, thereby changing the autocorrelation function and spectral characteristics of the signal, thus improving the anti-interference capability of the satellite navigation signal system. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the QMBOC signal waveform and modulation method in one embodiment;

[0047] Figure 2 This is a schematic diagram of the theoretical power spectral density function of a periodic binary hyperbolic frequency-modulated subcarrier signal in one embodiment; where (a) is the periodic binary hyperbolic frequency-modulated subcarrier signal taking...

[0048] BOC-HFM(0.25*k,1,1,1ms), k=1:6, (b) is the periodic binary hyperbolic frequency modulation subcarrier signal taken as BOC-HFM(1,0.5*k,1,1ms), k=1:4;

[0049] Figure 3 This is a schematic diagram of the autocorrelation function of a periodic binary hyperbolic frequency-modulated subcarrier signal;

[0050] Figure 4 The image below is a schematic diagram of Gabor bandwidth in one embodiment;

[0051] Figure 5 This is a graph comparing the multipath suppression performance with that of traditional satellite navigation signals in one embodiment;

[0052] Figure 6 Here is a comparison chart of the anti-interference quality factor and the traditional navigation signal in one embodiment; (a) is the periodic binary hyperbolic frequency modulated subcarrier signal with BOC-HFM (0.5, 1, 1, 1 ms), (b) is the periodic binary hyperbolic frequency modulated subcarrier signal with BOC-HFM (1, 0.5, 1, 1 ms);

[0053] Figure 7 The diagram in the middle shows a comparison of the Gabor bandwidth of traditional satellite navigation signals and QMBOC-HFM (6,1,4 / 33,0.3,1.4,1ms), QMBOC-HFM (6,1,4 / 33,0.5,1,1ms), and QMBOC-HFM (6,1,4 / 33,0.7,0.6,1ms) signals with that of QMBOC in one embodiment.

[0054] Figure 8 This is a schematic diagram comparing the multipath suppression performance of QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms), QMBOC-HFM(6,1,4 / 33,0.5,1,1ms), and QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) with that of traditional satellite navigation signals in a scenario with a range of 0 to 500 meters, as shown in one embodiment.

[0055] Figure 9 This is a comparison of the anti-interference quality factor of narrowband interference, matched spectrum interference, and band-limited interference with that of traditional navigation signals in one embodiment using an incoherent early-delay amplitude phase detection method, with a front-end filter bandwidth of 1-99MHz and the narrowband interference center frequency being the signal main lobe center frequency; where (a) is QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms), (b) is QMBOC-HFM(6,1,4 / 33,0.5,1,1ms), and (c) is QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms);

[0056] Figure 10 This is a block diagram of the QMBOC signal waveform and modulation device in one embodiment;

[0057] Figure 11 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0059] In one embodiment, such as Figure 1 As shown, a QMBOC signal waveform and modulation method is provided, including the following steps:

[0060] Step 102: Construct the first parameter and the second parameter based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal.

[0061] Step 104: Construct an expression for the hyperbolic signal based on the first and second parameters.

[0062] The expression for a hyperbolic signal is a periodic function whose frequency changes with time.

[0063] Step 106: Multiply the spread spectrum signal with the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency modulated subcarrier.

[0064] Step 108: Perform QMBOC modulation on the navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier to obtain the QMBOC signal.

[0065] In the aforementioned QMBOC signal waveform and modulation method, compared with traditional BOC modulation, the navigation signal modulation method based on periodic binary hyperbolic frequency-modulated subcarrier has a binary subcarrier with a frequency that varies with time in each period. This changes the characteristics of the spreading code signal in the time and frequency domains, thereby giving the navigation signal better spectral characteristics. As the bandwidth increases, the main peak of the navigation signal becomes sharper, the side lobes decrease, and the interference tracking performance is better, so as to meet the navigation performance when the number of satellite navigation signals increases. In addition, when performing QMBOC signal modulation, the subcarrier uses a periodic binary hyperbolic frequency-modulated waveform to replace the original BOC(1,1) while keeping the BOC(6,1) component unchanged, thereby changing the autocorrelation function and spectral characteristics of the signal, thus improving the anti-interference capability of the satellite navigation signal system.

[0066] In one embodiment, the first parameter f0 and the second parameter m are constructed based on the maximum frequency and the initial frequency of the hyperbolic frequency modulated signal, respectively:

[0067]

[0068]

[0069] Among them, f L f represents the initial frequency. H Indicates the maximum frequency.

[0070] In another embodiment, the expression for constructing the hyperbolic signal based on the first and second parameters is as follows:

[0071]

[0072] Where s(t) represents the expression for the hyperbolic signal, and T represents the period.

[0073] In this embodiment, similar to BOC modulation, the spreading code signal is multiplied by the binary periodic subcarrier to construct a binary offset HFM carrier modulation based on hyperbolic subcarriers, denoted as BOC-HFM(a,b,n,T), where the initial frequency of the HFM subcarrier is a*1.023MHz, the bandwidth of the HFM subcarrier is b*1.023MHz, the spreading code rate is n*1.023MHz, and T is the period of the HFM subcarrier.

[0074] In one embodiment, the time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is:

[0075]

[0076] Among them, signal BOC_HFM Here is the time-domain expression for a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier, where c(t) represents the spread spectrum signal, SC(t) represents the subcarrier signal, and sign(·) represents the sign function. In this embodiment, the waveform is changed and the performance is improved by altering the implementation of SC(t). Compared to the binary sine and cosine of the traditional BOC signal, SC(t) here is transformed into a binary HFM signal.

[0077] In one embodiment, the navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier is QMBOC modulated to obtain a QMBOC signal; the power spectral density function of the QMBOC signal is:

[0078]

[0079] Where Tc is the chip delay of the BOC(m,n) spreading code, T c = 1 / (n*1.023MHz), Ts2 is the BOC(m,n) subcarrier chip delay, T s2= 1 / (2m*1.023MHz), where a*1.023MHz is the starting frequency of the hyperbolic FM subcarrier, b*1.023MHz is the single-sided bandwidth of the hyperbolic FM subcarrier, n*1.023MHz is the spreading code frequency of the BOC-HFM signal, T is the period of the binary hyperbolic FM subcarrier based on the periodic binary hyperbolic FM subcarrier signal, and γ is the power ratio of BOC(m,n).

[0080] In this embodiment, the concept of QMBOC is adopted, and the BOC(n,n) component in QMBOC is replaced with the BOC-HFM proposed in this paper. This can change the spectral characteristics of the signal and construct a satellite signal system with superior performance. Based on the previously proposed BOC-HFM signal and combined with QMBOC in MBOC, a novel QMBOC signal based on binary hyperbolic frequency modulated subcarrier is proposed and named QMBOC-HFM.

[0081] The above embodiments provide a specific form of navigation signal based on periodic binary hyperbolic frequency modulated subcarrier, and its performance is analyzed below.

[0082] In the BOC-HFM(a,b,n,T) signal, 'a' determines the subcarrier's start frequency, 'b' determines the subcarrier's bandwidth, 'n' determines the signal's pseudocode rate, and 'T' determines the subcarrier's period. It is generated according to the time-domain expression described above. The values ​​of 'a' and 'b' largely determine the signal's time-frequency domain characteristics. For example... Figure 2 (a) is a schematic diagram of the theoretical power spectral density function when the signal takes BOC-HFM(0.25*k,1,1,1ms) and k=1:6. As k increases, that is, as the initial frequency of the binary subcarrier continues to increase, the other parameters remain unchanged. The power spectrum of the signal gradually changes from a single lobe to a double lobe. As the initial frequency continues to increase, the shape of the main lobe remains basically unchanged, but the frequency band shifts outward and the frequency point of the main lobe continues to rise. Figure 2 (b) is a schematic diagram of the theoretical power spectral density function of BOC-HFM (1, 0.5*k, 1, 1ms), k = 1:4. As k increases, under the condition of constant initial frequency, the bandwidth increases, the main lobe of the spectrum also widens, and the shape of the main lobe gradually changes from a standard "inverted U-shape" to a wider shape. It can be seen that BOC-HFM has different spectral characteristics from traditional BOC signals.

[0083] Figure 3 (a) and Figure 3 (b) is used to illustrate the effect of different initial frequencies and subcarrier bandwidths on the autocorrelation function of the BOC-HFM signal. Figure 3 In (a), the parameter is taken as:

[0084] BOC-HFM(k*0.1,1,1,1ms), k=1:10, using the autocorrelation functions of BOCs(1,1), BOCc(1,1), and BPSK as comparisons, as k increases, the initial frequency continuously increases, the main peak becomes sharper, but the side lobes also increase, and the oscillations become more obvious. Figure 3 In (b),

[0085] BOC-HFM(k*0.1,2,1,1ms), k=1:10, and Figure 3 Compared to the parameters in (a), the bandwidth changed from 1MHz to 2MHz, while the other parameters remained the same. Figure 3 As in (a), it can be observed that as the bandwidth increases, the main peak becomes sharper, while the side lobes decrease accordingly.

[0086] Figure 4 This is used to illustrate the code tracking performance of the BOC-HFM signal. When there is no interference and the signal receiving loop and the signal's carrier-to-noise ratio parameters are constant, the spread spectrum code tracking measurement accuracy for different signal systems is determined by the integral of the following formula, which is expressed as:

[0087]

[0088] The signal is defined as the root mean square bandwidth or Gabor bandwidth, and G(f) is the power spectral density function of the signal. Gabor bandwidth is generally used to characterize the code tracking performance of a signal, and a larger Gabor bandwidth indicates better tracking performance. To simplify the analysis, Gabor bandwidth is simulated here, assuming the front-end filter bandwidth is 1–99 MHz. The Gabor bandwidths of traditional satellite navigation signals and BOC-HFM(0.5,1,1,1ms) and BOC-HFM(1,0.5,1,1ms) signals are as follows: Figure 4 As shown in the figure, it is clear that BOC-HFM(1,0.5,1,1ms) has the best tracking performance. Taking a front-end bandwidth of 25MHz as an example, its tracking performance is improved by 7% compared to BOCc(1,1). Its code tracking performance is significantly better than that of BOCc(1,1).

[0089] Figure 5 This is used to illustrate the multipath envelope resistance of BOC-HFM signals. In real-world environments, multipath signals are unavoidable. Multipath refers to the phenomenon where a signal travels from the transmitter to the receiver via multiple paths. The receiver may simultaneously receive both direct and multipath signals. Multipath signals cause variations in the amplitude and phase of the received signal, leading to errors in carrier and pseudorange measurements. To simplify analysis, navigation signal performance evaluation generally assumes a single multipath signal, and the amplitude ratio of this single signal to the direct signal is defined as... Delay difference is defined as The baseband signal can then be represented as

[0090]

[0091] Where x(t) is the complex envelope of the transmitted signal, τ0 is the propagation delay of the direct signal, and a0 is the amplitude of the direct signal. This refers to the phase of the direct signal. Multipath signals primarily cause a zero-crossing shift in the discriminator curve. After receiving, processing, and calculation, the error ε caused by the multipath signal can be obtained. r .

[0092] When the correlator interval d approaches 0, ε r and The relationship can be approximated as:

[0093]

[0094] Where τ1 is the delay of the multipath signal relative to the direct signal; a1 is the multipath directness ratio; G s (f) represents the normalized power spectral density of each signal within the transmission bandwidth, β r This refers to the signal bandwidth.

[0095] Based on the multipath error envelope, the average multipath error envelope can be used to more intuitively evaluate the multipath error, and its expression is:

[0096]

[0097] In the formula, For multipath direct-to-phase errors with a phase difference of 0 degrees and a multipath delay of τ1,

[0098] The multipath error is defined as a multipath direct phase difference of 180 degrees and a multipath delay of τ1.

[0099] Simulation analysis is performed on the multipath resistance performance of the BOC-HFM signal. The multipath assumption is a single multipath signal with an amplitude ratio of -6dB to the direct signal. The front-end bandwidth is set to 10MHz, and the correlation interval is 0.1 chip. The average multipath error envelope is simulated and analyzed. As a reference analysis, [the following is added]...

[0100] The anti-multipath performance of signals such as BOCs(1,1), BOCc(1,1), and BPSK is compared.

[0101] A comparison of the multipath suppression performance of BOC-HFM with that of traditional satellite navigation signals in a 0-500 meter scenario, with parameters set to BOC-HFM(0.5,1,1,1ms) and BOC-HFM(1,0.5,1,1ms), and with a front-end bandwidth of 10MHz and a correlation interval of 0.1 chip, is presented.

[0102] BOC-HFM(0.5,1,1,1ms) and BOC-HFM(1,0.5,1,1ms) outperform BOCs(1,1) in scenarios ranging from 0 to 500 meters, only slightly underperforming the BOCc(1,1) signal in multipath delay scenarios around 110 meters. Overall, their anti-multipath performance is superior to that of traditional BOC signals.

[0103] Figure 6 (a) and Figure 6 (b) Used to illustrate the anti-interference performance of BOC-HFM. In the evaluation of satellite navigation signal anti-interference performance, the carrier-to-noise ratio (CNR) is typically calculated using the effects of virtual white noise, equivalent thermal noise, and non-white noise to assess the anti-interference performance quality of GNSS signals. This CNR is defined as the equivalent carrier-to-noise ratio. Its expression is:

[0104]

[0105] Where Q is the anti-interference quality factor, f c For the spreading code rate, C S For the desired received signal power, C l This represents the power of the received interference signal. The higher the equivalent carrier-to-noise ratio (ACNR), the better its anti-interference performance.

[0106] Calculating the equivalent carrier-to-noise ratio (CNR) is quite complex. To simplify the analysis, the interference immunity factor (IMF) can be used to characterize the signal's interference immunity. Assuming the receiver front-end filter is an ideal low-pass filter, the IMF expression is:

[0107]

[0108] Where β is the bandwidth of the signal's front-end filter.

[0109] Common types of interference sources include narrowband interference and matched spectrum interference. When the interference source is narrowband interference, the interference signal can be equivalent to an impulse function, and the signal's quality factor against narrowband interference is...

[0110]

[0111] When the interference source is matched spectrum interference, the power spectrum of the interfering signal is the same as that of the desired signal, such as multiple access interference or interference waveforms with spectra similar to the original signal. In this case, the signal's quality factor against matched interference is:

[0112]

[0113] The larger the anti-interference quality factor, the higher the equivalent carrier-to-noise ratio and the better the anti-interference performance. Therefore, the larger the anti-interference factor, the better.

[0114] picture Figure 6(a) and (b) compare the anti-narrowband interference and anti-matching spectrum interference performance using incoherent early-delay amplitude phase detection, with a front-end filter bandwidth of 1–99 MHz and the narrowband interference center frequency being the signal main lobe center frequency. The figures show that BOC-HFM(0.5,1,1,1ms) has the best anti-narrowband interference performance, with a significant advantage, followed by BOC-HFM(1,0.5,1,1ms). With a front-end bandwidth of 20 MHz, the anti-narrowband interference performance is 28.8% higher than BOCc(1,1). The anti-matching spectrum interference quality factor of BOC-HFM(0.5,1,1,1ms) and BOC-HFM(1,0.5,1,1ms) is better than that of the traditional BOC(1,1) signal and BPSK(2). With a front-end bandwidth of 20 MHz, the anti-matching spectrum interference performance is 26.3% higher than that of BOCc(1,1).

[0115] Based on the BOC-HFM signal constructed above, QMBOC modulation is performed to obtain the QMBOC-HFM signal. The performance of the QMBOC-HFM signal is described below:

[0116] Figure 7 This is used to illustrate the code tracking performance of the QMBOC-HFM signal. When there is no interference and the signal receiving loop and the signal's carrier-to-noise ratio parameters are constant, the spread spectrum code tracking measurement accuracy for different signal systems is determined by the integral of the following formula, which is expressed as:

[0117]

[0118] The signal is defined as the root mean square bandwidth or Gabor bandwidth, and G(f) is the power spectral density function of the signal. Gabor bandwidth is generally used to characterize the code tracking performance of a signal, and a larger Gabor bandwidth indicates better tracking performance. To simplify the analysis, a simulation of the Gabor bandwidth is performed here, assuming the front-end filter bandwidth is 1–99 MHz. Figure 7 The Gabor bandwidth of the QMBOC-HFM(6,1,4 / 33,a,b,T) signal under different front-end bandwidths was simulated. Comparison and analysis with QMBOC(6,1,4 / 33) show that the QMBOC-HFM(6,1,4 / 33,a,b,T) signal has a higher Gabor bandwidth and superior code tracking performance potential. Furthermore, it can be seen that QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) has the best code tracking performance potential. Under a front-end bandwidth of 30MHz, the Gabor bandwidth of the QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) signal is improved by 14.5% compared to QMBOC(6,1,4 / 33).

[0119] Figure 8This is used to illustrate the multipath envelope resistance performance of QMBOC-HFM signals. In real-world environments, multipath signals are unavoidable. Multipath refers to the phenomenon where a signal travels from the transmitter to the receiver via multiple paths. The receiver may simultaneously receive both direct and multipath signals. Multipath signals cause variations in the amplitude and phase of the received signal, leading to errors in carrier and pseudorange measurements. To simplify analysis, navigation signal performance evaluation generally assumes a single multipath signal, and the amplitude ratio of this single signal to the direct signal is defined as... Delay difference is defined as The baseband signal can then be represented as

[0120]

[0121] Where x(t) is the complex envelope of the transmitted signal, τ0 is the propagation delay of the direct signal, and a0 is the amplitude of the direct signal. This refers to the phase of the direct signal. Multipath signals primarily cause a zero-crossing shift in the discriminator curve. After receiving, processing, and calculation, the error ε caused by the multipath signal can be obtained. r .

[0122] When the correlator interval d approaches 0, ε r and The relationship can be approximated as:

[0123]

[0124] Where τ1 is the delay of the multipath signal relative to the direct signal; a1 is the multipath directness ratio; G s (f) represents the normalized power spectral density of each signal within the transmission bandwidth, β r This refers to the signal bandwidth.

[0125] Based on the multipath error envelope, the average multipath error envelope can be used to more intuitively evaluate the multipath error, and its expression is:

[0126]

[0127] In the formula, For multipath direct-to-phase errors with a phase difference of 0 degrees and a multipath delay of τ1,

[0128] The multipath error is defined as a multipath direct phase difference of 180 degrees and a multipath delay of τ1.

[0129] Simulation analysis of the multipath suppression performance of the QMBOC-HFM signal shows that, with a front-end bandwidth of 30MHz, the high-frequency components consist of the sidelobes of the BOC-HFM signal and the BOC(6,1) signal. Under short multipath delays (less than 60m), the multipath error envelope of the QMBOC-HFM(6,1,4 / 33,a,b,T) signal is basically consistent with that of QMBOC(6,1,4 / 33), indicating similar multipath suppression performance. Under medium-to-long multipath delays (greater than 60m), the multipath error envelope of the QMBOC-HFM(6,1,4 / 33,a,b,T) signal is significantly smaller than that of QMBOC(6,1,4 / 33), demonstrating improved multipath suppression performance. Furthermore, the total multipath error envelope area is reduced by up to 23.69% compared to QMBOC(6,1,4 / 33). The multipath performance of the QMBOC-HFM signal remains consistent across different parameter settings.

[0130] Figure 9 (a), 9(b), and 9(c) illustrate the anti-interference performance of QMBOC-HFM. In the evaluation of satellite navigation signal anti-interference performance, the carrier-to-noise ratio (CNR) is typically calculated using the effects of virtual white noise, equivalent thermal noise, and non-white noise to assess the anti-interference performance quality of GNSS signals. This CNR is defined as the equivalent carrier-to-noise ratio. Its expression is:

[0131]

[0132] Where Q is the anti-interference quality factor, f c For the spreading code rate, C S For the desired received signal power, C l This represents the power of the received interference signal. The higher the equivalent carrier-to-noise ratio (ACNR), the better its anti-interference performance.

[0133] Calculating the equivalent carrier-to-noise ratio (CNR) is quite complex. To simplify the analysis, the interference immunity factor (IMF) can be used to characterize the signal's interference immunity. Assuming the receiver front-end filter is an ideal low-pass filter, the IMF expression is:

[0134]

[0135] Where β is the bandwidth of the signal's front-end filter.

[0136] Common types of interference sources include narrowband interference and matched spectrum interference. When the interference source is narrowband interference, the interference signal can be equivalent to an impulse function, and the signal's quality factor against narrowband interference is...

[0137]

[0138] When the interference source is matched spectrum interference, the power spectrum of the interfering signal is the same as that of the desired signal, such as multiple access interference or interference waveforms with spectra similar to the original signal. In this case, the signal's quality factor against matched interference is:

[0139]

[0140] The larger the anti-interference quality factor, the higher the equivalent carrier-to-noise ratio and the better the anti-interference performance. Therefore, the larger the anti-interference factor, the better.

[0141] When the interference source is band-limited white noise, the power spectrum of the interference signal is flat, and the center frequency is f. l And the frequency range is f l -β / 2~f l +β / 2, power spectral density is 1 / β l Then the signal's anti-matching interference quality factor is

[0142]

[0143] The larger the anti-interference quality factor, the higher the equivalent carrier-to-noise ratio and the better the anti-interference performance. Therefore, the larger the anti-interference factor, the better.

[0144] Figure 9 (a), 9(b), and 9(c) compare the anti-narrowband interference and anti-matched spectrum interference performance under the conditions of noncoherent early-delay amplitude phase detection, front-end filter bandwidth of 1-99MHz, and narrowband interference center frequency being the signal main lobe center frequency.

[0145] Figure 9 (a) The anti-interference quality factor of the QMBOC-HFM signal under narrowband interference conditions was simulated. In the figure, compared with QMBOC(6,1,4 / 33), the newly constructed QMBOC-HFM(6,1,4 / 33,a,b,T) has a better anti-narrowband interference quality factor. Among them, QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms) has the best anti-narrowband interference performance. Therefore, the larger the bandwidth of the hyperbolic frequency modulated subcarrier, the better the anti-narrowband interference performance. With a front-end bandwidth of 20MHz, the interference immunity quality factors of QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms), QMBOC-HFM(6,1,4 / 33,0.5,1,1ms), and QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) are improved by 55.8%, 50.14%, and 37.26% respectively compared to QMBOC(6,1,4 / 33).

[0146] Figure 9(b) The anti-interference quality factor of the QMBOC-HFM signal under matched spectrum interference conditions was simulated. The figure above shows the anti-matched spectrum quality factor curves of different QMBOC-HFM signals. By comparing with QMBOC(6,1,4 / 33), it can be seen that different QMBOC-HFM signals have better anti-matched spectrum interference performance. Among them, QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms) has the best anti-matched spectrum interference performance, and the larger the bandwidth of the hyperbolic frequency modulated subcarrier, the better the anti-matched spectrum interference performance. With a front-end bandwidth of 20MHz, the anti-matching spectrum interference quality factors of QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms), QMBOC-HFM(6,1,4 / 33,0.5,1,1ms), and QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) are improved by 49.72%, 62.76%, and 51.23% respectively compared to QMBOC(6,1,4 / 33).

[0147] Figure 9 In (c), by comparing the quality factor curves of different QMBOC-HFM signals against band-limited white noise interference, it can be seen that, with a front-end bandwidth of 20MHz, the quality factors of QMBOC-HFM(6,1,4 / 33,0.3,1.4,1ms), QMBOC-HFM(6,1,4 / 33,0.5,1,1ms), and QMBOC-HFM(6,1,4 / 33,0.7,0.6,1ms) against matched spectrum interference are improved by 3.5%, 7.3%, and 9.86% respectively compared to QMBOC(6,1,4 / 33). It is worth noting that when the front-end bandwidth is less than 5MHz, QMBOC(6,1,4 / 33) exhibits better performance against band-limited white noise interference.

[0148] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0149] In one embodiment, such as Figure 10As shown, a QMBOC signal waveform and modulation device is provided, including: a parameter setting module 1002, a hyperbola expression construction module 1004, a navigation signal generation module 1006, and a QMBOC signal modulation module 1008, wherein:

[0150] The parameter setting module 1002 is used to construct the first parameter and the second parameter based on the maximum frequency and the initial frequency of the hyperbolic frequency modulated signal;

[0151] The hyperbola expression construction module 1004 is used to construct an expression for a hyperbola signal based on the first parameter and the second parameter; wherein the expression for the hyperbola signal is a periodic function whose frequency changes with time;

[0152] The navigation signal generation module 1006 is used to multiply the spread spectrum signal with the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier.

[0153] The QMBOC signal modulation module 1008 is used to perform QMBOC modulation on the navigation signal based on the periodic binary hyperbola frequency modulated subcarrier to obtain a QMBOC signal.

[0154] In one embodiment, the parameter setting module 1002 is further configured to construct the first parameter f0 and the second parameter m based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, respectively:

[0155]

[0156] Among them, f L f represents the initial frequency. H Indicates the maximum frequency.

[0157] In one embodiment, the hyperbola expression construction module 1004 is further configured to construct an expression for the hyperbola signal based on the first parameter and the second parameter as follows:

[0158]

[0159] Where s(t) represents the expression for the hyperbolic signal, and T represents the period.

[0160] In one embodiment, the time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is:

[0161]

[0162] Among them, signal BOC_HFMHere is the time-domain expression for the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier, where c(t) represents the spread spectrum signal, SC(t) represents the subcarrier signal, and sign(·) represents the sign function.

[0163] In one embodiment, the QMBOC signal modulation module 1008 is further configured to perform QMBOC modulation on the navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier to obtain a QMBOC signal; the power spectral density function of the QMBOC signal is:

[0164]

[0165] Where Tc is the chip delay of the BOC(m,n) spreading code, T c = 1 / (n*1.023MHz), Ts2 is the BOC(m,n) subcarrier chip delay, T s2 = 1 / (2m*1.023MHz), where a*1.023MHz is the starting frequency of the hyperbolic FM subcarrier, b*1.023MHz is the single-sided bandwidth of the hyperbolic FM subcarrier, n*1.023MHz is the spreading code frequency of the BOC-HFM signal, T is the period of the binary hyperbolic FM subcarrier based on the periodic binary hyperbolic FM subcarrier signal, and γ is the power ratio of BOC(m,n).

[0166] Specific limitations regarding the QMBOC signal waveform and modulation device can be found in the limitations regarding the QMBOC signal waveform and modulation method described above, and will not be repeated here. Each module in the aforementioned QMBOC signal waveform and modulation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in the computer device, or stored in software in the memory of the computer device, so that the processor can call and execute the corresponding operations of each module.

[0167] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 11As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a QMBOC signal waveform and modulation method. The display screen can be a liquid crystal display (LCD) or an e-ink display. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0168] Those skilled in the art will understand that Figure 11 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0169] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the method described above.

[0170] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0171] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0172] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A QMBOC signal waveform and modulation method, characterized in that, The method includes: Based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal, construct the first parameter and the second parameter; Based on the first parameter and the second parameter, an expression for the hyperbolic signal is constructed; wherein, the expression for the hyperbolic signal is a periodic function whose frequency changes with time; Multiply the spread spectrum signal by the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier. The navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier is subjected to QMBOC modulation to obtain the QMBOC signal; Based on the maximum and minimum frequencies of the hyperbolic frequency modulated signal, construct the first and second parameters, including: The first parameter is constructed based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal. Second parameter They are respectively: in, Indicates the initial frequency. Indicates the maximum frequency; Based on the first parameter and the second parameter, an expression for the hyperbolic signal is constructed, including: Based on the first parameter and the second parameter, the expression for the hyperbolic signal is constructed as follows: in, The expression representing a hyperbolic signal. Indicates period; The time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is: in, Here is the time-domain expression for a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier. Indicates spread spectrum signal, Indicates the subcarrier signal. Represents a symbolic function; Based on the navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier, QMBOC modulation is performed to obtain the QMBOC signal waveform and the modulation signal mode, including: The navigation signal based on the periodic binary hyperbolic frequency-modulated subcarrier is subjected to QMBOC modulation to obtain a QMBOC signal; the power spectral density function of the QMBOC signal is: in for Spread code chip delay, , for Subcarrier chip delay, ,and This is the starting frequency of the hyperbolic frequency-modulated subcarrier. The single-sided bandwidth of the hyperbolic frequency modulated subcarrier. Let T be the spreading code frequency of the BOC-HFM signal, and let T be the period of the binary hyperbolic frequency modulated subcarrier based on the periodic binary hyperbolic frequency modulated subcarrier signal. for Power ratio.

2. A QMBOC signal waveform and modulation device, characterized in that, The device includes: The parameter setting module is used to construct the first and second parameters based on the maximum and initial frequencies of the hyperbolic frequency modulated signal. The hyperbola expression construction module is used to construct an expression for a hyperbola signal based on the first parameter and the second parameter; wherein the expression for the hyperbola signal is a periodic function whose frequency changes with time; The navigation signal generation module is used to multiply the spread spectrum signal with the subcarrier of the hyperbolic signal to obtain a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier. The QMBOC signal modulation module is used to perform QMBOC modulation on the navigation signal based on the periodic binary hyperbola frequency-modulated subcarrier to obtain a QMBOC signal. The parameter setting module is also used to construct the first parameter based on the maximum frequency and initial frequency of the hyperbolic frequency modulated signal. Second parameter They are respectively: in, Indicates the initial frequency. Indicates the maximum frequency; The hyperbola expression construction module is also used to construct the expression for the hyperbola signal based on the first parameter and the second parameter as follows: in, The expression representing a hyperbolic signal. Indicates period; The time-domain expression of the navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier is: in, Here is the time-domain expression for a navigation signal based on a periodic binary hyperbolic frequency-modulated subcarrier. Indicates spread spectrum signal, Indicates the subcarrier signal. Represents a symbolic function; The QMBOC signal modulation module is also used to perform QMBOC modulation on the navigation signal based on the periodic binary hyperbolic frequency modulated subcarrier to obtain a QMBOC signal; the power spectral density function of the QMBOC signal is: in for Spread code chip delay, , for Subcarrier chip delay, ,and This is the starting frequency of the hyperbolic frequency-modulated subcarrier. The single-sided bandwidth of the hyperbolic frequency modulated subcarrier. Let T be the spreading code frequency of the BOC-HFM signal, and let T be the period of the binary hyperbolic frequency modulated subcarrier based on the periodic binary hyperbolic frequency modulated subcarrier signal. for Power ratio.

3. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method of claim 1.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method of claim 1.

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