Single antenna time hop integration capture system and method for two-dimensional ballistic correction fuze
By combining carrier NCO, pseudo-code NCO, matched filter, time-hopping integration channel and FFT precise carrier discriminator, the problem of low satellite signal acquisition sensitivity under single antenna rotation condition is solved, and high-sensitivity satellite signal acquisition and stable tracking are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2023-11-06
- Publication Date
- 2026-07-03
AI Technical Summary
When a single antenna rotates during the two-dimensional ballistic correction fuze, the received satellite signals are discontinuous, weak, and easily affected by projectile obstruction, resulting in low acquisition sensitivity, a small number of satellites, and poor acquisition performance.
A combined system employing a carrier NCO, pseudocode NCO, matched filter, time-hopping integration channel, threshold discriminator, and FFT precise carrier discriminator achieves high-sensitivity acquisition of satellite signals through carrier and pseudocode stripping correlation operations, segmented integration, and signal-to-noise ratio discrimination.
It improves the sensitivity of satellite signal acquisition, enables stable tracking and rapid positioning of satellite signals, reduces computational load, and improves real-time performance.
Smart Images
Figure CN117518208B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of satellite signal acquisition technology, and more specifically to a single-antenna time-hopping integration acquisition system and method for a two-dimensional ballistic correction fuze. Background Technology
[0002] When the single antenna mounted on the side of the two-dimensional ballistic correction fuse rotates, the received satellite signals are discontinuous and weak, and are easily interfered with by factors such as rotation and antenna obstruction by the projectile, resulting in low acquisition sensitivity, few satellites, and poor acquisition effect.
[0003] The existing solution is to install an omnidirectional antenna at the front end of the fuze. When the projectile rotates the fuze, the omnidirectional antenna will not be blocked by the projectile due to its omnidirectional characteristics. The satellite signal has a high signal-to-noise ratio, and satellite signal acquisition can be achieved through conventional linear matched filtering acquisition methods, parallel frequency acquisition methods, and parallel code phase acquisition methods.
[0004] Utilizing a single antenna mounted on the side of the cylindrical part of the fuze to receive satellite signals offers advantages such as small antenna size, low cost, and simple structure. It also enables satellite signal-based roll attitude measurement, making it necessary to study acquisition methods using this mounting configuration. However, when receiving satellite signals, the single antenna mounted on the side of the cylindrical part of the fuze is affected by projectile obstruction, causing the signal strength to change periodically over time. Conventional acquisition methods cannot distinguish the signal strength of satellites in a rotating state, resulting in low acquisition sensitivity. Currently, no technical solution has been found to address these issues. Summary of the Invention
[0005] In view of this, the present invention provides a single-antenna time-hopping integration acquisition system and method for two-dimensional ballistic correction fuses, which can improve the acquisition sensitivity of satellite signals received under single-antenna rotation conditions and provide frequency / phase information of satellite signal carrier / code for stable satellite signal tracking and rapid positioning.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows: the system includes a carrier NCO, a pseudocode NCO, a matched filter, a time-hopping integration channel, a threshold discriminator, and an FFT precise carrier discriminator.
[0007] After the satellite signal is input, it is first subjected to carrier stripping correlation operation with the in-phase sin branch and the quadrature cos branch signal of the carrier NCO. The correlation result after carrier stripping is sent to the matched filter.
[0008] The local pseudocode generated by the pseudocode NCO is fed into the matched filter.
[0009] In the matched filter, the local pseudocode is divided into code units, and the correlation result after carrier stripping is used to perform code stripping correlation operation with the local pseudocode after code unit division. The correlation result after code stripping is input into the time-hopping integral channel.
[0010] The time-skip integration channel performs segmented integration based on the current rotational speed, and the integration results are accumulated into the four channels.
[0011] The threshold discriminator detects the signal-to-noise ratio (SNR) of the four channels and uses the highest signal strength of a particular satellite among all channels as the standard. When the SNR is higher than the threshold value, it determines that the satellite exists and obtains the acquisition result.
[0012] All captured satellite signals are fed into the FFT precise carrier frequency discriminator for FFT-based precise carrier frequency identification in order to achieve satellite signal tracking.
[0013] In all four channels, for satellites not detected by the ephemeris, the carrier Doppler is predicted based on the ephemeris satellites. By lengthening the integration time and expanding the frequency range, the detection frequency range of the feedback control carrier NCO and pseudocode NCO is expanded from ±3000Hz to ±5000Hz.
[0014] Furthermore, the signal processing procedure for the time-hopping integration channel is as follows: the satellite signal of one rotation cycle is divided into four segments proportionally, with each segment having an integration duration of one-quarter of the rotation cycle; the 1ms signal is divided into 10 units, each with a duration of 0.1ms; when the segment duration is not an integer millisecond, 1ms coherent integration is performed on the integer millisecond portion, and the portion less than an integer millisecond is added to the unit preceding that non-integer millisecond until the total integration duration is 1ms; finally, all 1ms coherent integration results are converted into 1ms incoherent integration values, and all 1ms incoherent integration values are accumulated to obtain the integration results for all segments. The segments are accumulated again at intervals of four, which are the accumulated amplitudes for the four channels.
[0015] Another embodiment of the present invention provides a single-antenna time-hopping integration acquisition method for a two-dimensional ballistic correction fuze, which performs the following steps in real time:
[0016] Step 1: Receive satellite signal input, perform carrier stripping correlation calculation with the in-phase sin branch and quadrature cos branch signals of carrier NCO, and obtain the correlation results after carrier stripping.
[0017] Step 2: Local pseudocode generated by the pseudocode NCO.
[0018] Step 3: Divide the local pseudocode into code units, and perform code stripping correlation operation between the correlation result after carrier stripping and the local pseudocode after code unit division to obtain the correlation result after code stripping.
[0019] Step 4: Perform segmented integration based on the current rotation speed, and accumulate the integration results into 4 channels.
[0020] Step 5: Detect the signal-to-noise ratio of the four channels. Using the highest signal strength of a certain satellite in all channels as the standard, when the signal-to-noise ratio is higher than the threshold, it is determined that the satellite exists and the acquisition result is obtained.
[0021] Accurate carrier frequency identification based on FFT is performed on all captured satellite signals to achieve satellite signal tracking.
[0022] For all four channels, perform step 6 for satellites whose ephemeris data was not detected.
[0023] Step 6: For satellites not detected in the ephemeris, predict the carrier Doppler based on the ephemeris satellites, and expand the frequency range by increasing the integration time and expanding the frequency range. Expand the detection frequency range of the feedback control carrier NCO and pseudo-code NCO from ±3000Hz to ±5000Hz. If there are still satellite signals input, return to step 1; otherwise, end this process.
[0024] Further, step 4 is as follows: Divide the satellite signal of one rotation cycle into 4 segments, with each segment having an integration duration of one-quarter of the rotation cycle; divide the 1ms signal into 10 units, each unit having a duration of 0.1ms; when the segment duration is not an integer millisecond, perform 1ms coherent integration on the integer millisecond portion, adding the portion less than an integer millisecond to the unit before that non-integer millisecond, until the total integration duration is 1ms; finally, convert all 1ms coherent integration results into 1ms incoherent integration values, and then accumulate all 1ms incoherent integration values to obtain the integration results of all segments. Accumulate the results again between segments at intervals of 4, which are the accumulated amplitudes for the 4 channels.
[0025] Beneficial effects:
[0026] The purpose of this invention is to address the problems of low sensitivity, limited satellite signal acquisition, and poor acquisition performance under single-antenna rotation conditions. This invention enables high-sensitivity satellite signal acquisition, providing frequency / phase information of the satellite signal carrier / code for stable tracking and rapid positioning. In terms of computational efficiency, the matched-filter convolution algorithm performs correlation calculations through convolution. Compared to FFT-based acquisition algorithms, matched filtering does not require frequency domain transformation, and a large-scale parallel correlator can meet the receiver's computational requirements, offering advantages such as low computational complexity and high real-time performance. Attached Figure Description
[0027] Figure 1This is a block diagram illustrating the principle of a single-antenna time-hopping integration and acquisition system for a two-dimensional ballistic correction fuze, provided in an embodiment of the present invention.
[0028] Figure 2 A schematic diagram of the time-skipping integration method provided by this invention;
[0029] Figure 3 This is a schematic diagram of the time-hopping integration result of a 250Hz signal in an embodiment of the present invention; Figure 3 In this context, 'a' represents the case where the signal is divided into 1ms periods. Figure 3 In this context, 'b' represents the cumulative value across the four channels. Detailed Implementation
[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0031] This invention provides a single-antenna time-hopping integration and acquisition system for a two-dimensional ballistic correction fuze, the composition of which is as follows: Figure 1 As shown, it specifically includes the following components: carrier NCO1, pseudocode NCO2, matched filter 3, time-hopping integration channel 4, threshold discriminator 5, and FFT precise carrier discriminator 6.
[0032] After the satellite signal is input, it is first subjected to carrier stripping correlation operation with the in-phase sin branch and the quadrature cos branch signal of carrier NCO1. The correlation result after carrier stripping is sent to matched filter 3.
[0033] The local pseudocode generated by pseudocode NCO2 is fed into matched filter 3;
[0034] In matched filter 3, the local pseudo-code is divided into code units, and the correlation result after carrier stripping is performed with the local pseudo-code after code unit division. The correlation result after code stripping is input into time-hopping integral channel 4.
[0035] The time-skip integration channel 4 performs segmented integration based on the current speed, and the integration results are accumulated into the four channels;
[0036] Threshold discriminator 5 detects the signal-to-noise ratio of the four channels. It takes the highest signal strength of a certain satellite in all channels as the standard. When the signal-to-noise ratio is higher than the threshold value, it determines that the satellite exists and obtains the acquisition result.
[0037] All captured satellite signals are sent to the FFT precise carrier frequency discriminator 6 for FFT-based precise carrier frequency discrimination in order to achieve satellite signal tracking.
[0038] In all four channels, for satellites not detected by the ephemeris, the carrier Doppler is predicted based on the ephemeris satellites. By lengthening the integration time and expanding the frequency range, such as increasing the detection time, the detection frequency range of the feedback control carrier NCO1 and pseudocode NCO2 is expanded from ±3000Hz to ±5000Hz, thereby further detecting satellite signals in a larger frequency range.
[0039] The signal processing procedure for time-hop integration channel 4 is as follows: The satellite signal of one rotation cycle is divided into four segments proportionally, with each segment's integration duration being one-quarter of the rotation cycle. However, the segment duration may not be an integer millisecond period; the C / A code coherent integration time must be an integer millisecond period, otherwise coherent integration attenuation will occur. By dividing the 1ms signal into 10 units, each unit having a duration of 0.1ms, when the segment duration is not an integer millisecond, 1ms coherent integration is performed on the integer millisecond portion. The portion less than an integer millisecond is added to the unit preceding that non-integer millisecond until the total integration duration is 1ms. Finally, all 1ms coherent integration results are converted into 1ms non-coherent integration values, and then all 1ms non-coherent integration values are accumulated to obtain the integration results for all segments. The summation is performed again at intervals of four segments, resulting in the accumulated amplitude for all four channels. Using the highest signal strength of a particular satellite among all channels as the criterion, when the signal-to-noise ratio is higher than a threshold, the presence of that satellite is determined, and the acquisition result is obtained.
[0040] For example, at a speed of 230 rpm, the principle of the time-skip integral capture method is as follows: Figure 2 As shown in the diagram. In Unit i,j, i represents the number of milliseconds, and j represents the unit number within that millisecond. At 230 revolutions per second, the rotation period is 4.35ms. After dividing into 4 segments, the duration of each segment should be 1.09ms. To achieve a 0.1ms unit division, the duration of each segment after unit division is taken as 1.1ms. Each segment contains 11 units, and the 0.01ms time error has a very small impact on the capture. Segment 1 contains unit numbers Unit1,1 to Unint2,1, and is integrated twice at 1ms intervals: [Unit1,1 to Unit1,10] and [Unit1,2 to Unint2,1]. Segment 2 contains unit numbers Unit2,2 to Unint3,2, and is integrated twice at 1ms intervals: [Unit2,2 to Unint3,1] and [Unit2,3 to Unint3,2]. Segments 3 and 4 are processed in the same way. The segments are then accumulated again at intervals of 4, which is the accumulated amplitude for the 4 channels.
[0041] The basic principle of the time-skip integration method is as follows:
[0042] Generate an ideal sinusoidal signal with a duration of 10ms, an initial phase of 90°, and a frequency of 250Hz, as follows: Figure 2 As shown, the sinusoidal signal is divided into segments of 1ms duration, and the amplitude within each 1ms segment is integrated to simulate the 1ms coherent integral of the satellite signal.
[0043] The integration results are accumulated incoherently, skipping intermediate values with a period of 4ms. According to... Figure 3 In (a), the signal amplitudes of regions with the same shape are accumulated to form... Figure 3 In (b) of the image, the summation results of the four channels with different shapes show that the sinusoidal signal energy at different times can be clearly distinguished. This time-hopping integration method can concentrate the signal energy in one or more channels, isolate the satellite signal from noise, and enable the acquisition algorithm to have higher acquisition sensitivity in the rotating state.
[0044] Using the highest signal strength of a particular satellite across all channels as the benchmark, the presence of that satellite is determined when the signal-to-noise ratio (SNR) exceeds a threshold, thus yielding the acquisition result. This method avoids the problem of non-integer millisecond integration, and because the overlapping portions of each integration segment have the same overlap duration, their energy values increase proportionally, without affecting the acquisition result. Furthermore, the integrated segments remain within the pre-defined time range, ensuring that signal energy is not dispersed.
[0045] To achieve the function of dividing the pseudocode signal into 0.1ms units and performing segmented integration, a matched filter convolution algorithm is used for local pseudocode block division and correlation calculation. The local code phase is divided into 10 0.1ms code signals of equal duration, which are then sequentially matched-filtered and coherently integrated with the input signal. After segmented integration, the results are accumulated into the four channels to achieve channel energy differentiation of the satellite signal.
[0046] This invention also provides a single-antenna time-hop integration acquisition method for a two-dimensional ballistic correction fuze, which performs the following steps in real time:
[0047] Step 1: Receive satellite signal input, perform carrier stripping correlation calculation with the in-phase sin branch and quadrature cos branch signals of carrier NCO, and obtain the correlation results after carrier stripping;
[0048] Step 2: Local pseudocode generated by the pseudocode NCO;
[0049] Step 3: Divide the local pseudocode into code units, and perform code stripping correlation operation between the correlation result after carrier stripping and the local pseudocode after code unit division to obtain the correlation result after code stripping;
[0050] Step 4: Perform segmented integration based on the current rotation speed, and accumulate the integration results across the four channels. The specific process of Step 4 is as follows: Divide the satellite signal of one rotation cycle into four segments, with each segment's integration duration being one-quarter of the rotation cycle. Divide the 1ms signal into 10 units, each unit having a duration of 0.1ms. When the segment duration is not an integer millisecond, perform 1ms coherent integration on the integer millisecond portion. Add the portion less than an integer millisecond to the unit preceding that non-integer millisecond until the total integration duration is 1ms. Finally, convert all 1ms coherent integration results into 1ms incoherent integration values, and then accumulate all 1ms incoherent integration values to obtain the integration results for all segments. Accumulate the results again between segments at intervals of four, resulting in the accumulated amplitude across the four channels.
[0051] Step 5: Detect the signal-to-noise ratio (SNR) of the four channels. Using the highest signal strength of a particular satellite in all channels as the standard, if the SNR is higher than the threshold, it is determined that the satellite exists, and the acquisition result is obtained.
[0052] Perform precise carrier frequency identification based on FFT on all captured satellite signals to achieve satellite signal tracking;
[0053] For all four channels, perform step 6 for satellites whose ephemeris data was not detected.
[0054] Step 6: For satellites not detected in the ephemeris, predict the carrier Doppler based on the ephemeris satellites, and expand the frequency range by increasing the integration time and expanding the frequency range. Expand the detection frequency range of the feedback control carrier NCO and pseudo-code NCO from ±3000Hz to ±5000Hz. If there are still satellite signals input, return to step 1; otherwise, end this process.
[0055] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A single-antenna time-hopping integration and acquisition system for a two-dimensional ballistic correction fuze, characterized in that, It includes carrier NCO (1), pseudocode NCO (2), matched filter (3), time-hopping integration channel (4), threshold discriminator (5), and FFT precise carrier discriminator (6). After the satellite signal is input, it is first subjected to carrier stripping correlation operation with the in-phase sin branch and the quadrature cos branch signal of the carrier NCO (1). The correlation result after carrier stripping is sent into the matched filter (3). The local pseudocode generated by the pseudocode NCO(2) is fed into the matched filter(3); The matched filter (3) divides the local pseudocode into code units and performs code stripping correlation operation on the correlation result after carrier stripping and the local pseudocode after code unit division. The correlation result after code stripping is input into the time-hopping integration channel (4). The jump-time integration channel (4) performs segmented integration based on the current rotational speed, and the integration results are accumulated into the four channels; The threshold discriminator (5) detects the signal-to-noise ratio of the four channels and takes the highest signal strength of a certain satellite in all channels as the standard. When the signal-to-noise ratio is higher than the threshold value, it determines that the satellite exists and obtains the acquisition result. All captured satellite signals are sent to the FFT precise carrier frequency discriminator (6) to perform FFT-based precise carrier frequency discrimination in order to achieve satellite signal tracking. In all four channels, for satellites not detected by the ephemeris, the carrier Doppler is predicted based on the ephemeris satellites. By lengthening the integration time and expanding the frequency range, the detection frequency range of the feedback control carrier NCO(1) and pseudocode NCO(2) is expanded from ±3000Hz to ±5000Hz. The signal processing procedure of the time-hopping integration channel (4) is as follows: the satellite signal of one rotation cycle is divided into 4 segments in equal proportion, that is, the integration time of each segment is one-quarter of the rotation cycle; by dividing the 1ms signal into 10 units, the time length of each unit is 0.1ms, when the segment length is not an integer millisecond, the integer millisecond part is coherently integrated for 1ms, and the part that is less than an integer millisecond is added to the unit before the non-integer millisecond until the total integration time is 1ms; finally, all 1ms coherent integration results are converted into 1ms non-coherent integration values, and all 1ms non-coherent integration values are accumulated to obtain the integration results of all segments. The segments are accumulated again at intervals of 4, which is the accumulated amplitude under the 4 channels.
2. A single-antenna time-hopping integration acquisition method for two-dimensional ballistic correction fuses, characterized in that, Execute the following steps in real time: Step 1: Receive satellite signal input, perform carrier stripping correlation calculation with the in-phase sin branch and quadrature cos branch signals of carrier NCO, and obtain the correlation results after carrier stripping; Step 2: Local pseudocode generated by the pseudocode NCO; Step 3: Divide the local pseudocode into code units, and perform code stripping correlation operation between the correlation result after carrier stripping and the local pseudocode after code unit division to obtain the correlation result after code stripping; Step 4: Perform segmented integration based on the current rotation speed, and accumulate the integration results into 4 channels. Specifically, Step 4 involves dividing the satellite signal of one rotation cycle into 4 segments, with each segment's integration duration being one-quarter of the rotation cycle. The 1ms signal is divided into 10 units, each unit having a duration of 0.1ms. When a segment duration is not an integer millisecond, coherent integration is performed on the integer millisecond portion for 1ms. The portion less than an integer millisecond is added to the unit preceding that non-integer millisecond until the total integration duration is 1ms. Finally, all 1ms coherent integration results are converted to 1ms incoherent integration values, and all 1ms incoherent integration values are accumulated to obtain the integration results for all segments. The segments are then accumulated again at intervals of 4, resulting in the accumulated amplitude for the 4 channels. Step 5: Detect the signal-to-noise ratio (SNR) of the four channels. Using the highest signal strength of a particular satellite in all channels as the standard, if the SNR is higher than the threshold, it is determined that the satellite exists, and the acquisition result is obtained. Perform precise carrier frequency identification based on FFT on all captured satellite signals to achieve satellite signal tracking; For all four channels, perform step 6 for satellites whose ephemeris data was not detected; Step 6: For satellites not detected in the ephemeris, predict the carrier Doppler based on the ephemeris satellites, and expand the frequency range by increasing the integration time and expanding the frequency range. Expand the detection frequency range of the feedback control carrier NCO and pseudo-code NCO from ±3000Hz to ±5000Hz. If there are still satellite signals input, return to step 1; otherwise, end this process.