Pseudo code ranging device and ranging method with variable code rate

Abstract

The invention discloses a variable code rate pseudo code distance measuring device and a distance measuring method, and mainly solves the problem of super-high altitude tracking error height of a fixed code rate pseudo code distance measuring device. Comparing the height values captured twice: if the absolute value of the height difference value captured and solved twice continuously is within a pre-value range, judging that the signal is a normal signal, and outputting an effective height to the outside; if the absolute value of the height difference value obtained through continuous two times of capturing and resolving is within the superaltitude pre-value range, it is judged that the distance measuring equipment conducts internal tracking, and invalid height is output outwards; and if the absolute value of the height difference obtained by two continuous capturing and resolving is in other conditions, judging that the distance measuring equipment performs abnormal tracking, and continuously searching to ensure that the distance measuring equipment outputs normally during super-high-altitude tracking. The method can prevent the false tracking height of the pseudo code ranging equipment, improves the interference suppression capability of the ranging equipment, and can be used for measuring the flight height in aerospace crafts or radar equipment.

Description

Technical Field

[0001] The present invention belongs to the field of testing technology, and in particular relates to a pseudo-code radio ranging device and method, which can be used for measuring flight altitude in an aerospace vehicle or a radar device. Background Art

[0002] Radio ranging equipment can quickly and accurately measure the actual height of various aircraft from the horizontal reference plane. It is not affected by weather and seasons and can work all day long. Due to its large measurement range and adaptability to a large attitude angle, it has been widely used and developed in the fields of aircraft takeoff and landing, automatic driving, and missile guidance, such as real-time altitude measurement of aircraft.

[0003] Traditional pseudo-code ranging mainly utilizes the good autocorrelation characteristics of pseudo-random codes. The ranging device generates a pseudo-random code with a fixed length and fixed rate, which is then modulated to RF transmission by the transmitting module. The target reflected signal enters the receiving module through the receiving antenna, and outputs the intermediate frequency signal after mixing. The intermediate frequency signal is sent to the digital processing module for calculation, and the height is calculated by comparing the phase difference between the transmitting code and the receiving code. Since the number of pseudo-code sequences used in this method is fixed in length, the pseudo-code rate control word is also fixed, and the maximum unambiguous distance of the device is fixed, when the aircraft's altitude to the ground exceeds the maximum unambiguous distance of the ranging device and the echo signal is strong enough, the ranging device will enter the tracking state, and the echo signal will be compared with the next cycle of the transmitting code. The measurement calculation will produce an erroneous altitude value, resulting in erroneous tracking, leading to erroneous ranging results, affecting the execution of the aircraft's high-altitude mission.

[0004] To solve this problem, the prior art distance measuring equipment has made the following two improvements:

[0005] One is to increase the maximum unambiguous distance of the ranging device by increasing the pseudo code sequence length. However, this solution reduces the performance of the ranging device because the time required to switch from searching to tracking after changing the code length is too long.

[0006] The second is to introduce pressure altitude information and compare the radio altitude with the pressure altitude in real time: if the absolute value of the difference between the two exceeds the set range, it is considered that the radio altitude has a distance ambiguity and the output is set to invalid. However, since this method only uses pressure altitude to confirm the final calculation result of the radio ranging equipment to determine whether the external output is valid, its ranging equipment is too dependent on pressure altitude information. If the pressure altitude information is wrong, the ranging equipment will be unavailable. Therefore, how to solve the problem of tracking the wrong altitude when the aircraft flies outside the maximum unambiguous distance of the ranging equipment is an important problem that needs to be solved in the use of pseudo-code ranging equipment. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to propose a pseudo-code ranging device and method with a variable code rate to solve the problem of tracking the wrong altitude when the aircraft flies outside the maximum unambiguous distance of the ranging device, thereby improving the accuracy of flight tracking.

[0008] The technical idea of ​​the present invention is: utilizing the different maximum unambiguous distances corresponding to different code rates, the ranging device adopts two captures, and the two captures adopt different code rates, designing a time domain filtering algorithm for the heights of the two captures, if the absolute value of the height difference calculated by two consecutive captures is within a preset range, it is judged as a normal signal, and the effective height is output externally, if the absolute value of the height difference calculated by two consecutive captures is within a preset range of the ultra-high altitude state, it is considered that the current state is in the ultra-high altitude state, and the signal of the next cycle of the ranging device transmitting code is tracked, at this time, the ultra-high altitude flag is set in the ranging software, the ranging device tracks internally, and the invalid height is output externally, if the absolute value of the height difference calculated by two consecutive captures is other situations, it is judged as abnormal tracking, the ranging device does not establish tracking, and continues to be in the search state.

[0009] According to the above ideas, the implementation scheme of the present invention includes the following:

[0010] 1. A variable code rate pseudo-code ranging device, comprising a receiving antenna, a transmitting antenna, a transmitting high-frequency cable, a receiving high-frequency cable, and a transceiver, wherein the transceiver is provided with:

[0011] The RF transceiver component is used to provide the modulated and amplified carrier transmission signal to the transmitting antenna, and mix, filter and amplify the echo signal reflected by the receiving antenna to generate an intermediate frequency signal and output it to the AD sampling unit;

[0012] The AD sampling unit is used to perform AD sampling on the intermediate frequency signal and then output it to the signal processing unit for digitization;

[0013] An interface unit, used for data transmission with external equipment;

[0014] The signal processing unit is used to generate a pseudo code sequence and output it to the radio frequency transceiver component, perform correlation processing on the digital intermediate frequency signal output by the AD sampling unit and the local code, and perform capture tracking and height calculation of the ranging device, and output the results to the interface unit;

[0015] The power supply unit is used to provide working voltage to the RF transceiver component, AD sampling unit, interface unit, and signal processing unit.

[0016] Furthermore, the RF transceiver unit includes a transmitting unit and a receiving unit; the transmitting unit is used to generate a carrier signal, and modulate the transmission code generated by the signal processing unit onto the carrier signal to form a code-modulated carrier signal and output it to the transmitting antenna; the receiving unit is used to mix, filter, and amplify the echo signal reflected by the target received by the receiving antenna to generate an intermediate frequency signal and output it to the AD sampling unit.

[0017] Furthermore, the AD sampling unit is connected to the analog intermediate frequency signal of the receiving unit and is used to convert the analog intermediate frequency into a digital intermediate frequency signal and output it to the signal processing unit.

[0018] Furthermore, the interface unit is connected to the processing unit and the external device, and completes data communication between the signal processing unit and the external device according to the LVDS bus protocol and the CAN bus protocol.

[0019] Furthermore, the signal processing unit includes a field programmable logic module FPGA and a digital signal processing module DSP; the field programmable logic module FPGA is used to generate a transmission code and a local code, output the transmission code to the transmitting unit, perform correlation accumulation operations on the intermediate frequency signal input by the AD sampling unit after digital orthogonal down-conversion processing with the local code, calculate the correlation peak value and local code phase information and output them to the digital signal processing module DSP; the digital signal processing module DSP is used to generate a control code rate control word and output it to the field programmable logic module, and correlate the correlation peak value and local code phase information input by the field programmable logic module FPGA into capture tracking and height calculation of the ranging device, and output the result to the interface unit.

[0020] Furthermore, the power supply unit is respectively connected to the RF transceiver component, the interface unit, the A / D adopting unit and the signal processing unit, and is used to convert the 28V power provided by the external device into 5V, 12V, 3.3V, 1.2V and 1.8V, and provide 5V and 12V operating voltages for the RF transceiver component, 3.3V operating voltage for the A / D unit and the interface unit, and 3.3V, 1.2V and 1.8V operating voltages for the signal processing unit.

[0021] 2. A method for performing variable code rate pseudo code ranging using the pseudo code ranging device, characterized in that it comprises the following steps:

[0022] 1) After the ranging device is powered on and initialized, the DSP presets the code rate control word to the slow code rate control word W A , set the first capture flag First_Flag to 0, and the slow code rate control word W A Send to the first code rate latch submodule;

[0023] 2) Real-time monitoring of the code rate control word of the transmission code in FPGA to prevent DSP and FPGA from working out of sync, regularly read the code rate control word of the transmission code generation submodule, and compare it with the code rate control word latched by the first code rate latch submodule:

[0024] If the comparison results of the two are inconsistent, the code rate control submodule rewrites the code rate control word into the first code rate latch submodule;

[0025] Otherwise, go to step 3);

[0026] 3) The transmission code generation submodule and the local code generation submodule generate transmission code sequences and local code sequences of corresponding code rates according to the code rate control word, and modulate the transmission code onto the carrier signal of the transmission unit and transmit it through the transmission antenna. The receiving antenna receives the echo signal reflected by the target. The echo signal is input into the receiving unit for mixing, filtering, and amplification to generate an intermediate frequency signal, which is output to the AD sampling unit for analog-to-digital conversion;

[0027] 4) The digital intermediate frequency signal sent by the AD sampling unit is mixed and filtered with the digital intermediate frequency local oscillator signal, and then down-converted to obtain the received pseudo code sequence, which is serially XORed with the current local code sequence and accumulated. The operation result is compared with the predetermined statistical noise threshold:

[0028] If the operation result is greater than the threshold value, the signal is judged to be captured.

[0029] If the operation result is less than or equal to the threshold value, it is determined that the signal is not captured;

[0030] 5) After completing the signal capture, the local code element counting submodule is controlled to count according to the signal processing result sent by the digital orthogonal down-conversion submodule, and the local code is controlled to move sequentially in units of one chip. The propagation time of the transmitted code in space is calculated by the number N of local code element movements, and the distance value R is calculated according to the time;

[0031] 6) The ranging equipment uses a slow code rate control word W A Perform the first signal capture and altitude calculation. After the first capture is successful, record the altitude value H. A , and set the first capture flag First_Flag to 1, and change the code rate control word to the fast code rate control word W B , and the fast code speed control word W B Send to the first code rate latch submodule;

[0032] 7) The ranging equipment uses fast code speed control word W B Perform the second signal capture and height solution, and repeat steps 2) to 5): If the second capture fails, set the first capture flag First_Flag to 0, and change the code rate control word to the slow code rate control word WA , and the slow code speed control word W A Send it to the first code rate latch submodule. If the second capture is successful, record the capture height value H B , set the first capture flag First_Flag to 0, and set the tracking flag Gz_Flag to 1;

[0033] 8) Capture the height values ​​H twice A and H B The absolute value of the difference ΔH is used for judgment:

[0034] If the absolute value of the height difference calculated by two consecutive captures ΔH is not greater than the preset value ΔH Α , the altitude calculated by the ranging device is judged to be normal altitude, and the device switches to tracking state and outputs the effective altitude externally;

[0035] If the absolute value of the height difference calculated by two consecutive captures ΔH is within the preset range ΔH Β If the distance measuring device is in the ultra-high altitude state, the distance measuring device will be tracked internally, and the external output will be invalid.

[0036] If the absolute value ΔH of the height difference calculated by two consecutive captures is in other states, it is judged that the ranging device tracking is abnormal, and the tracking is not established, and the slow code rate control word W is A The first code rate is sent to the latch submodule, and the ranging device continues to be in the searching state.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] First, the present invention adopts full digital technology through the signal processing unit, and the control is simple, flexible and stable.

[0039] Secondly, the present invention adopts two code rates during signal capture, which expands the maximum unambiguous distance of the pseudo-code ranging equipment, solves the problem of tracking the wrong altitude when the original pseudo-code ranging equipment works outside the maximum unambiguous distance, and can ensure the stability and reliability of altitude data, ensuring the correct execution of high-altitude tasks.

[0040] Third, the present invention uses two captures during signal capture, and performs time domain filtering on the heights of the two captures, which can greatly reduce the problem of occasional random tracking of the ranging device caused by external interference when the ranging device works in a complex electromagnetic environment, and improve the ability of the ranging device to suppress interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the overall structural diagram of the present invention;

[0042] Figure 2 is a structural diagram of a signal processing unit in the present invention;

[0043] Figure 3 The present invention is a flow chart for implementing variable code rate ranging. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0045] Reference Figure 1 The radio distance measuring device of this example includes five parts: receiving antenna 1, transmitting antenna 2, receiving high-frequency cable 3, transmitting high-frequency cable 4, and transceiver 5. The transceiver 5 includes a radio frequency transceiver component 51, an AD sampling unit 52, an interface unit 53, a signal processing unit 54, and a power supply unit 55, wherein the radio frequency transceiver component 51 is composed of a transmitting unit 511 and a receiving unit 512. Its working principle is as follows:

[0046] The transmission code generated by the signal processing unit 54 is modulated and amplified by the RF transceiver component transmitting unit 511 to form a modulated carrier RF signal to be transmitted. The RF signal is transmitted to the transmitting antenna 2 through the transmitting high-frequency cable 4, and the transmitting antenna 2 radiates toward the ground; the echo signal reflected from the ground is input to the RF transceiver component receiving unit 512 through the receiving antenna 1 and the receiving high-frequency cable 3, which mixes, filters, gain-controls and amplifies the echo signal and outputs an analog intermediate frequency signal to the A / D sampling unit 52; the A / D sampling unit 52 completes the analog-to-digital conversion and sends the digital intermediate frequency to the signal processing unit 54; the signal processing unit 54 performs carrier stripping and demodulation processing through digital down-conversion to obtain a receiving code, and the receiving code is correlated and accumulated with the local pseudo code and then compared with the statistical noise threshold: if the correlation accumulation value is greater than the threshold, the phase difference between the local pseudo code and the receiving pseudo code is compared, and the height value is calculated based on the phase difference, and the height value is output to the external device through the interface unit 53; otherwise, the ranging device continues to be in the search state, and the external output is invalid.

[0047] The power supply unit 55 converts the 28V power provided by the external device into various voltages required for the operation of the ranging device. Its main power supply module adopts but is not limited to the DC-DC power supply module ZHDC28D512G / 15W of Zhenhua Micro Corporation to perform +5V and +12V voltage conversion. The input voltage range of the power supply module is 16V to 42V, and the output power is 15W. The other power supply parts adopt the switching power supply chip SM4644MPY of Shenzhen Guowei Corporation to perform +3.3V, +1.8V and +1.2V voltage conversion, and respectively provide 5V and 12V working voltages for the RF transceiver component 51, 3.3V working voltage for the A / D adopting unit 52 and the interface unit 53, and 3.3V, 1.2V and 1.8V working voltages for the signal processing unit 54.

[0048] This example uses pseudo-code modulation continuous wave technology to capture and track the ground echo signal to complete the altitude measurement task. The pseudo-random code sequence length and code rate control word generated by the existing pseudo-code altimeter signal processing unit are fixed. When the aircraft's altitude to the ground exceeds the maximum unambiguous distance of the ranging device and the echo signal is strong enough, the ranging device will enter the tracking state, compare the echo signal with the next cycle of the transmitted code, and calculate the altitude value, causing the ranging device to track a low altitude, affecting the aircraft's high-altitude mission execution.

[0049] In order to solve the shortcomings of the pseudo-code altimeter, the present invention focuses on improving the algorithm structure of the signal processing unit 54, that is, a two-capture algorithm is used to capture the ranging device, and different code rates are used for the two captures. Since the maximum unambiguous distances corresponding to pseudo-random codes with different code rates are different, there is a fixed height difference in the calculation results corresponding to different code rates when calculating the altitude after the two captures. According to the height difference, it is identified whether the ranging device has entered the ultra-high altitude tracking state to ensure that its external output is normal during ultra-high altitude tracking.

[0050] Reference Figure 2 The signal processing unit 54 includes a field programmable logic module FPGA and a digital signal processing module DSP; wherein the FPGA is composed of a first code rate latch submodule 541, a second code rate latch submodule 542, a transmission code element counting submodule 543, a transmission code generation submodule 544, a local code element counting submodule 545, a local code generation submodule 546, a correlation accumulation operation submodule 547 and a digital orthogonal down-conversion submodule 548; the DSP is composed of a code rate control submodule 549, a fault tolerance processing submodule 5410, a height output submodule 5411, a time domain filtering submodule 5412, a height calculation submodule 5413, a signal capture submodule 5414 and a local code shift control submodule 5415. Its working principle is as follows:

[0051] The code rate control submodule 549 determines the currently required code rate control word according to the comparison result of the ranging device tracking flag sent by the time domain filtering submodule 5412 and the output of the fault tolerance processing submodule 5410, and writes it into the first code rate latch submodule 541 through the data bus for latching; the transmission code element counting submodule 543 enables the first code rate latch submodule 541 to send the code rate control word to the second code rate latch submodule 542 and the transmission code generation submodule 544; the transmission code generation submodule 544 generates a transmission code of the corresponding code rate according to the code rate control word and sends it to the transmission code generation submodule 544; The RF transceiver component transmitting unit 511 performs modulation and forms a transmission signal for external transmission; the local code element counting submodule 545 enables the second code rate latching submodule 542 under the control of the local code shift control submodule 5415 to send the code rate control word to the local code generating submodule 546; the local code generating submodule 546 generates a local code of the corresponding code rate according to the code rate control word and sends it to the relevant accumulation operation submodule 547; the digital orthogonal down-conversion submodule 548 mixes, filters, and down-converts the digital intermediate frequency signal sent by the AD sampling unit 52 with the digital intermediate frequency local oscillator signal. The received code sequence is obtained by frequency addition, and is sent to the correlation accumulation operation submodule 547 and the local code shift control submodule 5415 respectively; the correlation accumulation operation submodule 547 performs serial XOR operation on the local code sequence and the received code sequence and accumulates them, and sends the accumulated result and the local code phase information to the signal capture submodule 5414 for calculation and judgment processing; the signal capture submodule 5414 compares the calculation result sent by the correlation accumulation operation submodule 547 with the predetermined noise voltage threshold: if the calculation result is greater than the threshold value, the signal is judged to be captured, and the local code symbol is shifted by The number and capture status are sent to the altitude calculation submodule 5413 at the same time; if the calculation result is less than or equal to the threshold value, it is judged that the signal is not captured, and the ranging device continues to be in the searching state; the local code shift control submodule 5415 controls the counting of the local code element counting submodule 545 according to the capture status of the time domain filtering submodule 5412, so that the code elements of the ranging device can slide sequentially to search or continuously track the correct altitude; the altitude calculation submodule 5413 calculates the altitude according to the number of local code element movements and the capture status, and sends the calculated altitude value to the time domain filtering submodule 5412. The time domain filtering submodule 5412 determines whether the ranging device has completed two capture and tracking, and sends its tracking flag Gz_Flag and altitude value to the altitude output submodule 5411, and sends its tracking flag Gz_Flag to the code rate control submodule 549 and the local code shift control submodule 5415; the altitude output submodule 5411 performs data smoothing on the tracking flag and altitude value and sends them to the interface unit 53; the fault tolerance processing submodule 5410 reads the code rate control word of the transmission code generation submodule 544 when the code rate control submodule 549 is enabled, compares it with the code rate control word determined by the code rate control submodule 549, and sends the comparison result to the code rate control submodule 549.

[0052] Reference Figure 3 The steps for implementing variable code rate ranging of the present invention include the following:

[0053] Step 1 System initialization.

[0054] 1.1) Initialize system parameters;

[0055] 1.2) Set the first capture flag First_Flag to 0, so that the ranging device is in the search state;

[0056] 1.3) Set the code rate control word to the slow code rate control word W A .

[0057] Among them, W A The slow code rate control word is a 64-bit binary number used to control the generation of the slow code rate V A The transmission code and local code.

[0058] Step 2 determines the current working code rate control word.

[0059] 2.1) Send the corresponding code rate control word to the first code rate latch submodule of FPGA according to the code rate currently used by the ranging device;

[0060] 2.2) Compare the current code rate control word and the code rate control word of the transmission code generation submodule to see if they are consistent:

[0061] If the code rate control words are consistent, execute step 3;

[0062] If the code rate control words are inconsistent, return to step 2.1).

[0063] Step 3 generates a transmission code and a local code, and generates a modulated radio frequency signal to transmit externally.

[0064] 3.1) According to the code rate control word written into the FPGA, the 10-stage shift register performs a modulo-2 sum operation through the corresponding feedback taps to generate the transmission code and local code of the corresponding code rate;

[0065] 3.2) The transmitting unit of the RF transceiver assembly modulates the transmission code onto the carrier signal to form a modulated carrier RF signal, and uses a power amplifier to amplify the modulated carrier RF signal and transmit it to the ground through a transmitting antenna.

[0066] Step 4: Receive the echo signal and convert it into a digital intermediate frequency signal.

[0067] 4.1) The receiving antenna receives the ground echo signal and sends the echo signal to the RF transceiver component. The receiving unit of the RF transceiver component performs low-noise amplification, mixing and intermediate frequency amplification on the echo signal to convert it into an analog intermediate frequency signal;

[0068] 4.2) Perform AD sampling on the analog intermediate frequency signal to convert it into a digital intermediate frequency signal.

[0069] Step 5: Determine whether the signal is captured:

[0070] 5.1) The digital orthogonal down-conversion submodule performs carrier stripping and digital down-conversion processing on the digital intermediate frequency signal to obtain a received code sequence, which is output to the relevant accumulation operation submodule;

[0071] 5.2) The correlation accumulation operation submodule multiplies the received code sequence and the local code sequence through a digital multiplier and completes the signal accumulation of one code cycle through an accumulator, and sends the accumulation result to the signal capture submodule;

[0072] 5.3) The signal capture submodule compares the signal correlation accumulation calculation result with the predetermined statistical noise threshold:

[0073] If the calculated result is greater than the threshold value, the signal is determined to be captured and step 6 is executed;

[0074] If the operation result is not greater than the threshold value, it is determined that the signal is not captured, and the local code element counting module is controlled to count, so that the local code slides to the next code chip, and the first capture flag First_Flag is set to 0, and returns to step 2.

[0075] Step 6 calculates the height value and determines whether the two captures are completed.

[0076] 6.1) Read the number of local code element movements N in the signal acquisition submodule, and calculate the distance value R based on the pseudo code continuous wave radar ranging:

[0077] R=N / V*C / 2

[0078] Where N is the number of local code element movements, V is the transmission code rate, and C is the speed of light;

[0079] 6.2) Determine whether the ranging device has completed two captures:

[0080] If the first capture flag First_Flag is 1, the two captures are completed and the calculated height value is recorded as H B , set the first capture flag First_Flag to 0, and execute step 9;

[0081] If the first capture flag First_Flag is 0, the two captures are not completed, and the calculated height value is recorded as H AAt the same time, set the first capture flag First_Flag to 1, and set the code rate control word to the fast code rate control word W B , return to step 2.

[0082] Step 7 determines the tracking status and external output status of the ranging device.

[0083] 7.1) Calculate the pre-value ΔH according to the sequence length M of the pseudo code sequence Α :

[0084] ΔH A =V H ×M×T

[0085] Where V H is the maximum vertical speed of the ranging device, and T is the time it stays at a chip position when searching in the ranging software.

[0086] 7.2) According to the sequence length M and code rate V of the pseudo code sequence A 、V B Calculate the pre-value ΔH Β , which is implemented as follows:

[0087] 7.2.a) According to the sequence length M of the pseudo code sequence in the ranging software and the code rate V used in the first search and tracking A , calculate the maximum unambiguous distance H corresponding to the slow code rate Amax :

[0088]

[0089] Where C is the speed of light;

[0090] 7.2.b) According to the sequence length M of the pseudo code sequence in the ranging software and the code rate V used in the second search and tracking B , calculate the maximum unambiguous distance H corresponding to the fast code rate Bmax :

[0091]

[0092] 7.2.c) Calculate the maximum unambiguous distance difference ΔH between the slow code and the fast code based on the results of 8a) and 8b) AB :

[0093] ΔH AB =H Amax -H Bmax ;

[0094] 7.2.d) According to the result of 8c) and the predicted value ΔH Α Calculate the range of the altitude value that the ranging device tracks and resolves outside the maximum unambiguous distance ΔH Β :

[0095] (ΔH AB -ΔH A )≤ΔH Β ≤(ΔH AB +ΔH A )

[0096] 7.3) Determine whether the ranging device has entered the tracking state:

[0097] If the absolute value of the height difference calculated by two consecutive captures ΔH is not greater than the preset value ΔH Α , then the altitude calculated by the ranging device is judged to be normal altitude, and the state is switched to tracking state, and step 7.4 is executed;

[0098] If the absolute value of the height difference calculated by two consecutive captures ΔH is within the preset range ΔH Β If the range measuring device is within the range, it is judged that the range measuring device is in the ultra-high altitude state, the range measuring device is internally tracked, the tracking flag Gz_Flag is set to 1, and step 7.4 is executed;

[0099] If the absolute value of the height difference calculated by two consecutive captures is ΔH, it is judged that the ranging device is tracking abnormal, and the first capture flag First_Flag is set to 0. ， Set the code rate control word to slow code rate control word W A , return to step 2.

[0100] 7.4) Determine whether the external output of the ranging device is valid:

[0101] If the tracking flag Gz_Flag is 0, the ranging device outputs the effective altitude to the outside;

[0102] If the tracking flag Gz_Flag is 1, the ranging device outputs invalidity.

[0103] The above description is only a specific example of the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention. For example, in addition to being applied to pseudo-code ranging equipment, the present invention can also be applied to radar equipment. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A variable code rate pseudo-code ranging device, comprising a receiving antenna (1), a transmitting antenna (2), a receiving high-frequency cable (3), a transmitting high-frequency cable (4), and a transceiver (5), characterized in that: The transceiver is provided with: The radio frequency transceiver component (51) is used to provide a modulated and amplified carrier transmission signal to the transmitting antenna, and mix, filter and amplify the echo signal reflected by the receiving antenna to generate an intermediate frequency signal and output it to the AD sampling unit; An AD sampling unit (52) is used to perform AD sampling on the intermediate frequency signal and digitize it, and then output it to the signal processing unit; An interface unit (53) for performing data transmission with an external device; The signal processing unit (54) is used to generate a pseudo code sequence and output it to the radio frequency transceiver component, perform correlation processing on the digital intermediate frequency signal output by the AD sampling unit and the local code, and perform capture tracking and height calculation of the ranging device, and output the result to the interface unit; The power supply unit (55) is used to provide working voltage to the radio frequency transceiver component, the AD sampling unit, the interface unit, and the signal processing unit.

2. The device according to claim 1, characterized in that: The radio frequency transceiver unit (51) comprises a transmitting unit (511) and a receiving unit (512); The transmitting unit (511) is used to generate a carrier signal, and modulate the transmission code generated by the signal processing unit (54) onto the carrier signal to form a carrier signal with code modulation and output it to the transmitting antenna; The receiving unit (512) is used for mixing, filtering and amplifying the echo signal reflected by the receiving antenna from the target to generate an intermediate frequency signal and output it to the AD sampling unit (52).

3. The device according to claim 1, characterized in that: The AD sampling unit (52) is connected to the analog intermediate frequency signal of the receiving unit (512) and is used to convert the analog intermediate frequency into a digital intermediate frequency signal and output it to the signal processing unit (54).

4. The device according to claim 1, characterized in that: The interface unit (53) is connected to the signal processing unit (54) and the external device, and completes data communication between the signal processing unit (54) and the external device according to the LVDS bus protocol and the CAN bus protocol.

5. The device according to claim 1, characterized in that: The signal processing unit (54) comprises a field programmable logic module FPGA and a digital signal processing module DSP; the FPGA is used to generate a transmission code and a local code, output the transmission code to the transmission unit (511), perform correlation accumulation operation on the intermediate frequency signal input by the AD sampling unit (52) after digital orthogonal down-conversion processing and the local code, calculate the correlation peak value and local code phase information and output them to the DSP; The DSP is used to generate a control code rate control word and output it to the FPGA, and to correlate the correlation peak value and local code phase information input by the FPGA into the capture tracking and height calculation of the ranging device, and output the result to the interface unit (53).

6. The device according to claim 5, characterized in that: The FPGA includes: A first code rate latching submodule (541), used for latching a code rate control word generated by a code rate control submodule (549); The second code rate latch submodule (542) is used to latch the code rate control word input by the first code rate latch submodule (541); A transmission code element counting submodule (543), used for counting the number of transmitted code elements and generating a transmission code rate switching enable signal; A transmission code generation submodule (544), used for generating a transmission code of a corresponding code rate and outputting it to a transmission unit (511); A local code element counting submodule (545), used for counting the number of local code elements and generating a local code rate switching enable signal; A local code generation submodule (546), used to generate a local pseudo code of a corresponding code rate and output it to a related accumulation operation module (547); A correlation accumulation operation submodule (547) is used to perform correlation accumulation on the received code sequence obtained by the digital down-conversion submodule (548) and the local code sequence, and output the accumulation result and the local code phase information to the signal capture submodule (5414) for processing; The digital orthogonal down-conversion submodule (548) is used to perform carrier stripping and demodulation processing on the digital intermediate frequency signal input by the AD sampling unit (52), obtain a received code sequence and output it to the correlation accumulation operation submodule (547).

7. The device according to claim 5, characterized in that: The DSP includes: A code rate control submodule (549), used for determining a currently required code rate control word and outputting it to the first code rate latch submodule (541); The fault-tolerant processing submodule (5410) is used to read the code rate control word of the transmission code generation submodule (544) and the code rate control word latched by the first code rate latch submodule (541), and compare the two, and determine whether to re-issue the code rate control word according to the comparison result; The height output submodule (5411) is used to judge the capture height input by the time domain filtering submodule (5412) and output it externally; The time domain filtering submodule (5412) is used to determine whether the ranging device has entered the tracking state, and whether it has completed two captures, and output the capture results to the altitude output submodule (5411); A height calculation submodule (5413) is used to perform height calculation on the number N of local code element shifts and the capture state input by the signal capture submodule (5414); The signal capture submodule (5414) is used to perform accumulation operation on the data input by the relevant accumulation operation submodule (547), and compare the operation result with the preset noise threshold to determine whether the ranging device has completed the capture; The local code shift control submodule (5415) is used to control the counting of the local code element counting submodule (545) and control the sequential shift of the local code.

8. The device according to claim 1, characterized in that: The power supply unit (55) is respectively connected to the radio frequency transceiver component (51), the interface unit (52), the A / D adopting unit (53) and the signal processing unit (54), and is used to convert the 28V power provided by the external device into 5V, 12V, 3.3V, 1.2V and 1.8V, and respectively provide 5V and 12V working voltages for the radio frequency transceiver component (51), provide 3.3V working voltage for the A / D unit (52) and the interface unit (53), and provide 3.3V, 1.2V and 1.8V working voltages for the signal processing unit (54).

9. A method for performing variable code rate pseudo code ranging using the pseudo code ranging device of claim 1, characterized in that: The steps include: 1) After the ranging device is powered on and initialized, the DSP presets the code rate control word to the slow code rate control word W A , set the first capture flag First_Flag to 0, and the slow code rate control word W A Send to the first code rate latch submodule; 2) Real-time monitoring of the code rate control word of the transmission code in the FPGA to prevent the DSP and the FPGA from working out of sync, regularly reading the code rate control word of the transmission code generation submodule (544), and comparing it with the code rate control word latched by the first code rate latch submodule (541): If the comparison results of the two are inconsistent, the code rate control submodule (549) rewrites the code rate control word into the first code rate latch submodule (541); Otherwise, go to step 3); 3) The transmission code generation submodule and the local code generation submodule generate transmission code sequences and local code sequences of corresponding code rates according to the code rate control word, and modulate the transmission code onto the carrier signal of the transmission unit and transmit it through the transmission antenna. The receiving antenna receives the echo signal reflected by the target. The echo signal is input into the receiving unit for mixing, filtering, and amplification to generate an intermediate frequency signal, which is output to the AD sampling unit for analog-to-digital conversion; 4) The digital intermediate frequency signal sent by the AD sampling unit is mixed and filtered with the digital intermediate frequency local oscillator signal, and then down-converted to obtain the received pseudo code sequence, which is serially XORed with the current local code sequence and accumulated. The operation result is compared with the predetermined statistical noise threshold: If the operation result is greater than the threshold value, the signal is determined to be captured; If the operation result is not greater than the threshold value, it is determined that the signal is not captured; 5) After completing the signal capture, the local code element counting submodule (5415) is controlled to count according to the signal processing result sent by the digital orthogonal down-conversion submodule (548), and the local code is controlled to move sequentially in units of one code chip, and the propagation time of the transmitted code in space is calculated by the number N of local code element movements, and the distance value R is calculated by the time; 6) The ranging equipment uses a slow code rate control word W A Perform the first signal capture and altitude calculation. After the first capture is successful, record the altitude value H. A , and set the first capture flag First_Flag to 1, and change the fast code speed control word W B , and the fast code speed control word W B Send to the first code rate latch submodule (541); 7) The ranging equipment uses fast code speed control word W B Perform the second signal capture and height calculation, and repeat steps 2) to 5): If the second capture fails, set the first capture flag First_Flag to 0, and change the code rate control word to the slow code rate control word W A , and the slow code speed control word W A The first code rate latch submodule (541) is sent to the second capture module. If the second capture is successful, the capture height value H is recorded. B , set the first capture flag First_Flag to 0; 8) Capture the height values ​​H twice A and H B The absolute value of the difference ΔH is used to judge: If the absolute value of the height difference calculated by two consecutive captures ΔH is not greater than the preset value ΔH Α , the altitude calculated by the ranging device is judged to be normal altitude, the device switches to tracking state, and outputs the effective altitude externally; If the absolute value of the height difference calculated by two consecutive captures ΔH is within the preset range ΔH Β If the distance measuring device is in the ultra-high altitude state, the distance measuring device will be tracked internally, and the external output will be invalid. If the absolute value of the height difference ΔH calculated by two consecutive captures is in other states, it is judged that the ranging device tracking is abnormal, and the tracking is not established, and W A The code rate control word is sent to the first code rate latch submodule (541) to keep the distance measuring device in the search state.

10. The method according to claim 9, characterized in that: In the step 1), A The slow code rate control word is a 64-bit binary number used to control the generation of the slow code rate V A The transmission code and local code; In the step 7), B The fast code rate control word is a 64-bit binary number used to control the generation of the fast code rate V B The transmission code and local code.

11. The method according to claim 9, characterized in that The pre-value ΔH in step 8) Α , is the maximum height change of the ranging device when the ranging software completes a search within the entire ranging range. It is determined by the maximum vertical speed of the ranging device in the technical requirements, the sequence length of the pseudo code sequence in the ranging software, and the time the ranging software stays at a chip position during the search. The formula is as follows: ΔH A =V H ×M×T Where V H is the maximum vertical speed of the ranging device, M is the sequence length of the pseudo code sequence in the ranging software, and T is the time it stays at a chip position during the search in the ranging software.

12. The method according to claim 9, characterized in that The preset range ΔH in step 8) Β , is the range of the altitude value that the ranging device tracks and solves outside the maximum unambiguous distance, and its implementation is as follows: 8a) According to the sequence length M of the pseudo code sequence in the ranging software and the code rate V used in the first search and tracking A , calculate the maximum unambiguous distance H corresponding to the slow code rate Amax : Where C is the speed of light; 8b) According to the sequence length M of the pseudo code sequence in the ranging software and the code rate V used in the second search and tracking B , calculate the maximum unambiguous distance H corresponding to the fast code rate Bmax : 8c) Calculate the maximum unambiguous distance difference ΔH between the slow code and the fast code based on the results of 8a) and 8b) AB : ΔH AB =H Amax -H Bmax ; 8d) According to the result of 8c) and the pre-value ΔH Α Calculate the range of the altitude value that the ranging device tracks and resolves outside the maximum unambiguous distance ΔH Β : (ΔH AB -ΔH A )≤ΔΗ Β ≤(ΔH AB +ΔH A ) 13. The method according to claim 9, characterized in that The distance value R is calculated in step 5) based on the pseudo-code continuous wave radar ranging, and is calculated by the following formula: R=N / V*C / 2 Among them, V is the transmission code rate, N is the number of local code element movements, and C is the speed of light.

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