CN112630775B - Method and system for measuring distance of target flying object - Google Patents
Method and system for measuring distance of target flying object Download PDFInfo
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- CN112630775B CN112630775B CN202011391711.8A CN202011391711A CN112630775B CN 112630775 B CN112630775 B CN 112630775B CN 202011391711 A CN202011391711 A CN 202011391711A CN 112630775 B CN112630775 B CN 112630775B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/003—Bistatic radar systems; Multistatic radar systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/28—Details of pulse systems
- G01S7/282—Transmitters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/28—Details of pulse systems
- G01S7/285—Receivers
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- Radar Systems Or Details Thereof (AREA)
Abstract
The invention relates to the field of high-altitude flying object ranging, and provides a method and a system for ranging a target flying object, wherein the method comprises the following steps: step S1: the ground equipment loads the ranging inquiry pulse to the first microwave and sends the first microwave to the target flying object; step S2: the transmitting system on the target flying object transmits second microwaves at preset time intervals and receives the first microwaves during the period of not transmitting the second microwaves; after receiving the first microwave, the transmitting system detects a ranging inquiry pulse, generates frame data according to the ranging inquiry pulse, assembles the frame data into a data group frame, loads the data group frame on a second microwave, and transmits the second microwave back to the ground equipment; step S3: the ground equipment receives and processes the second microwave, extracts data framing and acquires frame data, and calculates the distance between the ground equipment and the target flying object according to the frame data; the first microwave and the second microwave have the same frequency. The invention can accurately calculate the distance of the target flying object by a digital signal processing technology.
Description
Technical Field
The invention relates to the field of high-altitude flying object ranging, in particular to a method and a system for ranging a target flying object.
Background
The distance measurement principle of the existing high-altitude sounding rocket system or satellite system and the like is as follows: the sounding rocket system or the satellite system sends sounding data to the ground equipment at intervals, and in the interval time of sending the sounding data twice, the sounding data is modulated on a subcarrier through amplitude modulation, and sine waves of 800kHz are continuously sent to the ground equipment. When the distance needs to be measured, the ground equipment can transmit an inquiry pulse to the sounding rocket system or the satellite system, and the sounding rocket system or the satellite system is excited after receiving the inquiry pulse to generate a 'notch' on the transmitted sine wave. The ground equipment receives and detects the notch, and measures the distance between the sounding rocket system or the satellite system and the ground according to the time of launching and receiving the notch.
Because the signal of the sounding rocket system or the satellite system is easily influenced by the environment, the measurement signal can be greatly changed in different environments, and for the 'gap' of ranging, under the condition that the signal quality of the sounding rocket system or the satellite system is poor, the generated 'gap' is shallow and is difficult to identify artificially, so that the ranging error exceeds dozens of meters, and even can reach 375 meters.
Therefore, there is a need to develop a method and system for measuring the distance between the high-altitude target flying object and the ground equipment with high precision.
Disclosure of Invention
The technical purpose of the present invention is to solve the above-mentioned defects of the prior art, and to provide a method and a system for measuring a distance of a target flying object, so that the accuracy of measuring the distance of a high-altitude target flying object is improved.
As a first aspect of the present invention, the present invention provides a method for measuring a distance to a target flying object, comprising the steps of:
step S1: the ground equipment loads the ranging inquiry pulse to the first microwave and transmits the first microwave to the target flying object;
step S2: the transmitting system on the target flying object transmits second microwaves at preset time intervals and receives the first microwaves during the period of not transmitting the second microwaves; after receiving the first microwave, the transmitting system detects a ranging inquiry pulse, generates frame data according to the ranging inquiry pulse, assembles the frame data into a data group frame, loads the data group frame on a second microwave, and transmits the second microwave back to the ground equipment;
step S3: the ground equipment receives and processes the second microwave, extracts data framing and acquires frame data, and calculates the distance between the ground equipment and the target flying object according to the frame data; the first microwave and the second microwave have the same frequency.
The microwave refers to electromagnetic waves with the frequency of 300MHz-300 GHz.
Because the signal of the ranging inquiry pulse sent by the ground equipment and the signal of the received data framing are loaded on the microwaves with equal frequency, the same frequency is transmitted and received, and the corresponding time and distance can be directly and accurately calculated; and secondly, the frequency of the microwave is very high, and the anti-interference capability is strong in the transmission process.
According to an exemplary embodiment of the invention, the first microwave and the second microwave each have a frequency of 1-3 GHz.
According to an example embodiment of the present invention, in step S2, the method for loading the data framing onto the second microwave includes:
and after PSK phase modulation is carried out on the data framing, modulation of radio frequency signals is carried out.
According to an exemplary embodiment of the present invention, the signal is blanked before modulation of the radio frequency signal.
According to an example embodiment of the present invention, in step S2, the method for generating frame data according to ranging interrogation pulse includes:
detecting a ranging inquiry pulse, judging whether the ranging inquiry pulse is effective, if so, recording the phase of a phase accumulator at the front edge of the ranging inquiry pulse, and starting counting by a clock of a transmitting end system; when the data framing is started, the clock of the transmitting end system stops counting;
the frame data comprises a clock count value of a transmitting end system and a ranging zero correction value;
the ranging zero correction value is the phase accumulator phase of the leading edge of the ranging interrogation pulse.
The clock counting value of the transmitting end system is the number of times of clock counting of the transmitting end system.
According to an example embodiment of the present invention, the method of generating frame data according to a ranging interrogation pulse further comprises:
if the detected ranging interrogation pulse is valid, then the interrogation pulse count value is incremented by one; the frame data also includes an interrogation pulse count value.
According to an exemplary embodiment of the present invention, before the distance between the ground device and the target flying object is calculated through the frame data, it is determined whether the target flying object detects a valid ranging inquiry pulse through an inquiry pulse count value, if the inquiry pulse count value is the same as the last received inquiry pulse count value, the target flying object does not detect a valid ranging inquiry pulse, and the current measurement result is invalid; if the inquiry pulse count value is increased by one than the inquiry pulse count value received last time, the target flying object detects effective ranging inquiry pulses, and the measurement result is effective.
According to an example embodiment of the present invention, the method for calculating the distance between the ground device and the target flying object through the frame data includes:
and calculating the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data group frame to the target device through the frame data, and calculating the distance between the ground device and the target flying object according to the sum of the times.
According to an example embodiment of the present invention, the sum of the time the ranging interrogation pulse is transmitted to the target flying object and the time the data burst is transmitted to the target device is calculated using equation (1):
T＝T2-T1 (1)
wherein, T2 is the time from the ground equipment sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
t1 is the time in seconds from the detection of the ranging interrogation pulse to the start of the framing of the data by the transmitting system on the target flying object;
t is the sum of the time that the ranging interrogation pulse is transmitted to the target flying object and the time that the data framing is transmitted to the target device, and is expressed in seconds.
According to an exemplary embodiment of the present invention, the distance between the ground device and the target flying object calculated according to the sum of the time is calculated by using formula (2):
R＝T·C/2 (2)
wherein R is the distance between the ground equipment and the target flying object and the unit is meter;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
c is the speed of light in meters per second.
According to an example embodiment of the present invention, in step S1, when the ground device transmits the first microwave, the ground system clock starts counting; in step S3, when the ground device processes the second microwave, the ground device further detects a data framing frame header, and when the data framing frame header is detected, the ground system clock stops counting and records a receiving bit synchronization phase zero, where the receiving bit synchronization phase zero is a phase of a frame header phase accumulator of the data framing received by the ground device.
According to an exemplary embodiment of the present invention, the calculation method of T2 adopts formula (3):
T2＝Discount2/sysclk2+Bitphase/216/Rc (3)
wherein, T2 is the time from the ground equipment sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
the count2 is the clock count value of the slave ground system;
sysclk2 is the ground system clock frequency in Hz;
Bitphase/216synchronizing the phase zero for the normalized received bit;
Rcin bps for information rate.
According to an exemplary embodiment of the present invention, the calculation method of T1 adopts formula (4):
T1＝Discount1/sysclk1+Phase/216/Rc (4)
wherein T1 is the time in seconds from the detection of the ranging interrogation pulse by the transmitting system on the target flying object to the start of the assembly of the data framing;
the count1 is the count of the clock of the transmitting end system;
sysclk1 is the clock frequency of the transmitting end system in Hz;
Phase/216zero correction value for normalized distance measurement;
Rcin bps for information rate.
As a second aspect of the present invention, there is provided a system for measuring a distance to a target flying object, comprising:
the ground equipment is used for transmitting first microwaves with ranging inquiry pulses to the target flying object, receiving and processing second microwaves transmitted by a transmitting system on the target flying object, extracting frame data in a data group frame, and calculating the distance between the ground equipment and the target flying object through the frame data;
the transmitting system is arranged on the target flying object and used for receiving the first microwave, detecting the ranging inquiry pulse, generating frame data according to the ranging inquiry pulse, assembling the frame data into a data framing, loading the data framing onto the second microwave and transmitting the second microwave to the ground equipment; the first microwave and the second microwave have the same frequency.
According to an example embodiment of the invention, the ground equipment comprises:
the pulse generating and loading module is used for generating a ranging inquiry pulse and loading the ranging inquiry pulse to the first microwave;
the transmitting and receiving module is used for transmitting first microwaves and receiving second microwaves;
the down-conversion module is used for reducing the frequency of the second microwave;
a synchronization module for synchronizing data framing;
the data extraction module is used for extracting frame data in the data framing;
and the distance calculation module is used for calculating the distance between the ground equipment and the target flying object according to the frame data.
According to an example embodiment of the present invention, the transmission system includes:
the pulse detection module is used for detecting a ranging inquiry pulse;
the frame data generating module is used for generating frame data according to the ranging inquiry pulse;
a framing module for assembling the frame data into data framing;
the PSK modulation module is used for carrying out PSK modulation on the data framing;
the analog modulation module is used for completing modulation, amplification and output of radio frequency signals;
and the circulator is used for transmitting the second microwave and receiving the first microwave.
According to an exemplary embodiment of the invention, the first microwave and the second microwave each have a frequency of 1-3 GHz.
The invention has the beneficial effects that:
the method and the system for measuring the distance of the target flying object have the advantages that the receiving and sending are same in frequency and very high in frequency, the information rate of 1MHz is adopted, the PSK phase modulation mode is adopted, the distance between the ground equipment and the target flying object can be directly and accurately calculated through the digital signal processing technology, and compared with the existing amplitude modulation mode, the performance is more stable, and the precision is higher.
According to the method and the system, when the distance between the ground equipment and the target flying object is calculated, the distance measurement precision is further corrected by collecting the phase of the accumulator, and the system error caused by the phase deviation is avoided.
Drawings
FIG. 1 is a schematic structural diagram of a surface installation;
FIG. 2 shows a schematic diagram of a transmitting system;
FIG. 3 shows a timing diagram of ranging for a target flying object;
fig. 4 shows a diagram of data framing generation and modulation principles for a transmission system.
The system comprises a ground device 1, a pulse generation loading module 11, a transmitting and receiving module 12, a down-conversion module 13, a synchronization module 14, a data extraction module 15, a distance calculation module 16, a transmitting system 2, a pulse detection module 21, a frame data generation module 22, a sounding code receiving module 23, a telemetry data receiving module 24, a framing module 25, a PSK modulation module 26, a signal vacancy processing module 27, an analog modulation module 28 and a circulator 29.
Detailed Description
The following detailed description of embodiments of the invention, but the invention can be practiced in many different ways, as defined and covered by the claims.
According to a first aspect of the present invention, there is provided a system for ranging a target flying object, which is a flying object in a near space, including a rocket, a satellite, etc.
The system comprises a ground device 1 and a launching system 2 arranged on a target flying object. The ground facility 1 transmits a first microwave with a ranging interrogation pulse to a transmission system 2 of the target aircraft. After receiving the first microwave, the transmitting system 2 detects the ranging interrogation pulse, generates frame data according to the ranging interrogation pulse, assembles the frame data into a data group frame, loads the data group frame on a second microwave with the same frequency as the first microwave, and transmits the second microwave to the ground equipment 1. The ground equipment 1 receives the second microwave and extracts frame data in the data group frame on the second microwave, and the distance between the ground equipment 1 and the target flying object is calculated through the frame data.
As shown in fig. 1, the floor device 1 includes:
the pulse generating and loading module 11 is used for generating a ranging inquiry pulse and loading the ranging inquiry pulse to a first microwave;
a transmitting and receiving module 12 for transmitting a first microwave and receiving a second microwave;
a down-conversion module 13 for reducing the frequency of the second microwave;
a synchronization module 14 for synchronizing the framing of the data on the second microwave;
the data extraction module 15 is used for extracting frame data in the data framing;
and the distance calculation module 16 is used for calculating the distance between the ground equipment and the target flying object according to the frame data.
As shown in fig. 2, the transmission system 2 includes:
a pulse detection module 21 for detecting a ranging interrogation pulse;
a frame data generating module 22, configured to generate frame data according to the ranging inquiry pulse;
the sounding code receiving module 23 is configured to receive circuit data acquired by the sonde;
a telemetry data receiving module 24 for receiving telemetry data;
a framing module 25, configured to assemble frame data, circuit data collected by the sonde, and telemetry data into data frames;
a PSK modulation module 26, configured to PSK modulate the data framing;
a signal vacancy processing module 27, configured to perform vacancy processing on the PSK-modulated signal;
the analog modulation module 28 is used for completing modulation, amplification and output of radio frequency signals;
a circulator 29 for transmitting the second microwave and receiving the first microwave.
According to a second aspect of the invention, the above system is used for measuring the distance of a target flying object, as shown in fig. 3, the method comprising the steps of:
step S1: the pulse generating and loading module 11 of the ground equipment 1 loads the ranging interrogation pulse on the first microwave and generates the first microwave to the transmitting system 2 of the target flying object through the transmitting and receiving module 12.
At this time, the ground system clock of the ground device 1 starts counting. The frequency of the first microwave is 1780 MHz.
The ground equipment 1 transmits signals and receives signals to be matched with the transmitting system 2 on the target flying object, the transmitting frame length of the transmitting system 2 on the target flying object is 1000bit, the transmitted signals are 1:1 vacancy, namely, the signals are data of 1 mu s, and the data of 1 mu s is transmitted after 1 mu s vacancy. Therefore, the ranging period of the surface device 1 is 1000 × 2 μ s — 2 ms. The frequency of the ranging interrogation pulse is 500Hz, i.e. 500 ranging interrogation pulses are transmitted in 1 second. The maximum unambiguous distance is 300 km.
Step S2: as shown in fig. 4, the transmitting system 2 on the target flying object transmits the second microwave through the circulator 29 every 1 μ s, the time for transmitting the second microwave every time is 1 μ s, and the length of the transmitting frame is 1000 bits. The first microwave is received through the circulator 29 in the vacant period in which the second microwave is not transmitted, the pulse detection module 21 detects the ranging inquiry pulse and confirms whether the ranging inquiry pulse is valid, and if so, outputs a pulse signal of TTL level. And carrying out clock counting of a transmitting end system on the rising edge of the pulse signal, and recording the phase of a 1Mbps phase accumulator at the leading edge of the ranging interrogation pulse. The 1Mbps phase accumulator is selected because the modulation rate of the PSK modulation module 26 is 1Mbps, which is consistent with the rate at which the terrestrial device 1 demodulates.
When the last data framing is finished, the framing module 25 starts framing, the clock counting of the transmitting end system stops, and the frame data generating module 22 generates frame data. The frame data comprises a ranging frame header, a ranging frame header count, a transmitting end system clock count value, a ranging zero header correction value and an interrogation pulse count value. The head of the ranging frame is the starting part of the frame data, and other information of the frame data can be found through the head of the ranging frame. The counting value of the ranging frame head is the number of the recorded transmitted frames, the ground equipment 1 compares the counting value of the ranging frame head with the received frame number to judge whether to demodulate the frame loss, and if the counting of the demodulating frame head is discontinuous, the frame loss is indicated. The transmit-end system clock count value is the number of counts of the transmit-end system clock from the time a valid ranging pulse is detected to the beginning of the assembly of the data burst frame. The ranging zero-head correction value is the phase of the 1Mbps phase accumulator at the leading edge of the ranging interrogation pulse, that is, when a valid ranging interrogation pulse is detected, the phase value corresponding to the accumulator when the transmitting system 2 generates a 1Mbps information rate, because the phase value has a deviation from the phase value corresponding to the information rate generated by the ground device 1, it needs to be calculated in the time consumed on the transmitting system 2. The interrogation pulse count value represents a cumulative number of valid ranging interrogation pulses recorded, the interrogation pulse count value being incremented by 1 if a valid ranging interrogation pulse is detected; ground device 1 may know whether transmitting system 2 identified a valid ranging interrogation pulse by interrogating the pulse count value.
The framing module 25 frames the frame data generated by the frame data generating module 22, the circuit data acquired by the sonde in the sounding code receiving module 23, and the telemetry data acquired by the telemetry data receiving module 24 into data according to a certain format, and a frame header is further provided at the front end of the data framing for synchronization.
The PSK modulation module 26 BPSK modulates the data framing at 1Mbps, which is generated using a 1Mbps phase accumulator. After the null processing of the signal null processing module 27, there is a null of 1 μ s between every two modulation signals of 1 μ s, that is, the modulation signals of 1 μ s are transmitted every 1 μ s, and the circulator 29 receives the first microwave in the null period. The modulation and amplification of the radio frequency signal are completed through the analog modulation module 28, and the framing of the data is completed and the data is loaded on the second microwave, wherein the frequency of the second microwave is 1780 MHz. The second microwaves are transmitted to the surface installation 1 by means of the circulator 29.
The data frames are transmitted while being assembled, so the time for modulation and radio frequency processing is negligible, and the time consumed from the detection of the ranging interrogation pulse to the transmission of the response signal (frame data) is the time from the detection of the ranging interrogation pulse to the start of the assembly of the data frames, and the time from the detection of the ranging interrogation pulse to the waiting of the completion of the transmission of the previous frame data frame.
Step S3: as shown in fig. 1, the transmitting and receiving module 12 of the surface equipment 1 receives the second microwave, and the down-conversion module 13 reduces the frequency of the second microwave.
The synchronization module 14 detects the frame header of the data framing, stops counting by the ground system clock, records the phase of the phase accumulator when the frame header of the data framing is detected, and obtains the data framing through carrier synchronization, bit synchronization and frame synchronization of the signals with reduced frequency.
The data extraction module 15 extracts data in the data framing, packs the ground system clock count value recorded by the ground device 1, the receiving bit synchronization phase zero header and the demodulated data framing without the frame header, and reports the packed data to the monitoring computer. The receive bit synchronization phase null refers to a phase value of a corresponding phase accumulator when the ground device 1 detects a frame header of a received signal data framing, and the phase accumulator refers to a phase accumulator which generates a 1Mbps information rate required for demodulation. For correcting the time at which the ground equipment 1 receives the data and thus the distance.
The format of the packed frame is as follows:
the above-mentioned packet frame has 136 bytes, wherein a frame header of 4 bytes is used for frame synchronization, a ground system clock count of 2 bytes, and a received bit synchronization phase zero header of 2 bytes. The data framing without the frame header includes frame data generated by the frame data generating module 22, circuit data acquired by the sonde in the sounding code receiving module 23, and telemetry data generating data framing acquired by the telemetry data receiving module 24. The data framing of the removed frame header can be 121 bytes, and can also be longer or shorter, and the length of the data framing is determined according to the telemetry data and the data of the sonde.
After the data extraction module 15 packs the data into a packed frame, the packed frame is sent to the monitoring computer of the ground equipment 1, and meanwhile, the starting pulse generation loading module 11 generates a ranging inquiry pulse.
The monitoring computer is internally provided with a distance calculation module 16 and also comprises other modules for processing circuit data and telemetering data acquired by the sonde.
Before calculating the distance, the distance calculation module 16 first determines whether the measurement is valid, and the determination method is as follows: comparing the inquiry pulse count value in the frame data with the inquiry pulse count value received last time, if the value is increased by 1, the obtained measurement data is valid, and performing the distance calculation of the next step; if the numerical value is not changed, the obtained measurement data is invalid, and if the numerical value is invalid, the distance does not need to be calculated.
When calculating the distance, the distance calculation module 16 calculates the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data group frame to the target device through the packed frame data, and then calculates the distance between the ground device 1 and the target flying object according to the time.
The method for calculating the sum of the time of transmission of the ranging interrogation pulse to the target flying object and the time of transmission of the data framing to the target device adopts the formula (1):
T＝T2-T1(1)
wherein, T2 is the time from the ground device 1 sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
t1 is the time in seconds from the detection of the ranging interrogation pulse to the assembly into a data frame by the transmitting system 2 on the target flying object;
t is the sum of the time that the ranging interrogation pulse is transmitted to the target flying object and the time that the data framing is transmitted to the target device, and is expressed in seconds.
The calculation method of T2 adopts formula (3):
T2＝Discount2/sysclk2+Bitphase/216/Rc (3)
wherein, T2 is the time from the ground device 1 sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
the count2 is the count value of the ground system clock;
sysclk2 is the ground system clock frequency in Hz;
bitphase is the zero head of the receiving bit synchronous phase;
Bitphase/216synchronizing the phase zero for the normalized received bit;
rc is the information rate of 1Mbps in bps.
The calculation method of T1 adopts formula (4):
T1＝Discount1/sysclk1+Phase/216/Rc (4)
where T1 is the time in seconds from the detection of the ranging interrogation pulse by the transmitting system 2 on the target flight to the framing of the data set (i.e., the time spent on the target flight);
the count1 is the count value of the clock of the transmitting terminal system;
sysclk1 is the clock frequency of the transmitting end system in Hz;
phase is a ranging zero correction value;
Phase/216zero correction value for normalized distance measurement;
Rcan information rate of 1Mbps in bps.
The time T2 from the transmission of the ranging inquiry pulse to the reception of the frame data by the ground device 1 includes: the time when the ranging inquiry pulse is transmitted to the target flying object, the time T1 when the transmission system 2 is worn (waiting for the last frame data to be transmitted), and the time when the data group frame is transmitted to the ground device 1. In fact, the time T of the data signal coming and going on the road is T2-T1, and since the frequency of the first microwave is the same as that of the second microwave, the time of the data signal coming and going can be considered to be the same, which is convenient for calculating the distance and is also beneficial to improving the precision. Meanwhile, the frequency of the first microwave and the frequency of the second microwave are 1780MHz, so that the frequency is quite high, the anti-interference capability is strong, and the detection precision is further improved.
The recorded time T2 of the surface device 1 is calculated by the surface system clock count value and the reception bit synchronization phase zero header. The count of the ground system clock is counted by taking 1/sysclk1 as a unit, and the receiving bit synchronization phase null is the phase value of the corresponding phase accumulator when the ground device 1 detects the frame header of the received signal data framing. The time T1 spent on the transmitting system 2 is calculated by the transmitting system clock count value and the ranging zero correction value. The count of the transmit end system clock is counted in units of 1/sysclk2 and the ranging zero correction value is the phase difference calculated when a valid ranging interrogation pulse is detected. The ground system clock frequency and the transmitting end system clock frequency may be the same or different. RcThe symbol rate is the same as the rate of BPSK modulation of the transmission system 2 and the demodulation rate of the terrestrial device 1, thereby achieving high accuracy.
The calculation method of the distance between the ground equipment 1 and the target flying object adopts a formula (2):
R＝T·C/2 (2)
wherein R is the distance between the ground equipment and the target flying object and the unit is meter;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
c is the speed of light in meters per second.
The sampling rate of the ranging output is 20 Hz/s.
Because the distance measurement is carried out for a plurality of times, if the difference between the one-time distance measurement value and other distance measurement values is larger, the elimination can also be carried out.
By the distance measurement method, a digital signal processing technology can be adopted, and the distance is calculated after phase modulation processing is carried out by adopting the information rate of 1Mbps, so that the detection result is more accurate; the method can be realized on an SDR (Software Defined Radio) platform, has universality and modularization, provides good technical support for atmospheric environment detection of space-approaching rocket systems, satellite systems and the like, and has certain popularization and application values.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A method for measuring the distance of a target flying object is characterized by comprising the following steps:
step S1: the ground equipment loads the ranging inquiry pulse to the first microwave and transmits the first microwave to the target flying object; when the ground equipment transmits the first microwave, the ground system clock starts counting;
step S2: the transmitting system on the target flying object transmits second microwaves at preset time intervals and receives the first microwaves during the period of not transmitting the second microwaves; after receiving the first microwave, the transmitting system detects a distance measurement inquiry pulse, generates frame data according to the distance measurement inquiry pulse, assembles the frame data into a data group frame, loads the data group frame on a second microwave, and transmits the second microwave back to the ground equipment; the method for generating frame data according to the ranging interrogation pulse comprises the following steps: detecting a ranging inquiry pulse, judging whether the ranging inquiry pulse is effective, if so, recording the phase of a phase accumulator at the front edge of the ranging inquiry pulse, and starting counting by a clock of a transmitting end system; when the data framing is started, the clock of the transmitting end system stops counting; the frame data comprises a counting value of a clock of a transmitting end system and a ranging zero-head correction value; the ranging zero correction value is the phase accumulator phase of the leading edge of the ranging interrogation pulse;
step S3: the ground equipment receives and processes the second microwave, extracts data framing and acquires frame data, and calculates the distance between the ground equipment and the target flying object according to the frame data; the ground equipment also detects the frame head of the data framing frame when processing the second microwave, when detecting the frame head of the data framing frame, the ground system clock stops counting and records a receiving bit synchronous phase zero head, wherein the receiving bit synchronous phase zero head is the phase of a frame head time phase accumulator when the ground equipment receives the data framing frame; the method for calculating the distance between the ground equipment and the target flying object through the frame data comprises the following steps:
calculating the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data group frame to the target device through the frame data, and calculating the distance between the ground device and the target flying object according to the sum of the times;
the sum of the time that the ranging interrogation pulse is transmitted to the target flying object and the time that the data framing is transmitted to the target device is calculated using equation (1):
T＝T2-T1 (1)
wherein, T2 is the time from the ground equipment sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
t1 is the time in seconds from the detection of the ranging interrogation pulse to the start of the framing of the data by the transmitting system on the target flying object;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
and calculating the distance between the ground equipment and the target flying object according to the sum of the time by adopting a formula (2):
R＝T·C/2 (2)
wherein R is the distance between the ground equipment and the target flying object and the unit is meter;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
c is the speed of light, and the unit is meter/second;
the calculation method of the T2 adopts the formula (3):
T2＝Discount2/sysclk2+Bitphase/216/Rc (3)
wherein, the count2 is a ground system clock count value;
sysclk2 is the ground system clock frequency in Hz;
Bitphase/216synchronizing the phase zero for the normalized received bit;
Rcis the information rate, in bps;
the calculation method of the T1 adopts the formula (4):
T1＝Discount1/sysclk1+Phase/216/Rc (4)
the count1 is a clock count value of the transmitting end system;
sysclk1 is the clock frequency of the transmitting end system in Hz;
Phase/216zero correction value for normalized distance measurement;
Rcis the information rate, in bps;
the first microwave and the second microwave have the same frequency.
2. A method as claimed in claim 1, wherein the first and second microwaves have a frequency of 1-3 GHz.
3. The method for ranging a target flying object according to claim 1, wherein in the step S2, the method for loading the data framing on the second microwave comprises:
and carrying out PSK phase modulation on the data framing, and then carrying out modulation on the radio frequency signal.
4. A method as claimed in claim 1, wherein in step S2, the method for generating frame data according to ranging interrogation pulse further comprises:
if the detected ranging interrogation pulse is valid, then the interrogation pulse count value is incremented by one; the frame data further includes an interrogation pulse count value;
in step S3, before the distance between the ground device and the target flying object is calculated through the frame data, it is first determined whether the target flying object detects a valid ranging inquiry pulse through an inquiry pulse count value, if the inquiry pulse count value is the same as the last received inquiry pulse count value, the target flying object does not detect a valid ranging inquiry pulse, and the current measurement result is invalid; if the inquiry pulse count value is increased by one than the inquiry pulse count value received last time, the target flying object detects effective ranging inquiry pulses, and the measurement result is effective.
5. A system for ranging a target flying object, comprising: the ground equipment (1) and the transmitting system (2);
the ground equipment (1) is used for transmitting first microwaves with ranging inquiry pulses to the target flying object, receiving and processing second microwaves transmitted by the transmitting system (2) on the target flying object, extracting frame data in a data group frame, and calculating the distance between the ground equipment (1) and the target flying object through the frame data; when the ground equipment (1) transmits the first microwave, the ground system clock starts counting; the ground equipment also detects the frame head of the data framing frame when processing the second microwave, when detecting the frame head of the data framing frame, the ground system clock stops counting and records a receiving bit synchronous phase zero head, wherein the receiving bit synchronous phase zero head is the phase of a frame head time phase accumulator when the ground equipment receives the data framing frame; the method for calculating the distance between the ground equipment and the target flying object through the frame data comprises the following steps:
calculating the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data group frame to the target device through the frame data, and calculating the distance between the ground device and the target flying object according to the sum of the times;
the sum of the time that the ranging interrogation pulse is transmitted to the target flying object and the time that the data framing is transmitted to the target device is calculated using equation (1):
T＝T2-T1 (1)
wherein, T2 is the time from the ground equipment sending the ranging inquiry pulse to the detection of the data framing frame header, and the unit is second;
t1 is the time in seconds from the detection of the ranging interrogation pulse to the start of the framing of the data by the transmitting system on the target flying object;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
and calculating the distance between the ground equipment and the target flying object according to the sum of the time by adopting a formula (2):
R＝T·C/2 (2)
wherein R is the distance between the ground equipment and the target flying object and the unit is meter;
t is the sum of the time of transmitting the ranging inquiry pulse to the target flying object and the time of transmitting the data framing to the target equipment, and the unit is second;
c is the speed of light, and the unit is meter/second;
the calculation method of the T2 adopts the formula (3):
T2＝Discount2/sysclk2+Bitphase/216/Rc (3)
wherein, the count2 is a ground system clock count value;
sysclk2 is the ground system clock frequency in Hz;
Bitphase/216synchronizing the phase zero for the normalized received bit;
Rcis the information rate, in bps;
the calculation method of the T1 adopts the formula (4):
T1＝Discount1/sysclk1+Phase/216/Rc (4)
the count1 is a clock count value of the transmitting end system;
sysclk1 is the clock frequency of the transmitting end system in Hz;
Phase/216zero correction value for normalized distance measurement;
Rcis the information rate, in bps;
the transmitting system (2) is arranged on the target flying object and used for receiving the first microwave, detecting the ranging inquiry pulse, generating frame data according to the ranging inquiry pulse, assembling the frame data into a data frame, loading the data frame onto the second microwave and transmitting the second microwave to the ground equipment (1); the method for generating frame data according to the ranging interrogation pulse comprises the following steps: detecting a ranging inquiry pulse, judging whether the ranging inquiry pulse is effective, if so, recording the phase of a phase accumulator at the front edge of the ranging inquiry pulse, and starting counting by a clock of a transmitting end system; when the data framing is started, the clock of the transmitting end system stops counting; the frame data comprises a counting value of a clock of a transmitting end system and a ranging zero-head correction value; the ranging zero correction value is the phase accumulator phase of the leading edge of the ranging interrogation pulse;
the first microwave and the second microwave have the same frequency.
6. System for ranging a target flying object according to claim 5, characterized in that said ground equipment (1) comprises:
the pulse generating and loading module (11) is used for generating a ranging inquiry pulse and loading the ranging inquiry pulse to the first microwave;
a transmitting and receiving module (12) for transmitting first microwaves and receiving second microwaves;
a down-conversion module (13) for reducing the frequency of the second microwave;
a synchronization module (14) for synchronizing the framing of the data;
a data extraction module (15) for extracting frame data in the data framing;
and the distance calculation module (16) is used for calculating the distance between the ground equipment (1) and the target flying object according to the frame data.
7. A system as claimed in claim 6, wherein the launching system comprises:
a pulse detection module (21) for detecting a ranging interrogation pulse;
a frame data generating module (22) for generating frame data according to the ranging interrogation pulse;
a framing module (25) for assembling the frame data into data frames;
a PSK modulation module (26) for PSK modulating the data framing;
the analog modulation module (28) is used for completing modulation, amplification and output of radio frequency signals;
a circulator (29) for transmitting the second microwave and receiving the first microwave.
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