CN108957501B - Digital ground multimedia broadcast synchronous foundation navigation positioning method and system - Google Patents
Digital ground multimedia broadcast synchronous foundation navigation positioning method and system Download PDFInfo
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- CN108957501B CN108957501B CN201810562349.2A CN201810562349A CN108957501B CN 108957501 B CN108957501 B CN 108957501B CN 201810562349 A CN201810562349 A CN 201810562349A CN 108957501 B CN108957501 B CN 108957501B
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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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/18523—Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service
Abstract
The invention discloses a foundation navigation positioning method and system for digital ground multimedia broadcast synchronization. The method for positioning the foundation navigation positioning system of the digital ground multimedia broadcasting synchronization mainly comprises the following steps: 1) the transmitting station transmits a digital terrestrial multimedia broadcasting signal. 2) A digital terrestrial multimedia broadcast signal is captured. 3) And calculating the time difference Dt between the arrival time T2 of the super frame head pseudo-random sequence of the digital terrestrial multimedia broadcasting signal and the universal reference arrival time T1. 4) The ground based navigation beacon transmitter transmits a ground based navigation beacon signal at time T3. 5) And positioning the ground-based navigation beacon receiver. The multiple ground navigation beacon transmitters of the invention adopt digital ground multimedia broadcast signals to carry out time synchronization, thus overcoming the problem of dependence of the existing system on satellite navigation.
Description
Technical Field
The invention relates to a radio navigation technology, in particular to a foundation navigation positioning method and a foundation navigation positioning system for digital terrestrial multimedia broadcasting synchronization.
Background
In recent years, with the development of artificial intelligence technology, unmanned aerial vehicles and unmanned vehicles are widely used. The existing unmanned technology mostly adopts a satellite positioning navigation system as a navigation positioning time service means, and has the main problems that ground signals are weak, and the signals are easily unusable due to shielding and interference. With the maturation of satellite navigation jamming and countermeasure technologies, and military countermeasures across large countries, there is increasing concern about the availability of satellite navigation systems.
The adoption of the ground-based navigation beacon for navigation positioning is an important backup and alternative means of satellite navigation, but the problem of low cost and high precision time synchronization among transmitters of the ground-based navigation beacon must be solved. If time synchronization between transmitters is still achieved by relying on satellite navigation positioning time service, it is likely that synchronization between ground based navigation beacon transmitters will also be affected if satellite navigation positioning is unavailable. Therefore, means other than the satellite navigation positioning system must be found to achieve time synchronization between the ground based navigation beacon transmitters.
Disclosure of Invention
The present invention is directed to solving the problems of the prior art.
The technical scheme adopted for achieving the purpose of the invention is as follows: a foundation navigation positioning system for digital ground multimedia broadcast synchronization comprises a digital ground multimedia broadcast transmitting station, a global navigation satellite system, a foundation navigation beacon transmitter and a foundation navigation beacon receiver.
The digital terrestrial multimedia broadcasting transmitting station transmits a digital terrestrial multimedia broadcasting signal.
The global navigation satellite system transmits satellite navigation signals. Generally, the gnss mainly includes common space-based mid-orbit radio navigation positioning systems such as GPS, beidou, galileo, glonass navigation satellites, and the like.
And the ground-based navigation beacon transmitter captures and tracks the digital ground multimedia broadcast signals and calculates the arrival time of the digital ground multimedia broadcast signals and the super-frame header pseudorandom sequence. And the ground-based navigation beacon transmitter also receives satellite navigation signals, and calculates the difference value between the arrival time of the pseudo-random sequence and the world coordination time when acquiring the position of the ground-based navigation beacon transmitter and the world coordination. Further, the ground based navigation beacon transmitter generates and transmits a ground based navigation beacon signal time-synchronized with other ground based navigation beacon transmitters with reference to the arrival time of the pseudo random sequence and the difference value.
The ground-based navigation beacon receiver receives and processes the ground-based navigation beacon signal to obtain self-position information.
Furthermore, the ground navigation beacon transmitter mainly comprises a digital ground multimedia broadcast capturing and tracking module, a satellite navigation receiving module, a ground navigation beacon transmitting time adjusting module and a ground navigation beacon signal generating and transmitting module.
The satellite navigation receiving module receives and processes the satellite navigation signal to obtain a universal reference arrival time T1, and transmits the universal reference arrival time T1 to the ground-based navigation beacon transmission time adjusting module.
The digital terrestrial multimedia broadcasting capturing and tracking module tracks and captures digital terrestrial multimedia broadcasting signals. The digital terrestrial multimedia broadcasting capturing and tracking module calculates the arrival time T2 of the digital terrestrial multimedia broadcasting signal super frame header pseudo-random sequence and transmits the arrival time T2 to the ground-based navigation beacon transmitting time adjusting module.
The ground-based navigation beacon transmission time adjusting module calculates a time difference Dt between an arrival time T2 of a super frame header pseudorandom sequence of the digital terrestrial multimedia broadcast signal and a universal reference arrival time T1. According to the time difference Dt, the ground-based navigation beacon transmission time adjusting module adjusts the transmission reference time T3 of the ground-based navigation beacon signal, and transmits the transmission reference time T3 to the ground-based navigation beacon signal generating and transmitting module.
The ground based navigation beacon signal generation and transmission module generates and transmits a ground based navigation beacon signal at time T3.
The ground-based navigation beacon receiver receives and processes the ground-based navigation beacon signal to obtain self-position information.
Furthermore, the ground-based navigation beacon receiver mainly comprises a digital ground multimedia broadcast receiving module, a ground-based navigation beacon database, a position initial estimation module, a ground-based navigation beacon capturing and tracking module and a ground-based navigation beacon positioning module.
And the digital terrestrial multimedia broadcasting receiving module receives and demodulates the digital terrestrial multimedia broadcasting signal so as to obtain the auxiliary information of the foundation navigation beacon and the geographic coordinates of the digital terrestrial multimedia broadcasting transmitting station. And recording the geographical coordinates of the digital terrestrial multimedia broadcasting transmitting station as a position initial estimation result.
And the digital terrestrial multimedia broadcasting receiving module outputs the geographical coordinates of the transmitting broadcasting station to the position initial estimation module.
And the foundation navigation beacon database receives the auxiliary information and the initial position estimation result of the foundation navigation beacon sent by the digital ground multimedia broadcast receiving module, and determines a spreading code set I of the foundation navigation beacon transmitter according to the initial position estimation result and the auxiliary information. The set II of spreading codes of the ground-based navigation beacon transmitters which can be received by the database of the ground-based navigation beacon is a subset of the set I of spreading codes of the ground-based navigation beacon transmitters.
Further, the auxiliary information of the ground-based navigation beacon mainly comprises the geographic coordinates of the transmitter of the ground-based navigation beacon, a spreading code adopted by the transmitter of the ground-based navigation beacon, an information modulation mode of the transmitter of the ground-based navigation beacon, the transmitting power of the transmitter of the ground-based navigation beacon, the signal coverage of the transmitter of the ground-based navigation beacon and whether the transmitter of the ground-based navigation beacon is in an effective working state.
And the ground-based navigation beacon receiver retrieves a ground-based navigation beacon database according to the position initial estimation result, and brings the spread spectrum code of the ground-based navigation beacon transmitter which is in an effective working state at present and has a coverage range containing the position initial estimation result into a spread spectrum code set I of the ground-based navigation beacon transmitter.
The position initial estimation module receives the geographical coordinates of a transmitting broadcast station from the digital terrestrial multimedia broadcast receiving module as a position initial estimation result.
And the ground-based navigation beacon acquisition tracking module acquires and tracks the ground-based navigation beacon signals according to the spread spectrum code set, extracts the measurement quantity from the tracked ground-based navigation beacon signals and outputs the measurement quantity.
And the ground-based navigation beacon positioning module is used for positioning the ground-based navigation beacon receiver.
A method for positioning a foundation navigation positioning system of digital ground multimedia broadcasting synchronization mainly comprises the following steps:
1) the digital terrestrial multimedia broadcasting transmitting station transmits the digital terrestrial multimedia broadcasting signal and sets the universal reference arrival time T1 of the super frame head pseudo random sequence of the digital terrestrial multimedia broadcasting signal.
2) The ground-based navigation beacon transmitter tracks and captures the digital terrestrial multimedia broadcasting signal and records the arrival time T2 of the pseudo-random sequence of the superframe header of the digital terrestrial multimedia broadcasting signal.
3) And calculating the time difference Dt between the arrival time T2 of the super frame head pseudo-random sequence of the digital terrestrial multimedia broadcasting signal and the universal reference arrival time T1.
The main steps of calculating the time difference Dt between the arrival time T2 of the super-frame header pseudorandom sequence and the universal reference arrival time T1 are as follows:
3.1) continuously monitoring the navigation satellite tracking condition of the satellite navigation receiver.
3.2) when the condition that a satellite navigation receiver tracks a navigation satellite is good, acquiring the arrival time of k +1 times of the super-frame header pseudo-random sequenceT2, and form a set { T2 }0，T21，T23，…，T2k}。
The following two schemes are mainly used for judging the good condition of the satellite navigation receiver for tracking the navigation satellite:
I) when the satellite navigation receiver receives signals of more than M navigation satellites, the tracking condition is good.
II) when more than M navigation satellites are received and all the pseudo-moment residuals are less than L, the tracking condition is good.
Based on the set { T20，T21，T23，…，T2kCalculating the time difference Dt for each element in the sequence D, thereby obtaining a time difference sequence D0-k＝{dt0,dt1,dt2,…dtk}。
3.3) sequence D according to the time difference0-kOnline solving of time difference D of current momenttk。
Solving the time difference D of the current momenttkThe main steps are as follows:
3.3.1) calculating the time difference sequence D of the past N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkMean value of }
Sum square root error σt。
3.3.2) calculating the time difference sequence D within N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkEach element in (f) and σtThe absolute value x of the difference between x, if x>3σtEliminating the elements corresponding to the x to obtain an updated time difference sequence D 'in the N time moments'NK。
3.3.3) according to the updated time difference sequence D 'in the N time moments'NKTo obtain Dtk。
3.4) keeping D when no navigation satellite signal can be tracked at all and/or not welltkDoes not change and does not update D0-k。
4) According to the time difference Dt, sending a foundation navigation beaconThe transmitter adjusts the transmission reference time T3 of the ground-based navigation beacon signal so that T3 is T2-Dtk。
The main steps of the ground based navigation beacon transmitter adjusting the transmission reference time T3 of the ground based navigation beacon signal are as follows:
4.1) ground based navigation Beacon transmitter maintains a 125 ms counter, the clock period T of whichcAs follows:
Tc＝1/fc。 (1)
in the formula (f)cThe counter clock nominal frequency.
The counter starts counting at 0 and has a maximum value of 0.125fc-1。
4.2) starting a counter at the arrival time T1 of the current super-frame header pseudo-random sequence.
4.3) when the counting of the counter reaches the maximum value, calculating the difference between the current time and the arrival time of the nearest super frame header pseudo-random sequence and recording the difference as a k time counting difference Dck。
4.4) counting the difference Dc according to the k-timekFine-tuning local clock frequency to obtain the count difference at the next time when the counter counts to the maximum value, i.e. the k +1 time count difference Dck+1And decreases.
4.5) repeating the steps 3 and 4, so that the difference D between the time corresponding to the maximum value counted by the counter and the arrival time of the most adjacent super frame header pseudo-random sequenceCIs maintained in a minimum state. In this case, the time at which the counter counts up to the maximum value is counted as the time at which the counter counts up to the maximum value.
5) The ground based navigation beacon transmitter transmits a ground based navigation beacon signal at time T3.
The method for transmitting the ground navigation beacon signal by the ground navigation beacon transmitter comprises the following steps:
5.1) let the basic time slot length of time division multiple access be 125 ms. And determining an exclusive transmitting time slot and an exclusive spread spectrum code of the foundation navigation beacon transmitter according to a collision avoidance rule.
And 5.2) the ground-based navigation beacon transmitter transmits a ground-based navigation beacon signal by utilizing the exclusive spread spectrum code in the exclusive transmission time slot.
6) And the ground-based navigation beacon receiver receives the ground-based navigation beacon signal and positions the ground-based navigation beacon receiver.
The method for receiving the ground navigation beacon signal and positioning the ground navigation beacon receiver comprises the following steps:
6.1) the receiving module of the digital terrestrial multimedia broadcasting preliminarily determines the geographical position of the transmitting station of the digital terrestrial multimedia broadcasting, namely obtaining the initial position estimation result.
6.2) determining a spreading code set I of the ground-based navigation beacon transmitter according to the position initial estimation result and the auxiliary information of the ground-based navigation beacon.
The foundation navigation beacon receiver determines a spreading code set I of a foundation navigation beacon transmitter according to the position initial estimation result and the auxiliary information of the foundation navigation beacon, and the method comprises the following steps:
6.3) acquiring and tracking the ground-based navigation beacon signal by the ground-based navigation beacon receiver according to the spread spectrum code set I.
6.4) the ground based navigation beacon receiver extracting measurements from the acquired tracking ground based navigation beacon signals, thereby locating the ground based navigation beacon receiver. The measurement quantity mainly comprises the carrier frequency in seconds of the ground-based navigation beacon signal and the pseudo range.
The technical effect of the present invention is undoubted. The invention takes the digital ground multimedia broadcast signal as the synchronization means of the ground navigation beacon transmitters and the navigation auxiliary means of the receiver, and the plurality of ground navigation beacon transmitters adopt the digital ground multimedia broadcast signal to carry out time synchronization, thereby overcoming the problem of the dependence of the prior system on satellite navigation. The method and the system for the ground navigation positioning utilize the digital ground multimedia broadcast signals to realize the synchronization between the transmitters of the ground navigation beacon, and overcome the dependence on satellite navigation positioning time service.
Drawings
FIG. 1 is a block diagram of a digital terrestrial multimedia broadcasting synchronized ground based navigation positioning system according to the present invention;
fig. 2 is a four-layer structure of a digital terrestrial multimedia broadcasting signal multiframe;
FIG. 3 is a digital terrestrial multimedia broadcasting signal frame structure;
FIG. 4 is a block diagram of a ground based navigation beacon transmitter in accordance with the present invention;
FIG. 5 is a block diagram of a ground based navigation beacon receiver according to the present invention;
FIG. 6 is a flow chart of a digital terrestrial multimedia broadcasting synchronized ground based navigation positioning method according to the present invention;
FIG. 7 is a flowchart of a method for estimating a time difference between an arrival time of a super-frame pseudo-random sequence and a universal reference time according to the present invention;
fig. 8 is a flowchart of a method for adjusting a transmission reference time of a ground based navigation beacon signal by a ground based navigation beacon transmitter according to the present invention.
Detailed Description
The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.
Example 1:
the digital Terrestrial multimedia broadcasting, i.e. dtmb (digital Terrestrial multimedia broadcasting) technology, refers to a digital Terrestrial television broadcasting technology represented by the national Terrestrial digital television transmission standard GB20600-2006 digital television Terrestrial broadcasting transmission system frame structure, channel coding and modulation, and its evolution technology.
Fig. 2 is a four-layer structure of a digital terrestrial multimedia broadcasting signal multiframe. In the figure h represents hour, min represents minute, ms represents millisecond, us represents microsecond, am represents morning, pm represents afternoon, PN sequence, i.e. pseudorandom sequence. According to the frame structure, channel coding and modulation of the digital television terrestrial broadcasting transmission system GB20600-2006, the digital terrestrial multimedia broadcasting data frame structure has four layers. The basic unit of the data frame structure is a signal frame, and the signal frame consists of a frame head and a frame body. A superframe is defined as a group of signal frames. A superframe is defined as a group of superframes. The top layer of the Frame structure becomes a daily Frame (caledar Day Frame, CDF). The signal structure is periodic and kept in synchronization with the natural time. The time length of the superframe is 125 ms, and the time length of 8 superframes is 1 microsecond, so that the time alignment with a timing system is convenient. The first signaling frame in the superframe is defined as the first frame and is indicated by the related information of the system information. The signal frame is a basic unit of a system frame structure, and one signal frame consists of a frame head and a frame body which are two time domain signals. The baseband symbol rates of the header and body signals are the same (7.56 Msps). The frame head part is composed of a pseudo-random sequence, and the pillow length has three options. The frame head signal adopts 4QAM modulation with the same I path and Q path. The frame body part contains system information of 36 symbols and data of 3744 symbols for a total of 3780 symbols. The frame body length is 500 microseconds (3780 × 1/7.56 microseconds).
Fig. 3 is a frame structure of a dmb signal. As shown in fig. 3, the dmb frame consists of two parts, i.e., a frame header and a frame body, and three optional frame header modes and corresponding frame structures are defined to adapt to different applications, as shown in fig. 2, a), b), and c). The frame body length and the superframe length of the signal frames corresponding to the three frame head modes are kept unchanged. For the frame structure of a) in the figure, one superframe is formed every 255 signal frames (225 × 4200 × 1/7.56 μ sec — 125 ms). For the frame structure of b) in fig. 3, each 216 signal frames constitute one superframe (216 × 4375 × 1/7.56 μ sec — 125 ms). For the frame structure of c) in fig. 3, every 200 signal frames constitute one superframe (200 × 4725 × 1/7.56 μ sec — 125 ms). Each signal frame includes a frame header consisting of a PN sequence and a frame body consisting of data blocks.
The invention discloses a foundation navigation positioning system for digital terrestrial multimedia broadcasting synchronization, which realizes time synchronization by utilizing a PN sequence in a digital terrestrial multimedia broadcasting signal frame structure.
Example 2:
a digital terrestrial multimedia broadcasting synchronized ground-based navigation positioning system, as shown in fig. 1, fig. 4 and fig. 5.
Fig. 3 is a block diagram of a digital terrestrial multimedia broadcasting-synchronized ground-based navigation positioning system according to the present invention. As shown in fig. 3, the ground based navigation positioning system for digital terrestrial multimedia broadcasting synchronization according to the present invention includes a digital terrestrial multimedia broadcasting transmitting station, a global navigation satellite system, a ground based navigation beacon transmitter, and a ground based navigation beacon receiver.
The digital terrestrial multimedia broadcasting transmitting station transmits a digital terrestrial multimedia broadcasting signal.
The global navigation satellite system transmits satellite navigation signals. Generally, the gnss mainly includes common space-based mid-orbit radio navigation positioning systems such as GPS, beidou, galileo, glonass navigation satellites, and the like.
And the ground-based navigation beacon transmitter captures and tracks the digital ground multimedia broadcast signals and calculates the arrival time of the digital ground multimedia broadcast signals and the super-frame header pseudorandom sequence. And the ground-based navigation beacon transmitter also receives satellite navigation signals, and calculates the difference value between the arrival time of the pseudo-random sequence and the world coordination time when acquiring the position of the ground-based navigation beacon transmitter and the world coordination. Further, the ground based navigation beacon transmitter generates and transmits a ground based navigation beacon signal time-synchronized with other ground based navigation beacon transmitters with reference to the arrival time of the pseudo random sequence and the difference value.
It should be noted that the ground based navigation beacon transmitter is a device for transmitting a radio signal similar to a satellite navigation signal on the ground, and the pseudolite generally refers to a special ground based navigation beacon transmitter capable of transmitting a radio positioning signal having the same frequency as a satellite positioning navigation system.
The ground-based navigation beacon receiver receives and processes the ground-based navigation beacon signal to obtain self-position information.
Fig. 4 is a block diagram of a ground based navigation beacon transmitter in accordance with the present invention. As shown in fig. 4, the ground-based navigation beacon transmitter further includes a digital terrestrial multimedia broadcasting acquisition tracking module, a satellite navigation receiving module, a ground-based navigation beacon transmission time adjusting module, and a ground-based navigation beacon signal generating and transmitting module.
The satellite navigation receiving module receives and processes the satellite navigation signal to obtain a universal reference arrival time T1, and transmits the universal reference arrival time T1 to the ground-based navigation beacon transmission time adjusting module.
The digital terrestrial multimedia broadcasting capturing and tracking module tracks and captures digital terrestrial multimedia broadcasting signals. The digital terrestrial multimedia broadcasting capturing and tracking module calculates the arrival time T2 of the digital terrestrial multimedia broadcasting signal super frame header pseudo-random sequence and transmits the arrival time T2 to the ground-based navigation beacon transmitting time adjusting module.
The ground-based navigation beacon transmission time adjusting module calculates a time difference Dt between an arrival time T2 of a super frame header pseudorandom sequence of the digital terrestrial multimedia broadcast signal and a universal reference arrival time T1. According to the time difference Dt, the ground-based navigation beacon transmission time adjusting module adjusts the transmission reference time T3 of the ground-based navigation beacon signal, and transmits the transmission reference time T3 to the ground-based navigation beacon signal generating and transmitting module.
The ground based navigation beacon signal generation and transmission module generates and transmits a ground based navigation beacon signal at time T3.
Fig. 5 is a block diagram of a ground based navigation beacon receiver according to the present invention. The ground-based navigation beacon receiver receives and processes the ground-based navigation beacon signal to obtain self-position information. As shown in fig. 5, the ground-based navigation beacon receiver further includes a digital terrestrial multimedia broadcasting receiving module, a ground-based navigation beacon database, a position initial estimation module, a ground-based navigation beacon capture tracking module, and a ground-based navigation beacon positioning module.
And the digital terrestrial multimedia broadcasting receiving module receives and demodulates the digital terrestrial multimedia broadcasting signal so as to obtain the auxiliary information of the foundation navigation beacon and the geographic coordinates of the digital terrestrial multimedia broadcasting transmitting station. And recording the geographical coordinates of the digital terrestrial multimedia broadcasting transmitting station as a position initial estimation result.
And the digital terrestrial multimedia broadcasting receiving module outputs the geographical coordinates of the transmitting broadcasting station to the position initial estimation module.
And the foundation navigation beacon database receives the auxiliary information and the initial position estimation result of the foundation navigation beacon sent by the digital ground multimedia broadcast receiving module, and determines a spreading code set I of the foundation navigation beacon transmitter according to the initial position estimation result and the auxiliary information. The set II of spreading codes of the ground-based navigation beacon transmitters which can be received by the database of the ground-based navigation beacon is a subset of the set I of spreading codes of the ground-based navigation beacon transmitters.
Further, the auxiliary information of the ground-based navigation beacon mainly comprises the geographic coordinates of the transmitter of the ground-based navigation beacon, a spreading code adopted by the transmitter of the ground-based navigation beacon, an information modulation mode of the transmitter of the ground-based navigation beacon, the transmitting power of the transmitter of the ground-based navigation beacon, the signal coverage of the transmitter of the ground-based navigation beacon and whether the transmitter of the ground-based navigation beacon is in an effective working state.
And the ground-based navigation beacon receiver retrieves a ground-based navigation beacon database according to the position initial estimation result, and brings the spread spectrum code of the ground-based navigation beacon transmitter which is in an effective working state at present and has a coverage range containing the position initial estimation result into a spread spectrum code set I of the ground-based navigation beacon transmitter.
The position initial estimation module receives the geographical coordinates of a transmitting broadcast station from the digital terrestrial multimedia broadcast receiving module as a position initial estimation result.
And the ground-based navigation beacon acquisition tracking module acquires and tracks the ground-based navigation beacon signals according to the spread spectrum code set, extracts the measurement quantity from the tracked ground-based navigation beacon signals and outputs the measurement quantity.
And the ground-based navigation beacon positioning module is used for positioning the ground-based navigation beacon receiver.
The output end of the digital terrestrial multimedia broadcasting capturing and tracking module is connected with one input end of the foundation navigation beacon transmitting time adjusting module.
One output end of the digital terrestrial multimedia broadcast receiving module is connected with one input end of the foundation navigation beacon database, and the other output end of the digital terrestrial multimedia broadcast receiving module is connected with the input end of the position initial estimation module.
The output end of the position initial estimation module is connected with one input end of the foundation navigation beacon database.
And the other output end of the foundation navigation beacon database is connected with the input end of the foundation navigation beacon acquisition tracking module.
The output end of the ground navigation beacon capturing and tracking module is connected with the input end of the ground navigation beacon positioning module.
And the other input end of the ground-based navigation beacon transmitting time adjusting module is connected with the output end of the satellite navigation receiving module. The output end of the ground navigation beacon emission time adjusting module is connected with the ground navigation beacon signal generating and sending module.
The digital ground multimedia broadcast capturing and tracking module, the satellite navigation receiving module and the ground navigation beacon signal generating and transmitting module are respectively connected with respective antennas.
Example 3:
a method for positioning by a digital terrestrial multimedia broadcasting synchronous ground-based navigation positioning system is shown in figures 6, 7 and 8.
Fig. 6 is a flowchart of a digital terrestrial multimedia broadcasting-synchronized ground-based navigation positioning method according to the present invention. As shown in fig. 6, the method for positioning by the ground based navigation positioning system for digital terrestrial multimedia broadcasting synchronization according to the present invention mainly comprises the following steps:
1) the digital terrestrial multimedia broadcasting transmitting station transmits the digital terrestrial multimedia broadcasting signal and sets the universal reference arrival time T1 of the super frame head pseudo random sequence of the digital terrestrial multimedia broadcasting signal.
2) The ground-based navigation beacon transmitter tracks and captures the digital terrestrial multimedia broadcasting signal and records the arrival time T2 of the pseudo-random sequence of the superframe header of the digital terrestrial multimedia broadcasting signal.
3) And calculating the time difference Dt between the arrival time T2 of the super frame head pseudo-random sequence of the digital terrestrial multimedia broadcasting signal and the universal reference arrival time T1.
As shown in fig. 7, the main steps of calculating the time difference Dt between the arrival time T2 of the super-frame header pseudo-random sequence and the universal reference arrival time T1 are as follows:
3.1) continuously monitoring the navigation satellite tracking condition of the satellite navigation receiver.
3.2) when the satellite navigation receiver tracks the navigation satellite well, acquiring the arrival time T2 of the super frame header pseudo-random sequence k +1 times, and forming a set { T2 }0，T21，T23，…，T2k}。
The following two schemes are mainly used for judging the good condition of the satellite navigation receiver for tracking the navigation satellite:
a) when the satellite navigation receiver receives signals of more than M navigation satellites, the tracking condition is good. In this embodiment, M is set to 8.
b) When more than M navigation satellites are received and all the pseudo-moment residuals are less than L, the tracking condition is good. In this embodiment, L is set to 3 meters.
Based on the set { T20，T21，T23，…，T2kCalculating the time difference Dt for each element in the sequence D, thereby obtaining a time difference sequence D0-k＝{dt0,dt1,dt2,…dtk}。
3.3) sequence D according to the time difference0-kOnline solving of time difference D of current momenttk。
Solving the time difference D of the current momenttkThe main steps are as follows:
3.3.1) calculating the time difference sequence D of the past N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkMean value of }
Sum square root error σt。
3.3.2) calculating the time difference sequence D within N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkEach element in (f) and σtThe absolute value x of the difference between x, if x>3σtEliminating the elements corresponding to the x to obtain an updated time difference sequence D 'in the N time moments'NK。
3.3.3) according toTime difference sequence D 'in N new time moments'NKCalculating Dtk。
Further, according to D'NKCalculating DtkOne of the methods of (1) is to let Dt bekIs equal to D'NKAnother method is to use a filtering method, such as finite impulse response filtering or infinite impulse response filtering. An example of the infinite impulse response filtering method is to set coefficients a and b such that a + b is 1 and a and b are not 0, Dtk is a Dtk-1+b*dtk. Typically, a is much larger than b, which represents multiplication, for example, 0.99 for a and 0.01 for b.
Further, time difference DtkThe time difference { dt over N time points may also be takenk-N+1,dtk-N+2,…dtkMean of.
3.4) maintaining Dt when no navigation satellite signal can be tracked at all and/or not wellkDoes not change and does not update D0-k。
Further, the universal reference time T1 is a time system used by the ground based navigation beacon transmitter, and is generally used in the world coordination, sometimes also in the GPS time or the beidou time. As the super frame header of the digital terrestrial multimedia broadcasting signal appears once every 125 milliseconds, the delay between the arrival time of the pseudo-random sequence of the super frame header and the universal reference time is DtkThe delay between the arrival time of the last super frame header pseudo-random sequence and the general reference time is Dtk-1。
Further, another method for calculating the difference Dt between the reference time output by the satellite navigation receiver and the arrival time of the super-frame header pseudorandom sequence mainly comprises the following steps:
I) the digital terrestrial multimedia broadcasting signal transmitting broadcasting station carries the geographical coordinates of the digital terrestrial multimedia broadcasting signal transmitting broadcasting station in the digital terrestrial multimedia broadcasting signal.
II) demodulating the digital terrestrial multimedia broadcasting signal by the ground-based navigation beacon transmitter to obtain the geographic coordinates of the digital terrestrial multimedia broadcasting signal.
III) the ground based navigation beacon transmitter determines the geographic coordinates of itself by using the satellite navigation receiver.
IV) the ground navigation beacon transmitter calculates the distance between the digital ground multimedia broadcast signal transmitter and the ground navigation beacon transmitter by using the geographic coordinates of the digital ground multimedia broadcast signal transmitting broadcast station and the geographic coordinates of the ground navigation beacon transmitter, and records the distance as d, and further obtains Dt which is d/c, wherein c is the light speed.
In order to further reduce the cost, the geographic coordinates of the digital terrestrial multimedia broadcasting signal transmitting broadcasting station and the geographic coordinates of the ground-based navigation beacon transmitter can be manually input into the ground-based navigation beacon transmitter to calculate d, and even d or Dt calculated by other means can be directly input into the ground-based navigation beacon transmitter.
4) According to the time difference Dt, the ground-based navigation beacon transmitter adjusts the transmission reference time T3 of the ground-based navigation beacon signal so that T3 is T2-Dtk。
As shown in fig. 8, the main steps of the ground based navigation beacon transmitter adjusting the transmission reference time T3 of the ground based navigation beacon signal are as follows:
4.1) ground based navigation Beacon transmitter maintains a 125 ms counter, the clock period T of whichcAs follows:
Tc＝1/fc。 (1)
in the formula (f)cIs the counter clock nominal frequency in hertz.
The counter starts counting at 0 and has a maximum value of 0.125fc-1。
4.2) starting a counter at the arrival time T1 of the current super-frame header pseudo-random sequence. 125 ms-Dt is reached at time T1k。
4.3) when the counting of the counter reaches the maximum value, calculating the difference between the current time and the arrival time of the nearest super frame header pseudo-random sequence and recording the difference as a k time counting difference Dck。
4.4) counting the difference Dc according to the k-timekFine-tuning local clock frequency to obtain the count difference at the next time when the counter counts to the maximum value, i.e. the k +1 time count difference Dck+1And decreases.
4.5) repetitionStep 3 and step 4, the difference D between the time corresponding to the maximum value counted by the counter and the arrival time of the nearest super frame header pseudo-random sequenceCIs maintained in a minimum state. In this case, the time at which the counter counts up to the maximum value is counted as the time at which the counter counts up to the maximum value.
5) The ground based navigation beacon transmitter transmits a ground based navigation beacon signal at time T3. When the ground navigation beacon signal is transmitted, the ground navigation beacon transmitter adopts a basic technical system of time division multiple access and code division multiple access. The main function of time division multiple access is to overcome the near-far effect of multiple transmitters, and the main function of code division multiple access is to perform high-precision radio measurement by using spread spectrum codes.
The method for transmitting the ground navigation beacon signal by the ground navigation beacon transmitter comprises the following steps:
5.1) let the basic time slot length of time division multiple access be 125 ms. And determining an exclusive transmitting time slot and an exclusive spread spectrum code of the foundation navigation beacon transmitter according to a collision avoidance rule. 125 ms is the basic slot length, and 125 ms may be further divided into a plurality of sub-slots, such as 5 slots 25 ms long, or 25 slots 5 ms long, or even 125 slots 1 ms long. Another way is to combine multiple 125 ms together to form a longer time slot.
And 5.2) the ground-based navigation beacon transmitter transmits a ground-based navigation beacon signal by utilizing the exclusive spread spectrum code in the exclusive transmission time slot. The pilot message is typically modulated onto a spreading code for transmission. The sensitivity of the ground based navigation beacon receiver is limited due to the presence of the navigation message. In fact, the ground-based navigation beacon transmitter does not move, so that the position information of the ground-based navigation beacon transmitter can be distributed to the ground-based navigation beacon receiver through an additional channel, and the ground-based navigation beacon transmitter can only transmit spread spectrum codes without transmitting navigation messages.
6) And the ground navigation beacon receiver receives the ground navigation beacon signal and calculates the position information of the ground navigation beacon receiver. When the navigation beacon signal sent by the ground-based navigation beacon transmitter only has the ranging code and does not have the navigation message, an additional means is needed to acquire the position of the ground-based navigation beacon transmitter.
Because there are likely more ground-based navigation beacon transmitters, if the ground-based navigation beacon receiver does not have the prior information of the spreading codes of the ground-based navigation beacon transmitters, the blind acquisition time is longer. To overcome the disadvantages, the ground-based navigation beacon receiver according to the present invention further accelerates the positioning process by receiving the digital terrestrial multimedia broadcasting signal, and the specific process thereof is divided into the following steps:
6.1) demodulating the geographic position of the transmitting station of the digital terrestrial multimedia broadcasting from the digital terrestrial multimedia broadcasting to be used as an initial estimation result of the position of the transmitting station.
6.1.1) the digital terrestrial multimedia broadcasting transmitting station transmits the digital terrestrial multimedia broadcasting signal carrying the geographical coordinates of the digital terrestrial multimedia broadcasting transmitting station.
6.1.2) the receiver demodulates the digital terrestrial multimedia broadcasting signal to obtain the geographic coordinate of the transmitting station of the digital terrestrial multimedia broadcasting.
6.1.3) taking the geographical coordinates of the digital terrestrial multimedia broadcasting transmitting station as the initial position estimation result.
6.2) determining a spreading code set I of the ground-based navigation beacon transmitter according to the position initial estimation result and the auxiliary information of the ground-based navigation beacon.
The foundation navigation beacon receiver determines a spreading code set I of a foundation navigation beacon transmitter according to the position initial estimation result and the auxiliary information of the foundation navigation beacon, and the method comprises the following steps:
6.2.1) the digital terrestrial multimedia broadcasting transmitting station carries the ground-based navigation beacon assistance information in the digital terrestrial multimedia broadcasting signal.
6.2.2) the ground based navigation beacon receiver demodulates the digital terrestrial multimedia broadcasting signal and saves the ground based navigation beacon auxiliary information into a ground based navigation beacon database.
6.2.3) according to the position initial estimation result, searching a foundation navigation beacon database, and bringing the spread spectrum code of the foundation navigation beacon transmitter which is in an effective working state at present and the coverage range of which contains the position initial estimation result into a foundation navigation beacon transmitter spread spectrum code set which can be received by a foundation navigation beacon receiver, namely a foundation navigation beacon transmitter spread spectrum code set I.
6.3) acquiring and tracking the ground-based navigation beacon signal by the ground-based navigation beacon receiver according to the spread spectrum code set I.
6.4) the ground based navigation beacon receiver extracting measurements from the acquired tracking ground based navigation beacon signals, thereby locating the ground based navigation beacon receiver. Similar to the satellite navigation receiver, the measurement quantities mainly include the number of carrier cycles in seconds of the ground-based navigation beacon signal and the pseudo-range.
Claims (10)
1. A foundation navigation positioning system for digital terrestrial multimedia broadcasting synchronization is characterized in that: the system mainly comprises a digital ground multimedia broadcast transmitting station, a global navigation satellite system, a foundation navigation beacon transmitter and a foundation navigation beacon receiver;
the digital terrestrial multimedia broadcasting transmitting station transmits a digital terrestrial multimedia broadcasting signal;
the global navigation satellite system mainly comprises a GPS, a Beidou, a Glonass and a Galileo satellite navigation system;
the ground-based navigation beacon transmitter captures and tracks the digital ground multimedia broadcast signals and calculates the arrival time of a super-frame header pseudo-random sequence of the digital ground multimedia broadcast signals;
the ground navigation beacon transmitter also receives satellite navigation signals, and calculates the difference value between the arrival time of the pseudo-random sequence and the world coordination time when acquiring the position of the ground navigation beacon transmitter and the world coordination time;
the ground-based navigation beacon transmitter generates and transmits ground-based navigation beacon signals which are time-synchronized with other ground-based navigation beacon transmitters by taking the arrival time of the pseudo-random sequence and the difference value as references;
the ground-based navigation beacon receiver receives and processes the ground-based navigation beacon signal to obtain self-position information.
2. The synchronized ground-based navigation positioning system for digital terrestrial multimedia broadcasting according to claim 1, wherein: the ground navigation beacon transmitter mainly comprises a digital ground multimedia broadcast capturing and tracking module, a satellite navigation receiving module, a ground navigation beacon transmitting time adjusting module and a ground navigation beacon signal generating and transmitting module;
the satellite navigation receiving module receives and processes the satellite navigation signal to obtain a universal reference arrival time T1, and transmits the universal reference arrival time T1 to the ground-based navigation beacon transmission time adjusting module;
the digital terrestrial multimedia broadcasting capturing and tracking module tracks and captures digital terrestrial multimedia broadcasting signals; the digital terrestrial multimedia broadcasting capturing and tracking module calculates the arrival time T2 of a digital terrestrial multimedia broadcasting signal super frame header pseudo-random sequence and transmits the arrival time T2 to the ground-based navigation beacon transmitting time adjusting module;
the ground-based navigation beacon transmitting time adjusting module calculates the time difference Dt between the arrival time T2 of the digital terrestrial multimedia broadcasting signal super frame header pseudo-random sequence and the universal reference arrival time T1; according to the time difference Dt, the ground-based navigation beacon transmitting time adjusting module adjusts the transmitting reference time T3 of the ground-based navigation beacon signal and transmits the transmitting reference time T3 to the ground-based navigation beacon signal generating and sending module;
the ground based navigation beacon signal generation and transmission module generates and transmits a ground based navigation beacon signal at time T3.
3. The synchronized ground-based navigation positioning system for digital terrestrial multimedia broadcasting according to claim 1, wherein: the ground-based navigation beacon receiver mainly comprises a digital ground multimedia broadcast receiving module, a ground-based navigation beacon database, a position initial estimation module, a ground-based navigation beacon capturing and tracking module and a ground-based navigation beacon positioning module;
the digital ground multimedia broadcast receiving module receives and demodulates the digital ground multimedia broadcast signals so as to obtain the auxiliary information of the ground-based navigation beacon and the geographic coordinates of the digital ground multimedia broadcast transmitting station;
the digital terrestrial multimedia broadcasting receiving module outputs the geographic coordinates of the digital terrestrial multimedia broadcasting transmitting station to the position initial estimation module;
the foundation navigation beacon database receives the foundation navigation beacon auxiliary information and the position initial estimation result sent by the digital ground multimedia broadcast receiving module, and determines a foundation navigation beacon transmitter spread spectrum code set I according to the position initial estimation result and the auxiliary information; the method comprises the following steps that a foundation navigation beacon transmitter spread spectrum code set II which can be received by a foundation navigation beacon database is a subset of a foundation navigation beacon transmitter spread spectrum code set I;
the foundation navigation beacon receiver retrieves a foundation navigation beacon database according to the position initial estimation result, and brings the spread spectrum code of the foundation navigation beacon transmitter which is in an effective working state at present and the coverage area of which comprises the position initial estimation result into a foundation navigation beacon transmitter spread spectrum code set I;
the position initial estimation module receives the geographical coordinates of the digital terrestrial multimedia broadcasting transmitting station from the digital terrestrial multimedia broadcasting receiving module as a position initial estimation result;
the ground navigation beacon acquisition tracking module acquires and tracks ground navigation beacon signals according to the spread spectrum code set, extracts measurement quantity from the tracked ground navigation beacon signals and outputs the measurement quantity;
and the ground-based navigation beacon positioning module is used for positioning the ground-based navigation beacon receiver.
4. The synchronized ground-based navigation and positioning system of claim 3, wherein the auxiliary information of the ground-based navigation beacon mainly includes geographic coordinates of the transmitter of the ground-based navigation beacon, a spreading code used by the transmitter of the ground-based navigation beacon, an information modulation mode of the transmitter of the ground-based navigation beacon, a transmission power of the transmitter of the ground-based navigation beacon, a signal coverage of the transmitter of the ground-based navigation beacon, and whether the transmitter of the ground-based navigation beacon is in an effective operation state.
5. A method for positioning by using the digital terrestrial multimedia broadcasting synchronized ground-based navigation positioning system according to any one of claims 1 to 4, which mainly comprises the following steps:
1) the digital terrestrial multimedia broadcasting transmitting station transmits a digital terrestrial multimedia broadcasting signal and sets a universal reference arrival time T1 of a super frame header pseudo-random sequence of the digital terrestrial multimedia broadcasting signal;
2) the ground-based navigation beacon transmitter tracks and captures the digital terrestrial multimedia broadcasting signals and records the arrival time T2 of the digital terrestrial multimedia broadcasting signal super-frame header pseudo-random sequence;
3) calculating the time difference Dt between the arrival time T2 of the super frame header pseudorandom sequence of the digital terrestrial multimedia broadcasting signal and the universal reference arrival time T1;
4) according to the time difference Dt, the ground-based navigation beacon transmitter adjusts the transmission reference time T3 of the ground-based navigation beacon signal so that T3 is T2-Dtk(ii) a T2 is the arrival time of the super frame header pseudo random sequence; dtkThe time difference at the current moment;
5) the ground-based navigation beacon transmitter transmits a ground-based navigation beacon signal at the time T3, and the method mainly comprises the following steps:
5.1) setting the length of a basic time slot of the time division multiple access to be 125 milliseconds; determining an exclusive transmitting time slot and an exclusive spread spectrum code of the foundation navigation beacon transmitter according to a collision avoidance rule;
5.2) the ground navigation beacon transmitter transmits a ground navigation beacon signal by utilizing the exclusive spread spectrum code in the exclusive transmission time slot;
6) and the ground-based navigation beacon receiver receives the ground-based navigation beacon signal and positions the ground-based navigation beacon receiver.
6. The method of claim 5, wherein the ground based navigation positioning system synchronized with digital terrestrial multimedia broadcasting comprises: the main steps of calculating the time difference Dt between the arrival time T2 of the super-frame header pseudorandom sequence and the universal reference arrival time T1 are as follows:
1) continuously monitoring the navigation satellite tracking condition of the satellite navigation receiving module; the satellite navigation receiving module receives and processes the satellite navigation signal to obtain a universal reference arrival time T1, and transmits the universal reference arrival time T1 to the ground-based navigation beacon transmission time adjusting module;
2) when the condition that the satellite navigation receiving module tracks the navigation satellite is good, the arrival time T2 of the super frame header pseudorandom sequence is obtained k +1 times, and a set { T2 is formed0，T21，T22，…，T2k}; based on the set { T20，T21，T22，…，T2kCalculating the time difference Dt for each element in the sequence D, thereby obtaining a time difference sequence D0-k＝{dt0,dt1,dt2,…dtk}；
3) According to the time difference sequence D0-kOnline solving of time difference D of current momenttk；
4) Maintaining D when any satellite navigation signal is not tracked at all or welltkDoes not change and does not update D0-k。
7. The method of claim 6, wherein the ground based navigation positioning system synchronized with digital terrestrial multimedia broadcasting comprises: solving the time difference D of the current momenttkThe main steps are as follows:
1) calculating a time difference sequence D of past N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkMean value of }
Sum square root error σt；
2) Calculating a time difference sequence D in N momentsNK＝{dtk-N+1,dtk-N+2，…，dtkEach element in (f) and σtThe absolute value x of the difference between x, if x>3σtEliminating the elements corresponding to the x to obtain an updated time difference sequence D 'in the N time moments'NK；
3) According to the updated time difference sequence D 'in the N time moments'NKTo obtain Dtk。
8. The method of claim 6, wherein the ground based navigation positioning system synchronized with digital terrestrial multimedia broadcasting comprises: the main steps of the ground based navigation beacon transmitter adjusting the transmission reference time T3 of the ground based navigation beacon signal are as follows:
1) the ground based navigation beacon transmitter maintains a 125 millisecond counter, the clock period T of whichcAs follows:
Tc＝1/fc； (1)
in the formula (f)cA nominal frequency of the counter clock;
the counter starts counting at 0 and has a maximum value of 0.125fc-1；
2) Starting a counter at the arrival time T2 of the current super-frame header pseudorandom sequence;
3) when the counting of the counter reaches the maximum value, calculating the difference between the current time and the arrival time of the nearest super frame header pseudorandom sequence, and recording the difference as a k time counting difference Dck；
4) Counting the difference Dc according to the k timekFine-tuning local clock frequency to obtain the count difference at the next time when the counter counts to the maximum value, i.e. the k +1 time count difference Dck+1Decrease;
5) repeating the step 3) and the step 4) to enable the counter to count the difference D between the time corresponding to the maximum value and the arrival time of the nearest adjacent super frame header pseudo-random sequenceCMaintained in a minimum state; at this time, the counter counts the time corresponding to the maximum value.
9. The method of claim 6, wherein the ground based navigation positioning system synchronized with digital terrestrial multimedia broadcasting comprises: the following two schemes are mainly used for judging the good condition of the satellite navigation receiving module for tracking the navigation satellite:
1) when the satellite navigation receiving module receives signals of more than M navigation satellites, the tracking condition is good;
2) when more than M navigation satellites are received and all the pseudo-moment residuals are less than L, the tracking condition is good.
10. The method of claim 5, wherein the ground based navigation positioning system synchronized with digital terrestrial multimedia broadcasting comprises: the method for receiving the ground navigation beacon signal and positioning the ground navigation beacon receiver comprises the following steps:
1) taking the geographical position of the digital terrestrial multimedia broadcasting transmitting station as a position initial estimation result;
2) determining a spreading code set I of a foundation navigation beacon transmitter according to the position initial estimation result and the foundation navigation beacon auxiliary information;
3) acquiring and tracking a ground navigation beacon signal by a ground navigation beacon receiver according to the spread spectrum code set I;
4) the ground-based navigation beacon receiver extracts the measurement quantity from the captured and tracked ground-based navigation beacon signal so as to position the ground-based navigation beacon receiver; the measurement quantity mainly comprises the carrier frequency in seconds of the ground-based navigation beacon signal and the pseudo range.
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