CN111123249A - Distance measurement method and system based on TDMA network - Google Patents
Distance measurement method and system based on TDMA network Download PDFInfo
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- CN111123249A CN111123249A CN201911259942.0A CN201911259942A CN111123249A CN 111123249 A CN111123249 A CN 111123249A CN 201911259942 A CN201911259942 A CN 201911259942A CN 111123249 A CN111123249 A CN 111123249A
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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
- G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
- G01S11/12—Systems for determining distance or velocity not using reflection or reradiation using electromagnetic waves other than radio waves
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0652—Synchronisation among time division multiple access [TDMA] nodes, e.g. time triggered protocol [TTP]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/18—Network planning tools
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Abstract
The invention discloses a distance measuring method and a system based on a TDMA network, wherein the method comprises the following steps: adding a plurality of devices with the distances to be measured into a TDMA network established by time reference equipment; performing synchronous processing on clocks of all devices to be measured in the TDMA network; sending and receiving messages among the multiple devices to be tested, and calculating the distance R between the current sending device and the current receiving device: and repeating the previous steps to obtain the distance between any two devices in the distance to be measured devices in real time. The method of the invention forms the equipment which needs to finish the distance measurement into a TDMA network, and utilizes the characteristic of the time synchronization of the network stations, the distance can be measured as long as the information sent by other stations is received, the data real-time performance is high, the distance data of other nodes of the network can be measured as long as one time frame is 6.08ms, the distance measurement precision is high, the data real-time performance is good, the influence of environmental factors such as weather is small, and a certain data channel function can be provided for the distance measurement equipment.
Description
Technical Field
The invention relates to the field of wireless navigation, in particular to a distance measurement method and a distance measurement system based on a TDMA network.
Background
At present, the range finding modes used on the airplane are a laser range finding method and a radar range finding method.
The laser ranging method converts the distance by measuring the time of the laser beam in the round trip propagation on the distance to be measured, and the conversion formula is as follows:
d＝ct/2
the distance measuring instrument sends out light pulses, the light pulses return to a receiving system of the distance measuring instrument after being transmitted by a measured target, and the time interval between the transmission and the reception of the pulses is measured, namely the round-trip propagation time t of the light pulses on a distance to be measured, and c is the light speed d which is a distance value. However, the laser has a short working distance and is susceptible to environmental influences such as cloud and mist.
The radar ranging method is that a radar transmitter generates enough electromagnetic energy, the electromagnetic energy is transmitted to an antenna through a transceiving switch, the antenna radiates the electromagnetic energy into the atmosphere, the electromagnetic energy is concentrated in a certain narrow direction to form a beam, and the beam is transmitted forwards. When the electromagnetic waves encounter a target in a wave beam, reflection is generated along all directions, and a part of electromagnetic energy is reflected back to the radar direction and is acquired by a radar antenna. The energy obtained by the antenna is transmitted to the receiver through the transmitting-receiving conversion switch to form an echo signal of the radar. The delay time from the time of transmission to the time of reception of the echo is measured, the delay time being the time of the electromagnetic wave from the transmitter to the target and from the target back to the radar receiver. From the propagation velocity of the electromagnetic wave, the distance formula of the target can be determined as:
S＝CT/2
wherein S is the target distance, T is the time from the emission of the electromagnetic wave from the radar to the reception of the target echo, and C is the speed of light. However, the radar ranging accuracy is poor, and the azimuth coverage is poor.
Disclosure of Invention
The invention mainly solves the technical problem of providing a distance measuring method based on a TDMA network, and solves the problems of short working distance, poor precision and the like of the traditional distance measuring method.
The invention provides a distance measurement method based on a TDMA network, which comprises the following steps:
r is C × TOA type one
Wherein TOA is the propagation time of the message, TOA t2-t 1; c is the speed of light;
and 4, repeating the step 3 to obtain the distance between any two devices in the device to be measured in real time.
Further, the distance measuring method according to claim 1, wherein the step 2 of synchronizing the clocks of all devices to be measured in the TDMA comprises:
the device to be measured comprises a reference member device and a non-reference member device, wherein the non-reference member device sends an inquiry message to the reference member device at an inquiry time point T1 distributed to the non-reference member device;
after receiving the inquiry message at the time point T2, the reference member device transmits a response message to the non-reference member device at a response time point T3 assigned thereto;
the non-reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
the non-reference member device is time-calibrated based on the first time error △ t to achieve clock synchronization between the non-reference member device and the reference member device.
Further, error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
Further, the adding, in step 1, a TDMA network established by the time reference device to the plurality of devices with distances to be measured includes:
enabling time reference equipment to send a network access message, wherein the network access message comprises a message section and a frame synchronization code, and the frame synchronization code is arranged at a preset position in the network access message;
and if any equipment to be measured receives the network access message, the equipment completes network access.
The invention also provides a ranging system based on the TDMA network, which comprises:
the network access module is used for adding a TDMA network established by time reference equipment to the plurality of devices to be measured;
the clock synchronization module is used for performing synchronization processing on the clocks of all the devices to be measured in the TDMA;
a ranging module, configured to select one device from multiple devices to be ranged as a current receiving device, select one device from the remaining devices to be ranged as a current sending device, send a message to the current ranging device at time t1, and obtain a distance R between the current sending device and the current receiving device by using a formula one when the current ranging device receives the message at time t 2:
r is C × TOA type one
Wherein, TOA is the propagation time of the message, and TOA is t2-t 1; and C is the speed of light.
Further, the clock synchronization module performs synchronization processing on clocks of all devices to be measured in the TDMA, and the synchronization processing includes:
the device to be measured comprises a reference member device and a non-reference member device, wherein the non-reference member device sends an inquiry message to the reference member device at an inquiry time point T1 distributed to the non-reference member device;
after receiving the inquiry message at the time point T2, the reference member device transmits a response message to the non-reference member device at a response time point T3 assigned thereto;
the non-reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
the non-reference member device is time-calibrated based on the first time error △ t to achieve clock synchronization between the non-reference member device and the reference member device.
Further, error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
Further, the networking module performs networking communication on the multiple devices to be measured, and includes:
at least enabling any device to be measured to send a data message, wherein the data message comprises a message segment and a frame synchronization code, and the frame synchronization code is arranged at a preset position in the data message;
and if any distance measuring equipment receives the data message, the equipment completes data communication with the distance measuring equipment.
Compared with the prior art, the invention has the following effects:
the method of the invention forms the equipment which needs to finish the distance measurement into a TDMA network, and utilizes the characteristic of the time synchronization of the network stations, the distance can be measured as long as the information sent by other stations is received, the data real-time performance is high, the distance data of other nodes of the network can be measured as long as one time frame is 6.08ms, the distance measurement precision is high, the data real-time performance is good, the influence of environmental factors such as weather is small, and a certain data channel function can be provided for the distance measurement equipment.
Drawings
FIG. 1 is a flow chart of a ranging method based on a TDMA network;
FIG. 2 is a clock synchronization diagram of an embodiment;
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
TDMA: time Division Multiple Access, also known as Time Division Multiple Access, is a communication technology for implementing a shared transmission medium (generally in the radio domain) or network. It allows multiple users to use the same frequency in different time slices (time slots). The TDMA protocol divides a time axis into a certain time element, each time element is divided into time slots, each network station is allocated with a certain number of time slots and signals are transmitted in each time element, and signals transmitted by other stations are received in the time slots in which the signals are not transmitted. Each network station has an accurate clock, and in order to realize the time division multiple access work, the clock of a specified station is used as a reference, and the clocks of other stations are predicted to be synchronous to form a uniform system clock.
The first embodiment is as follows:
referring to fig. 1, the present embodiment provides a ranging method based on a TDMA network, including:
dividing time into three categories of time elements, time frames and time slots according to the time slice division characteristics of the TDMA, and cycling by taking the time elements as periods. One time element is divided into a plurality of time frames, and one time frame is divided into a plurality of time slots.
In the TDMA network design in this embodiment, the maximum network capacity is X sites, each member site occupies one time slot, and two dedicated time slots are added for network access and clock synchronization, which total X +2 time slots. The time slot 0 of the time frame number 0 of each time element is used for the time reference station to transmit the network access message, and the time slots 0 of the rest time frames are used for the time reference station to transmit the response message. The difference between the network-entry message and the reply message is only the difference between the pseudo random codes of the synchronization headers. The fixed time slot of each time frame is used for transmitting inquiry information by the timing station, one inquiry time slot is needed in each frame, and X-1 inquiry time slots are needed in total, so that one time element can finish timing of the whole network member by needing X-1 inquiry time slots and is sequentially distributed to X-1 stations except the time reference station.
In order to establish frame synchronization of a transmitting system and a receiving system in a TDMA network, a frame synchronization code having a specific code pattern needs to be inserted into a fixed position in each frame (or several frames) to ensure that a receiving end can correctly recognize the frame synchronization code, so that information transmitted by a transmitting end can be correctly received. And the time slot No. 0 of the time frame No. 0 of each time element is used for the time reference station to transmit the network access message. The synchronization head of the network-accessing message adopts a specific pseudo random code (frame synchronization code), and the message section is still the content of the response message. Under normal conditions, the station equipment enters a capture state of the network access message after finishing initialization. And once the network access message is received, coarse synchronization is realized, and the network access work is finished. The clock error after the rough synchronization is the propagation time of the electric wave from the time reference station to the network access station. The network access time is longest one epoch.
specifically, the method comprises the following steps:
the device to be measured comprises time reference member devices and non-time reference member devices, and the non-time reference member devices send inquiry messages to the time reference member devices at inquiry time points T1 distributed to the non-time reference member devices;
after receiving the inquiry message at time point T2, the time reference member device transmits a response message to the non-time reference member device at a response time point T3 assigned thereto;
the non-time reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
as can be seen from fig. 2, there is a first time error △ t between the non-time-referenced member device and the time-referenced member device, which is obtained by the non-time-referenced member device sending the inquiry message and the time-referenced member device sending the reply message after receiving the inquiry message.
Error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
The non-time reference member device is time-calibrated based on the time error △ t to achieve clock synchronization between the non-time reference member device and the time reference member device.
The non-time reference member equipment can finish one-time clock accurate synchronization by performing one-time timing, and each non-time reference member equipment can be ensured to perform at least one-time active timing in each timing period (time element) to finish the accurate synchronization of the equipment clock.
r is C × TOA type one
Wherein, TOA is the propagation time of the message, and TOA is t2-t 1; c is the speed of light;
and 4, repeating the step 3 to obtain the distance between any two devices in the distance to be measured devices in real time.
Because TDMA time division multiple access working system is adopted among a plurality of devices with distances to be measured, when the message sent by the current sending device is received, the message arrival time TOA can be accurately obtained.
Example two:
referring to fig. 2, the present embodiment provides a ranging system based on a TDMA network, including:
the network access module is used for adding a plurality of devices to be measured into a TDMA network established by the time reference device;
the clock synchronization module is used for performing synchronization processing on the clocks of all the devices to be measured in the TDMA;
the time reference equipment carries out time service to other non-time reference equipment in the network, and equipment used in the network is ensured to be in a unified time point;
a ranging module, configured to select one device from multiple devices to be ranged as a current receiving device, select one device from the remaining devices to be ranged as a current sending device, send a message to the current ranging device at time t1, and obtain a distance R between the current sending device and the current receiving device by using a formula one when the current ranging device receives the message at time t 2:
r is C × TOA type one
Wherein, TOA is the propagation time of the message, and TOA is t2-t 1; and C is the speed of light.
The clock synchronization module is used for performing synchronization processing on the clocks of all devices to be measured in the TDMA, and comprises the following steps:
the device to be measured comprises time reference member devices and non-time reference member devices, and the non-time reference member devices send inquiry messages to the time reference member devices at inquiry time points T1 distributed to the non-time reference member devices;
after receiving the inquiry message at time point T2, the time reference member device transmits a response message to the non-time reference member device at a response time point T3 assigned thereto;
the non-time reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
the non-time reference member device is time calibrated based on the first time error △ t to achieve clock synchronization between the non-time reference member device and the time reference member device.
Error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
The adding a TDMA network established by time reference equipment to the equipment to be measured in the network access module comprises the following steps:
enabling time reference equipment to send a network access message, wherein the network access message comprises a message section and a frame synchronization code, and the frame synchronization code is arranged at a preset position in the network access message;
and if any equipment to be measured receives the network access message, the equipment completes network access.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (8)
1. A ranging method based on a TDMA network, comprising:
step 1, adding a plurality of devices to be measured into a TDMA network established by time reference devices;
step 2, synchronizing the clocks of all the devices to be measured in the TDMA;
step 3, the multiple devices to be measured perform networking communication (send/receive messages), one device selected from the multiple devices to be measured is selected as a current receiving device, one device selected from the other devices to be measured is selected as a current sending device, a message is sent to the current distance measuring device at the time t1, the current distance measuring device receives the message at the time t2, and the distance R between the current sending device and the current receiving device is obtained according to the formula one:
r is C × TOA type one
Wherein TOA is the propagation time of the message, TOA t2-t 1; c is the speed of light;
and 4, repeating the step 3 to obtain the distance between any two devices in the device to be measured in real time.
2. The ranging method according to claim 1, wherein the step 2 of synchronizing the clocks of all devices to be measured in the TDMA comprises:
the device to be measured comprises a reference member device and a non-reference member device, wherein the non-reference member device sends an inquiry message to the reference member device at an inquiry time point T1 distributed to the non-reference member device;
after receiving the inquiry message at the time point T2, the reference member device transmits a response message to the non-reference member device at a response time point T3 assigned thereto;
the non-reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
the non-reference member device is time-calibrated based on the first time error △ t to achieve clock synchronization between the non-reference member device and the reference member device.
3. The ranging method of claim 2, wherein the error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
4. The ranging method according to claim 1, wherein the step 1 of adding the TDMA network established by the time reference device to the plurality of devices with the distance to be measured comprises:
enabling time reference equipment to send a network access message, wherein the network access message comprises a message section and a frame synchronization code, and the frame synchronization code is arranged at a preset position in the network access message;
and if any equipment to be measured receives the network access message, the equipment completes network access.
5. A ranging system based on a TDMA network, comprising:
the network access module is used for adding a plurality of devices to be measured into a TDMA network established by the time reference device;
the clock synchronization module is used for performing synchronization processing on the clocks of all the devices to be measured in the TDMA;
a ranging module, configured to select one device from multiple devices to be ranged as a current receiving device, select one device from the remaining devices to be ranged as a current sending device, send a message to the current ranging device at time t1, and obtain a distance R between the current sending device and the current receiving device by using a formula one when the current ranging device receives the message at time t 2:
r is C × TOA type one
Wherein, TOA is the propagation time of the message, and TOA is t2-t 1; and C is the speed of light.
6. The ranging system according to claim 1, wherein the clock synchronization module synchronizes clocks of all devices to be ranged in the TDMA, comprising:
the device to be measured comprises a reference member device and a non-reference member device, wherein the non-reference member device sends an inquiry message to the reference member device at an inquiry time point T1 distributed to the non-reference member device;
after receiving the inquiry message at the time point T2, the reference member device transmits a response message to the non-reference member device at a response time point T3 assigned thereto;
the non-reference member device receives the reply message at time point T4;
calculating an error △ T according to the time point T1, the time point T2, the time point T3 and the time point T4;
the non-reference member device is time-calibrated based on the first time error △ t to achieve clock synchronization between the non-reference member device and the reference member device.
7. The ranging system of claim 2 wherein the error △ t is calculated according to equation two:
where Td is the interval between sending the query message and sending the response message.
8. The range finding system of claim 1, wherein the networking module performs networking communication on the plurality of devices to be measured, and comprises:
at least enabling any device to be measured to send a data message, wherein the data message comprises a message segment and a frame synchronization code, and the frame synchronization code is arranged at a preset position in the data message;
and if any distance measuring equipment receives the data message, the equipment completes data communication with the distance measuring equipment.
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