CN112526468A - DT correction method and system suitable for wide area multipoint positioning system - Google Patents
DT correction method and system suitable for wide area multipoint positioning system Download PDFInfo
- Publication number
- CN112526468A CN112526468A CN202011488122.1A CN202011488122A CN112526468A CN 112526468 A CN112526468 A CN 112526468A CN 202011488122 A CN202011488122 A CN 202011488122A CN 112526468 A CN112526468 A CN 112526468A
- Authority
- CN
- China
- Prior art keywords
- duration
- message
- time length
- acquiring
- transmission
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000012937 correction Methods 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000005540 biological transmission Effects 0.000 claims abstract description 63
- 238000012545 processing Methods 0.000 claims abstract description 60
- 238000004364 calculation method Methods 0.000 claims abstract description 29
- 230000008054 signal transmission Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- 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
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
- G01S7/4021—Means for monitoring or calibrating of parts of a radar system of receivers
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Position Fixing By Use Of Radio Waves (AREA)
Abstract
The invention discloses a DT correction method applicable to a wide area multipoint positioning system, which comprises the following steps: acquiring the message processing time length of a transmitter and the processing time length of a radio frequency card; acquiring the transmission signal duration of a transmitting antenna; acquiring a linear distance between a transmitting antenna and a receiving feeder line, and calculating the transmission time of a message space; acquiring an original message output by a ground station, and demodulating a small time scale; the DT correction value is equal to the small time scale minus the message processing duration and the radio frequency processing duration of the transmitter, the transmission signal duration of the transmitting antenna and the message space transmission duration. The method does not need to receive signals simultaneously by all ground stations and measure the time length of signal transmission by a feeder line, can effectively measure the DT value of each station, has simple calculation and simple and convenient operation, and can obtain accurate and reliable DT value, thereby providing accurate data base for subsequent positioning calculation and improving the positioning precision.
Description
Technical Field
The invention relates to the technical field of aviation, in particular to a DT correction method and a DT correction system suitable for a wide area multipoint positioning system.
Background
The wide-area multipoint positioning system is one of novel monitoring technologies, is completely compatible with SSR radar and ADS-B downlink data transmission links, has the advantages of target identification capability, high-precision positioning capability and the like, and is particularly suitable for areas unsuitable for building radar systems, such as mountainous areas, hills, deserts and the like. Several countries have adopted this technology to monitor terminal areas and routes, and the basic principle is shown in fig. 1. Assuming that the time when the Target sends the message is t, the position coordinates are (x, y, z), the times when the message reaches the ground stations F1, F2 and F3 are t1, t2 and t3, and the position coordinates of F1, F2 and F3 are (x1, y1, z1), (x2, y2, z2), (x3, y3 and z3), respectively, thus obtaining:
four unknowns (x, y, z, t), to solve for the three-dimensional position, 4 receivers are involved in the calculation. Multi-point positioning system block diagram as shown in fig. 2, the multi-point positioning system includes a transmitter, a plurality of ground stations and a central station, and the receivers of the ground stations receive messages transmitted by the transmitter. Specifically, the calculation of the receiver position is actually the calculation of the position of the receiving feeder, and the receiving times t1, t2 and t3 are obtained by the receiver SP card, and the time includes the feeder transmission time length, the radio frequency card processing time length and the SP card processing time length. Therefore, the time length correction, the so-called DT correction, needs to be removed when actually calculating the receiver position.
The traditional solution is as follows:
the signals transmitted by the beacon machines are received by a plurality of receivers simultaneously, and DT values of all stations are calculated through the time difference of arrival (TDOA) among the stations by taking one station as a reference.
And measuring the length of the feeder line when the station is built, and calculating the transmission time length of the feeder line through length feedback. And simultaneously, measuring the processing time length of the radio frequency card and the processing time length of the SP card of each receiver through an oscilloscope.
Disadvantages with conventional solutions include:
the traditional method is not suitable for a wide area multipoint positioning system because the sites of the wide area multipoint positioning system are scattered, and it is difficult for all the sites to receive the signals of the beacon machine at the same time. Even if partial stations can receive signals simultaneously, due to the fact that the distance is long and interference is large, the received signal quality is poor, and the DT values calculated according to the received signal quality are unreliable.
The method for measuring the length of the feeder line and calculating the transmission time of the feeder line is not suitable for all situations, and for part of equipment built on a telecommunication tower, the feeder line is too long and the measurement difficulty is too large.
Disclosure of Invention
Aiming at the defects in the prior art, the embodiment of the invention provides the DT correction method and the DT correction system which are suitable for the wide area multipoint positioning system, all stations are not required to receive signals simultaneously, the time length of feeder line transmission signals is not required to be measured, the calculation is simple, the operation is simple and convenient, and the calculated DT value is accurate and reliable.
In a first aspect, an embodiment of the present invention provides a DT correction method suitable for a wide area multipoint positioning system, where the method includes:
acquiring the message processing time length of a transmitter and the processing time length of a radio frequency card;
acquiring the transmission signal duration of a transmitting antenna;
acquiring a linear distance between a transmitting antenna and a receiving feeder line, and calculating the transmission time of a message space;
acquiring an original message output by a ground station, and demodulating a small time scale;
and the DT correction value is the sum of the receiving feeder transmission time length, the receiver radio frequency processing time length and the SP card processing time length, and is equal to the small time scale minus the message processing time length and the radio frequency processing time length of the transmitter, the transmission antenna transmission signal time length and the message space transmission time length.
Optionally, the specific method for calculating the message space transmission duration includes: the linear distance between the transmitting antenna and the receiving feed is divided by the speed of light.
Optionally, the transmitter and the receiver both use high-precision clock modules, and the second pulse jitter value is within 10 ns.
Optionally, the message processing duration, the radio frequency processing duration, and the transmission signal duration of the transmitting antenna are fixed values.
Optionally, the DT correction value is a sum of a reception feeder transmission time length, a receiver radio frequency processing time length, and an SP card processing time length.
In a second aspect, an embodiment of the present invention provides a DT correction system suitable for a wide area multipoint positioning system, including: a first acquisition module, a second acquisition module, a spatial transmission duration calculation module, a demodulation module and a DT correction value calculation module, wherein,
the first acquisition module is used for acquiring the message processing time length of the transmitter and the processing time length of the radio frequency card;
the second acquisition module is used for acquiring the transmission signal duration of the transmitting antenna;
the space transmission duration calculation module is used for acquiring a linear distance between the transmitting antenna and the receiving feeder line and calculating the message space transmission duration;
the demodulation module is used for acquiring an original message output by the ground station and demodulating a small time scale;
and the DT correction value calculation module is used for subtracting the message processing time length and the radio frequency processing time length of the transmitter, the transmission signal time length of the transmitting antenna and the message space transmission time length from the hour mark.
Optionally, the specific method for calculating the message space transmission duration by the space transmission duration calculation module is as follows: the linear distance between the transmitting antenna and the receiving feed is divided by the speed of light.
Optionally, the transmitter and the receiver both use high-precision clock modules, and the second pulse jitter value is within 10 ns.
Optionally, the message processing duration, the radio frequency processing duration, and the transmission signal duration of the transmitting antenna are fixed values.
Optionally, the DT correction value is a sum of a reception feeder transmission time length, a receiver radio frequency processing time length, and an SP card processing time length.
The invention has the beneficial effects that:
the DT value of each station can be effectively measured, the calculation is simple, the operation is simple and convenient, the calculated DT value is accurate and reliable, an accurate data base is provided for the subsequent positioning calculation, and the positioning precision is improved.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
FIG. 1 shows a schematic diagram of a multi-point positioning implementation;
FIG. 2 shows a schematic of the structure of a multipoint positioning system;
fig. 3 is a flowchart illustrating a DT correction method applicable to a wide area multipoint positioning system according to a first embodiment of the present invention;
fig. 4 is a schematic structural diagram illustrating a DT correction system suitable for a wide area multipoint positioning system according to a second embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
As used in this specification and the appended claims, the term "if" may be interpreted contextually as "when", "upon" or "in response to a determination" or "in response to a detection". Similarly, the phrase "if it is determined" or "if a [ described condition or event ] is detected" may be interpreted contextually to mean "upon determining" or "in response to determining" or "upon detecting [ described condition or event ]" or "in response to detecting [ described condition or event ]".
It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.
As shown in fig. 3, a flowchart of a DT correction method for a wide area multipoint positioning system according to a first embodiment of the present invention is shown, where the method includes:
acquiring the message processing time length of a transmitter and the processing time length of a radio frequency card;
acquiring the transmission signal duration of a transmitting antenna;
acquiring a linear distance between a transmitting antenna and a receiving feeder line, and calculating the transmission time of a message space;
acquiring an original message output by a ground station, and demodulating a small time scale;
the DT correction value is equal to the small time scale minus the message processing duration and the radio frequency processing duration of the transmitter, the transmission signal duration of the transmitting antenna and the message space transmission duration.
In the figure, Δ T1 is the message processing duration and RF processing duration of the transmitter, Δ T2 is the transmission signal duration of the transmitting antenna, Δ T3 is the message space transmission duration, Δ T4 is the transmission duration of the message on the receiver feeder, and Δ T5 is the RF processing and SP processing duration of the receiver. d is the linear distance between the transmitting antenna and the receiving antenna, and assuming that the measured coordinates of the transmitting antenna and the receiving antenna are (x1, y1, z1) and (x2, y2, z2), respectively, the linear distance d between the transmitting antenna and the receiving antenna is:
the message output of the transmitter in the figure is driven by the PPS (pulse per second), the jitter of which can be controlled within 10ns, and the PPS time can be regarded as the zero time. The delta T1 is the message processing time length and the RF processing time length of the transmitter, and the delta T2 is the transmission time length of the transmitting antenna, and both the absolute values can be measured by an oscilloscope. Δ T3 is the spatial transmission duration, which can be obtained by dividing the linear distance d between the antennas by the speed of light,i.e., Δ T3 ═ d/c, where c is the speed of light 3 × 108m/s。
The transmitter and the receiver both adopt high-precision clock modules, and the jitter value of the PPS is within 10 ns. Under the effect of the PPS, the transmitter transmits one identical message per second. The computer acquires an original message output by the ground station and demodulates the TOA small time scale according to the original message. From the above analysis, the DT correction values can be:
DT＝ΔT4+ΔT5＝TOA-ΔT1-ΔT2-ΔT3
i.e. the DT correction value contains two parts: (1) receive feeder transmission duration, i.e., Δ T4, (2) receiver RF processing duration and SP processing duration, i.e., Δ T5. In this embodiment, for the same transmitter, the message processing time length, the RF processing time length, and the transmission time length of the transmitting antenna are fixed values, and can be eliminated when calculating the TDOA. Thus, in actual calculations, the DT values are:
at the time of the actual test,
the DT value of each packet is calculated, and for the accuracy of the calculated result, the DT value is often measured for more than 30 minutes, and the average value of the calculated DT values is obtained.
The DT correction method applicable to the wide area multipoint positioning system provided by the embodiment of the invention has the advantages that all ground stations are not required to receive signals simultaneously, the time length of signal transmission by a feeder line is not required to be measured, the DT value of each station can be effectively measured, the calculation is simple, the operation is simple and convenient, the DT value obtained by calculation is accurate and reliable, an accurate data base is provided for subsequent positioning calculation, and the positioning precision is improved.
In the first embodiment, a DT calibration method suitable for a wide area multipoint positioning system is provided, and correspondingly, another embodiment of the present application further provides a DT calibration system suitable for a wide area multipoint positioning system. Please refer to fig. 4, which is a schematic structural diagram of a DT calibration system suitable for a wide area multipoint positioning system according to a second embodiment of the present invention. Since the apparatus embodiments are substantially similar to the method embodiments, they are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for relevant points. The device embodiments described below are merely illustrative.
As shown in fig. 4, there is shown a schematic structural diagram of a DT correction system suitable for a wide area multipoint positioning system according to a second embodiment of the present invention, where the system includes: a first acquisition module, a second acquisition module, a spatial transmission duration calculation module, a demodulation module and a DT correction value calculation module, wherein,
the first acquisition module is used for acquiring the message processing time length of the transmitter and the processing time length of the radio frequency card;
the second acquisition module is used for acquiring the transmission signal duration of the transmitting antenna;
the space transmission duration calculation module is used for acquiring a linear distance between the transmitting antenna and the receiving feeder line and calculating the message space transmission duration;
the demodulation module is used for acquiring an original message output by the ground station and demodulating a small time scale;
and the DT correction value calculation module is used for subtracting the message processing time length and the radio frequency processing time length of the transmitter, the transmission signal time length of the transmitting antenna and the message space transmission time length from the hour mark.
The above description is directed to an exemplary embodiment of a DT correction system suitable for a wide area multipoint positioning system according to the second exemplary embodiment of the present invention.
The DT correction system applicable to the wide area multipoint positioning system provided by the embodiment does not need to receive signals simultaneously by all ground stations and measure the time length of the feeder line transmission signals, can effectively measure the DT value of each station, is simple in calculation and simple and convenient to operate, obtains accurate and reliable DT values through calculation, provides an accurate data base for subsequent positioning calculation, and improves the positioning precision.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (10)
1. A DT correction method for use in a wide area multipoint positioning system, the method comprising:
acquiring the message processing time length of a transmitter and the processing time length of a radio frequency card;
acquiring the transmission signal duration of a transmitting antenna;
acquiring a linear distance between a transmitting antenna and a receiving feeder line, and calculating the transmission time of a message space;
acquiring an original message output by a ground station, and demodulating a small time scale;
the DT correction value is equal to the small time scale minus the message processing duration and the radio frequency processing duration of the transmitter, the transmission signal duration of the transmitting antenna and the message space transmission duration.
2. The DT correction method of claim 1, wherein the specific method of calculating the message space transmission duration is: the linear distance between the transmitting antenna and the receiving feed is divided by the speed of light.
3. The DT correction method of claim 1, wherein the transmitter and receiver both use high precision clock modules and the second pulse jitter value is within 10 ns.
4. The DT correction method of claim 1, wherein the transmitter message processing duration and the radio frequency processing duration and the transmit antenna transmission signal duration are fixed values.
5. The DT correction method of claim 1, wherein the DT correction value is the sum of a receive feeder transmission duration, a receiver radio frequency processing duration and an SP card processing duration.
6. A DT correction system adapted for use in a wide area multipoint positioning system, comprising: a first acquisition module, a second acquisition module, a spatial transmission duration calculation module, a demodulation module and a DT correction value calculation module, wherein,
the first acquisition module is used for acquiring the message processing time length of the transmitter and the processing time length of the radio frequency card;
the second acquisition module is used for acquiring the transmission signal duration of the transmitting antenna;
the space transmission duration calculation module is used for acquiring a linear distance between the transmitting antenna and the receiving feeder line and calculating the message space transmission duration;
the demodulation module is used for acquiring an original message output by the ground station and demodulating a small time scale;
and the DT correction value calculation module is used for subtracting the message processing time length and the radio frequency processing time length of the transmitter, the transmission signal time length of the transmitting antenna and the message space transmission time length from the hour mark.
7. The DT correction system of claim 6, wherein the specific method for the spatial transmission duration calculation module to calculate the message spatial transmission duration is: the linear distance between the transmitting antenna and the receiving feed is divided by the speed of light.
8. The DT correction system of claim 6, wherein the transmitter and receiver each employ high precision clock modules with pulse-per-second jitter values within 10 ns.
9. The DT correction system of claim 6, wherein the transmitter message processing duration and the radio frequency processing duration and the transmit antenna transmission signal duration are fixed values.
10. The DT correction system of claim 6, wherein the DT correction value is a sum of a receive feeder transmission duration, a receiver radio frequency processing duration and an SP card processing duration.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011488122.1A CN112526468A (en) | 2020-12-16 | 2020-12-16 | DT correction method and system suitable for wide area multipoint positioning system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011488122.1A CN112526468A (en) | 2020-12-16 | 2020-12-16 | DT correction method and system suitable for wide area multipoint positioning system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112526468A true CN112526468A (en) | 2021-03-19 |
Family
ID=75000641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011488122.1A Pending CN112526468A (en) | 2020-12-16 | 2020-12-16 | DT correction method and system suitable for wide area multipoint positioning system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112526468A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472463A (en) * | 2013-10-03 | 2013-12-25 | 中国电子科技集团公司第五十四研究所 | Delay calibration method of satellite navigation receiving set |
| CN105871495A (en) * | 2015-12-29 | 2016-08-17 | 中国科学院国家天文台 | Time synchronization method, communication ground station and user terminal |
| CN107070567A (en) * | 2017-04-06 | 2017-08-18 | 中国科学院国家授时中心 | Time delay calibrating method between a kind of ground satellite station station based on pseudo satellite, pseudolite |
| CN110518964A (en) * | 2019-09-06 | 2019-11-29 | 中国电子科技集团公司第五十四研究所 | A kind of ground satellite station high-precision time synchronization method based on light-carried wireless network |
| CN111856520A (en) * | 2019-08-15 | 2020-10-30 | 郑州市质量技术监督检验测试中心 | Time delay measuring system of satellite navigation receiver |
-
2020
- 2020-12-16 CN CN202011488122.1A patent/CN112526468A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472463A (en) * | 2013-10-03 | 2013-12-25 | 中国电子科技集团公司第五十四研究所 | Delay calibration method of satellite navigation receiving set |
| CN105871495A (en) * | 2015-12-29 | 2016-08-17 | 中国科学院国家天文台 | Time synchronization method, communication ground station and user terminal |
| CN107070567A (en) * | 2017-04-06 | 2017-08-18 | 中国科学院国家授时中心 | Time delay calibrating method between a kind of ground satellite station station based on pseudo satellite, pseudolite |
| CN111856520A (en) * | 2019-08-15 | 2020-10-30 | 郑州市质量技术监督检验测试中心 | Time delay measuring system of satellite navigation receiver |
| CN110518964A (en) * | 2019-09-06 | 2019-11-29 | 中国电子科技集团公司第五十四研究所 | A kind of ground satellite station high-precision time synchronization method based on light-carried wireless network |
Non-Patent Citations (4)
| Title |
|---|
| 周钰;熊耀恒;: "利用卫星进行双向时间传递", 天文研究与技术, no. 01 * |
| 崔小准;毕少筠;钟兆丰;王庆华;朱剑涛;: "一种星间链路天线时延零值测试方法", 测绘科学技术学报, no. 06 * |
| 谢军;张建军;王岗;: "北斗卫星导航系统测量误差指标体系", 宇航学报, no. 09 * |
| 谢维华 等: "北斗卫星导航系统用户终端时延标定方法", 全球定位系统, vol. 41, no. 1, pages 32 - 36 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107454670B (en) | Positioning system | |
| CN101808359B (en) | Method and device for positioning terminal in long-term evolution system | |
| KR101220794B1 (en) | Rtls system using tdoa | |
| CN110167135B (en) | TDOA wireless positioning method and system free of clock synchronization | |
| CN107113762B (en) | Positioning method, positioning server and positioning system | |
| CA2795529A1 (en) | Network location and synchronization of peer sensor stations in a wireless geolocation network | |
| CN109001675B (en) | Positioning method for measuring distance difference based on phase difference | |
| CN102023290A (en) | High-precision distributed pulse signal time difference of arrival detection system | |
| JP2010511155A (en) | Method, software and system for determining the position of a user device | |
| CN1932549B (en) | Low-level flying target passive location method and system | |
| Li et al. | TDOA-based passive localization of standard WiFi devices | |
| WO2021235621A1 (en) | Indoor positioning system and method using gps location information mapping | |
| JPWO2009145325A1 (en) | Mobile body relative position detection system and mobile body performing relative position detection | |
| CN102573055A (en) | Method for locating nodes in wireless sensor network | |
| US2637841A (en) | Position finding of electrical disturbances | |
| CN112526468A (en) | DT correction method and system suitable for wide area multipoint positioning system | |
| KR100958412B1 (en) | Self-location cognition system of mobile robot and method thereof | |
| CN110658491A (en) | Direction finding system, direction finding method, positioning system and positioning method | |
| JP5326982B2 (en) | Position measuring method and position measuring apparatus | |
| US6266012B1 (en) | Use of global positioning system in locating a radio transmitter | |
| CN102692617A (en) | Position movement detection equipment and detection method thereof | |
| CA2171333A1 (en) | Apparatus and method for locating cellular telephones and similar transmitters | |
| KR100841356B1 (en) | Apparatus and method for time check | |
| CN207675951U (en) | Indoor GNSS antenna array and positioning system | |
| RU2814218C1 (en) | Method and system for locating object |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |