GB2458969A - Multilateration apparatus for locating an aircraft emitting a radio signal - Google Patents

Multilateration apparatus for locating an aircraft emitting a radio signal Download PDF

Info

Publication number
GB2458969A
GB2458969A GB0812211A GB0812211A GB2458969A GB 2458969 A GB2458969 A GB 2458969A GB 0812211 A GB0812211 A GB 0812211A GB 0812211 A GB0812211 A GB 0812211A GB 2458969 A GB2458969 A GB 2458969A
Authority
GB
United Kingdom
Prior art keywords
time
multilateration
arrival
window
data
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.)
Granted
Application number
GB0812211A
Other versions
GB0812211D0 (en
GB2458969B (en
Inventor
Adam Alexander Baker
Timothy John Quilter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Roke Manor Research Ltd
Original Assignee
Roke Manor Research Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Roke Manor Research Ltd filed Critical Roke Manor Research Ltd
Publication of GB0812211D0 publication Critical patent/GB0812211D0/en
Priority to NZ574507A priority Critical patent/NZ574507A/en
Priority to EP09151920A priority patent/EP2107387A3/en
Priority to AU2009200419A priority patent/AU2009200419B8/en
Priority to US12/409,947 priority patent/US8174448B2/en
Priority to CA2660503A priority patent/CA2660503C/en
Priority to CN2009101302775A priority patent/CN101551449B/en
Publication of GB2458969A publication Critical patent/GB2458969A/en
Application granted granted Critical
Publication of GB2458969B publication Critical patent/GB2458969B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

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
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
    • G01S13/878—Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/021—Calibration, monitoring or correction
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0221—Receivers
    • G01S5/02213—Receivers arranged in a network for determining the position of a transmitter
    • G01S5/02216—Timing or synchronisation of the receivers
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/06—Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
    • G01S13/78—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe
    • G01S13/781—Secondary Surveillance Radar [SSR] in general

Abstract

A multilateration system 1 is disclosed comprising a controller 20 having a time of arrival correlator 28 for performing a time of arrival correlation using a time of arrival window based on receiver location, the window comprising the time difference that may be experienced for receipt of a signal by receivers 2-6 in the multilateration system 1. The window is applied to received synchronised time of arrival data to determine which data has a low and which data has a high probability of originating from a single aircraft 7, and passing the data with a high probability to the multilateration controller 20, which performs a multilateration to determine the position of the aircraft 7. The window may be chosen dynamically such that it is the optimum for the configuration of receivers used. The arrangement may further be applied to receivers in different neighbouring multilateration systems.

Description

Multilateration Apparatus This invention relates to a multilateration apparatus particularly but not exclusively for locating aircraft emitting a radio signal.
A multilateration system is an arrangement of receiver stations located at different geographical locations which receive a signal transmitted from an object the position of which is to be located. An aircraft positioning system is an example of a current application for multilateration. The aircraft transmits a signal which is received by io ground based receivers. From the time of arrival of the signal at the receivers, and a knowledge of their positions, the position of the aircraft at the time of transmission may be determined. Such a system is described in GB2250154A the contents of which are incorporated herein by reference.
Each receiver station in the system needs an accurate frequency source for successful operation. As will be appreciated, for such safety critical applications involving often fast moving aircraft, accuracy and reliability is not a trivial matter. It is therefore not unusual to have expensive atomic clock based local frequency references such as a rubidium or caesium oscillator. However, even these suffer from performance drift particularly with environmental changes such as, in particular, temperature variations.
The time of arrival of the signal is usually measured against a time reference derived from the frequency source which is then correlated with a global time reference such as a Global Navigation Satellite System. In effect, the time of arrival of the signal (TOA) is measured at each receiver against a global clock using a time of arrival (TOA) correlator. The correlator monitors for the expected signal and ensures that the correct one is used to perform the multilateration calculation.
The correlated emissions from the aircraft are then used to provide TOA vectors which are then processed to derive the aircraft's position.
The present invention arose in an attempt to enhance the correlation of received signals in a multilateration system. In particular, to ensure speed and accuracy of 3s correlation and to cater for performance changes and configuration changes.
According to the invention therefore there is provided a multilateration system controller comprising a time of arrival correlator for performing a time of arrival correlation using a time of arrival window based on receiver location which window comprising the time difference that may be experienced for receipt of a signal by receivers in the multilateration system, applying the window to received synchronised time of arrival data to determine which data has a low and which data has a high probability of originating in the same aircraft and passing at least the data with a high probability to multilateration processor which performs a multilateration to determine the position of the source.
By providing a time of arrival window which is based on the receiver locations, the window may be chosen to be the optimum for the configuration of receivers used.
Advantageously, this will be done in a dynamic way based on the receiver combination used which allows for different time of arrival windows to be used for different receiver sets or subsets.
The invention is even more advantageous where receivers in different neighbouring multilateration systems are used. It has been proposed to use in boundary regions between systems the receivers from a first system in conjunction with receivers from a second system to provide a positioning capability covering the boundary area. A group of receivers may be formed from the two systems and their returns combined.
GB2440572 describes such a system. The difficulty of using two systems is that they may work in accordance with different system clocks and other components which will be difficult to synchronise. Even when synchronised, as components age, synchronisation differences may arise. In a described embodiment of this invention this problem is alleviated by providing a correlation window which is at least in part based on a permissible synchronisation error which ensures correlation of received signals. The inventors have also appreciated that the systems may also experience differing environmental conditions due to weather which may also affect the system performance.
In the broadest aspect there is also provided a time of arrival correlation window applied to data from receivers in two or more different multilateration systems.
Preferably, the time of arrival window is determined, at least in part, with reference to the receiver locations used. Again, preferably, the time of arrival window is determined, at least in part, from a determination of a potential system synchronisation mismatch.
The time of arrival window will be determined on considerations of the path lengths between the receivers used. The time of arrival window may therefore be changed io as the combination of receivers used is varied. Whilst a worst possible case time of arrival window based on the maximum possible path length difference may be used, it is preferable for a number of windows to be used which are tailored to each receiver. This will maximise the number of correlated received signals.
The time of arrival window will be determined with reference to the speed of transmitted radio waves and the time thus taken for the signal to respective receivers depending upon the path length difference. This may be treated as the speed of light C in a vacuum but it may be a more accurate figure for the transmission of radio waves through the air. Means may be provided to adjust the figure used in accordance with the prevailing atmospheric conditions.
The time of arrival window may be defined and held in a memory table or it may be calculated prior to use.
A specific embodiment of the invention will now be described, by way of example only, with reference to the drawing in which: Figure 1 shows an overview of a multilateratiori system in accordance with the invention; Figure 2 shows a correlator used in the system shown in figure 1; and Figure 3 shows the manner in which the invention may be used to correlate received signals from receivers in two distinct multilateration systems which are combined.
As is shown in figure 1, a multilateration system 1 includes a plurality of receiver stations 2 to 6 positioned at a number of locations on the ground. These receive a transmitted signal including a code from a transponder mounted on an aircraft 7. The code is a Secondary Surveillance RADAR code which may be a mode A, mode S, mode C or may be an unknown mode of code.
Receiver station 4 is termed a master station because it includes a controller which uses the data from the receivers to perform the multilateration process. (In alternative embodiments it need not be co-located with the receiver.) The data from the receiver stations 2, 3, 5 and 6 is passed to the master station 4 over data links 8.
The controller 20 is microprocessor based and is shown in greater detail in figure 2. It includes a number of input ports 21 to 24 linked to the data links 8 and hence to the receiver stations. The input ports 21 to 24 are connected to a timing correction processor 25. This corrects for the variation in timing at each of the receiver stations using correction values derived in a known manner from Global Navigation Satellite System data provided by the receiver stations. This is received from the stations at ports 26 to a synchronisation processor 27. The synchronisation processor 27 applies a synchronisation algorithm to produce the required time correction. The time correction values are input to the timing correction processor 25. It will be appreciated that the timing correction may be a time difference that may be experienced for receipt of a signal by receivers in a multilateration system or in other ways.
The time corrected or synchronised time of arrival messages are coupled to a time of arrival correlator 28. The correlator 28 forms the data into sets which originate for particular transmissions of codes or events. The events are correlated by reference to time by application of a time of arrival window held in memory 29. Thus, if a mode A, mode C, mode S or an unknown mode code arrive within a certain time window or frame then they are considered to originate from the same aircraft as the same emission event. The correlator also ties up Time Of Arrival information from the same event for all the receivers as a so-called Time Of Arrival vector which may be of arbitrary length dependent upon the receivers that received a particular emission of a code. The vectors are then passed to a time difference of arrival processor 29 which applies a known multilateration process (for example, such as that disclosed in GB2349531) to produce track data which is passed to a track memory 30. The track memory 30 provides the tracks to a plotting system for the tracks of the aircraft and positions to be displayed.
The TOA correlator has the function of identifying and correlating the same signal received at the receivers. The signals are correlated according to their time of arrival using a time of arrival window held in the memory 29. There is a maximum difference in the time of arrivals that could arise from the same signal being received at different receivers. This is primarily due to the path differences between receiver sites and in this embodiment has a maximum value of 540 micro seconds. (This may vary according to the system so should be determined on a system to system basis.) If the signal arrives within the window it will have a high probability of arising from the same emission event.
In alternative embodiments, the time of arrival window may be determined when required. Also, more than one time window may be applied. For example, a system maximum path length case may be used to derive the window or it may be determined on a receiver to receiver basis. Thus a number of windows may be used in a dynamic manner to cater for the use of different combinations of receivers.
Figure 3 shows a further embodiment. In this embodiment, a first multilateration system A provides time or arriva' values which are correlated by using a window WA.
Multilateration system B provides time of arrival values which are correlated by use of a window WB based on the path lengths involved in that system. The values are then provided to a combined system processor which correlates the time of arrival data using a correlation window WC. The window WC will be a window based on a consideration of the path lengths and the speed of propagation of radio waves to derive a time delay between the receivers in the effectively combined systems and also a time value which caters for the potential synchronisation differences or miss-match between system A and B. This is particularly advantageous since each system will have different system clocks and components which have parameters which may vary over time. Also environmental conditions over such geographically dispersed systems may very considerably which again may cause system performance miss-matches. This may be taken into account when the window is established by the use of data provided by environmental sensors located with the receivers and systems.
Environmental sensor outputs may also be used to determine factors which will affect the propagation of the radio waves. This will have a bearing on the width of the time of arrival window used for correlation as the speed of propagation will determine the time delay due to path length differences.

Claims (6)

  1. Claims 1. A multilateration system controller comprising a time of arrival correlator for performing a time of arrival correlation using a time of arrival window based on receiver location which window comprising the time difference that may be experienced for receipt of a signal by receivers in a multilateration system, applying the window to received synchronised time of arrival data to determine which data has a low and which data has a high probability of originating in the same aircraft and passing at least the data with a high probability to multilateration processor which performs a multilateration to determine the position of the source.
  2. 2. A multilateration system controller as claimed in claim 1 in which the applied time of arrival window is determined with reference a maximum time difference for the system for signals received by any receiver.
  3. 3. A multilateration system controller as claimed in claim 1 in which the applied time of arrival window is determined with reference to particular receivers.
  4. 4. A multilateration system controller as claimed in any preceding claim in which the time of arrival correlator performs a correlation on data received from receivers in two or more multilateration systems using a time of arrival window based on a time difference that may be experienced for receipt of a signal by receivers in the multilateration systems.
  5. 5. A multilateration system controller as claimed in claim 4 wherein the time of arrival window is further determined in accordance with a predicted synchronisation mismatch between the systems.
  6. 6. A multilateration system controller substantially as hereinbefore described with reference to the accompanying drawings.Amendments to the claims have been filed as follows 1. A multilateration system controller comprising a time of arrival correlator for performing a time of arrival correlation using a time of arrival window based on receiver location which window comprising the time difference that may be experienced for receipt of a signal by receivers in a multilateration system, applying the window to received synchronised time of arrival data to determine which data has a low and which data has a high probability of originating from a single aircraft and passing at least the data with a high probability to a multilateration processor which performs a multilateration to determine the position of the aircraft.2. A multilateration system controller as claimed in claim 1 in which the applied time of amval window is determined with reference a maximum time difference for the system for signals received by any receiver.3. A multilateration system controller as claimed in claim 1 in which the applied time of amval window is determined with reference to particular receivers.4. A multilateration system controller as claimed in any preceding claim in which the time of amval correlator performs a correlation on data received from receivers in two or more multilateration systems using a time of arrival window based on a time difference that may be experienced for receipt of a signal by receivers in the multilateration systems. * ***** 25 5. A multilateration system controller as claimed in claim 4 wherein the time of arrival window is further determined in accordance with a predicted synchronisation mismatch between the systems.***SS* * * 6. A multilateration system controller substantially as hereinbefore described a.., * I with reference to the accompanying drawings. a
GB0812211A 2008-03-31 2008-07-04 Multilateration apparatus Expired - Fee Related GB2458969B (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NZ574507A NZ574507A (en) 2008-03-31 2009-01-29 Multilateration apparatus
EP09151920A EP2107387A3 (en) 2008-03-31 2009-02-03 Multilateration Apparatus
AU2009200419A AU2009200419B8 (en) 2008-03-31 2009-02-04 Multilateration apparatus
US12/409,947 US8174448B2 (en) 2008-03-31 2009-03-24 Multilateration apparatus
CA2660503A CA2660503C (en) 2008-03-31 2009-03-27 Multilateration apparatus
CN2009101302775A CN101551449B (en) 2008-03-31 2009-03-30 Multilateration apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB0805787.9A GB0805787D0 (en) 2008-03-31 2008-03-31 A multilateration method and apparatus

Publications (3)

Publication Number Publication Date
GB0812211D0 GB0812211D0 (en) 2008-08-13
GB2458969A true GB2458969A (en) 2009-10-07
GB2458969B GB2458969B (en) 2010-02-17

Family

ID=39387018

Family Applications (2)

Application Number Title Priority Date Filing Date
GBGB0805787.9A Ceased GB0805787D0 (en) 2008-03-31 2008-03-31 A multilateration method and apparatus
GB0812211A Expired - Fee Related GB2458969B (en) 2008-03-31 2008-07-04 Multilateration apparatus

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GBGB0805787.9A Ceased GB0805787D0 (en) 2008-03-31 2008-03-31 A multilateration method and apparatus

Country Status (7)

Country Link
US (1) US8174448B2 (en)
EP (1) EP2107387A3 (en)
CN (1) CN101551449B (en)
AU (1) AU2009200419B8 (en)
CA (1) CA2660503C (en)
GB (2) GB0805787D0 (en)
NZ (1) NZ574507A (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE143116T1 (en) * 1992-03-30 1996-10-15 Michael Robert Corbett PRODUCTION OF PIPE CONNECTIONS
US9377524B2 (en) * 2011-04-12 2016-06-28 Era A.S. Time synchronization via over-determined measurements
FR2974184B1 (en) * 2011-04-14 2015-03-27 Thales Sa METHOD FOR LOCATING AIRCRAFT INDEPENDENT OF ANY SATELLITE NAVIGATION SYSTEM
CN102590786A (en) * 2012-02-03 2012-07-18 中国电子科技集团公司第三十八研究所 Multilateral positioning system based on distributed clock
CN103869281A (en) * 2014-03-13 2014-06-18 中国民用航空总局第二研究所 Passive multipoint positioning system-based double-threshold association method
CN105699939B (en) * 2016-01-29 2018-02-13 申研 A kind of high-precision real-time positioning apparatus and its method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6094169A (en) * 1998-12-11 2000-07-25 Rannoch Corporation Multilateration auto-calibration and position error correction
EP1881339A1 (en) * 2006-07-03 2008-01-23 Roke Manor Research Limited An apparatus for multilateration and method
US20080062043A1 (en) * 2006-09-13 2008-03-13 Sinan Gezici Radio ranging using sequential time-difference-of-arrival estimation

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040054A (en) * 1975-08-27 1977-08-02 Westinghouse Electric Corporation Tracking of radar signals
GB2250154B (en) * 1990-11-21 1994-10-26 Roke Manor Research Apparatus and method for locating an object
US7132982B2 (en) * 1999-03-05 2006-11-07 Rannock Corporation Method and apparatus for accurate aircraft and vehicle tracking
GB2349531B (en) 1999-04-29 2003-08-27 Roke Manor Research Improvements in or relating to object location
US6191738B1 (en) * 1999-09-30 2001-02-20 Motorola, Inc. Method and apparatus for locating a remote unit within a communication system
JP3308966B2 (en) * 2000-06-12 2002-07-29 松下電器産業株式会社 Inter-node synchronization device and inter-node synchronization method
US7420947B2 (en) * 2002-08-30 2008-09-02 Qualcomm Incorporated Communication system performance using position location information
CN100502594C (en) * 2003-06-25 2009-06-17 美商内数位科技公司 Method for downlink transmission synchronization and determining data buffer size in a radio access network
US7319878B2 (en) * 2004-06-18 2008-01-15 Qualcomm Incorporated Method and apparatus for determining location of a base station using a plurality of mobile stations in a wireless mobile network
CN100433926C (en) * 2005-12-15 2008-11-12 华为技术有限公司 Method for accuretely positioning mobile station in double-arriving-time positioning
GB2440572A (en) 2006-08-01 2008-02-06 Roke Manor Research Method and apparatus for controlling a clock and frequency source at a receiver
GB2444300B (en) * 2006-12-01 2008-12-24 Roke Manor Research Method for use in a multilateration system and a multilateration system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6094169A (en) * 1998-12-11 2000-07-25 Rannoch Corporation Multilateration auto-calibration and position error correction
EP1881339A1 (en) * 2006-07-03 2008-01-23 Roke Manor Research Limited An apparatus for multilateration and method
US20080062043A1 (en) * 2006-09-13 2008-03-13 Sinan Gezici Radio ranging using sequential time-difference-of-arrival estimation

Also Published As

Publication number Publication date
AU2009200419B8 (en) 2015-01-15
US20090273519A1 (en) 2009-11-05
AU2009200419A1 (en) 2009-10-15
GB0812211D0 (en) 2008-08-13
EP2107387A3 (en) 2010-05-19
AU2009200419A8 (en) 2015-01-15
GB0805787D0 (en) 2008-04-30
US8174448B2 (en) 2012-05-08
CN101551449B (en) 2013-07-17
CN101551449A (en) 2009-10-07
CA2660503A1 (en) 2009-09-30
CA2660503C (en) 2014-05-27
EP2107387A2 (en) 2009-10-07
NZ574507A (en) 2010-05-28
AU2009200419B2 (en) 2014-08-07
GB2458969B (en) 2010-02-17

Similar Documents

Publication Publication Date Title
US8174448B2 (en) Multilateration apparatus
EP2148214B1 (en) Spacecraft position estimating system and method
EP1751580B1 (en) High precision surveillance system by means of multilateration of secondary surveillance radar (ssr) signals
CA3016332A1 (en) Position estimation in a low earth orbit satellite communications system
US8599956B1 (en) Doppler compensated communications link
WO2014011264A2 (en) A system and method for aircraft navigation based on diverse ranging algorithm using ads-b messages and ground transceiver responses
Khalife et al. On the achievability of submeter-accurate UAV navigation with cellular signals exploiting loose network synchronization
JP5669168B2 (en) Distance measuring system and distance measuring method
US20120268321A1 (en) Global Positioning System Signal Reception with Increased Resistance to Interference
KR20080025667A (en) Method and system for calibration of a radio direction finder
EP1887379B1 (en) A method and apparatus for controlling a frequency source
CN102809754A (en) Geographical positioning system of wireless signal transmitter located on the surface of the earth and associated distributed interferometry method
US20150247929A1 (en) Positioning system and method
JP6573328B2 (en) Wireless communication system and wireless communication device
KR102041470B1 (en) METHOD AND APPARATUS FOR eLoran-BASED TIME SYNCHRONIZATION
US3550002A (en) Pulsar communication systems
US7940693B2 (en) Wireless communication system for calculating time of flight
GB2585191A (en) Positioning system and method with inertial navigation and position estimate
US20240125884A1 (en) Method for testing a telecommunication standard-based positioning, navigation, and timing system and test device
JP4948485B2 (en) Direction finding device
SE545367C2 (en) Method and system for position determination
Linde et al. Low cost resolution enhancement in hyperbolic localization
KR20200011318A (en) Unidentified cospas-sarsat beacon location estimation method and system

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20150704