GB1262223A

GB1262223A – Improvements in or relating to location systems
– Google Patents

GB1262223A – Improvements in or relating to location systems
– Google Patents
Improvements in or relating to location systems

Info

Publication number
GB1262223A

GB1262223A
GB3113370A
GB3113370A
GB1262223A
GB 1262223 A
GB1262223 A
GB 1262223A
GB 3113370 A
GB3113370 A
GB 3113370A
GB 3113370 A
GB3113370 A
GB 3113370A
GB 1262223 A
GB1262223 A
GB 1262223A
Authority
GB
United Kingdom
Prior art keywords
register
value
adder
correction
station
Prior art date
1970-06-26
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.)

Expired

Application number
GB3113370A
Inventor
Rodney William Gibson
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.)

Philips Components Ltd

Original Assignee
Mullard 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.)
1970-06-26
Filing date
1970-06-26
Publication date
1972-02-02

1970-06-26
Application filed by Mullard Ltd
filed
Critical
Mullard Ltd

1970-06-26
Priority to GB3113370A
priority
Critical
patent/GB1262223A/en

1972-02-02
Publication of GB1262223A
publication
Critical
patent/GB1262223A/en

1973-02-07
Priority to GB1354667D
priority
patent/GB1354667A/en

Status
Expired
legal-status
Critical
Current

Links

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Global Dossier

Discuss

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

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

G01S5/14—Determining absolute distances from a plurality of spaced points of known location

Abstract

1,262,223. Radio position finders. MULLARD Ltd. 26 June, 1970, No. 31133/70. Heading H4D. In a location system for determining the position of a mobile station by measuring the arrival times of signals passing between the mobile station and at least three fixed stations, the position of said mobile station arid the time or times of origin of said signal or signals are first assumed and subsequently iteratively corrected to a required degree of accuracy. Radio signals are generally used, but the system is also applicable to light or sound signals. If there are three fixed stations 1, 2, 3, Fig. 2 with respective rectangular co-ordinates (x 1 , y 1 ), (x 2 , y 2 ), (x 3 , y 3 ) and a mobile station at A from which a signal, conveniently a pulse of very short duration (e.g. one micro-second), is received at respective times t 1 , t 2 , t 3 , then it may be assumed that the mobile station is at B, with co-ordinates (x, y), and that the signal was sent at time t1. The distance G 1 of the point B from the fixed station 1 is given by, and, assuming for convenience that the signal propagation velocity is unity, the nominal distance T, is given by, An error factor F 1 is given by, and similarly error factors F 2 , F 3 are derived for the fixed stations 2, 3. Corrections are iteratively applied so as to reduce each error factor in turn, whereby the assumed position of the mobile station is brought nearer and nearer to the true position. Instead of the usual correction of F/2T an approximation such as F/2W is used, where W is given by rounding up T to the nearest integral power of 2. The directions of movement of the assumed position of the mobile station may be made parallel to imaginary lines joining the fixed stations. A system for performing the required computations when there are four fixed stations comprises a subtractor SUB, Fig. 3, having inputs t 1 to t 4 and t1 and outputs T 1 to T 4 , a first digital multiplexer MX1 with inputs x, y, and T 1 to T 4 , and a second digital multiplexer MX2 with inputs selected from a read-only memory ROM in which the known coordinates x 1 to x 4 and y 1 to y 4 are stored. The system also comprises a first shift register SR1 which recirculates via a digital adder DA, second and third shift registers SR2, SR3, a shift control SH, a sign control logic unit SC, a digital multiplexer DM, a digital accumulator ACC, a «true/ complement/zero» logic unit TC, a decoder DEC and a sequence controller SEQ. The multiplexer MX1 steps in synchronism with the register SR1 so that, at the beginning of a cycle, its contents are arranged as shown in Fig. 3. The register SR1 is stepped by the controller SEQ so that each of the contents appears at the output stage at the appropriate time. In similar fashion, the multiplexer MX2 is stepped so that the appropriate fixed information from the memory ROM is fed into the shift register SR2; the outputs of both registers being combined to produce the terms required in the error factor equations. The fixed station co-ordinates are stored in the memory ROM as negative binary numbers, i.e. – x 1 , – y 1 etc., so that the terms (x – x 1 ) etc. are produced by addition in the adder DA. With the register SR1 in the position shown, x is fed into the adder DA from the register SR1 and – x 1 is fed from the register SR2. The term (x – x 1 ) appears at the output of the adder DA. The digital multiplier DM operates on the said output to produce the term (x – x 1 )2, which is fed into the accumulator ACC. The register SR2, the adder DA and the multiplier DM are then cleared. The register SR1 and the multiplexer MX2 are then stepped by the controller SEQ to the y and y 1 positions respectively; the term – y 1 being stored in the register SB2. The adder DA produces (y – y 1 ) which is squared in the multiplier DM and added to the existing information in the accumulator ACC to produce The register SR2, the adder DA and the multiplier DM are now cleared and the register SR1 is stepped to the T 1 position. In the ease of the T terms, the adding function of the adder DA is not required since no term is required from the register SR2. This is effected by retaining the register SR2 at zero so that the adder DA produces the term (T-O) which is squared in multiplier DM to produce +T2. It can happen in the course of applying corrections that a T value may become negative in sign, this fact being recorded by an appropriate sign digit stored in the most significant digit position of the relevant T information in the register SR1. The sign digit is fed via the sign control logic unit SC to the multiplier DM and is used to cause the T2 term in the multiplier to be subtracted from (if T is positive) or added to (if T is negative) the value (x – x 1 )2 + (y – y 1 )2 already stored in the accumulator ACC. The value for F 1 is therefore now stored in the accumulator. The F values are divided by a scaling factor W to produce the correction factors and the x and y values are modified by components respectively denoted u and v to produce corrections to the coordinates (x, y). The approximation for W used in this particular embodiment is W = 2n x (T rounded off to next lower integer power of 2). This is achieved by the W shift control logic SH which governs the transfer of the F value from the accumulator ACC to the register SR2. The T value in the register SR1 is duplicated in the register SR3 under control of the controller SEQ. The F 1 value is shifted from the accumulator ACC via the true/complement/zero logic unit TC into the register SR2 together with and at the same rate as the T value in the register SR3. When the most significant non-zero digit in the register SR3 reaches the last stage of this register, the shift pulses to the register SR2 from the shift control SH are inhibited. The effect of this is that the final position of the F value in the register SR2 is controlled by the value of T as given by the bracketed term in the above equation for W. The 2n term in this equation is implemented by the controller SEQ which produces the appropriate number of additional shift pulses so that the position of the F value in the register SR2 accords with the desired value of n. The desired value of n may be changed during the progressive computation, e.g., the sequence controller SEQ may be arranged so as to vary the value of n after a predetermined number of iterations. If the controller SEQ is arranged to produce the preferred cycle of operations in which a correction to the assumed time t1 is first made in respect of the first station error correction (F 1 ¸W now stored in the register SR2), each of the T values is stepped in turn to appear at the output of the register SR1 while the contents of the register SR2 are held static. In this way, each of the four T values has the correction added to it when it passes via the adder DA back into the register SR1; thus, in effect, applying a correction to assumed time t1 dependent upon the error in the assumed position with respect to station 1. Alternatively, if the method being used is to correct the assumed position with respect to station 1, the sequence controller is arranged to control the operation of the equipment in regard to station 1 in the same manner as will now be described for station 2. The value F 2 is computed and stored in the accumulator ACC in the same manner as described for F 1 ; except of course that the terms x, x 2 , y, y 2 and T2 are selected by the register SR1 and the multiplexer MX2. In this case, the assumed position is to be corrected and this involves resolving the correction magnitude F 2 ¸W into its components (F 2 ¸W) Î u along the OX axis and (F 2 ¸W) x v along the OY axis and adding these to the x and y terms respectively. The direction components are effected by multiplying the F 2 value by + 1, – 1, or 0 in the logic unit TC which either passes the F 2 digits unchanged (multiply by +1), inverts them (multiply by – 1), or suppresses them (multiply by 0). The decoder DEC uses signals from the sequence controller SEQ to select the appropriate function corresponding to the appropriate u or v value. In the manner, a correction for either the T values or for the x and y values can be produced in the register SR2. A shift pulse from the sequence controller then causes the sum of the existing value and the correction to be reentered into the register SR1. The process is repeated for F 3 and F 4 and the whole cycle then repeated; so applying successive corrections to the assumed position to cause it to converge in steps on the true position until the desired accuracy has been achieved. During the cycling, the values of x and y are progressively corrected and, at the end of the complete operation, the corrected values of x and y are taken from an output OP in turn for use by indicating equipment such as a map plotter or display unit.

GB3113370A
1970-06-26
1970-06-26
Improvements in or relating to location systems

Expired

GB1262223A
(en)

Priority Applications (2)

Application Number
Priority Date
Filing Date
Title

GB3113370A

GB1262223A
(en)

1970-06-26
1970-06-26
Improvements in or relating to location systems

GB1354667D

GB1354667A
(en)

1970-06-26
1973-02-07
Location systems

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

GB3113370A

GB1262223A
(en)

1970-06-26
1970-06-26
Improvements in or relating to location systems

Publications (1)

Publication Number
Publication Date

GB1262223A
true

GB1262223A
(en)

1972-02-02

Family
ID=10318510
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB3113370A
Expired

GB1262223A
(en)

1970-06-26
1970-06-26
Improvements in or relating to location systems

Country Status (1)

Country
Link

GB
(1)

GB1262223A
(en)

Cited By (3)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

GB2222922A
(en)

*

1988-06-16
1990-03-21
Spectronics Micro Syst Ltd
Vehicle location system

GB2230397A
(en)

*

1989-03-06
1990-10-17
Motorola Inc
Passive location method

CN100461969C
(en)

*

2006-09-22
2009-02-11
华为技术有限公司
A method to position the mobile station

1970

1970-06-26
GB
GB3113370A
patent/GB1262223A/en
not_active
Expired

Cited By (5)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

GB2222922A
(en)

*

1988-06-16
1990-03-21
Spectronics Micro Syst Ltd
Vehicle location system

GB2222922B
(en)

*

1988-06-16
1993-01-20
Spectronics Micro Syst Ltd
Vehicle location system

GB2230397A
(en)

*

1989-03-06
1990-10-17
Motorola Inc
Passive location method

GB2230397B
(en)

*

1989-03-06
1994-01-12
Motorola Inc
Passive location method

CN100461969C
(en)

*

2006-09-22
2009-02-11
华为技术有限公司
A method to position the mobile station

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