NL1025107C2 - Method and device for estimating a position using a GPS satellite signal. - Google Patents

Description

Brief indication: Method and device for estimating a position using a GPS satellite signal.

The invention relates to a method and a device, by means of which the position of a position estimation device is estimated using a number of satellite signals, which are delivered with predetermined time differences by one or more satellites of a worldwide positioning system (GPS).

Position estimation methods using the GPS satellite system generally estimate a range between the GPS satellite and the antenna of a position estimation device (e.g., a GPS receiver) using triangulation and pure and acquisition (C / A, or coarse and acquisition) code issued by the GPS satellite.

The GPS satellite always transmits an L1 frequency of 1575.42 MHz, which carries a C / A code. A position estimation device generates the same code as the C / A code. The generated C / A code is compared with the received C / A code from the GPS satellite. From the result of the comparison, the time period during which the C / A code issued by the GPS satellite arrives at the position estimation device is measured.

The position estimation device measures the range between the GPS satellite and the position estimation device using the result of the light speed multiplication (the speed of the C / A code issued by the GPS satellite) and the time period from delivery to arrival. Since the C / A code comprises a pseudo-will random noise code, which code in itself is substantially noise, and the measured range between the GPS satellite and the position estimator contains errors, the range is referred to as a pseudo-range.

A conventional position estimation device receives satellite signals issued by at least four GPS satellites in a timely manner, measures the pseudo-range corresponding to each satellite signal, and estimates the position of the position estimation device from the measurement results. That is, the position estimator is a three-dimensional 1025107

-2 - I

dimensional position of the position estimation device estimates by I

by using four or more simultaneously, by four or I

more GPS satellites issued satellite signals. I

Due to the influence of the environment, the position chat I

The device does not have at least four signals at certain moments

received at the same time. In this case, the conventional position I

estimator does not estimate its three-dimensional position. I

The invention is directed to a method and a device I

for determining a position using a global I

10 wide positioning system (GPS) satellite signal. In a receiver I

becomes from a first GPS satellite in a first position I

received the first GPS signal. A second GPS signal is received I

of the satellite in a second position of the satellite. The position I

of the receiver is determined using the first and I

15 second GPS signals. I

A third GPS signal can be from the first GPS satellite in an I

third position of the first GPS satellite to be received, and the I

third GPS signal can be used in determining position I

from the recipient. A fourth GPS signal can be received from the I

20 first GPS satellite in a fourth position of the first GPS satellite I

and the fourth GPS signal can be used in determining I

of the receiver's position. The fourth GPS signal can also be from I

a second GPS satellite in a first position of the second GPS combination

tellite and this fourth GPS signal can be used I

25 when determining the position of the receiver. I

The third GPS signal can also be received from a second I

GPS satellite in a first position of the second GPS satellite. This I

third GPS signal can be used in determining position I

from the recipient. The fourth GPS signal can be received from the I

30 second GPS satellite in a second position of the second GPS satellite

and this fourth GPS signal can be used in determining I

of the receiver's position. This fourth GPS signal can also be I

receiving a third GPS satellite in a first position of the I

GPS satellite, and this fourth GPS signal can be used with the I

35 determining the position of the receiver. I

The device for determining a position comprises a receiver

catcher for receiving the GPS signals and a position calculation

unit for determining the position of the receiver. An I

controller detects a number of usable satellites that can I

10 ^ 51-07- I

- 3 - are used in determining the position. A stationary measurement request and selection unit may request the user to remain stationary during position determination. The position calculating unit may include a time difference measurement determiner that requests the user to remain stationary during position determination if the number of usable satellites is below a threshold value. The position calculation unit may also include a time difference measurement calculator, which calculator calculates the position by measuring time differences between the GPS signals.

According to the invention, the position of a receiver, such as a GPS receiver, can be determined using fewer than four GPS signals from GPS satellites. As a result, a more reliable position determination or estimation system 15 is provided, particularly in cases where circumstances, such as environmental conditions, prevent the reception of GPS signals from four or more satellites.

The foregoing and other objects, features, and advantages of the invention will become apparent from the following detailed description of preferred embodiments of the invention as shown in the accompanying drawings, in which like reference numerals refer to the same parts in the various views. . The drawings are not necessarily to scale, but the emphasis is on illustrating the principles of the invention.

FIG. 1 is a diagram showing a position estimation method according to a first embodiment of the invention.

FIG. 2 is a diagram showing the position estimation method according to the first embodiment of the invention in greater detail.

FIG. 3 is a diagram showing a position estimation method according to a second embodiment of the invention.

FIG. 4 is a diagram showing the position estimation method according to the second embodiment of the invention in greater detail.

FIG. 5 is a block diagram of a position estimation device according to an embodiment of the invention.

FIG. 6 is a detailed block diagram of the controller and the position calculation unit shown in FIG. 5.

10251 0-7

- 4 - I

FIG. 7 is a flowchart that is determined by a position estimation I

method according to the invention shows steps based on I

the number of satellites that can be measured. I

FIG. 8 is a flow chart showing the position I in greater detail

5 estimation method according to the invention of a device shown in FIG

position estimation device. I

With reference to Fig. 1, the reference numeral 11 denotes the I

position of a GPS satellite at time (t1), and gives it

reference numeral 12 the position of the GPS satellite at time point (t2) after I

10 the expiration of a predetermined period from time (t1) I

On. I

If the pseudo-ranges of the satellite signals pass through the

identical GPS satellite at time (t1) and time (t2) have been delivered

are each measured and then results of the two ranges

Comparisons can be obtained, the data I

estimated positions of the position estimator, e.g., an H

GPS receiver, two locations (13A, 13B) if the positions in I

lie flat. I

Since the position of the position estimator in I

20 space coordinates is given and is variable, and there is a time difference I

between the GPS satellite measurements for the position estimation device I

However, four range comparisons are required to determine the position of the I

position estimation device. The method for I

however, positioning the position estimation device is not limited

25 is limited to the method that uses the pseudo-range. I

FIG. 2 is a diagram illustrating the position chat I in greater detail

The method according to the first preferred embodiment of the invention

shows. In the position estimation method according to the invention I

becomes a number of satellite output signals with predetermined time I

30 differences from one or more GPS satellites, and is set in

response to each of the received satellite signals, the position of the I

position estimation device estimated. I

With reference to Fig. 2, coordinates (x, y, z) give an I

estimated position of a position estimator, indicate I

35 coordinates (xl, yl, zl, tl) positional data (xl, yl, zl) of a GPS I

satellite 21 at time (t1), and p1 it at time (t1) I

pseudo-range measured by the position estimator. The I

it is preferred here that the position estimation device 25 is standing

or fixed. I

1 02 51 #? - I

- 5 -

Coordinates (x2, y2, z2, g2) indicate positional data (x2, y2, z2) of a GPS satellite 22 at time point (t2), and p2 indicates the pseudo-range measured at time point (t2) by the position estimation device On. Herein, time (t2) indicates the expiration of a predetermined period from time (t1).

Coordinates (x3, y3, z3, g3) indicate positional data (x3, y3, z3) of a GPS satellite 23 at time point (t3), and p3 indicates the pseudo-range measured at time point (t3) by the position estimator On. Herein, time (t3) indicates the expiration of a predetermined period from time (t2).

Coordinates (x4, y4, z4, g4) indicate positional data (x4, y4, z4) of a GPS satellite 24 at time point (t4), and p4 indicates the pseudo-range measured at time point (t4) by the position estimator On. Herein, time (t4) indicates the expiration of a predetermined period from time (t3). Reference numerals 21-24 do not indicate four different satellites, but the same satellite at four different times and locations.

The identification numbers (ID) of the GPS satellites 21 to 24 can be identical or different numbers. For example, the IDs of at least two or more GPS satellites can be identical numbers.

The following equation 1 shows four positional data ((x1, yl, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4) of the GPS satellites and measured pseudo ranges (p1, p2, p2, p4) at 25 time points (t1, t2, t3, t4) expressed range comparisons.

Accordingly, the position estimator receives positional data ((x1, y1, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4)) transmitted by respective GPS satellites 21 to 24 have been delivered at respective times (t1, t2, t3, t4). By measuring respective pseudo-ranges (p1, p2, p3, p4) and obtaining solutions (or roots) for the four range equations given as equation 1, the position 25, for example spatial coordinates (x, y, z) of the position estimator are calculated or estimated.

35 1 0 2510-7

I -6 - I

ψχΐ- χ) 2 + (yl - y) 2 + (zl - z) 2 + cAt = pl I

I ^ (x2 - x) 2 + (y2 - y) 2 + (z2 - z) 2 + cAt = p2 I

I 5 7 <x3 "χ) 2 + (y3 ~ y) 2 + (z3 - z) 2 + cAt = p3 I

I ν <χ4 - χ) 2 + (y4 - y) 2 + (z4 - z) 2 + cAt = p4 ... (1) I

I Herein c indicates the speed of light and At the difference between the I

I 10 time of a GPS satellite and the time of the position estimation I

direction. I

I To spatial coordinates (x, y, z) of the position chat I

To be obtained, there are at least four range comparisons

Is required, as shown in equation 1. The number of I

15 GPS satellites, the satellite signals of which can be simultaneously I

Therefore received the minimum number of measurements of pseudo-I

I reach. I

For example, if the position estimator of two I

GPS satellites can receive satellite signals, I receive

The position estimation device emits from the two GPS satellites

I satellite signals at a time and measures respective pseudo-be I

I reach out. The position estimator then receives on an an-I

I of the time the satellite signals issued by the two GPS satellites

(or two satellite signals issued by two GPS satellites) and I

I measures respective pseudo-ranges. By doing so, four I

I range comparisons, as shown in equation 1, are compared

I got it. I

I In this case the position 25 of the position estimation device

I, ie, the spatial coordinates (x, y, z)

I, the pseudo-range becomes at least twice on each of the I

measured at different times. I

If the position estimation device by three GPS satellites I

can receive issued satellite signals, the position chat I receives

The satellite device issued by the three GPS satellites

I signals at a time and measures respective pseudo-ranges. Then I

The position estimator receives the I at a different time

I satellite signal output from one of the three GPS satellites and I

I measures the pseudo-range. By doing so, four range ver

Equations, as shown in equation 1, are obtained. I

1 0251 07

- 7 -

To obtain the position of the position estimation device, that is, the spatial coordinates (x, y, z), the pseudo-range is therefore measured twice at each of the different times.

If the height (i.e., the coordinate of the z-axis) of the position estimation device is already known, the minimum number of measurements of pseudo-ranges for estimating the spatial coordinates of the position estimation device is at least one smaller than the minimum number for estimating the spatial coordinates, when the height is unknown.

FIG. 3 is a conceptual diagram showing a position estimation method according to a second preferred embodiment of the invention. The position estimation device estimates the position of the position estimation device by using the differences of each pair of pseudo-ranges that are close to each other in time.

In this method, a pseudo-range is measured from each of a number of satellite signals, which signals are issued with a relatively short time difference by a single GPS satellite (e.g., the GPS satellite ID, each time point, positional data at 20 respective time points) . The position of the position estimator is then estimated using the measured pseudo-ranges. Delays usual for the satellite signals, for example ionospheric and tropospheric delay, compensate each other such that the position of the position estimation device 25 can be estimated more accurately.

When the position estimator position is estimated using the differences of each pair of pseudo-ranges that are close to each other in time, the approximate positions of the position estimator correspond to coordinates on hyperboles. The intersections at which two or more hyperboles intersect each other are therefore the estimated positions of the position estimator.

Referring to FIG. 3, reference numerals 31, 32 and 33 indicate positions of a single GPS satellite, which satellite 35 has an identical ID at different times, and p1, p2, and p3 by the position estimation device at positions 31, 32 33 measured pseudo-ranges respectively.

Intersect in a plane the hyperbole (k1), in which the value of (p1 - p2) is constant, and the hyperbole (k2), in which the value of 1 025107 "

I - 8 - I

(p2-p3) is constant, apart in two points (34A, 34B), so that the two I

I points (34Ά, 34B) correspond to an estimated position of the po

I s estimation device. I

I Since the position of the position estimator is an I

I 5 is a three-dimensional spatial position, the pseudo-ranges serve I

However, be taken at least four times at different times

I measure to estimate the position of the position estimator. I

I If the height (that is, the coordinate of the z-axis) of the I

position estimation device is known, the position estimation device may be I

The spatial position of the position estimation device estimates I

Through at least three times at different times

Measuring pseudo-ranges. I

FIG. 4 is a diagram illustrating the position chat I in greater detail

The method according to the first preferred embodiment of the invention

15 shows the invention. Coordinates (x, y, z) give an approximate position of I

I a position estimation device 45, coordinates (x1, yl, zl, tl) I

I provide positional data (xl, yl, zl) of a GPS satellite 41 on time I

I (t1), and p1 gives it on time (t1) through the position estimation in-I

I direction measured pseudo-range. Coordinates (x2, y2, z2, t2) give I

I position data (x2, y2, z2) from a GPS satellite 42 at time point (t2) I

I, and p2 indicates it at time point (t2) through the position estimator

Measured pseudo-range. Herein, the time point (t2) gives the I

I expiration of a predetermined period from time (tl) to. I

I Coordinates (x3, y3, z3, t3) give position data (x3, y3, z3) of I

I indicates a GPS satellite 43 at time (t3), and p3 indicates it at time I

I (t3) pseudo-range measured by the position estimator. I

Herein, time (t3) indicates the expiry of a predetermined period

Period from time (t2) on. Coordinates (x4, y4, z4, t4) give pol

I sition data (x4, y4, z4) of a GPS satellite 44 at time (t4) I

I 30, and p4 indicates it at time point (t4) through the position estimator

Measured pseudo-range. Herein, time (t4) indicates the expiry I

I of a predetermined period from time (t3) to. Herein are the I

I GPS satellites 41 to 44, the same GPS satellite, and the I

I prefer that the position estimation device 45 be stationary or I

I 35 is still. I

The following equation 2 shows four pseudo-range comparisons

I gene, which is passed through respective positional data ((x1, yl, zl), (x2, y2, z2), I

I (x3, y3, z3), (x4, y4, z4)) of the GPS satellite at times (t1, I

T2, t3, t4) and measured pseudo-ranges (p1, p2, p3, p4) are calculated

1025107-1

- 9 -. Herein k1 denotes a hyperbole in which the value of (p1-p2) is constant, k2 denotes a hyperbole in which the value of (p2-p3) is constant, and k3 denotes a hyperbole in which the value of (p1 p3-p4) is constant.

Therefore, the position estimator receives positional data ((x1, y1, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4)) transmitted by the same GPS satellite on respective times (t1, t2, t3, t4) have been delivered. By measuring respective pseudo-ranges (p1, p2, p3, p4) and obtaining solutions (or roots) for the range comparisons given as equation 2, the position 45, for example spatial coordinates (x , y, z) of the position estimation devices are calculated or estimated.

V (x1 - X) 2 + (yl - y) 2 + {z1 - z) 2 - ^ {xZ - x) 2 + (y2 - y) 2 + (z2 - z) 2 = kl 15 V (x2 - x) 2 + (y2 - y) 2 + (z2 - z) 2 - - x) 2 + (y3 - y) 2 + (z3 - z) 2 = k2 V (x3 - x) 2 + (y3 - y) ) 2 + (z3 - z) 2 - ^ (x4 - x) 2 + (y4 - y) 2 + (z4 - z) 2 = k3. .. (2) FIG. 5 is a block diagram of a position estimation device according to a preferred embodiment of the invention. With reference to Fig. 5, the position estimation device (e.g., a GPS receiver 500) includes an antenna 510, a signal processing unit 520, a position calculation unit 540, and a stationary measurement request and selection unit 550.

The antenna 510 receives a satellite signal from a satellite. The signal processing unit 520 calculates correlation values between C / A codes loaded on the satellite signal received via the antenna 510 and automatically generated C / A codes, and then outputs delay information based on the calculation result to the position calculation unit 540 .

The signal processing unit 520 includes a preamplifier 521, a down converter 523, an analog-to-digital (A / D) converter 525, an automatic gain factor controller (AGC) 527, a mixer 529, a carrier numerically controlled oscillator (NCO) 531, a code generator 533, a correlator 535, a code NCO 537 and a controller 539.

1025107

-10 - I

The preamplifier 521 amplifies it through the antenna 510 of the I

satellite received satellite signal and gives the amplified satellite I

drain signal at the down converter 523.

The down converter 523 receives the amplified satellite signal,

5 converts this signal into an intermediate frequency signal in response to the I

output signal from the AGC 527, and gives the converted signal to the I

A / D converter 525. H

The A / D converter 525 receives the intermediate frequency signal and sets I

this signal into a digital signal. H

The AGC 527 controls the gain factor of the down converter I

523 in response to the output signal from the A / D converter 525. I

The carrier NCO 531 generates I (in phase) sine waves and Q (kw

sine waves around a Doppler effect of the satellite signal

sew to compensate. I

The mixer 529 mixes the output signal of the A / D converter 525 H

with the I and Q sine waves emitted by the carrier NCO 531 around the I

Doppler effect of shifting the satellite signal. The mixer 529 H

therefore provides C / A codes issued by a GPS satellite to the H

correlator 535. H

The code NCO 537 generates delayed codes according to an I

delayed delay of the satellite signal from the

533 generated C / A codes, and gives the generated codes to the I

correlator 535. The code generator 533 generates C / A codes on the basis of I

of a reference time of the position estimator 500 and an H

25 identification (ID) number of a satellite to be detected. I

The correlator 535 calculates a correlation value between the at I

the output signal from the mixer 529 and the C / A code loaded by the

code NCO 537 issued C / A code, and gives the delay information on H

539 on the basis of the calculation result. H

The controller 539 detects the satellite signal in response H

on the output signal of the correlator 535. If no satellite H

signal is detected, the controller 539 controls the following H

expected doppler frequency, delayed code value or a code value I

from another satellite to the mixer 529 or the correlator 535 via

35, the carrier NCO 531 and the code NCO 537. The operation I

of the correlator 535 is thus iteratively executed. H

The position calculation unit 540 obtains in response to the I

Delay signal I issued by signal processing unit 520

pseudo-ranges and / or solutions from equations 1 and 2 from H

1025107 I

- 11 - printed distance comparisons. In this case, when the number of simultaneously measurable satellites is generally smaller than the number of satellites required to estimate the position of the position estimator 500, the position calculating unit 540 requests a user of the position estimator 500 to stop or remain stationary by of voice or text via the stationary measurement request and selection unit 550, which uses the position estimation method according to the invention.

After the user has stopped, the stationary measurement request and selection unit 550 selects a stationary measurement function to then output a predetermined selection signal to the position calculation unit 540. Thus, the position calculation unit 540 starts the estimation of the stationary position of the position estimation device 500 using the position estimation method 15 according to the invention.

FIG. 6 is a detailed diagram of the controller 539, the stationary measurement request and selection unit 550 and the position calculation unit 540 shown in FIG. Referring to Figures 5 and 6, the stationary measurement request and selection unit 550 includes a stop request display 5501 and a stop selector 5503. The controller 539 includes a stationary signal processor 5391 and a receiver controller 5393. The position calculation unit 540 includes a time difference measurement determiner 5401, a time difference measurement calculator 5403 and a GPS position calculator 5405.

The time difference measurement determiner 5401 determines whether or not a time difference measurement is initiated in response to the delay information output from the controller 539. The time difference measurement calculator 5403 calculates the position of the position estimation device 500 by measuring the time difference. The GPS-30 position calculator 5405 calculates the position of the position estimation device 500 by a conventional method. That is, the GPS position calculator 5405 is an exemplary circuit for estimating the position of the position estimator 500 from a plurality of simultaneously received satellite signals.

If the receiver controller 5393 outputs delay information corresponding to data from detected satellites, that is, satellite signals emitted from measurable satellites, to the time difference measuring determiner 5401 of the position calculating unit 540, the time difference measuring determiner 5401 determines whether there is sufficient satellite difference.

I - 12 - I

I signal signals are present around the position of the position estimator

direction 500 based on the delay information received

I mation. I

I If the number of satellite signals received is sufficient, I

5, the time difference measurement determiner 5401 structures the general GPS position I

I calculator 5405 for the position of the position estimator 500 I

I to calculate. If the number of satellite signals received is insufficient I

Is the time difference measurement determiner 5401 sends a request signal I

I for stationary measurement at the stationary signal processor 5391. I

The stationary signal processor 5391, which passes through the time lapse

I peel measurement determiner 5401 has received a signal, the I shares

I user via the stop request display 5501 rod to stop. If I

I the user a stationary measurement via the stop selector 5503 I

I, the stop selector 5503 gives a permission signal via I

The stationary signal processor 5391 to the time difference measurement determiner I

I 5401. I

The time difference measurement determiner 5401, which is the permission signal I

I has received, the time difference measurement calculator 5403 instructs I

I start the time difference measurement according to the invention under the on I

In particular, that the user has stopped. I

I When stationary measurement is not allowed, not even I

If the user has been requested via the stop request display 5501 to I

I, the time difference measurement determiner 5401 can change the position of the po

I cannot calculate position estimation device 500 and continuously detects

I tellites, which are necessary for calculating the position of I

I the position estimation device 500. I

I Considering the user in the course of estimating the position

Iion of the position estimation device 500 using an I

If the time difference remains stationary, the user is constantly informed

I shared to stay stationary. To start a time difference measurement I

For example, I causes the stop request display 5501 to flicker slightly. The I

I light is switched on while measuring a time difference. The ge I

The user can therefore make a stop request for starting the time request

shell measurement and a stop request for maintaining the stationary I

35 state of each other. I

If the time difference measurement is not necessary as a result of I

of receiving sufficient satellite signals, while a time I

difference is measured, the stop request display 5501 switches on the light I

1 02 5 J 07 I

- 13 - in order to thereby inform the user that he / she need not remain stationary.

FIG. 7 is a flowchart according to the first and second preferred embodiments of the invention of steps performed in a position estimation method based on the number of satellites that can be measured. With reference to Figs. 5 to 7, the position calculating unit 540 can estimate the position of the position estimator 500 in response to a plurality of satellite signals output at least one or more GPS satellites with predetermined time differences.

The position calculating unit 540 receives a number of satellite signals, which are issued by one or more GPS satellites with predetermined time differences, and can then estimate the position of the position estimator 500.

If the position estimator 500 starts the position estimation in step 70, the time difference measurement determiner 5401 of the position calculating unit 540 determines in step 71 whether the number of satellites whose pseudo-range can be measured (hereinafter referred to as "the number of measurable satellites"), is greater than 3. That is, if satellite signals from four or more satellites can all be received or if the number of measurable satellites is greater than 3, the general GPS position calculating unit 5405 of the position calculating unit 540 in step 72 estimates its position in the usual method.

When the number of measurable satellites in step 73 is 3, the general GPS position calculating unit 5405 of the position calculating unit 540 in step 75 estimates its position in the conventional method, if the elevation information (coordinate z) of the position estimator 500 in step 74 already known.

However, if the number of measurable satellites in step 76 is one or two or if the number of measurable satellites is 3 and the height information of the position estimation device 500 is not known in steps 73 and 74, the stop request display 5501 asks the user of the position estimation device 500 and estimates the position of the position estimation device 500 according to the position estimation method of the invention. If the user stops in response to this in step 77 and starts performing the position estimation method according to the invention, the position estimation device 500 measures a pseudo-range in response to each of a plurality of 1025107

I - 14 - I

Satellite signals, which with predetermined time differences (hereinafter with I

I "time difference measurement" are entered), and estimate in step 78 I

I the position of the position estimator 500 based on the sa

I tellite signals and the respective pseudo-ranges. In this case I

I used equation 2. I

I If, however, no measurable satellites are present in step 76 I

I, or if the user does not respond to the stop request and in I

I step 77 does not perform a position estimation method, it is not possible I

I to determine the position of the position estimator 500 in step 79

I estimate. I

FIG. 8 is a flow chart showing the position I in greater detail

I estimation method according to the first and second embodiments of I

I shows the invention. That is, FIG. 8 is a flow chart, I

I showing step 78 of FIG. 7 in greater detail. I

If the position estimation of the position estimation device I

I 500 starts in step 78 by means of the time difference measurement, I determines

I the time difference measurement determiner 5401 of the position calculation unit I

540 in step 81 whether or not the number of measurable satellites is 3

I bear. If the result of this determination indicates that it is I

In step 81, I measure 20 measurable satellites 3, measure the position chat I

The device 500 has a pseudo-range in response to each of the satellite

I signal signals transmitted by the three measurable satellites on a first I

I have been issued, and measures the position estimator 500 I

I a pseudo-range in response to a satellite signal transmitted by each of I

The three measurable satellites at a second time after the expiry I

I of a predetermined period of time after the first point in time has been issued, I

I or one delivered by a new satellite other than the three satellites

I give satellite signal, in step 83. The minimum number of measurements from I

I time differences after the first time point is therefore one. I

If the number of measurable satellites in step 84 is 2, I

I time difference calculator 5403 measures a pseudo-range in I

I response to each of the satellite signals transmitted by the two measurable bands

I tellites have been delivered at a first time, and measure this calculation

A pseudo-range in response to each of the satellite signals

35, transmitted through the two measurable satellites at a second time after I

The expiration of a predetermined period of time from the first I

I have been issued at a time or by a new satellite other than I

I satellite signal issued to the two satellites, in step 85. The mini I

1025107 I

The number of measurements of time differences after the first point in time is therefore two.

If the number of measurable satellites in step 84 is 2 and the elevation information of the position estimator 500 is already known, the position estimator 500 measures a pseudo-range in response to the satellite signals emitted by the two measurable satellites at the second time in step 85. The minimum number of measurements of time differences after the first point in time is therefore one.

If in step 84 the number of measurable satellites is not 2, that is, if the number of measurable satellites is 1, the position estimator 500 measures a pseudo-range in response to the measurement by the measurable satellite at a second time after the expiration of a predetermined period of time from the first time satellite signal issued, or a satellite signal issued by a new satellite other than the measurable satellite, this device 500 measures a pseudo-range in response to the measurable satellite at a third time after the expiration of a predetermined period of time from the second point in time, or a satellite signal delivered by a new measurable satellite, and this device measures a pseudo-range 500 in response to the measurable satellite at a fourth time after the expiry of a predetermined period of time from the third point in time, a satellite signal issued by a new measurable sa tellite issued satellite signal.

The minimum number of measurements of time differences after the first time point 25 is therefore 3 in step 86.

However, if the elevation information of the position estimator 500 is already known, the position estimator 500 measures a pseudo-range in response to the satellite signal issued by the measurable satellite at the second time or a satellite signal delivered by a new measurable satellite. device 500 has a pseudo-range in response to the satellite signal emitted by the measurable satellite at the third time or a satellite signal emitted by a new measurable satellite. The minimum number of measurements of time differences after the first time point is therefore two and two in step 86.

When the time difference measurement is performed, the position estimation device 500 determines in step 87 at each time whether or not a measurable satellite is the same satellite. If the result of this determination indicates that the satellites have the same satellite 1 0251.07

I - 16 - I

I

I, the position estimator 500 measures the pseudo-range between I

I ’* the position estimation device 500 and the satellite with the time lapse

I shell, and this device 500 estimates the position of the position chat

I device 500 by using each pair by the ver

Equation 2 pseudo-ranges expressed in step 88. I

I If the result of the determination indicates that the satellite I

Are not an identical satellite, the position estimator estimates I

500 in step 89 its position by measuring the I

I pseudo-range between the position estimator 500 and the satellite

I left with the time difference. I

I By the position estimation method and device I

I according to the invention, the pseudo-ranges can be measured by I

I make use of time differences and can change the position of the position

The estimator can be accurately estimated or calculated by

To make use of the measured pseudo-ranges, even when the on I

I measurable satellites is 3 or less. I

Although the invention has been particularly shown and worked

I described with reference to preferred embodiments thereof, I

It will be apparent to those skilled in the art that various changes in I

I shape and detail can be applied to it without the thought and I

I the scope of the invention as defined by the attached I

I conclusions. I

I 1025107 I

Claims (44)

A method for determining a position using a global positioning system (GPS) satellite signal, comprising: receiving in a receiver a first GPS satellite from a first GPS satellite in a first position of the first GPS satellite GPS signal; receiving in the receiver a second GPS signal from the first GPS satellite in a second position of the first GPS satellite; and determining a position of the receiver using the first and second GPS signals. The method of claim 1, further comprising receiving in the receiver a third GPS signal from the first GPS satellite in a third position of the first GPS satellite. The method of claim 2, further comprising using the third GPS signal to determine the position of the receiver. 4. Method as claimed in claim 2 or 3, further comprising receiving in the receiver a fourth GPS signal originating from the first GPS satellite in a fourth position of the first GPS satellite. The method of claim 4, further comprising using the fourth GPS signal to determine the position of the receiver. The method of claim 4, further comprising using the third and fourth GPS signals to determine the position of the receiver. 7. Method as claimed in claim 2, further comprising receiving in the receiver a fourth GPS signal originating from a second GPS satellite in a first position of the second GPS satellite. The method of claim 7, further comprising using the fourth GPS signal to determine the position of the receiver. 1025107 I -18-I The method of claim 7, further comprising using the third and fourth GPS signals to determine the position of the receiver. I The method of claim 1, further comprising receiving in the receiver a third GPS signal from a second GPS satellite in a first I position of the second GPS satellite. I The method of claim 10, further comprising using the third GPS signal to determine the position of the receiver. 10 The method of claim 10, further comprising receiving a fourth GPS signal from the second GPS satellite in a second I-1 position from the second GPS satellite. I The method of claim 12, further comprising using the fourth GPS signal to determine the position of the receiver. I The method of claim 12, further comprising using the third and fourth GPS signals to determine the position of the receiver. I 15. The method of claim 10, further comprising receiving a fourth GPS signal from a third GPS satellite in a first I-1 position of the third GPS satellite. I The method of claim 15, further comprising using the fourth GPS signal to determine the position of the receiver. I 25 The method of claim 15, further comprising using the third and fourth GPS signals to determine the position of the receiver. I 18. Method according to any of claims 1-17, wherein the position of the receiver is determined using a time difference related to I 30 between the first and second GPS signals. I 19. Method according to any of claims 1-18, wherein the position of the receiver is determined according to the following equations: II II (x1 - x) 2 + (yl - y) 2 + ( z1 - z) 2 + cAt «p1 II yj {x2 - x) 2 + (y2 - y) 2 + (z2 - z) 2 + cAt - p2 II 1025107 I -19- • \ / (x3 - x) 2 + (y3 - y) 2 + (z3 - z) 2 + cAt = · p3 • ^ (x4 - x) 2 + (y4 - y) 2 + (z4 - z) 2 + cAt = p4 ... (1 ) P1, p2, p3 and p4 are the pseudo-ranges, c is the speed of light, At is a difference between the time in a satellite and the time in the receiver, (x1, yl, zl), (x2, y2, z2), (x3, y3, z3) and (χ4, y4, z4) represent position data, which position data was received at four different times t1, t2, t3, t4: and 10 V (x1 - X) 2 + (yl - y) 2 + (z1 - z) 2 - V (x2 - x) 2 + (y2 - y) 2 + (z2 - z) 2 - kl y / (x2 - x) 2 + (y2 - y) 2 + (z2 - z) 2 - J (x3 - x) 2 + (y3 - y) 2 + (z3 - z) 2 - k2 15 · \ / (χ3 - x) 2 + (y3 - y) 2 + (z3 - z) 2 - - \ / (x4 - x) 2 + (y4 - y) 2 + (z4 - z) 2 - k3 ... (2) where (x, y, z) position co are coordinates of the receiver and p1 - p2 = k1, a constant; P2 - p3 = k2, a constant; and p3 - p4 = k3, a constant. 20. Device for determining the position using a global positioning system (GPS) satellite signal, comprising: a receiver for receiving a signal from a first GPS satellite in a first position of the first GPS satellite first GPS signal and receiving a second GPS signal from the first GPS satellite in a second position from the first GPS satellite; and a processor for determining a position of the receiver using the first and second GPS signals. The apparatus of claim 20, wherein the receiver receives a third GPS signal from the first GPS satellite in a third position of the first GPS satellite. The device of claim 21, wherein the processor uses the third GPS signal to determine the position of the receiver. 1025107 I-20-I The apparatus of claim 21, wherein the receiver receives a fourth GPS signal from the first GPS satellite in a fourth position of the first GPS satellite. I The apparatus of claim 23, wherein the processor uses the fourth GPS signal to determine the position of the receiver. I The apparatus of claim 23, wherein the processor uses the third and fourth GPS signals to determine the position of the receiver. I 26. Device as claimed in claim 21, wherein the receiver receives a fourth GPS signal originating from a second GPS satellite in a first position of the second GPS satellite. I The apparatus of claim 26, wherein the processor uses the fourth GPS signal to determine the position of the receiver. I 28. Device as claimed in claim 26, wherein the processor uses the third and fourth GPS signals to determine the position of the receiver and I. I The apparatus of claim 20, wherein the receiver receives a third GPS signal from a second GPS satellite in a first position of the second GPS satellite. I 20 The apparatus of claim 29, wherein the processor uses the third GPS signal to determine the position of the receiver. I The apparatus of claim 29, wherein the receiver receives a fourth GPS signal from the second GPS satellite in a second position of the second GPS satellite. I The apparatus of claim 31, wherein the processor uses the fourth GPS signal to determine the position of the receiver. I The apparatus of claim 31, wherein the processor uses the third and fourth GPS signals to determine the position of the receiver I. I The apparatus of claim 29, wherein the receiver receives a fourth GPS signal from a third GPS satellite in a first position of the third GPS satellite. I The apparatus of claim 34, wherein the processor uses the fourth GPS signal to determine the position of the receiver. I The apparatus of claim 34, wherein the processor uses the third and fourth GPS signals to determine the position of the receiver I. I 1025107 I -21- An apparatus for determining a position using a global positioning system (GPS) satellite signal, comprising: a receiver for receiving a first from a first GPS satellite in a first position of the first GPS satellite GPS signal and for receiving a second GPS signal from the first GPS satellite in a second position from the first GPS satellite; and a position calculation unit for determining a position of the receiver using the first and second GPS signals. The apparatus of claim 37, further comprising a controller for detecting a number of usable satellites that can be used to determine the position. An apparatus according to claim 37 or 38, further comprising a stationary measurement request and selection unit to request the user to remain stationary during position determination. 40. Device according to any of claims 37-39, wherein the position calculating unit comprises a time difference measurement determiner, which requests the user to remain stationary during position determination if the number of usable satellites is below a threshold value. 41. Device, according to any of claims 37-40, wherein the position calculating unit comprises a time difference measuring calculator, which calculates the position by measuring time differences between GPS signals. 42. A method according to any of claims 1-19, wherein at least four satellite output signals with predetermined time differences are received from one or more GPS satellites, the position estimator is estimated in response to each of the received satellite signals, a minimum number of measurements is determined by a number of GPS satellites from which satellite signals can be received simultaneously. A method according to any of claims 10-19 or 42, wherein, when the number of satellites to be received simultaneously is smaller than the number of satellites required for estimating a position estimator position, a 1025107 I - 22 - H position calculation unit is a user of the position estimator requests to stop or remain stationary. A method according to any of claims 10-19 or 42, wherein, when the number of received satellite signals is sufficient to calculate the position, the position calculating unit informs the user I that the user need not remain stationary. 1 0251 0.7 I