Method of selecting satellite for positioning in global navigation satellite system, satellite signal receiver, and method of creating DOP index
View Patent ↗There is provided a method of selecting a satellite for positioning in a global navigation satellite system, which includes: receiving satellite signals from satellites that a receiver can receive; calculating DOP where pseudorange weight is applied for each of satellite signal combinations including at least four or more of the satellite signals by the receiver; and selecting a satellite signal combination having the smaller DOP than a standard in the satellite signal combinations by the receiver.
1. A method of selecting a satellite for positioning in a global navigation satellite system, the method comprising:
receiving, by a receiver, satellite signals from satellites;
calculating, by the receiver, Dilution of Precision (DOP) in which a pseudorange weight is applied for each of satellite signal combinations comprising at least four of the satellite signals; and
selecting, by the receiver, a satellite signal combination, among the satellite signal combinations, having a smaller DOP than a standard value of the satellite signal combinations, to be used to position the receiver.
2. The method of claim 1 , wherein the satellite signals comprise signals differing in either one or both of a transmission power and a modulation type.
3. The method of claim 1 , wherein the satellite signals comprise any one or any combination of any two or more of a GPS satellite signal, a Galileo satellite signal, and a GLONASS signal.
4. The method of claim 1 , wherein in the calculating, the receiver determines the pseudorange weight based on Tracking Error Standard Deviation (TESD) of a pseudorange of the satellite signals, and calculates the DOP using a DOP matrix comprising the pseudorange weight.
5. The method of claim 1 , wherein in the calculating, the receiver determines a weight providing a same or similar TESD in a reference range to the satellite signals in a Carrier-to-Noise Ratio (CNR), and calculates the DOP using a DOP matrix comprising the weight providing the same or similar TESD.
6. The method of claim 5 , wherein the receiver determines the weight using TESD at a worst CNR, in response to the receiver encountering difficulty in estimating a CNR.
7. The method of claim 1 , wherein in the calculating, the DOP is calculated by the following equation:
D proposed =tr [( H′ T H ′) −1 ],
where D proposed is the DOP, tr(•) is trace of a matrix, (•) T is transposition of a matrix, (•) −1 is an inversematrix,
H
′
=
[
α
1
h
11
α
1
h
12
α
1
h
13
1
α
2
h
21
α
2
h
22
α
2
h
23
1
⋮
⋮
⋮
⋮
α
n
h
n
1
α
n
h
n
2
α
n
h
n
3
1
]
,
(h i1 , h i2 , h i3 ) is a vector of line of sight from a user to an i-th satellite, and α i is a weight providing the same or similar TESD.
8. The method of claim 1 , wherein the satellite signal combination has a smallest DOP of the satellite signal combinations.
9. A satellite signal receiver, comprising:
a receiving unit configured to receive satellite signals in which either one or both of a transmission power and a modulation type is different;
a signal processing unit configured to calculate a Dilution of Precision (DOP) where a pseudorange weight is applied for satellite signal combinations comprising at least four of the satellite signals; and
a positioning unit configured to select a satellite signal combination, among the satellite signal combinations, having a smallest DOP calculated by the signal processing unit, and to position the receiver.
10. The satellite signal receiver of claim 9 , wherein the satellite signals comprise any one or any combination of any two or more of a GPS satellite signal, a Galileo satellite signal, and a GLONASS signal.
11. The satellite signal receiver of claim 9 , wherein signal processing unit is further configured to determine a weight for the satellite signals based on a Tracking Error Standard Deviation (TESD) of a pseudorange of the satellite signals included in the satellite signal combinations, and to calculate the DOP using a DOP matrix including the weight.
12. The satellite signal receiver of claim 9 , wherein the receiver is further configured to determine a weight providing a same or similar TESD in a reference range to the satellite signals in a Carrier-to-Noise Ratio (CNR), and to calculate the DOP using a DOP matrix having the weight.
13. The satellite signal receiver of claim 9 , wherein the DOP is calculated using the following equation:
D proposed =tr [( H′ T H ′) −1 ],
where D proposed is the DOP, tr(•) is trace of a matrix, (•) T is transposition of a matrix, (•) −1 is an inversematrix,
H
′
=
[
α
1
h
11
α
1
h
12
α
1
h
13
1
α
2
h
21
α
2
h
22
α
2
h
23
1
⋮
⋮
⋮
⋮
α
n
h
n
1
α
n
h
n
2
α
n
h
n
3
1
]
,
(h i1 , h i2 , h i3 ) is a vector of line of sight from a user to an i-th satellite, and α i is weight providing a same or similar TESD.