GPS reception method and GPS receiver

• US 20050168382A1
• Filed: 01/31/2005
• Published: 08/04/2005
• Est. Priority Date: 02/02/2004
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Awata, Hideki
• Granted Patent: US 7,053,827 B2
• Time in Patent Office: Days
• US Class Current: 342/357.680
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain

Abstract

The present invention is intended to provide the synchronization acquisition of signals received from four GPS satellites in a short time and with stability by the time in which an intermediate frequency carrier error of good accuracy can be obtained at the time of power-on sequence, for example. Prerequisites are that at least one GPS satellite signal be in the synchronization hold state, its intermediate frequency carrier frequency be known, the orbit information about that GPS satellite be stored in a storage section, and the position and current time of the GPS receiver be known. Under these prerequisites, an intermediate frequency carrier error is computed from the intermediate frequency carrier frequency, the position and velocity of the GPS satellite obtained from the orbit information and the current time, and the position of the GPS receiver. The intermediate frequency carrier frequency is corrected by the computed intermediate frequency carrier error. The signals received from other GPS satellites are acquired by use of the corrected intermediate frequency carrier frequency.

Claims

1. A GPS (Global Positioning System) reception method comprising the steps of:

if a signal received from at least one GPS satellite is a synchronization hold state, an intermediate frequency carrier frequency of said signal is known, orbit information about said GPS satellite in the synchronization hold state is stored in a storage section, and a position and a current time of a receiver of said signal are known,

computing an intermediate frequency carrier error as an error of said intermediate frequency carrier frequency on the basis of an oscillation frequency error of a reference oscillator of said receiver from said intermediate frequency carrier frequency of said signal, a position and a velocity of said GPS satellite in the synchronization hold state obtained from said orbit information and said current time, and said position of said receiver;

correcting said intermediate frequency carrier frequency by said computed intermediate frequency carrier error; and

acquiring signals received from other GPS satellites by use of said corrected intermediate frequency carrier frequency.

2. The GPS reception method according to claim 1, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said plurality of intermediate frequency carrier errors are averaged, said intermediate frequency carrier frequency is corrected by said average error, and a signal received from another GPS satellite is acquired by use of said corrected intermediate frequency carrier frequency.

3. The GPS reception method according to claim 1, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said intermediate frequency carrier frequency is corrected by said intermediate frequency carrier error obtained for a signal having a highest received signal level among said plurality of signals and a signal received from another GPS satellite is acquired by use of said corrected intermediate frequency carrier frequency.

4. The GPS reception method according to claim 1, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said intermediate frequency carrier frequency is corrected by an average value of said intermediate frequency carrier error obtained for a signal having a received signal level greater than a predetermined threshold value among said plurality of signals and a signal from another GPS satellite is acquired by use of said corrected intermediate frequency carrier frequency.

5. The GPS reception method according to claim 1, wherein said intermediate frequency carrier frequency is corrected by use of said obtained intermediate frequency carrier error in acquiring a signal received from another GPS satellite if the number of GPS satellites of which signals are in the synchronization hold state is less than four.

6. A GPS receiver comprising:

synchronization unit for synchronously acquiring a signal received from a GPS satellite by use of a given intermediate frequency carrier frequency and synchronously holding said acquired signal;

error computation unit for computing an intermediate frequency carrier error as an error of said intermediate frequency carrier frequency on the basis of an oscillation frequency error of a reference oscillator of said receiver from said intermediate frequency carrier frequency of said signal, a position and a velocity of said GPS satellite in the synchronization hold state obtained from said orbit information and said current time, and said position of said receiver if a signal received from at least one GPS satellite is a synchronization hold state, an intermediate frequency carrier frequency of said received signal is known, orbit information about said GPS satellite in the synchronization hold state is stored in a storage section, and a position and a current time of a receiver of said signal are known; and

correction unit for correcting said known intermediate frequency carrier frequency by said intermediate frequency carrier error computed by said error computation unit and supplying said corrected intermediate frequency carrier frequency to said synchronization unit.

7. The GPS receiver according to claim 6, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said error computation unit averages said plurality of intermediate frequency carrier errors and supplies said averaged intermediate frequency carrier error to said correction unit.

8. The GPS receiver according to claim 6, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said error computation unit supplies said intermediate frequency carrier error obtained for a signal having a highest signal level among said plurality of signals to said correction unit.

9. The GPS receiver according to claim 6, wherein, if there exist a plurality of GPS satellites of which signals are in a synchronization hold state and said intermediate frequency carrier error is obtained in the plural for signals received from said plurality of GPS satellites, said error computation unit supplies an average value of said intermediate frequency carrier error obtained for a received signal having a signal level greater than a predetermined threshold value among said plurality of signals to said correction unit.

10. The GPS receiver according to claim 6, wherein said intermediate frequency carrier frequency is corrected by use of said obtained intermediate frequency carrier error in acquiring a signal received from another GPS satellite when the number of GPS satellites of which signals are in the synchronization hold state is less than four.