GPS satellite signal tracking method for GPS receivers

• US 5,059,969 A
• Filed: 09/07/1990
• Issued: 10/22/1991
• Est. Priority Date: 11/30/1989
• Status: Expired due to Fees

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Ando, Hitoshi, Sakaguchi, Shozaburo
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US07/578,919
• Time in Patent Office: 410 Days
• Field of Search: 342/357, 342/352, 342/358, 342/99-103, 342/417, 342/418, 342/420, 342/421, 342/444, 375/1, 364/443
• US Class Current: 342/352
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence

Abstract

A method for recapturing a satellite at the highest elevation angle as quickly as possible with a GPS receiver having a plurality of receiving channels when a state of receiving satellite signals recovers to normal after having been interrupted by obstacles like a tunnel, wherein a search range of satellite signal receiving frequency is divided into a plurality of frequency bands and each of which is assigned to the plurality of receiving channels in a one-to-one relationship, a search frequency of each receiving channel is changed in step wise for searching a satellite signal simultaneously in the receiving channels, and further, by providing a time difference for a step wise change-over timing of the search frequency between receiving channels, a time required for recapturing the satellite is greatly reduced by increasing a change to lock up one of the receiving channels with the satellite signal receiving frequency, since there are as many chances as a number of receiving channels within one cycle of the step wise search frequency change-over for one receiving channel.

Claims

1. A satellite signal tracking method for a GPS receiver having a plurality of receiving channels, comprising the steps of:

selecting a GPS satellite, as a target, which is estimated to be at the maximum elevation angle when signals from all GPS satellites being tracked are interrupted for a specified period of time;

dividing a search range of satellite signal receiving frequency into a plurality of frequency bands;

assigning each of the divided frequency bands to each receiving channel; and

changing a search frequency of each receiving channel respectively within the assigned frequency band in order to search for a signal from the GPS satellite at the maximum elevation angle.

2. A satellite signal tracking method as claimed in claim 1, wherein the search range is divided into an upper frequency band and a lower frequency band.

3. A satellite signal tracking method as claimed in claim 1, wherein the search range is divided into an upper frequency band, a middle frequency band and a lower frequency band.

4. A satellite signal tracking method as claimed in claim 1, wherein the search frequency is changed in a step wise fashion.

5. A satellite signal tracking method for a GPS receiver having a plurality of receiving channels comprising the steps of:

selecting a GPS satellite, as a target, which is estimated to be at the maximum elevation angle when signals from all GPS satellites being tracked are interrupted for a specified period of time;

dividing a search range of satellite signal receiving frequency into a plurality of frequency bands;

assigning each of the divided frequency bands to each receiving channel;

allotting a time difference to a step wise change-over timing of a search frequency between receiving channels; and

changing the search frequency of each channel within the overall width of a search range of satellite signal receiving frequency in order to search for a signal from the GPS satellite at the maximum elevation angle.

6. A satellite signal tracking method as claimed in claim 5, wherein the search range is divided into an upper frequency band, a middle frequency band and a lower frequency band.

7. A satellite signal tracking method as claimed in claim 6, wherein the time difference is equal to one third of one period (T) of the step wise change-over.