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 chance 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.
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.
Claim 2
Dependent Claim
26 words
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.
Claim 3
Dependent Claim
26 words
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.
Claim 4
Dependent Claim
19 words
A satellite signal tracking method as claimed in claim 1, wherein the search frequency is changed in step wise.
Claim 5
Dependent Claim
132 words
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.
Claim 6
Dependent Claim
30 words
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.
Claim 7
Dependent Claim
28 words
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.
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