Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1999-02-18
2001-02-06
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490, C342S357490, C342S357490, C701S207000, C701S213000
Reexamination Certificate
active
06184824
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for initialization of a receiver and a receiver of position signals.
BACKGROUND INFORMATION
With the increasing popularity of traffic telematics and navigation devices, for example in motor vehicles, location functionality is becoming increasingly significant. In this context, greater use is being made of positioning receivers, for example for the NAVSTAR global positioning system (GPS), which allow a three-dimensional position determination by measuring time-of-flight to multiple GPS satellites. What is demanded for the receivers is not only the greatest possible position accuracy and available, but also the shortest possible “time to first fix” (TTFF), i.e. the time elapsing between activation of the receiver and the first calculation and output of a position. TTFF for GPS receivers is usually specified for different start modes, a distinction being made between hot and cold starts. In a cold start, no current system data or operating parameters are available in the receiver, or the data are outdated and may no longer conform to the actual system data or operating parameters. Because this information is lacking, the visible or favorably receivable satellites cannot be identified in the receiver, and the receiver is therefore instructed to test individually the 32 satellites provided in the GPS system specification. In this process, the receiver is initialized with so-called search sets, corresponding to the number of parallel channels available, which allow a more or less orderly search through the satellites. In an eight-channel receiver, it is known to use eight different satellite identifiers per search set, the satellite identifiers (which are listed as PRN numbers) being searched through in sequence. It is thus possible, depending on the position of the receiver, for a long period to elapse before a satellite is found that is available for communication.
SUMMARY OF THE INVENTION
The method according to the present invention has in contrast, the advantage that a specific sequence of transmitter identifiers, i.e. a specific search set, which with high probability contains an active and receivable satellite, is selected. In this context, the satellite identifiers selected for the search runs are those whose transmitters are known to be moving along orbital paths that are almost perpendicular to one another. With this feature, successfully receivable satellites are found with high probability after only the first search set.
It is particularly advantageous that transmission of all the transmitter parameters is begun after the first active transmitter is discovered; and that after these transmitter parameters have been completely transmitted, a calculation is made of the current sequence of transmitter identifiers, i.e. the current list of search sets, that can be used at the next receiver cold start. It is in turn advantageous, when calculating the current list of search sets, that the movement planes of the transmitters lie almost at right angles to one another. This increases the statistical probability that receivable transmitters will be found as quickly as possible upon a cold start.
It is furthermore advantageous that after the discovery of first receivable satellites, and after the associated reduction in the number of available receiver channels, the search sets are also partly loaded and processed. In this case, a number of satellite identifiers corresponding to the quantity of receiver channels is loaded from the list of search sets, and allocated to the unoccupied receiver channels. Provision is to be made that all the satellite identifiers are processed in the sequence defined by the list of search sets.
In a concluding process step, the calculation of the search sequences is stored in a resident memory so that the next time the receiver is initialized, a first, updated search set can be immediately accessed. The method has the advantage that the cold start time, or “time to first fix” time, is shortened. As a result, the navigation data of the receiver are available more quickly after activation. Because the search data are updated, the receiver can be adapted quickly and easily to the actual circumstances of the transmitter. It is very easy to react to failure of a satellite transmitter or to replacement of a satellite.
It is advantageous that the data of the search set stored in the memory are updated not only after each cold start, but rather at predefined time intervals.
It is further possible to supplement the stored data with information regarding initial position and most-recently used set of transmitter identifiers. This allows even faster initialization of the receiver.
The receiver according to the present invention has the advantage that a list of search sets is stored in the receiver, such that the transmitter identifiers of the individual search sets belong to transmitters which move in orbital planes located almost perpendicular to one another.
It is advantageous that the receiver has means which serve to calculate a current list of search sets.
It is further advantageous that the current search sets can be stored in the receiver.
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patent: 0 635 728 (1995-01-01), None
Cariveau, B.K. et al., “Satellite Data Management in DOD Navstar GPS Receivers,” Navigation into the 21st Century, Kissemmee, Nov. 29-Dec. 2, 1988, No. 1998, Nov. 29, 1988, IEEE, pp. 134-144.
Patent Abstracts of Japan, vol. 012, No. 396 (p-774), Oct. 21, 1988.
Bode Friedrich-Wilhelm
Tanneberger Volkmar
Gregory Bernarr E.
Kenyon & Kenyon
Robert & Bosch GmbH
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