No preamble frame sync
AssigneesSeiko Epson Corporation, eRide, Inc.
InventorsAkira Kimura, Paul W. McBurney
Life of this patent
Estimating the term…
Abstract
A navigation-satellite receiver uses a reference station accessible over a network to store NAV data subframes for pattern matching at a network client. Alternatively, the pattern matching is performed by the server when per-byte communication costs are high. The stored NAV data repeats ephemeris data every thirty seconds, and full almanac data every 12.5 minutes. This permits the client to instantly recognize where in the NAV data sequence its own received signals are, and it need not actually wait to receive the preambles in the TLM words. Several precious seconds are therefore saved in producing a rapid time-to-first-fix.
Claims11
A navigation satellite receiver system, comprising:
- a navigation-satellite-receiver reference-station network server for providing various parts of NAV data transmissions it receives from a first constellation orbiting navigation satellites;
- and
- a navigation-satellite-receiver network client for providing a user with a position solution based on transmissions it receives from a second constellation orbiting navigation satellites;
- wherein, the network server estimates a network transmission delay that exists between the network server and the network client, and modifies said various parts of NAV data transmissions so they arrive with current GPS time information at the network client;
- and
- wherein, the network client is able to synchronize to a NAV frame without using a TLM word preamble.
A navigation-satellite-receiver reference-station network server, comprising:
- a navigation-satellite receiver for receiving NAV data transmissions it receives from a first constellation orbiting navigation satellites;
- a database for storing parts of said NAV data transmissions;
- a server for connection to a network and able to respond to client requests for current NAV data;
- and
- a NAV data modification processor for adjusting information in said parts of said NAV data transmissions to appear as current data at a network client.
A navigation-satellite-receiver user network client, comprising:
- a navigation-satellite receiver for directly receiving current NAV data transmissions from orbiting navigation satellites, and initially needing integer millisecond (intMsec) information to begin operation;
- a client for connection to a network and able to issue to client requests to a server for NAV data patterns;
- and
- a pattern-matcher able to find correspondences between NAV data patterns provided by said server and said NAV data directly obtained;
- wherein, said server assists the client to achieve NAV data frame synchronization.
The network client of claim 4, wherein:
- the pattern matcher includes a processor for discarding unreliable pattern types.
A navigation-satellite-receiver user network client, comprising:
- a navigation-satellite receiver for directly receiving current NAV data transmissions from orbiting navigation satellites, and initially needing integer millisecond (intMsec) information to begin operation;
- a client for connection to a network and able to provide partial NAV data patterns to a network server that it has received itself directly;
- and
- a server-side pattern-matcher located at said server able to find correspondences between NAV data patterns provided by said client and a more complete NAV data directly obtained and stored in a database;
- wherein, said server assists the client to achieve NAV data frame synchronization.
A method for initializing a navigation-satellite-receiver network client, the method comprising the steps of:
- estimating a network delay between a server and a client on a network;
- collecting NAV data information and storing it in a database at said server;
- requesting a sample of said NAV data from said client;
- adjusting the information carried in a requested sample of said NAV data to arrive with current Z-count information at said client after said network delay;
- pattern-matching said sample of said NAV data with said adjusted information to another real-time NAV data being directly received by said client;
- and
- finding NAV data frame synchronization at said client without a TLM preamble search.
A method for initializing a navigation-satellite-receiver network client, the method comprising the steps of:
- estimating a network delay between a server and a client on a network;
- collecting NAV data information and storing it in a database at said server;
- requesting a sample of said NAV data from said client;
- adjusting the information carried in a requested sample of said NAV data to arrive with current Z-count information at said client after said network delay;
- pattern-matching said sample of said NAV data with said adjusted information to another real-time NAV data being directly received by said client;
- attempting to find NAV data frame synchronization at said client without a TLM preamble search;
- otherwise, conducting a TLM preamble search and thereby achieving NAV data frame synchronization.
Dependencies are inferred from the claim text.