GPS receivers with data ports for the uploading and downloading of absolute position information

• US 5,450,344 A
• Filed: 04/22/1994
• Issued: 09/12/1995
• Est. Priority Date: 04/22/1994
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Sprague, David S., Woo, Arthur
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Wieland, Susan
• Application Number:
  US08/232,830
• Time in Patent Office: 508 Days
• Field of Search: 364/449, 364/444, 364/443, 73/178 R, 434/239, 342/450, 342/451, 342/357, 395/275
• US Class Current: 701/213
• CPC Class Codes: G11B 27/10 Indexing; Addressing; Timing or synchronising; Measuring tape travel
• CPC Class Codes: G11B 27/3036 Time code signal

Abstract

A GPS receiver comprises a data input/output port for communication of datum-less position fixes in an earth-centered, earth-fixed (ECEF) coordinate style to avoid the errors associated with not communicating the datum choice with latitude longitude data communication formats.

Claims

1. A GPS navigation receiver comprising, in a single integrated unit, an antenna to receive datum-free radio signals from orbiting GPS satellites, a radio frequency (RF) stage connected to said antenna to amplify and downconvert such GPS radio signals, a static random access memory (SRAM), a microprocessor (CPU) connected to said RF stage and said SRAM, a user keyboard connected to said CPU, a GPS digital signal processor (GPS-DSP) connected to said RF stage and said CPU, an input/output (I/O) interface connected to said CPU for two-way data communication with external devices and databases, a date/time-tag unit connected said CPU with GPS-week and GPS-time, a read only memory (ROM) connected to said CPU for program storage and a user liquid crystal display (LCD) connected to said CPU, wherein:

said antenna and RF stage provide for the reception of range information from orbiting GPS satellites included in said downconverted signals from said RF stage to said GPS-DSP; and

said CPU is connected to the GPS-DEP and provides for decoding of said range information in said downconverted signals received and for a direct datum-free conversion of said range information a program stored in said ROM into earth-centered, earth-fixed (ECEF) position determinations which are temporarily stored in said SRAM.

2. The GPS receiver of claim 1, wherein:

said CPU provides for communicating earth-centered, earth-fixed (ECEF) data to said I/O interface from said position determinations temporarily stored in said SRAM.

3. The GPS receiver of claim 1, wherein:

said date/time-tag unit provides for an association of a date and time tag with said position determinations stored in said SRAM as said position determinations are collected in real-time.

4. The GPS receiver of claim 1, wherein:

said CPU provides for the generation and recognition of alphanumeric user identification codes, framing and de-framing of message packets shipping out and coming in over said I/O interface, and message protocol and error detection and correction for said message frames.

5. The GPS receiver of claim 1, wherein:

said I/O interface includes a first data input/output (I/O) port and a second data input/output (I/O) port for communicating with external devices in a coordinate style and a data format message frame type that is different than that used by the first data I/O port.

6. The GPS receiver of claim 1, wherein:

said I/O interface and said ROM provide for the connection of a database and an uploading of ECEF coordinate style position data from said database and conversion to latitude-longitude coordinate style expressed in the datum chosen by the user at said keyboard for display by said LCD as a waypoint and goal, and said uploaded ECEF coordinate style data is retained datum-free in its unconverted state within said SRAM together with any date-stamps or time-tags.

7. The GPS receiver of claim 6, wherein:

said I/O interface and said ROM further provide for communication of a data frame comprising a plurality of fields including a user ID field that uniquely identifies said GPS receiver alphanumerically to said database, a GPS position field that communicates any navigation position fix information that has been determined by said GPS receiver, a time tag field that permits any information in another field to be dated and thus coordinated when received by any other database, a velocity field that communicates a velocity and a heading of said GPS receiver identified at a time identified in said fields, and a miscellaneous information field for team identification codes and authorizations.

8. A method of communicating earth-centered, earth-fixed (ECEF) data from a GPS receiver out over a data input/output (I/O) port, comprising the steps of:

computing a position determination in an ECEF coordinate style directly from ranging information provided by a GPS navigation receiver comprising, in a single integrated unit, an antenna connected to receive data-free radio signals from orbiting GPS satellites, a radio frequency (RF) stage connected to said antenna to amplify and downconvert such GPS radio signals, a static random access memory (SRAM), a microprocessor (CPU) connected to said RF stage and said SRAM, a user keyboard connected to said CPU, a GPS digital signal processor (GPS-DSP) connected to said RF stage and said CPU, an input/output (I/O) interface connected to said CPU for two-way data communication with external devices and databases, a date/time-tag unit connected to said CPU with GPS-week and GPS-time, a read only memory (ROM) connected to said CPU for program storage and a user liquid crystal display (LCD) connected to said CPU;

time-tagging and date stamping with said date/time-tag unit each said position determination providing for later analysis and comparison;

storing said time-tagged and date-stamped position information in said SRAM as it is collected in real-time;

establishing a communication link-up through said I/O interlace to an external database; and

downloading out of said SRAM the time-tagged and date-stamped ECEF data to said external database.