GNSS receiver and external storage device system and GNSS data processing method

• US 7,808,428 B2
• Filed: 10/07/2008
• Issued: 10/05/2010
• Est. Priority Date: 10/08/2007
• Status: Active Grant

• Current Assignee: Hemisphere GNSS(USA) Incorporated
• Original Assignee: Hemisphere GPS LLC (Kubota Corporation)
• Inventors: McClure, John A., Whitehead, Michael L., Badke, Bradley P., Miller, Steven R.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US12/247,139
• Publication Number:
  US 20090091496A1
• Time in Patent Office: 728 Days
• Field of Search: 342/357.06, 342/357.12, 342/357.13, 342/357.15, 701/213, 701/215
• US Class Current: 342/357.21
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain

Abstract

A GNSS system includes a receiver connected to an external mass storage device. Applications for the system, including GNSS data processing methods are also disclosed. The external storage device can comprise a flash (thumb) drive, which can be connected to the receiver via a USB interconnection.

Claims

1. A method of operating a GNSS signal processing system, for processing GNSS signals from multiple satellite sources received by a receiver including a digital signal processor (DSP) and a general purpose central processing unit (CPU), which method comprises the steps of:

providing said CPU with USB host hardware;

providing said CPU with a USB serial interface;

providing the CPU with random access memory (RAM);

providing the receiver with nonvolatile memory;

providing said receiver with a real-time operating system (RTOS) including a hardware abstraction layer (HAL) and upper-level USB software enabling USB host capability;

interfacing the USB host controller hardware and the USB software with the HAL;

embedding USB host software in said CPU and including interrupt service routines (ISRs) and delayed service routines (DSRs) in said USB host software;

handling USB activities between the upper-level USB software and the HAL with the ISRs;

handling with the DSRs USB activities not handled by the ISRs;

executing the DSRs on a time slice basis as dictated by the RTOS;

providing the GNSS receiver software with a PC compatible file system; and

receiving raw analog GNSS ranging and timing signals;

downconverting the raw analog GNSS signals to digital signals with an AD converter;

correlating the digital signals with the digital signal processor (DSP);

closing code and carrier tracking loops with the CPU on a fixed time interval (interrupt) basis;

calculating a GNSS solution and communicating the GNSS solution with a user interface;

providing output signals representing the GNSS positioning solution on a USB;

providing compatibility for the RTOS and the files read from or written to the external USB storage device;

processing said output signals in real-time;

transferring said output signals over a mass storage interface between said USB host hardware and said storage device;

storing said output signals on an external USB storage device; and

post-processing said externally stored data with an external computer.

2. The method of claim 1, which includes the additional steps of:

providing said output signals corresponding to one or more of pseudorange, integrated carrier phase, Doppler, satellite navigation message data, satellite ephemeris parameters, satellite clock correction parameters and ionosphere delay parameters.

3. The method of claim 1, which includes the additional steps of:

providing said output signals in a proprietary format or over a communication link.

4. The method of claim 1, which includes the additional step of calculating a GNSS solution with a vector floating point.

5. The method of claim 1, which includes the additional step of uploading firmware directly from an external USB storage device to the GNSS receiver.

6. The method of claim 1, which includes the additional steps of storing data comprising map data or data for analysis.

7. The method of claim 1, which includes the additional steps of performing tracking and positioning functions using the converted GNSS positioning signals.

8. The method of claim 1, which includes the additional steps of:

providing a user command interface; and

selecting and naming data log files through said user command interface through one of said GNSS receiver, RS-232 or USB interface.

9. The method of claim 1, which includes the additional steps of:

said CPU turning on messages;

assigning said messages to be written to particular files;

outputting said messages to an output port connected to said CPU; and

writing said messages to said external USB storage device.

10. The method of claim 1 wherein said external USB storage device comprises a flash drive.

11. The method of claim 1, which includes the additional steps of:

logging a stream of GNSS receiver observables for playback;

reconstructing performance of said receiver off-line (in non-real time); and

troubleshooting said GNSS system with said receiver performance reconstructed from said receiver observables.

12. The method of claim 1, which includes the additional steps of:

logging data comprising GNSS-derived locations or tracks into a file; and

displaying said date on a map.

13. The method of claim 12, which includes the additional steps of:

real-time logging track, swath and/or area calculations and/or colorizations;

loading a format from a mapping application; and

providing a mapping output using said mapping format.

14. The method of claim 1, which includes the additional steps of:

monitoring an agricultural chemical-applying operation with said system;

logging chemical application coverages in GNSS-defined field areas; and

mapping said chemical application coverages on said field areas.

15. The method of claim 1, which includes the additional steps of logging to the external storage device data corresponding to one or more of:

real-time aircraft tracking;

roll code and carrier observables;

range/page/yaw information;

XYZ position;

speed; and

time.

16. The method of claim 1, which includes the additional step of:

loading firmware on an external USB storage device;

providing said firmware with a signature;

connecting the external USB storage device to the CPU;

scanning the external USB storage device;

detecting the firmware signature;

uploading the firmware into the CPU RAM; and

programming the firmware into the receiver'"'"'s nonvolatile memory.

17. The method of claim 1, which includes the additional steps of:

loading GNSS correction date comprising one or more of precise orbit files, ionosphere modeling parameters, and differential code biases onto said external storage device from the worldwide web (Internet); and

utilizing said GNSS correction date for enhancing positioning accuracy with said GNSS system.

18. The method of claim 1, which includes the additional steps of:

downloading precise GNSS orbit and clock files to a computer via the Internet;

saving said precise GNSS orbit and clock files to the external storage device;

uploading to said receiver said precise GNSS orbit and clock files from the external storage device;

gathering data in the field with said GNSS system; and

performing GNSS precise point positioning (PPP) with said system using said precise GNSS orbit and clock data.

19. The method of claim 1, which includes the additional steps of:

creating a parameter file including data messages corresponding to one or more of format to be logged, logging rate, start and end times, automated logging-on, exceeding speed limits and leaving complex geo-fence polygons;

detecting the parameter file with the CPU; and

accessing said parameter file with said CPU on power-up from a GNSS application.

20. The method of claim 1, which includes the additional steps of:

downloading logged GNSS data from said external USB storage device onto a remote personal computer with suitable USB interface;

comparing logged data with existing data; and

troubleshooting said GNSS receiver based on the results of the compared data.