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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
First Claim
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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.

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