\qquad 开源GPS项目HD-GR GNSS的自叙：
README the readme file for gpl-gps, a port of OpenSource GPS for the GP4020
Copyright (C) 2005 Andrew Greenberg
Distributed under the GNU GENERAL PUBLIC LICENSE (GPL) Version 2 (June 1991).
See the "COPYING" file distributed with this software for more information.
GPL-GPS
Open source software for Commercial, Off-the-Self Global Positioning System
GPS) receivers. <http://gps.psas.pdx.edu>
PURPOSE
To make high quality GPS software available to anyone for experimentation,
education, research, and new applications. Our software is intended to run on
inexpensive off-the-shelf commercial hardware while attaining the full accuracy
possible with the present civilian GPS configuration.
Possible applications include but are not limited to
Differential GPS featuring centimeter accuracy
Improved accuracy WAAS GPS
GPS aiding and complementary inertial navigation integration
Carrier phase for vehicle attitude determination
Multipath rejecting and jamm-resistant algorithms
Software GPS
GPS integration, for example as a subroutine in a software radio
Development of new GPS systems such as L5 capable receivers
A tool for teaching about the GPS
HISTORY
Around 1995 Clifford Kelly began working on open source GPS software. He called
the project OpenSource GPS (OSGPS) and as of 2005 it has reached version 1.17.
The project website is <http://home.earhlink.net/~cwkelley>, there is also a
project page on sourceforge <http://sourceforge.net/projects/osgps>.
By using a hacked commercial receiver based on the GP2021 chip, bypassing the
receiver's microprocessor and connecting the hardware correlator directly to
the PC-ISA bus, OSGPS is able to run all its software on the host PC.
Meanwhile, at Portland State University, a small group of students started a
rocket club, the Portland State Aerospace Society (PSAS) whose admittedly
ambitious purpose was to (eventually) send nano-satellites into orbit. Through
the late 1990's this group <http://psas.pds.edu> was semi-seriously discussing
the idea of open source software for inertial navigation with GPS aiding based
roughly on the complementary filter approach.
Finally in the year 2000 Andrew Greenberg, a PSAS started what became the
gpl-gps project. As circumstance unfolded, not much actual software got
written at first. The project moved slowly for several years until April
2003 when the gps.psas.pdx website was finally set up. This was followed by a
flurry of activity culminating in a meeting at the 2003 Institute of
Navigation conference. After the conference many distractions sapped the
energy away for GPS work and the project languished without progress.
Then in 2004 Takuji Ebinuma ported OSGPS to the GP4020
<http://www.geocities.com/tebinuma/osgps>. Unlike Cliff Kelly's effort,
Takuji's port ran on unmodified OEM hardware using the GP4020's built in
bootloader. Though both approaches have advantages, the off-the-shelf hardware
approach of Takuji's effort was more in keeping with the goals of gpl-gps, and
more to the point, Takuji was making progress. This, combined with the
realization that his graduate credit hours would soon begin to expire,
Andrew leaped into action and in April 2005 gpl-gps was revivified.
The gpl-gps project is now in the process of porting the combined mass of OSGPS
code to the ecos operating system using Linux as a development platform.
Currently we're targeting the SigTec MG5001 OEM board. Eventually we hope to
expand and improve all aspects of opensource GPS code using the neo-traditional
netwide collaborative model. Somewhere along the way Andrew hopes to complete
his masters degree.
The history continues...
In 2006 Peter Mumford and Yong Heo from the University of New South Wales SNAP lab
ported Andrews code to the Namuru (V1) FPGA based GPS receiver. This involved adjusting
the code to the different baseband design as well as a different processor and UART. This
was done using the NiosII IDE. In addition an eCos library was built. The code was stable
but the GPS performance was abysmal, with long acquisition times and satellite signals dropped
for no good reason.
In 2007, Alesandro Avanzi from University di Bologna spent some months at UNSW doing a Professional Praticum.
He looked into the problems and fixed many bugs. Most important, he worked on improving the
tracking loops, and documenting his findings.
Peter Mumford has ported this to the Namuru V2 board -
Use hyperterminal @ 57600 baud to view data.
In 2014-2015, Cheng Huaide ported the code of Peter Mumford and Yong Heo to the HD-GR
receiver - this is it!.
This involved adjusting the code to a different RTOS, optimizing the baseband design and
operation efficiency, supporting the application of GPS and BDS for dual system hybrid
positioning, and supporting the output of 1PPS. The code runs stably and has good performance,
and can complete the static positioning of single and dual systems for several hours. However,
it is not fully tested, and the acquisition time is long.