Integrating the GP2021 and Linux in Open Source GPS

摘要

The workhorse of signal processing GPS research for the last decade has been the GP2021 correlator. GEC Plessey originally shipped it on a development board for PCs accompanied by some MS-DOS software. This software is what most researchers based their research upon. However, because of the proprietary nature of this code it was impossible for researchers to legally share enhancements they made to the code. An effort known as the OSGPS project solved this problem by providing Free Software written from scratch for MS-DOS. However, MS-DOS lacks modern interfaces like PCI and USB as well as good networking code found in current operating systems like Linux. This paper describes the details of porting the OSGPS software from MS-DOS to Linux. The details of the data organization, timing issues and device driver design are all discussed as well as some of the features and basic usage of the software. A valuable feature ofrnthe Linux version is the division of the software between hardware interface code in the kernel and engineering level code in user space. This feature enables use of the standard (non-real-time) Linux kernel.