PARGPS USER MANUAL EXCERPTS

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The table of contents and selected excerpts from the PARGPS manual are shown below. The full text is available in PDF format at no charge from our downloads page.

CHAPTER 1: INTRODUCTION
The Symmetric Research PARGPS is a timing unit for providing highly accurate time stamping for data acquired with the SR PARxCH (x=1,4,8) 24 bit data acquisition systems. Connecting to the PARxCH and the PC serial port port, it sits outside the PC in its own vinyl covered steel enclosure for quiet noise free operation. Because it interfaces to the serial port, the system is easy to use with closed PC's such as laptops. For PC104 applications, an adapter plate is also available so the PARGPS can be used as part of a standard PC104 stack.

Based on the Trimble ACE-III GPS receiver, the system typically provices 10 usec timing accuracy. It provides both time and location data on an ongoing real time basis as data is acquired. It uses the industry standard RS232 NMEA messages for location and coarse timing, and the highly accurate pluse per second (PPS) signal for precision time. The NMEA messages are connected to the PC by a standard DB9 serial port cable to COM1 or COM2. The PPS signal is fed directly to the digital I/O connector of the PARxCH (x=1,4,8) for processing by the A/D system.

Software that comes with the board has both high level utility programs ready for immediate use and low level function libraries for those wishing to do custom programming. Support is provided for Win2K/XP and Linux. The Win2K/XP and Linux software features true kernel mode drivers for good performance and reliable operation.

Other items included with the board are a cable to daisy chain power with the PARxCH, a cable for connecting to the PARxCH digital I/O, a cable for connecting to the PC serial port, a mini-mag style antenna and circuit diagrams. Everything needed to be up and running right away.

CHAPTER 2: INSTALLATION
Installation of the PARGPS is straightforward. You'll need to plug in the wall transformer and daisy chain power to the PARxCH (x=1,4,8) and connect the antenna. Then connect to the PARxCH digital I/O header and the PC serial port, and install the software. The individual steps in more detail are:

CHAPTER 3: UTILITY PROGRAMS
The SR PARGPS comes with finished utility programs you can run immediately after installing the system. These include diagnostic programs and ones to update the timing information in DAT file headers. The source code is included for those wanting to modify these programs for custom applications.

CHAPTER 4: LIBRARY FUNCTIONS
The library functions are at the core of the software supplied with the SR PARGPS. They allow users to control board operations from high level languages without having to know the low level details of how the system operates. These functions can be statically linked to C programs for any OS. In addition, they are available as a Dynamic Link Library (DLL) under Windows and as a shared library (.so) under Linux. When used as a DLL, these functions can be called from other high level programming languages such as Microsoft Visual Basic.This chapter covers usage from programming environments like Visual C. For diagnosic and utility programs that are ready to run with no programming required, see the Utility Programs chapter.

The outline of how to use the PARGPS library functions is fairly simple. First call the Open function to open the driver and initialize the sampling rate and other parameters. Once the board has been initialized, call Start to begin timing. When you are done, call Stop and Close to stop acquiring data and close the driver.

APPENDIX A: ELECTRICAL SPECS
The PARGPS uses +5vdc to power the analog and digital circuitry. Off board power of at least 10 volts is recommended for reliable operation. The system requires approximately 130ma of current. Higher sampling rates result in more current draw.

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