19c2daa00SOllivier Robert<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 29c2daa00SOllivier Robert 39c2daa00SOllivier Robert<html> 49c2daa00SOllivier Robert 59c2daa00SOllivier Robert <head> 69c2daa00SOllivier Robert <meta http-equiv="Content-Type" content="text/html; charset=iso-8859- 1"> 79c2daa00SOllivier Robert <meta name="GENERATOR" content="Mozilla/4.06 [en] (X11; I; FreeBSD 3.0-CURRENT i386) [Netscape]"> 89c2daa00SOllivier Robert <title>Motorola Oncore GPS Receiver</title> 99c2daa00SOllivier Robert <link href="../scripts/style.css" type="text/css" rel="stylesheet"> 109c2daa00SOllivier Robert </head> 119c2daa00SOllivier Robert 129c2daa00SOllivier Robert <body> 139c2daa00SOllivier Robert <h3>Motorola Oncore GPS receiver</h3> 149c2daa00SOllivier Robert <hr> 159c2daa00SOllivier Robert <h4>Synopsis</h4> 169c2daa00SOllivier Robert <p>Address: 127.127.30.<i>u</i><br> 179c2daa00SOllivier Robert Reference ID: <tt>GPS</tt><br> 189c2daa00SOllivier Robert Driver ID: ONCORE<br> 199c2daa00SOllivier Robert Serial Port: <tt>/dev/oncore.serial.</tt><i>u</i>; 9600 baud, 8-bits, no parity.<br> 209c2daa00SOllivier Robert PPS Port: <tt>/dev/oncore.pps.</tt><i>u</i>; <tt>PPS_CAPTUREASSERT</tt> required, <tt>PPS_OFFSETASSERT</tt> supported.<br> 219c2daa00SOllivier Robert Configuration File: <tt>/etc/ntp.oncore</tt>, or <tt>/etc/ntp.oncore.</tt><i>u</i>, or <tt>/etc/ntp.oncore</tt><i>u</i>.</p> 229c2daa00SOllivier Robert <h4>Description</h4> 239c2daa00SOllivier Robert <p>This driver supports most models of the <a href="http://www.mot.com/AECS/PNSB/products">Motorola Oncore GPS receivers</a> (Basic, PVT6, VP, UT, UT+, GT, GT+, SL, M12), as long as they support the <i>Motorola Binary Protocol</i>.</p> 249c2daa00SOllivier Robert <p>The interesting versions of the Oncore are the VP, the UT+, the "Remote" which is a prepackaged UT+, and the M12 Timing. The VP is no longer available new, and the UT, GT, and SL are at end-of-life. The Motorola evaluation kit can be recommended. It interfaces to a PC straightaway, using the serial (DCD) or parallel port for PPS input and packs the receiver in a nice and sturdy box. Less expensive interface kits are available from <a href="http://www.tapr.org">TAPR</a> and <a href="http://www.synergy-gps.com">Synergy</a>.<br> 259c2daa00SOllivier Robert </p> 269c2daa00SOllivier Robert <center> 279c2daa00SOllivier Robert <table> 289c2daa00SOllivier Robert <tr> 299c2daa00SOllivier Robert <td><img src="../pic/oncore_utplusbig.gif" alt="gif" height="124" width="210"></td> 309c2daa00SOllivier Robert <td><img src="../pic/oncore_evalbig.gif" alt="gif" height="124" width="182"></td> 319c2daa00SOllivier Robert <td><img src="../pic/oncore_remoteant.jpg" alt="gif" height="188" width="178"></td> 329c2daa00SOllivier Robert </tr> 339c2daa00SOllivier Robert <tr> 349c2daa00SOllivier Robert <td> 359c2daa00SOllivier Robert <center> 369c2daa00SOllivier Robert UT+ oncore</center> 379c2daa00SOllivier Robert </td> 389c2daa00SOllivier Robert <td> 399c2daa00SOllivier Robert <center> 409c2daa00SOllivier Robert Evaluation kit</center> 419c2daa00SOllivier Robert </td> 429c2daa00SOllivier Robert <td> 439c2daa00SOllivier Robert <center> 449c2daa00SOllivier Robert Oncore Remote</center> 459c2daa00SOllivier Robert </td> 469c2daa00SOllivier Robert </tr> 479c2daa00SOllivier Robert </table> 489c2daa00SOllivier Robert </center> 499c2daa00SOllivier Robert <p>The driver requires a standard <tt>PPS</tt> interface for the pulse-per-second output from the receiver. The serial data stream alone does not provide precision time stamps (0-50msec variance, according to the manual), whereas the PPS output is precise down to 50 nsec (1 sigma) for the VP/UT models and 25 nsec for the M12 Timing. If you do not have the PPS signal available, then you should probably be using the NMEA driver rather than the Oncore driver.</p> 509c2daa00SOllivier Robert <p>The driver will use the "position hold" mode with user provided coordinates, the receivers built-in site-survey, or a similar algorithm implemented in this driver to determine the antenna position.</p> 519c2daa00SOllivier Robert <h4>Monitor Data</h4> 529c2daa00SOllivier Robert The driver always puts a lot of useful information on the clockstats file, and when run with debugging can be quite chatty on stdout. When first starting to use the driver you should definitely review the information written to the clockstats file to verify that the driver is running correctly. 539c2daa00SOllivier Robert <p>In addition, on platforms supporting Shared Memory, all of the messages received from the Oncore receiver are made available in shared memory for use by other programs. See the <a href="oncore-shmem.html">Oncore-SHMEM</a> manual page for information on how to use this option. For either debugging or using the SHMEM option, an Oncore Reference Manual for the specific receiver in use will be required.</p> 549c2daa00SOllivier Robert <h4>Fudge Factors</h4> 559c2daa00SOllivier Robert <dl> 569c2daa00SOllivier Robert <dt><tt>time1 <i>time</i></tt> 579c2daa00SOllivier Robert <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. 589c2daa00SOllivier Robert <dt><tt>time2 <i>time</i></tt> 599c2daa00SOllivier Robert <dd>Not used by this driver. 609c2daa00SOllivier Robert <dt><tt>stratum <i>number</i></tt> 619c2daa00SOllivier Robert <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. 629c2daa00SOllivier Robert <dt><tt>refid <i>string</i></tt> 639c2daa00SOllivier Robert <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. 649c2daa00SOllivier Robert <dt><tt>flag1 0 | 1</tt> 659c2daa00SOllivier Robert <dd>Not used by this driver. 669c2daa00SOllivier Robert <dt><tt>flag2 0 | 1</tt> 679c2daa00SOllivier Robert <dd>Specifies the PPS signal on-time edge: 0 for assert (default), 1 for clear. 689c2daa00SOllivier Robert <dt><tt>flag3 0 | 1</tt> 699c2daa00SOllivier Robert <dd>Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. 709c2daa00SOllivier Robert <dt><tt>flag4 0 | 1</tt> 719c2daa00SOllivier Robert <dd>Not used by this driver. 729c2daa00SOllivier Robert </dl> 739c2daa00SOllivier Robert <h4>Additional Information</h4> 749c2daa00SOllivier Robert <p>The driver was initially developed on FreeBSD, and has since been tested on Linux, SunOS and Solaris.</p> 759c2daa00SOllivier Robert <p><b>Configuration</b></p> 769c2daa00SOllivier Robert <p>There is a driver specific configuration file <tt>/etc/ntp.oncore</tt> (or <tt>/etc/ntp.oncore.</tt><i>u</i> or <tt>/etc/ntp.oncore</tt><i>u</i> if you must distinguish between more than one Oncore receiver) that contains information on the startup mode, the location of the GPS receiver, an offset of the PPS signal from zero, and the cable delay. The offset shifts the PPS signal to avoid interrupt pileups `on' the second, and adjust the timestamp accordingly. See the driver source for information on this file. The default with no file is: no delay, no offset, and a site survey is done to get the location of the gps receiver.</p> 779c2daa00SOllivier Robert <p>The edge of the PPS signal that is `on-time' can be set with either flag2 or in the driver specific configuration file with the keywords [ASSERT/CLEAR]. Flag3 (or the word HARDPPS in the driver specific configuration file) will cause the PPS signal to control the kernel PLL.</p> 789c2daa00SOllivier Robert <p><b>Performance</b></p> 799c2daa00SOllivier Robert <p>Really good. With the VP/UT+, the generated PPS pulse is referenced to UTC(GPS) with better than 50 nsec (1 sigma) accuracy. The limiting factor will be the timebase of the computer and the precision with which you can timestamp the rising flank of the PPS signal. Using FreeBSD, a FPGA based Timecounter/PPS interface, and an ovenized quartz oscillator, that performance has been reproduced. For more details on this aspect: <a href="http://phk.freebsd.dk/rover.html">Sub-Microsecond timekeeping under FreeBSD</a>.</p> 809c2daa00SOllivier Robert <hr> 819c2daa00SOllivier Robert <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> 829c2daa00SOllivier Robert </body> 839c2daa00SOllivier Robert 849c2daa00SOllivier Robert</html>
