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/4.01 [en] (Win95; I) [Netscape]"> 89c2daa00SOllivier Robert <title>Hewlett Packard 58503A 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>Hewlett Packard 58503A GPS Receiver</h3> 149c2daa00SOllivier Robert <hr> 159c2daa00SOllivier Robert <h4>Synopsis</h4> 169c2daa00SOllivier Robert <p>Address: 127.127.26.<i>u</i><br> 179c2daa00SOllivier Robert Reference ID: <tt>GPS</tt><br> 189c2daa00SOllivier Robert Driver ID: <tt>GPS_HP</tt><br> 199c2daa00SOllivier Robert Serial Port: <tt>/dev/hpgps<i>u</i></tt>; 9600 baud, 8-bits, no parity</p> 209c2daa00SOllivier Robert <h4>Description</h4> 219c2daa00SOllivier Robert <p>This driver supports the HP 58503A Time and Frequency Reference Receiver. It uses HP SmartClock (TM) to implement an Enhanced GPS receiver. The receiver accuracy when locked to GPS in normal operation is better than 1 usec. The accuracy when operating in holdover is typically better than 10 us per day. It receiver should be operated with factory default settings. Initial driver operation: expects the receiver to be already locked to GPS, configured and able to output timecode format 2 messages.</p> 229c2daa00SOllivier Robert <p>The driver uses the poll sequence <tt>:PTIME:TCODE?</tt> to get a response from the receiver. The receiver responds with a timecode string of ASCII printing characters, followed by a <cr><lf>, followed by a prompt string issued by the receiver, in the following format:</p> 239c2daa00SOllivier Robert <pre>T#yyyymmddhhmmssMFLRVcc<cr><lf></pre> 249c2daa00SOllivier Robert The driver processes the response at the <cr> and <lf><cr> and <lf>, so what the driver sees is the prompt from the previous poll, followed by this timecode. The prompt from the current poll is (usually) left unread until the next poll. So (except on the very first poll) the driver sees this: 259c2daa00SOllivier Robert <pre>T#yyyymmddhhmmssMFLRVcc<cr><lf></pre> 269c2daa00SOllivier Robert <p>The T is the on-time character, at 980 msec. before the next 1PPS edge. The # is the timecode format type. We look for format 2. Without any of the CLK or PPS stuff, then, the receiver buffer timestamp at the <cr>y is 24 characters later, which is about 25 msec. at 9600 bps, so the first approximation for fudge time1 is nominally -0.955 seconds. This number probably needs adjusting for each machine / OS type, so far: -0.955000 on an HP 9000 Model 712/80 HP-UX 9.05 -0.953175 on an HP 9000 Model 370 HP-UX 9.10</p> 279c2daa00SOllivier Robert <h4>Fudge Factors</h4> 289c2daa00SOllivier Robert <dl> 299c2daa00SOllivier Robert <dt><tt>time1 <i>time</i></tt> 309c2daa00SOllivier Robert <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. 319c2daa00SOllivier Robert <dt><tt>time2 <i>time</i></tt> 329c2daa00SOllivier Robert <dd>Not used by this driver. 339c2daa00SOllivier Robert <dt><tt>stratum <i>number</i></tt> 349c2daa00SOllivier Robert <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. 359c2daa00SOllivier Robert <dt><tt>refid <i>string</i></tt> 369c2daa00SOllivier Robert <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. 379c2daa00SOllivier Robert <dt><tt>flag1 0 | 1</tt> 389c2daa00SOllivier Robert <dd>Not used by this driver. 399c2daa00SOllivier Robert <dt><tt>flag2 0 | 1</tt> 409c2daa00SOllivier Robert <dd>Not used by this driver. 419c2daa00SOllivier Robert <dt><tt>flag3 0 | 1</tt> 429c2daa00SOllivier Robert <dd>Not used by this driver. 439c2daa00SOllivier Robert <dt><tt>flag4 0 | 1</tt> 449c2daa00SOllivier Robert <dd>Not used by this driver. 459c2daa00SOllivier Robert </dl> 469c2daa00SOllivier Robert <hr> 479c2daa00SOllivier Robert <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> 489c2daa00SOllivier Robert </body> 499c2daa00SOllivier Robert 509c2daa00SOllivier Robert</html>