1132451Sroberto<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2285612Sdelphij<html><head> 3285612Sdelphij <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>Generic NMEA GPS Receiver</title> 4285612Sdelphij <!-- Changed by: Harlan &, 31-Mar-2014 --> 5285612Sdelphij <link href="scripts/style.css" type="text/css" rel="stylesheet"> 6285612Sdelphij <style type="text/css"> 7285612Sdelphij table.dlstable { font-size:85%; } 8285612Sdelphij td.ttf{ font-family:Courier; font-weight:bold; } 9285612Sdelphij </style></head> 10132451Sroberto 11132451Sroberto 12132451Sroberto 13285612Sdelphij <body> 14285612Sdelphij <h3>Generic NMEA GPS Receiver</h3> 15285612Sdelphij<p>Last update: 16285612Sdelphij <!-- #BeginDate format:En2m -->31-Mar-2014 03:55<!-- #EndDate --> 17285612Sdelphij UTC</p> 18285612Sdelphij <hr> 19285612Sdelphij <h4>Synopsis</h4> 20132451Sroberto 21285612Sdelphij <p> 22285612Sdelphij Address: 127.127.20.<i>u</i><br> 23285612Sdelphij Reference ID: <tt>GPS</tt><br> 24285612Sdelphij Driver ID: <tt>GPS_NMEA</tt><br> 25285612Sdelphij Serial Port: <tt>/dev/gps<i>u</i></tt>; 4800 - 115200 bps, 8-bits, no parity<br> 26285612Sdelphij Serial Port: <tt>/dev/gpspps<i>u</i></tt>; for just the PPS signal (this 27285612Sdelphij is tried first for PPS, before <tt>/dev/gps<i>u</i></tt>)<br> 28285612Sdelphij Serial Port: <tt>/dev/gps<i>u</i></tt>; symlink to server:port (for nmead)<br> 29285612Sdelphij Features: <tt>tty_clk</tt> 30285612Sdelphij </p> 31132451Sroberto 32285612Sdelphij <h4>Description</h4> 33285612Sdelphij 34285612Sdelphij <p> 35285612Sdelphij This driver supports GPS receivers with 36285612Sdelphij the <tt>$GPRMC</tt>, <tt>$GPGLL</tt>, <tt>$GPGGA</tt>, <tt>$GPZDA</tt> 37285612Sdelphij and <tt>$GPZDG</tt> NMEA sentences by default. Note that Accord's 38285612Sdelphij custom NMEA sentence <tt>$GPZDG</tt> reports using the GPS timescale, 39285612Sdelphij while the rest of the sentences report UTC. The difference between 40285612Sdelphij the two is a whole number of seconds which increases with each leap 41285612Sdelphij second insertion in UTC. To avoid problems mixing UTC and GPS 42285612Sdelphij timescales, the driver disables processing of UTC sentences 43285612Sdelphij once <tt>$GPZDG</tt> is received. 44285612Sdelphij </p> 45285612Sdelphij <p> 46285612Sdelphij The driver expects the receiver to be set up to transmit at least one 47285612Sdelphij supported sentence every second. 48285612Sdelphij </p> 49285612Sdelphij <p> 50285612Sdelphij The accuracy depends on the receiver used. Inexpensive GPS models are 51285612Sdelphij available with a claimed PPS signal accuracy of 52285612Sdelphij 1 μs or better relative to the broadcast 53285612Sdelphij signal. However, in most cases the actual accuracy is limited by the 54285612Sdelphij precision of the timecode and the latencies of the serial interface and 55285612Sdelphij operating system. 56285612Sdelphij </p> 57285612Sdelphij <p> 58285612Sdelphij If the Operating System supports PPSAPI 59285612Sdelphij (<a href="http://www.ietf.org/rfc/rfc2783.txt">RFC 2783</a>), fudge flag1 60285612Sdelphij 1 enables its use. 61285612Sdelphij </p> 62285612Sdelphij <p> 63285612Sdelphij The various GPS sentences that this driver recognises look like this:<br> 64285612Sdelphij (others quietly ignored) 65285612Sdelphij </p> 66285612Sdelphij 67285612Sdelphij <p><table class="dlstable" border="1"> 68285612Sdelphij <caption>Accepted NMEA sentences</caption> 69285612Sdelphij <tbody><tr> 70285612Sdelphij <th>Sentence</th> 71285612Sdelphij <th>Vendor</th> 72285612Sdelphij </tr><tr> 73285612Sdelphij <td class="ttf">$GPRMC,UTC,POS_STAT,LAT,LAT_REF,LON,LON_REF,SPD,HDG,DATE,MAG_VAR,MAG_REF*CS<cr><lf></td> 74285612Sdelphij </tr><tr> 75285612Sdelphij <td class="ttf">$GPGLL,LAT,LAT_REF,LON,LON_REF,UTC,POS_STAT*CS<cr><lf></td> 76285612Sdelphij </tr><tr> 77285612Sdelphij <td class="ttf">$GPGGA,UTC,LAT,LAT_REF,LON,LON_REF,FIX_MODE,SAT_USED,HDOP,ALT,ALT_UNIT,GEO,G_UNIT,D_AGE,D_REF*CS<cr><lf></td> 78285612Sdelphij </tr><tr> 79285612Sdelphij <td class="ttf">$GPZDA,UTC,DD,MM,YYYY,TH,TM,*CS<cr><lf></td> 80285612Sdelphij </tr><tr> 81285612Sdelphij <td class="ttf">$GPZDG,GPSTIME,DD,MM,YYYY,AA.BB,V*CS<cr><lf></td> 82285612Sdelphij <td>Accord</td> 83285612Sdelphij </tr> 84285612Sdelphij </tbody></table></p> 85285612Sdelphij 86285612Sdelphij <p><table class="dlstable" border="1"> 87285612Sdelphij <caption>NMEA data items</caption> 88285612Sdelphij <tbody><tr> 89285612Sdelphij <th>Symbol</th> 90285612Sdelphij <th>Meaning and Format</th> 91285612Sdelphij </tr> 92285612Sdelphij 93285612Sdelphij <tr> 94285612Sdelphij <td class="ttf">UTC</td> 95285612Sdelphij <td>Time of day on UTC timescale. Hours, minutes and seconds [fraction (opt.)]. (hhmmss[.fff])</td> 96285612Sdelphij </tr><tr> 97285612Sdelphij <td class="ttf">POS_STAT</td> 98285612Sdelphij <td>Position status. (A = Data valid, V = Data invalid)</td> 99285612Sdelphij </tr><tr> 100285612Sdelphij <td class="ttf">LAT</td> 101285612Sdelphij <td>Latitude (llll.ll)</td> 102285612Sdelphij </tr><tr> 103285612Sdelphij <td class="ttf">LAT_REF</td> 104285612Sdelphij <td>Latitude direction. (N = North, S = South)</td> 105285612Sdelphij </tr><tr> 106285612Sdelphij <td class="ttf">LON</td> 107285612Sdelphij <td>Longitude (yyyyy.yy)</td> 108285612Sdelphij </tr><tr> 109285612Sdelphij <td class="ttf">LON_REF</td> 110285612Sdelphij <td>Longitude direction (E = East, W = West)</td> 111285612Sdelphij </tr><tr> 112285612Sdelphij <td class="ttf">SPD</td> 113285612Sdelphij <td>Speed over ground. (knots) (x.x)</td> 114285612Sdelphij </tr><tr> 115285612Sdelphij <td class="ttf">HDG</td> 116285612Sdelphij <td>Heading/track made good (degrees True) (x.x)</td> 117285612Sdelphij </tr><tr> 118285612Sdelphij <td class="ttf">DATE</td> 119285612Sdelphij <td>Date (ddmmyy)</td> 120285612Sdelphij </tr><tr> 121285612Sdelphij <td class="ttf">MAG_VAR</td> 122285612Sdelphij <td>Magnetic variation (degrees) (x.x)</td> 123285612Sdelphij </tr><tr> 124285612Sdelphij <td class="ttf">MAG_REF</td> 125285612Sdelphij <td>Magnetic variation (E = East, W = West)</td> 126285612Sdelphij </tr><tr> 127285612Sdelphij <td class="ttf">FIX_MODE</td> 128285612Sdelphij <td>Position Fix Mode (0 = Invalid, >0 = Valid)</td> 129285612Sdelphij </tr><tr> 130285612Sdelphij <td class="ttf">SAT_USED</td> 131285612Sdelphij <td>Number of Satellites used in solution</td> 132285612Sdelphij </tr><tr> 133285612Sdelphij <td class="ttf">HDOP</td> 134285612Sdelphij <td>Horizontal Dilution of Precision</td> 135285612Sdelphij </tr><tr> 136285612Sdelphij <td class="ttf">ALT</td> 137285612Sdelphij <td>Antenna Altitude</td> 138285612Sdelphij </tr><tr> 139285612Sdelphij <td class="ttf">ALT_UNIT</td> 140285612Sdelphij <td>Altitude Units (Metres/Feet)</td> 141285612Sdelphij </tr><tr> 142285612Sdelphij <td class="ttf">GEO</td> 143285612Sdelphij <td>Geoid/Elipsoid separation</td> 144285612Sdelphij </tr><tr> 145285612Sdelphij <td class="ttf">G_UNIT</td> 146285612Sdelphij <td>Geoid units (M/F)</td> 147285612Sdelphij </tr><tr> 148285612Sdelphij <td class="ttf">D_AGE</td> 149285612Sdelphij <td>Age of last DGPS Fix</td> 150285612Sdelphij </tr><tr> 151285612Sdelphij <td class="ttf">D_REF</td> 152285612Sdelphij <td>Reference ID of DGPS station</td> 153285612Sdelphij </tr><tr> 154285612Sdelphij <td class="ttf">GPSTIME</td> 155285612Sdelphij <td>Time of day on GPS timescale. Hours, minutes and seconds [fraction (opt.)]. (hhmmss[.f])</td> 156285612Sdelphij </tr><tr> 157285612Sdelphij <td class="ttf">DD</td> 158285612Sdelphij <td>Day of the month (1-31)</td> 159285612Sdelphij </tr><tr> 160285612Sdelphij <td class="ttf">MM</td> 161285612Sdelphij <td>Month of the year (1-12)</td> 162285612Sdelphij </tr><tr> 163285612Sdelphij <td class="ttf">YYYY</td> 164285612Sdelphij <td>Year</td> 165285612Sdelphij </tr><tr> 166285612Sdelphij <td class="ttf">AA.BB</td> 167285612Sdelphij <td>Denotes the signal strength (should be < 05.00)</td> 168285612Sdelphij </tr><tr> 169285612Sdelphij <td class="ttf">V</td> 170285612Sdelphij <td>GPS sync status<br> 171285612Sdelphij '0' => INVALID time,<br> 172285612Sdelphij '1' => accuracy of +/- 20ms,<br> 173285612Sdelphij '2' => accuracy of +/- 100ns</td> 174285612Sdelphij </tr><tr> 175285612Sdelphij <td class="ttf">CS</td> 176285612Sdelphij <td> Checksum</td> 177285612Sdelphij </tr><tr> 178285612Sdelphij <td class="ttf"><cr><lf></td> 179285612Sdelphij <td>Sentence terminator.</td> 180285612Sdelphij </tr> 181285612Sdelphij </tbody></table></p> 182285612Sdelphij 183285612Sdelphij 184285612Sdelphij <h4>The 'mode' byte</h4> 185285612Sdelphij 186285612Sdelphij <p> 187285612Sdelphij Specific GPS sentences and bitrates may be selected by setting bits of 188285612Sdelphij the 'mode' in the server configuration line:<br> <tt>server 189285612Sdelphij 127.127.20.x mode X</tt> 190285612Sdelphij </p> 191285612Sdelphij 192285612Sdelphij <table border="1"> 193285612Sdelphij <caption>mode byte bits and bit groups</caption> 194285612Sdelphij <tbody><tr> 195285612Sdelphij <th align="center">Bit</th> 196285612Sdelphij <th align="center">Decimal</th> 197285612Sdelphij <th align="center">Hex</th> 198285612Sdelphij <th align="left">Meaning</th> 199285612Sdelphij </tr> 200285612Sdelphij 201285612Sdelphij <tr> 202285612Sdelphij <td align="center">0</td> 203285612Sdelphij <td align="center">1</td> 204285612Sdelphij <td align="center">1</td> 205285612Sdelphij <td>process <tt>$GPMRC</tt></td> 206285612Sdelphij </tr><tr> 207285612Sdelphij <td align="center">1</td> 208285612Sdelphij <td align="center">2</td> 209285612Sdelphij <td align="center">2</td> 210285612Sdelphij <td>process <tt>$GPGGA</tt></td> 211285612Sdelphij </tr><tr> 212285612Sdelphij <td align="center">2</td> 213285612Sdelphij <td align="center">4</td> 214285612Sdelphij <td align="center">4</td> 215285612Sdelphij <td>process <tt>$GPGLL</tt></td> 216285612Sdelphij </tr><tr> 217285612Sdelphij <td align="center">3</td> 218285612Sdelphij <td align="center">8</td> 219285612Sdelphij <td align="center">8</td> 220285612Sdelphij <td>process <tt>$GPZDA</tt> or <tt>$GPZDG</tt></td> 221285612Sdelphij </tr><tr> 222285612Sdelphij <td rowspan="6" align="center">4-6</td> 223285612Sdelphij <td align="center">0</td> 224285612Sdelphij <td align="center">0</td> 225285612Sdelphij <td>linespeed 4800 bps</td> 226285612Sdelphij </tr><tr> 227285612Sdelphij <td align="center">16</td> 228285612Sdelphij <td align="center">0x10</td> 229285612Sdelphij <td>linespeed 9600 bps</td> 230285612Sdelphij </tr><tr> 231285612Sdelphij <td align="center">32</td> 232285612Sdelphij <td align="center">0x20</td> 233285612Sdelphij <td>linespeed 19200 bps</td> 234285612Sdelphij </tr><tr> 235285612Sdelphij <td align="center">48</td> 236285612Sdelphij <td align="center">0x30</td> 237285612Sdelphij <td>linespeed 38400 bps</td> 238285612Sdelphij </tr><tr> 239285612Sdelphij <td align="center">64</td> 240285612Sdelphij <td align="center">0x40</td> 241285612Sdelphij <td>linespeed 57600 bps</td> 242285612Sdelphij </tr><tr> 243285612Sdelphij <td align="center">80</td> 244285612Sdelphij <td align="center">0x50</td> 245285612Sdelphij <td>linespeed 115200 bps</td> 246285612Sdelphij </tr><tr> 247285612Sdelphij <td align="center">7</td> 248285612Sdelphij <td align="center">128</td> 249285612Sdelphij <td align="center">0x80</td> 250285612Sdelphij <td>Write the sub-second fraction of the receive time stamp to the 251285612Sdelphij clockstat file for all recognised NMEA sentences. This can be used to 252285612Sdelphij get a useful value for fudge time2.<br><strong>Caveat:</strong> This 253285612Sdelphij will fill your clockstat file rather fast. Use it only temporarily to 254285612Sdelphij get the numbers for the NMEA sentence of your choice.</td> 255285612Sdelphij </tr> 256285612Sdelphij </tr><tr> 257285612Sdelphij <td align="center">8</td> 258285612Sdelphij <td align="center">256</td> 259285612Sdelphij <td align="center">0x100</td> 260285612Sdelphij <td>process <tt>$PGRMF</tt></td> 261285612Sdelphij </tr><tr> 262285612Sdelphij <td align="center">9-15</td> 263285612Sdelphij <td align="center"></td> 264285612Sdelphij <td align="center">0xFE00</td> 265285612Sdelphij <td>reserved - leave 0</td> 266285612Sdelphij </tr><tr> 267285612Sdelphij <td align="center">16</td> 268285612Sdelphij <td align="center">65536</td> 269285612Sdelphij <td align="center">0x10000</td> 270285612Sdelphij <td>Append extra statistics to the clockstats line. 271285612Sdelphij Details below.</td> 272285612Sdelphij </tr> 273285612Sdelphij </tbody></table> 274285612Sdelphij 275285612Sdelphij 276285612Sdelphij <p> 277285612Sdelphij The default (mode 0) is to process all supported sentences at a linespeed 278285612Sdelphij of 4800 bps, which results in the first one received and recognised in 279285612Sdelphij each cycle being used. If only specific sentences should be 280285612Sdelphij recognised, then the mode byte must be chosen to enable only the selected 281285612Sdelphij ones. Multiple sentences may be selected by adding their mode bit 282285612Sdelphij values, but of those enabled still only the first received sentence in a 283285612Sdelphij cycle will be used. Using more than one sentence per cycle is 284285612Sdelphij impossible, because 285285612Sdelphij </p><ul> 286285612Sdelphij <li>there is only <a href="#fudgetime2">fudge time2</a> available to 287285612Sdelphij compensate for transmission delays but every sentence would need a 288285612Sdelphij different one and 289285612Sdelphij </li><li>using more than one sentence per cycle overstuffs the internal data 290285612Sdelphij filters. 291285612Sdelphij </li></ul> 292285612Sdelphij The driver uses 4800 bits per second by default, but faster bitrates can 293285612Sdelphij be selected using bits 4 to 6 of the mode field. 294285612Sdelphij <p></p> 295285612Sdelphij 296285612Sdelphij <p> 297285612Sdelphij <strong>Caveat:</strong> Using higher line speeds does not necessarily 298285612Sdelphij increase the precision of the timing device. Higher line speeds are 299285612Sdelphij not necessarily helpful for the NMEA driver, either. They can be 300285612Sdelphij used to accomodate for an amount of data that does not fit into a 301285612Sdelphij 1-second cycle at 4800 bps, but high-speed high-volume NMEA data is likely 302285612Sdelphij to cause trouble with the serial line driver since NMEA supports no 303285612Sdelphij protocol handshake. Any device that is exclusively used for time 304285612Sdelphij synchronisation purposes should be configured to transmit the relevant 305285612Sdelphij data only, e.g. one <tt>$GPRMC</tt> or <tt>$GPZDA</tt> per second, at a 306285612Sdelphij linespeed of 4800 bps or 9600 bps. 307285612Sdelphij </p> 308285612Sdelphij 309285612Sdelphij <h4>Monitor Data</h4> 310285612Sdelphij 311285612Sdelphij <p>The last GPS sentence that is accepted or rejected is written to the 312285612Sdelphij clockstats file and available with <code>ntpq -c clockvar</code>. 313285612Sdelphij (Logging the rejected sentences lets you see/debug why they were rejected.) 314285612Sdelphij Filtered sentences are not logged.</p> 315285612Sdelphij 316285612Sdelphij <p> 317285612Sdelphij If the 0x10000 mode bit is on and clockstats is enabled, several extra 318285612Sdelphij counters will be appended to the NMEA sentence that gets logged. 319285612Sdelphij For example: 320285612Sdelphij<pre> 321285612Sdelphij56299 76876.691 127.127.20.20 $GPGGA,212116.000,3726.0785,N,12212.2605,W,1,05,2.0,17.0,M,-25.7,M,,0000*5C 228 64 0 0 64 0 322285612Sdelphij</pre> 323285612Sdelphij </p> 324285612Sdelphij 325285612Sdelphij <table border="1"> 326285612Sdelphij <caption>Clockstats</caption> 327285612Sdelphij <tbody><tr> 328285612Sdelphij <th align="center">Column</th> 329285612Sdelphij <th align="center">Sample</th> 330285612Sdelphij <th align="left">Meaning</th> 331285612Sdelphij </tr> 332285612Sdelphij 333285612Sdelphij <tr> 334285612Sdelphij <td align="center">1</td> 335285612Sdelphij <td align="center">56299</td> 336285612Sdelphij <td>MJD</td> 337285612Sdelphij </tr><tr> 338285612Sdelphij <td align="center">2</td> 339285612Sdelphij <td align="center">76876.691</td> 340285612Sdelphij <td>Time of day in seconds</td> 341285612Sdelphij </tr><tr> 342285612Sdelphij <td align="center">3</td> 343285612Sdelphij <td align="center">127.127.20.20</td> 344285612Sdelphij <td>IP Address from server config line</td> 345285612Sdelphij </tr><tr> 346285612Sdelphij <td align="center">4</td> 347285612Sdelphij <td align="center">$GPGGA,...0*5C</td> 348285612Sdelphij <td>NMEA Sentence</td> 349285612Sdelphij </tr><tr> 350285612Sdelphij <td align="center">5</td> 351285612Sdelphij <td align="center">228</td> 352285612Sdelphij <td>Number of sentences received</td> 353285612Sdelphij </tr><tr> 354285612Sdelphij <td align="center">6</td> 355285612Sdelphij <td align="center">64</td> 356285612Sdelphij <td>Number of sentences accepted and used for timekeeping</td> 357285612Sdelphij </tr><tr> 358285612Sdelphij <td align="center">7</td> 359285612Sdelphij <td align="center">0</td> 360285612Sdelphij <td>Number of sentences rejected because they were marked invalid (poor signal)</td> 361285612Sdelphij </tr><tr> 362285612Sdelphij <td align="center">8</td> 363285612Sdelphij <td align="center">0</td> 364285612Sdelphij <td>Number of sentences rejected because of bad checksum or invalid date/time</td> 365285612Sdelphij </tr><tr> 366285612Sdelphij <td align="center">9</td> 367285612Sdelphij <td align="center">64</td> 368285612Sdelphij <td>Number of sentences filtered by mode bits or same second</td> 369285612Sdelphij </tr><tr> 370285612Sdelphij <td align="center">10</td> 371285612Sdelphij <td align="center">0</td> 372285612Sdelphij <td>Number of PPS pulses used, overrides NMEA sentences</td> 373285612Sdelphij </tr> 374285612Sdelphij </tbody></table> 375285612Sdelphij 376285612Sdelphij Sentences like $GPGSV that don't contain the time will get 377285612Sdelphij counted in the total but otherwise ignored. 378285612Sdelphij 379285612Sdelphij <p> 380285612Sdelphij <a href="https://support.ntp.org/bin/view/Support/ConfiguringNMEARefclocks">Configuring 381285612Sdelphij NMEA Refclocks</a> might give further useful hints for specific hardware 382285612Sdelphij devices that exhibit strange or curious behaviour. 383285612Sdelphij </p> 384285612Sdelphij 385285612Sdelphij <p> 386285612Sdelphij To make a specific setting, select the corresponding decimal values from 387285612Sdelphij the mode byte table, add them all together and enter the resulting 388285612Sdelphij decimal value into the clock configuration line. 389285612Sdelphij </p> 390285612Sdelphij 391285612Sdelphij <h4>Setting up the Garmin GPS-25XL</h4> 392285612Sdelphij 393285612Sdelphij Switch off all output with by sending it the following string. 394285612Sdelphij <pre>"$PGRMO,,2<cr><lf>"</pre> 395285612Sdelphij <p>Now switch only $GPRMC on by sending it the following string.</p> 396285612Sdelphij <pre>"$PGRMO,GPRMC,1<cr><lf>"</pre> 397285612Sdelphij 398285612Sdelphij <p>On some systems the PPS signal isn't switched on by default. It can be 399285612Sdelphij switched on by sending the following string.</p> 400285612Sdelphij <pre>"$PGRMC,,,,,,,,,,,,2<cr><lf>"</pre> 401285612Sdelphij 402285612Sdelphij <h4>Fudge Factors</h4> 403285612Sdelphij 404285612Sdelphij <dl> 405285612Sdelphij <dt><tt>time1 <i>time</i></tt></dt> 406285612Sdelphij <dd>Specifies the PPS time offset calibration factor, in seconds and fraction, with default 0.0.</dd> 407285612Sdelphij <dt><a name="fudgetime2"><tt>time2 <i>time</i></tt></a></dt> 408285612Sdelphij <dd>Specifies the serial end of line time offset calibration factor, in seconds and fraction, with default 409285612Sdelphij 0.0.</dd> 410285612Sdelphij <dt><tt>stratum <i>number</i></tt></dt> 411285612Sdelphij <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0.</dd> 412285612Sdelphij <dt><tt>refid <i>string</i></tt></dt> 413285612Sdelphij <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with 414285612Sdelphij default <tt>GPS</tt>.</dd> 415285612Sdelphij <dt><tt>flag1 0 | 1</tt></dt> 416285612Sdelphij <dd>Disable PPS signal processing if 0 (default); enable PPS signal processing if 1.</dd> 417285612Sdelphij <dt><tt>flag2 0 | 1</tt></dt> 418285612Sdelphij <dd>If PPS signal processing is enabled, capture the pulse on the rising edge if 0 (default); capture on the 419285612Sdelphij falling edge if 1.</dd> 420285612Sdelphij <dt><tt>flag3 0 | 1</tt></dt> 421285612Sdelphij <dd>If PPS signal processing is enabled, use the <tt>ntpd</tt> clock discipline if 0 (default); use the kernel 422285612Sdelphij discipline if 1.</dd> 423285612Sdelphij <dt><tt>flag4 0 | 1</tt></dt> 424285612Sdelphij <dd>Obscures location in timecode: 0 for disable (default), 1 for enable.</dd> 425285612Sdelphij </dl> 426285612Sdelphij 427285612Sdelphij <p>Additional Information</p> 428285612Sdelphij <p><tt>flag1</tt>, <tt>flag2</tt>, and <tt>flag3</tt> are ignored under Windows.</p> 429285612Sdelphij <p><a href="../refclock.html">Reference Clock Drivers</a></p> 430285612Sdelphij <hr> 431285612Sdelphij <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 432285612Sdelphij </body></html> 433