contrib/ntp/html/mx4200data.htm

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   7 <h1>MX4200 Receiver Data Format</h1>
   8
   9 <hr>
  10 <h2>Table of Contents</h2>
  11
  12 <ul>
  13  <li><a href="#control">Control Port Sentences</a></li>
  14  <li><a href="#input">Control Port Input Sentences</a></li>
  15  <ul>
  16   <li><a href="#input_000">$PMVXG,000</a> Initialization/Mode Control - Part A</li>
  17   <li><a href="#input_001">$PMVXG,001</a> Initialization/Mode Control - Part B</li>
  18   <li><a href="#input_007">$PMVXG,007</a> Control Port Configuration</li>
  19   <li><a href="#input_023">$PMVXG,023</a> Time Recovery Configuration</li>
  20   <li><a href="#input_gpq">$CDGPQ,YYY</a> Query From a Remote Device / Request to Output a Sentence</li>
  21  </ul>
  22  <li><a href="#output">Control Port Output Sentences</a></li>
  23  <ul>
  24   <li><a href="#output_000">$PMVXG,000</a> Receiver Status</li>
  25   <li><a href="#output_021">$PMVXG,021</a> Position, Height, Velocity</li>
  26   <li><a href="#output_022">$PMVXG,022</a> DOPs</li>
  27   <li><a href="#output_030">$PMVXG,030</a> Software Configuration</li>
  28   <li><a href="#output_101">$PMVXG,101</a> Control Sentence Accept/Reject</li>
  29   <li><a href="#output_523">$PMVXG,523</a> Time Recovery Configuration</li>
  30   <li><a href="#output_830">$PMVXG,830</a> Time Recovery Results</li>
  31  </ul>
  32 </ul>
  33
  34 <hr>
  35
  36 <h2><a name="control">Control Port Sentences</a></h2>
  37
  38 <p>The Control (CDU) Port is used to initialize, monitor, and control
  39 the receiver.  The structure of the control port sentences is based on
  40 the <cite>NMEA-0183</cite> Standard for Interfacing Marine Electronics
  41 Navigation Devices (version 1.5).  For more details, please refer to
  42 the <cite>NMEA-0183</cite> Specification available from the
  43 <a href="http://www.nmea.org/">National Marine Electronics
  44 Association</a>.</p>
  45
  46 <p>Reserved characters are used to indicate the beginning and the end
  47 of records in the data stream, and to delimit data fields within a
  48 sentence.  Only printable ASCII characters (Hex 20 through 7F) may be
  49 used in a sentence.  <a href="#table_2">Table 2</a> lists the reserved
  50 characters and defines their usage.  <a href="#table_1">Table 1</a>
  51 illustrates the general Magnavox proprietary NMEA sentence format.
  52 </p>
  53
  54 <h4><a name="table_1">Table 1. Magnavox Proprietary NMEA Sentence Format</a></h4>
  55 <code>
  56 $PMVXG,XXX,...................*CK
  57 </code>
  58
  59 <p>
  60
  61 <table border>
  62  <tr> <th>Character   <th>Meaning
  63  <tr> <td><code>$</code>   <td>Sentence Start Character
  64  <tr> <td><code>P</code>   <td>Special ID (P = Proprietary)
  65  <tr> <td><code>MVX</code> <td>Originator ID (MVX = Magnavox)
  66  <tr> <td><code>G</code>   <td>Interface ID (G = GPS)
  67  <tr> <td><code>XXX</code> <td>Sentence Type
  68  <tr> <td><code>...</code> <td>Data
  69  <tr> <td><code>*</code>   <td>Optional Checksum Field Delimiter
  70  <tr> <td><code>CK</code>  <td>Optional Checksum
  71 </table>
  72
  73 <h4><a name="table_2">Table 2. NMEA Sentence Reserved Characters</a></h4>
  74
  75 <table border>
  76  <tr> <th>Character             <th>Hex Value <th>Usage
  77  <tr> <td><code>$</code>        <td>24        <td>Start of Sentence Identifier
  78  <tr> <td><code>{cr}{lf}</code> <td>0D 0A     <td>End of Sentence Identifier
  79  <tr> <td><code>,</code>        <td>2C        <td>Sentence Delimiter
  80  <tr> <td><code>*</code>        <td>2A        <td>Optional Checksum Field Delimiter
  81 </table>
  82
  83 <p>Following the start character <code>$</code>, are five characters
  84 which constitute the block label of the sentence.  For Magnavox
  85 proprietary sentences, this label is always <code>PMVXG</code>.  The
  86 next field after the block label is the sentence type, consisting of
  87 three decimal digits.</p>
  88
  89 <p>The data, delimited by commas, follows the sentence type.  Note that
  90 the receiver uses a free-format parsing algorithm, so you need not send
  91 the exact number of characters shown in the examples.  You will need to
  92 use the commas to determine how many bytes of data need to be
  93 retrieved.</p>
  94
  95 <p>The notation <code>CK</code> shown in <a href="#table_1">Table 1</a>
  96 symbolically indicates the optional checksum in the examples.  The
  97 checksum is computed by exclusive-ORing all of the bytes between the
  98 <code>$</code> and the <code>*</code> characters.  The <code>$</code> ,
  99 <code>*</code> and the checksum are not included in the checksum
 100 computation.</p>
 101
 102 <p>Checksums are optional for Control Port input sentences, but are
 103 highly recommended to limit the effects of communication errors.
 104 Magnavox receivers always generate checksums for Control Port output
 105 sentences.</p>
 106
 107 <p>ASCII data characters are transmitted in the following format:</p>
 108
 109 <table border>
 110  <tr> <td> Data Bits       <td>8 (msb always 0)
 111  <tr> <td> Parity          <td>None
 112  <tr> <td> Stop Bits       <td>1
 113 </table>
 114
 115 <p>NULL fields are fields which do not contain any data.  They would
 116 appear as two commas together in the sentence format, except for the
 117 final field.  Some Magnavox proprietary sentences require that the
 118 format contain NULL fields.  mandatory NULL fields are identified by an
 119 '*' next to the respective field.</p>
 120
 121 <hr>
 122
 123 <h2><a name="input">Control Port Input Sentences</a></h2>
 124 These are the subset of the MX4200 control port input sentences sent by
 125 the NTP driver to the GPS receiver.
 126
 127 <hr>
 128
 129 <h3><a name="input_000">$PMVXG,000</a></h3>
 130 <h4>Initialization/Mode Control - Part A</h4>
 131 Initializes the time, position and antenna height of the MX4200.
 132
 133 <p>
 134 <table border>
 135  <tr> <th>Field <th>Description           <th>Units  <th>Format <th>Default <th>Range
 136  <tr> <td>1     <td>Day                   <td>&nbsp  <td>Int  <td>&nbsp <td>1-31
 137  <tr> <td>2     <td>Month                 <td>&nbsp  <td>Int  <td>&nbsp <td>1-12
 138  <tr> <td>3     <td>Year                  <td>&nbsp  <td>Int  <td>&nbsp <td>1991-9999
 139  <tr> <td>4     <td>GMT Time              <td>HHMMSS <td>Int  <td>&nbsp <td>000000-235959
 140  <tr> <td>5     <td>WGS-84 Latitude       <td>DDMM.MMMM<td>Float<td>0.0 <td>0 - 8959.9999
 141  <tr> <td>6     <td>North/South Indicator <td>&nbsp  <td>Char <td>N <td>N,S
 142  <tr> <td>7     <td>WGS-84 Longitude      <td>DDDMM.MMMM<td>Float<td>0.0 <td>0 - 17959.9999
 143  <tr> <td>8     <td>East/West Indicator   <td>&nbsp  <td>Char <td>E <td>E,W
 144  <tr> <td>9     <td>Altitude (height above Mean Sea Level) in meters (WGS-84) <td>Meters<td>Float<td>0.0<td>+/-99999.0
 145  <tr> <td>10    <td>Not Used              <td>&nbsp  <td>&nbsp     <td>&nbsp <td>&nbsp
 146 </table>
 147 Example:<br>
 148 <code>$PMVXG,000,,,,,,,,,,*48</code><br>
 149 <code>$PMVXG,000,,,,,5128.4651,N,00020.0715,W,58.04,*4F</code>
 150
 151 <hr>
 152
 153 <h3><a name="input_001">$PMVXG,001</a></h3>
 154 <h4>Initialization/Mode Control - Part B</h4>
 155 Specifies various navigation parameters: Altitude aiding, acceleration
 156 DOP limits, and satellite elevation limits.
 157
 158 <p>
 159 <table border>
 160  <tr> <th>Field <th>Description           <th>Units  <th>Format <th>Default <th>Range
 161  <tr> <td>*1    <td>Constrain Altitude    <td>&nbsp  <td>Int  <td>1 <td>0=3D Only<br>1=Auto<br>2=2D Only
 162  <tr> <td>2     <td>Not Used              <td>&nbsp  <td>&nbsp<td>&nbsp <td>&nbsp
 163  <tr> <td>*3    <td>Horizontal Acceleration Factor<td>m/sec^2   <td>Float <td>1.0 <td>0.5-10.0
 164  <tr> <td>*4    <td>Not Used              <td>&nbsp  <td>&nbsp<td>&nbsp <td>&nbsp
 165  <tr> <td>*5    <td>VDOP Limit            <td>&nbsp  <td>Int  <td>10 <td>1-9999
 166  <tr> <td>*6    <td>HDOP Limit            <td>&nbsp  <td>Int  <td>10 <td>1-9999
 167  <tr> <td>7     <td>Elevation Limit       <td>Deg    <td>Int  <td>5   <td>0-90
 168  <tr> <td>8     <td>Time Output Mode      <td>&nbsp  <td>Char <td>U <td>U=UTC<br>L=Local Time
 169  <tr> <td>9     <td>Local Time Offset     <td>HHMM   <td>Int  <td>0  <td>+/- 0-2359
 170 </table>
 171 Example:<br>
 172 <code>$PMVXG,001,3,,0.1,0.1,10,10,5,U,0*06</code>
 173
 174 <hr>
 175
 176
 177 <h3><a name="input_007">$PMVXG,007</a></h3>
 178 <h4>Control Port Output Configuration</h4>
 179 This message enables or disables output of the specified sentence and
 180 defines the output rate.  The user sends this message for each sentence
 181 that the receiver is to output.
 182
 183 <p>
 184 <table border>
 185  <tr> <th>Field <th>Description           <th>Units   <th>Format <th>Default <th>Range
 186  <tr> <td>1     <td>Control Port Output Block Label<td>&nbsp<td>Char <td>&nbsp <td>&nbsp
 187  <tr> <td>2     <td>Clear Current Output List<td>&nbsp<td>Int    <td>&nbsp <td>0=No<br>1=Yes
 188  <tr> <td>3     <td>Add/Delete Sentence from List<td>&nbsp<td>Int    <td>&nbsp <td>1=Append<br>2=Delete
 189  <tr> <td>4     <td>Not Used              <td>&nbsp   <td>&nbsp  <td>&nbsp <td>&nbsp
 190  <tr> <td>5     <td>Sentence Output Rate  <td>Sec     <td>Int    <td>&nbsp <td>1-9999
 191  <tr> <td>6     <td># digits of Precision for CGA and GLL sentences<td>&nbsp <td>Int <td>2 <td>2-4
 192  <tr> <td>7     <td>Not Used              <td>&nbsp   <td>&nbsp  <td>&nbsp <td>&nbsp
 193  <tr> <td>8     <td>Not Used              <td>&nbsp   <td>&nbsp  <td>&nbsp <td>&nbsp
 194 </table>
 195 Example:<br>
 196 <code>$PMVXG,007,022,0,1,,1,,,*4F</code>
 197
 198 <hr>
 199
 200
 201 <h3><a name="input_023">$PMVXG,023</a></h3>
 202 <h4>Time Recovery Configuration</h4>
 203 This message is used to enable/disable the time recovery feature of the
 204 receiver.  The time synchronization for the 1PPS output is specified in
 205 addition to a user time bias and an error tolerance for a valid pulse.
 206 This record is accepted in units configured for time recovery.  If the
 207 back panel contains a 1PPS outlet, the receiver is a time recovery
 208 unit.
 209
 210 <p>
 211 <table border>
 212  <tr> <th>Field <th>Description           <th>Units  <th>Format <th>Default <th>Range
 213  <tr> <td>*1    <td>Time Recovery Mode    <td>&nbsp  <td>Char   <td>D   <td>D=Dynamic<br>S=Static<br>K=Known Position<br>N=No Time Recovery
 214  <tr> <td>2     <td>Time Synchronization  <td>&nbsp  <td>Char   <td>G   <td>U=UTC<br>G=GPS
 215  <tr> <td>3     <td>Time Mark Mode        <td>&nbsp  <td>Char   <td>A   <td>A=Always<br>V=Valid Pulses Only
 216  <tr> <td>4     <td>Maximum Time Error    <td>Nsec   <td>Int    <td>100 <td>50-1000
 217  <tr> <td>5     <td>User Time Bias        <td>Nsec   <td>Int    <td>0   <td>+/- 99999
 218  <tr> <td>6     <td>ASCII Time Message Control<td>&nbsp<td>Int    <td>0   <td>0=No Output<br>1=830 to Control Port<br>2=830 to Equipment Port
 219  <tr> <td>7     <td>Known Pos PRN          <td>&nbsp <td>Int    <td>0   <td>1-32<br>0=Track All Sats
 220 </table>
 221 Example:<br>
 222 <code>$PMVXG,023,S,U,A,500,0,1,*16</code>
 223
 224 <hr>
 225
 226
 227 <h3><a name="input_gpq">$CDGPQ,YYY</a></h3>
 228 <h4>Query From a Remote Device / Request to Output a Sentence</h4>
 229 Enables the controller to request a one-time transmission of a specific
 230 block label.  To output messages at a periodic rate, refer to input
 231 sentence <a href="#input_007">$PMVXG,007</a>.
 232
 233 <p>
 234 <table border>
 235  <tr> <th>Field <th>Description           <th>Units  <th>Format <th>Default <th>Range
 236  <tr> <td>1:CD  <td>ID of Remote Device   <td>&nbsp  <td>Char   <td>&nbsp <td>(See <cite>NMEA-0183</cite>)
 237  <tr> <td>2:GP  <td>GPS                   <td>&nbsp  <td>Char   <td>&nbsp <td>(See <cite>NMEA-0183</cite>)
 238  <tr> <td>3:Q   <td>Query                 <td>&nbsp  <td>Char   <td>&nbsp <td>(See <cite>NMEA-0183</cite>)
 239  <tr> <td>4:YYY <td>Label of Desired Sentence<td>&nbsp<td>Char  <td>&nbsp <td>Any Valid NMEA or Magnavox Sentence Type
 240 </table>
 241 Example:<br>
 242 <code>$CDGPQ,030*5E</code>
 243
 244
 245
 246 <hr>
 247 <h2><a name="output">Control Port Output Sentences</a></h2>
 248 These are the subset of the MX4200 control port output sentences
 249 recognized by the NTP driver.
 250
 251 <hr>
 252
 253 <h3><a name="output_000">$PMVXG,000</a></h3>
 254 <h4>Receiver Status</h4>
 255 Returns the current status of the receiver including the operating
 256 mode, number of satellites visible, and the number of satellites being
 257 tracked.
 258
 259 <p>
 260 <table border>
 261  <tr> <th>Field <th>Description                         <th>Units  <th>Format <th>Range
 262  <tr> <td>1     <td>Current Receiver Status             <td>&nbsp  <td>Char   <td>ACQ=Reacquisition<br>ALT=Constellation Selection<br>IAC=Initial Acquisition<br>IDL=Idle, No Satellites<br>NAV=Navigating<br>STS=Search The Sky<br>TRK=Tracking
 263  <tr> <td>2     <td>Number of Satellites that should be Visible <td>&nbsp<td>Int  <td>0-12
 264  <tr> <td>3     <td>Number of Satellites being Tracked  <td>&nbsp  <td>Int    <td>0-12
 265  <tr> <td>4     <td>Time since Last Navigation          <td>HHMM   <td>Int    <td>0-2359
 266  <tr> <td>5     <td>Initialization Status               <td>&nbsp  <td>Int    <td>0=Waiting for Initialization<br>1=Initialization Complete
 267 </table>
 268 Example:<br>
 269 <code>$PMVXG,000,TRK,3,3,0122,1*19</code>
 270
 271 <hr>
 272
 273 <h3><a name="output_021">$PMVXG,021</a></h3>
 274 <h4>Position, Height, Velocity</h4>
 275 This sentence gives the receiver position, height, navigation mode and
 276 velocity north/east.  <em>This sentence is intended for post analysis
 277 applications.</em>
 278
 279 <p>
 280 <table border>
 281  <tr> <th>Field <th>Description            <th>Units  <th>Format <th>Range
 282  <tr> <td>1     <td>UTC Measurement Time   <td>Seconds into the week<td>Float<td>0-604800.00
 283  <tr> <td>2     <td>WGS-84 Latitude        <td>DDMM.MMMM<td>Float  <td>0-89.9999
 284  <tr> <td>3     <td>North/South Indicator  <td>&nbsp  <td>Char   <td>N, S
 285  <tr> <td>4     <td>WGS-84 Longitude       <td>DDDMM.MMMM  <td>Float    <td>0-179.9999
 286  <tr> <td>5     <td>East/West Indicator    <td>&nbsp  <td>Char   <td>E, W
 287  <tr> <td>6     <td>Altitude (MSL)         <td>Meters <td>Float  <td>&nbsp
 288  <tr> <td>7     <td>Geoidal Height         <td>Meters <td>Float  <td>&nbsp
 289  <tr> <td>8     <td>Velocity East          <td>M/Sec  <td>Float  <td>&nbsp
 290  <tr> <td>9     <td>Velocity North         <td>M/Sec  <td>Float  <td>&nbsp
 291  <tr> <td>10    <td>Navigation Mode        <td>&nbsp  <td>Int    <td><em>Navigating</em><br>
 292                                                                      1=Position From a Remote Device<br>
 293                                                                      2=2D<br>
 294                                                                      3=3D<br>
 295                                                                      4=2D differential<br>
 296                                                                      5=3D differential<br>
 297                                                                      <em>Not Navigating</em><br>
 298                                                                      51=Too Few Satellites<br>
 299                                                                      52=DOPs too large<br>
 300                                                                      53=Position STD too large<br>
 301                                                                      54=Velocity STD too large<br>
 302                                                                      55=Too many iterations for velocity<br>
 303                                                                      56=Too many iterations for position<br>
 304                                                                      57=3 Sat Startup failed
 305 </table>
 306 Example:<br>
 307 <code>$PMVXG,021,142244.00,5128.4744,N,00020.0593,W,00054.4,0047.4,0000.1,-000.2,03*66</code>
 308
 309 <hr>
 310
 311 <h3><a name="output_022">$PMVXG,022</a></h3>
 312 <h4>DOPs</h4>
 313 This sentence reports the DOP (Dilution Of Precision) values actually
 314 used in the measurement processing corresponding to the satellites
 315 listed.  The satellites are listed in receiver channel order.  Fields
 316 11-16 are output only on 12-channel receivers.
 317
 318 <p>
 319 <table border>
 320  <tr> <th>Field <th>Description            <th>Units  <th>Format <th>Range
 321  <tr> <td>1     <td>UTC Measurement Time   <td>Seconds into the week<td>Float<td>0-604800.00
 322  <tr> <td>2     <td>East DOP (EDOP)        <td>&nbsp  <td>Float  <td>&nbsp
 323  <tr> <td>3     <td>North DOP (NDOP)       <td>&nbsp  <td>Float  <td>&nbsp
 324  <tr> <td>4     <td>Vertical DOP (VDOP)    <td>&nbsp  <td>Float  <td>&nbsp
 325  <tr> <td>5     <td>PRN on Channel #1      <td>&nbsp  <td>Int    <td>1-32
 326  <tr> <td>6     <td>PRN on Channel #2      <td>&nbsp  <td>Int    <td>1-32
 327  <tr> <td>7     <td>PRN on Channel #3      <td>&nbsp  <td>Int    <td>1-32
 328  <tr> <td>8     <td>PRN on Channel #4      <td>&nbsp  <td>Int    <td>1-32
 329  <tr> <td>9     <td>PRN on Channel #5      <td>&nbsp  <td>Int    <td>1-32
 330  <tr> <td>10    <td>PRN on Channel #6      <td>&nbsp  <td>Int    <td>1-32
 331  <tr> <td>11    <td>PRN on Channel #7      <td>&nbsp  <td>Int    <td>1-32
 332  <tr> <td>12    <td>PRN on Channel #8      <td>&nbsp  <td>Int    <td>1-32
 333  <tr> <td>13    <td>PRN on Channel #9      <td>&nbsp  <td>Int    <td>1-32
 334  <tr> <td>14    <td>PRN on Channel #10     <td>&nbsp  <td>Int    <td>1-32
 335  <tr> <td>15    <td>PRN on Channel #11     <td>&nbsp  <td>Int    <td>1-32
 336  <tr> <td>16    <td>PRN on Channel #12     <td>&nbsp  <td>Int    <td>1-32
 337 </table>
 338 Example:<br>
 339 <code>$PMVXG,022,142243.00,00.7,00.8,01.9,27,26,10,09,13,23*77</code>
 340
 341 <hr>
 342
 343 <h3><a name="output_030">$PMVXG,030</a></h3>
 344 <h4>Software Configuration</h4>
 345 This sentence contains the navigation processor and baseband firmware
 346 version numbers.
 347
 348 <p>
 349 <table border>
 350  <tr> <th>Field <th>Description                      <th>Units <th>Format <th>Range
 351  <tr> <td>1     <td>Nav Processor Version Number     <td>&nbsp <td>Char   <td>&nbsp
 352  <tr> <td>2     <td>Baseband Firmware Version Number <td>&nbsp <td>Char   <td>&nbsp
 353 </table>
 354 Example:<br>
 355 <code>$PMVXG,030,DA35,015</code>
 356
 357 <hr>
 358
 359 <h3><a name="output_101">$PMVXG,101</a></h3>
 360 <h4>Control Sentence Accept/Reject</h4>
 361 This sentence is returned (on the Control Port) for every
 362 <strong>$PMVXG</strong> and <strong>$XXGPQ</strong> sentence that is
 363 received.
 364
 365 <p>
 366 <table border>
 367  <tr> <th>Field <th>Description                      <th>Units <th>Format <th>Range
 368  <tr> <td>1     <td>Sentence ID                      <td>&nbsp <td>Char   <td>&nbsp
 369  <tr> <td>2     <td>Accept/Reject Status             <td>&nbsp <td>Int    <td>0=Sentence Accepted<br>
 370                                                                               1=Bad Checksum<br>
 371                                                                               2=Illegal Value<br>
 372                                                                               3=Unrecognized ID<br>
 373                                                                               4=Wrong # of fields<br>
 374                                                                               5=Required Data Field Missing<br>
 375                                                                               6=Requested Sentence Unavailable
 376  <tr> <td>3     <td>Bad Field Index                  <td>&nbsp <td>Int    <td>&nbsp
 377  <tr> <td>4     <td>Requested Sentence ID (If field #1 = GPQ) <td>&nbsp <td>Char   <td>&nbsp
 378 </table>
 379 Example:<br>
 380 <code>$PMVXG,101,GPQ,0,,030*0D</code>
 381
 382 <hr>
 383
 384 <h3><a name="output_523">$PMVXG,523</a></h3>
 385 <h4>Time Recovery Configuration</h4>
 386 This sentence contains the configuration of the time recovery function
 387 of the receiver.
 388
 389 <p>
 390 <table border>
 391  <tr> <th>Field <th>Description                      <th>Units <th>Format <th>Range
 392  <tr> <td>1     <td>Time Recovery Mode               <td>&nbsp <td>Char   <td>D=Dynamic<br>S=Static<br>K=Known Position<br>N=No Time Recovery
 393  <tr> <td>2     <td>Time Synchronization             <td>&nbsp <td>Char   <td>U=UTC Time<br>G=GPS Time
 394  <tr> <td>3     <td>Time Mark Mode                   <td>&nbsp <td>Char   <td>A=Always Output Time Pulse<br>V=Only when Valid
 395  <tr> <td>4     <td>Maximum Time Error for which a time mark will be considered valid <td>Nsec  <td>Int    <td>&nbsp
 396  <tr> <td>5     <td>User Time Bias                   <td>Nsec  <td>Int    <td>&nbsp
 397  <tr> <td>6     <td>Time Message Control             <td>&nbsp <td>Int    <td>0=No Message<br>1=830 to Control Port<br>2=830 to Equipment Port
 398  <tr> <td>7     <td>Not Used                         <td>&nbsp <td>&nbsp  <td>&nbsp
 399 </table>
 400 Example:<br>
 401 <code>$PMVXG,523,S,U,A,0500,000000,1,0*23</code>
 402
 403 <hr>
 404
 405 <h3><a name="output_830">$PMVXG,830</a></h3>
 406 <h4>Time Recovery Results</h4>
 407 This sentence is output approximately 1 second preceding the 1PPS
 408 output.  It indicates the exact time of the next pulse, whether or not
 409 the time mark will be valid (based on operator-specified error
 410 tolerance), the time to which the pulse is synchronized, the receiver
 411 operating mode, and the time error of the <strong>last</strong> 1PPS
 412 output.  The leap second flag (Field #11) is not output by older
 413 receivers.
 414
 415 <p>
 416 <table border>
 417  <tr> <th>Field <th>Description                      <th>Units <th>Format <th>Range
 418  <tr> <td>1     <td>Time Mark Valid                  <td>&nbsp <td>Char   <td>T=Valid<br>F=Not Valid
 419  <tr> <td>2     <td>Year                             <td>&nbsp <td>Int    <td>1993-
 420  <tr> <td>3     <td>Month                            <td>&nbsp <td>Int    <td>1-12
 421  <tr> <td>4     <td>Day                              <td>Nsec  <td>Int    <td>1-31
 422  <tr> <td>5     <td>Time                             <td>HH:MM:SS<td>Int  <td>00:00:00-23:59:59
 423  <tr> <td>6     <td>Time Synchronization             <td>&nbsp <td>Char   <td>U=UTC<br>G=GPS
 424  <tr> <td>7     <td>Operating Mode                   <td>&nbsp <td>Char   <td>D=Dynamic<br>S=Static<br>K=Known Position
 425  <tr> <td>8     <td>Oscillator Offset - estimate of oscillator frequency error <td>PPB   <td>Int    <td>&nbsp
 426  <tr> <td>9     <td>Time Mark Error of last pulse    <td>Nsec  <td>Int    <td>&nbsp
 427  <tr> <td>10    <td>User Time Bias                   <td>Nsec  <td>Int    <td>&nbsp
 428  <tr> <td>11    <td>Leap Second Flag - indicates that a leap second will occur.
 429                     This value is usually zero except during the week
 430                     prior to a leap second occurence, when this value
 431                     will be set to +/-1.  A value of +1 indicates
 432                     that GPS time will be 1 second further ahead of
 433                     UTC time.
 434                                                      <td>&nbsp <td>Int    <td>-1,0,1
 435 </table>
 436 Example:<br>
 437 <code>$PMVXG,830,T,1998,10,12,15:30:46,U,S,000298,00003,000000,01*02</code>
 438
 439 <hr>
 440
 441
 442 </BODY>
 443 </HTML>