[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference unifix::sailing

Title:SAILING
Notice:Please read Note 2.* before participating in this conference
Moderator:UNIFIX::BERENS
Created:Wed Jul 01 1992
Last Modified:Mon Jun 02 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2299
Total number of notes:20724

2212.0. "NMEA topic" by TINCUP::CLAFLIN () Mon Apr 24 1995 20:27

The recent discussions on GPS's in note 452.70+ suggest tht maybe NMEA in
general and NMEA standard 0183 in particular would be of interest.

NMEA has a new contact location.  This came from rec.boats on the internet also.

NMEA has a new Executive Director and address.

        Cathy Moyer
        NMEA
        7074 Bembe Beach Rd. Ste 203
        Annapolis MD 21403

        Phone   410 263-1742
        Fax     410 263-1743

Doug 
dtn 592-4787
T.RTitleUserPersonal
Name
DateLines
2212.1It worked !OTOOA::MOWBRAYset profile /presonal_name= '';EXITTue Jun 27 1995 08:4517
    Thanks to the info that I picked up in the various notes, I hooked my
    Garmin GPS45 up to a terminal emulator on the weekend and discovered 2
    things ..... first that due to poor reception in my basement, the NMEA
    sentences are pretty boring reading and second, even if there was
    something good to read, I would not be able to understand it !
    
    Does anyone know the format and layout of the various messages ?  The
    format seems to be $XXYYY where $ is constant, XX is (perhaps) the
    device (GP=GPS etc.) and YYY is a specific transaction identifier,
    lat-long, cross track error etc.  After that header info is a series of
    data fields that are separated by commas although in my case I could
    not understand them as there was no data there to give their identity
    away.
    
    Any pointers would be appreciated.
    
    Graham
2212.2First level info...EYLAK::BATESKen BatesTue Jun 27 1995 10:5836
The '$' identifies the beginning of the sentence.

The 'GP' identifies the NMEA device as a GPS. Some sentences from the Garmin
may have a 'PGRM', which identifies it as Private (P) from manufacturer Garmin
(GRM).

The next 3 characters identify the message type (listed below). The fields for
the individual messages vary depending on the message type, and are all
separated by commas. The final field, preceded by a '*', is the checksum
(cumulative XOR) of the entire sentence, excluding the beginning '$' and the
checksum itself.

The sentences supported by the GPS-75 (and presumably the GPS-45) are:

case GPRMC:	/* Recommended minimum specific GPS/TRANSIT data */
case GPWPL:	/* Waypoint location */
case GPR00:	/* Unknown */
case GPGLL:	/* Geographic position */
case PGRMZ:	/* Altitude */
case PGRMM:	/* Map datum */
case GPXTE:	/* Cross track error */
case GPBWC:	/* Bearing to waypoint */
case GPVTG:	/* Vector, track, & SOG */
case PSLIB:	/* Configuration */
case GPRTE:	/* Routes */
case GPGGA:	/* Global Positioning System Fix Data */
case GPGSA:	/* GPS DOP and Active Satellites */
case GPGSV:	/* GPS Satellites in view */
case PGRME:	/* Unknown */

Most of the fields are self-evident once you get a good fix and have position
information. If the GPS-45 has a simulation mode (as does the GPS-75), enter a
position, speed, heading, and destination, and you should be able to figure
out what the rest of the fields are.

 - Ken
2212.3LEEL::LINDQUISTPluggin' preyTue Jun 27 1995 13:22347
    I saved this from a usenet post.   It's sort of long for
    decwindows readers, but if folks keep warning them about long
    notes, they'll never fix their code...

From rec.aviation.misc Mon Oct  4 13:35:13 1993
Xref: a2i rec.boats:15064 rec.aviation.misc:8563
Path: a2i!sgiblab!swrinde!cs.utexas.edu!math.ohio-state.edu!howland.reston.ans.net!agate!library.ucla.edu!news.mic.ucla.edu!unixg.ubc.ca!erich.triumf.ca!bennett
From: [email protected] (P.Bennett)
Newsgroups: rec.boats,rec.aviation.misc
Subject: NMEA 0183 sentence types, etc. (long)
Date: 3 Oct 1993 21:55 PST
Organization: TRIUMF: Tri-University Meson Facility
Lines: 344
Distribution: world
Message-ID: <[email protected]>
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]>
NNTP-Posting-Host: erich.triumf.ca
News-Software: VAX/VMS VNEWS 1.41    

The following is a short excerpt from a ~200K document I have on NMEA 0183 -
sorry for using so much net.bandwidth, but there does seem to be a lot of
interest in this...

                    TABLE 4 - TALKER IDENTIFIER MNEMONICS
                            (Address Characters 1 and 2)

        TALKER DEVICE                                        IDENTIFIER

        AUTOPILOT:              General                         *AG
                                Magnetic                         AP
        COMMUNICATIONS:         Digital Selective Calling (DSC) *CD
                                Satellite                       *CS
                                Radio-Telephone (MF/HF)         *CT
                                Radio-Telephone (VHF)           *CV
                                Scanning Receiver               *CX
        DECCA Navigation                                         DE
        Direction Finder                                        *DF
        Electronic Chart Display & Information System (ECDIS)    EC
        Emergancy Position Indicating Beacon (EPIRB)            *EP
        Engineroom Monitoring Systems                            ER
        Global Positioning System (GPS)                          GP
        HEADING SENSORS:        Compass, Magnetic               *HC
                                Gyro, North Seeking             *HE
                                Gyro, Non-North Seeking          HN
        Integrated Instrumentation                               II
        Integrated Navigation                                    IN
        LORAN:                  Loran-A                          LA
                                Loran-C                          LC
        OMEGA Navigation System                                  OM
        Proprietary Code                                         P
        Radar and/or ARPA                                       *RA
        Sounder, depth                                          *SD
        Electronic positioning system, other/general             TR
        Sounder, scanning                                        SS
        Turn Rate Indicator                                     *TI
        TRANSIT Navigation System                                TR
        VELOCITY SENSORS:       Doppler, other/general          *VD
                                Speed Log, Water, Magnetic       VM
                                Speed Log, Water, Mechanical     VW
        TRANSDUCER                                               YX
        TIMEKEEPERS, TIME/DATE: Atomic Clock                     ZA
                                Chronometer                      ZC
                                Quartz                           ZQ
                                Radio Update, WWV or WWVH        ZV
        Weather Instruments                                      WI


*
 Designated by I.E.C. for use with I.M.O. marine electronic
 devices. This is the minimum requirement for equipment that is
 specified by I.M.O. to meet S.O.L.A.S. regulations.

                                    Page 17
6.2 Field Definitions
       (continued)

                    TABLE 5 - APPROVED SENTENCE FORMATTERS

        AAM - Waypoint Arrival Alarm............................... 22
        ALM - GPS Almanac Data..................................... 22
        APB - Autopilot Sentence "B"............................... 23
       *ASD - Autopilot System Data................................ 23
        BEC - Bearing & Distance to Waypoint, Dead Reckoning....... 23
        BOD - Bearing, Origin to Destination....................... 24
        BWC - Bearing & Distance to Waypoint, Great Circle......... 24
        BWR - Bearing & Distance to Waypoint, Rhumb Line........... 24
        BWW - Bearing, Waypoint to Waypoint........................ 24
        DBT - Depth Below Transducer............................... 24
        DCN - Decca Position....................................... 25
       *DPT - Depth................................................ 25
       *FSI - Frequency Set Information............................ 25
        GGA - Global Positioning System Fix Data................... 26
        GLC - Geographic Position, Loran-C......................... 26
        GLL - Geographic Position, Latitude/Longitude.............. 27
        GSA - GPS DOP and Active Satellites........................ 27
        GSV - GPS Satellites in View............................... 27
        GXA - TRANSIT Position..................................... 28
       *HDG - Heading, Deviation & Variation....................... 28
       *HDT - Heading, True........................................ 28
        HSC - Heading Steering Command............................. 28
        LCD - Loran-C Signal Data.................................. 29
        MTW - Water Temperature.................................... 29
       *MWV - Wind Speed and Angle................................. 29
        OLN - Omega Lane Numbers................................... 29
       *OSD - Own Ship Data........................................ 30
        RMA - Recommend Minimum Specific Loran-C Data.............. 30
        RMB - Recommend Minimum Navigation Information............. 31
        RMC - Recommend Minimum Specific GPS/TRANSIT Data.......... 31
       *ROT - Rate of Turn......................................... 32
       *RPM - Revolutions.......................................... 32
       *RSA - Rudder Sensor Angle.................................. 32
       *RSD - RADAR System Data.................................... 32
        RTE - Routes............................................... 33
       *SFI - Scanning Frequency Information....................... 33
        STN - Multiple Data ID..................................... 34
        TRF - TRANSIT Fix Data..................................... 34
       *TTM - Tracked Target Message............................... 35
       *VBW - Dual Ground/Water Speed.............................. 35
        VDR - Set and Drift........................................ 35
        VHW - Water Speed and Heading.............................. 35
        VLW - Distance Traveled through the Water.................. 36
        VPW - Speed, Measured Parallel to Wind..................... 36
        VTG - Track Made Good and Ground Speed..................... 36
        WCV - Waypoint Closure Velocity............................ 36
        WNC - Distance, Waypoint to Waypoint....................... 36
        WPL - Waypoint Loacation................................... 36
        XDR - Transducer Measurements.............................. 37
        XTE - Cross-Track Error, Measured.......................... 37
        XTR - Cross-Track Error, Dead Reckoning.................... 38
        ZDA - Time & Date.......................................... 38
        ZFO - UTC & Time from Origin Waypoint...................... 38
        ZTG - UTC & Time to Destination Waypoint................... 38



 AAM - Waypoint Arrival Alarm

        Status of arrival (entering the arrival circle, or passing the
        perpendicular of the course line) at waypoint c--c.

     $--AAM,A,A,x.x,N,c--c*hh<CR><LF>
            | |  |  |  |
            | |  |  |  +---------------Waypoint ID
            | |  |  +------------------Units of radius, nautical miles
            | |  +---------------------Arrival circle radius
            | +------------------------Status: A = perpendicular passed at waypoint
            +--------------------------Status: A = arrival circled entered



 ALM - GPS Almanac Data

        Contains GPS week number, satellite health and the complete almanac
        data for one satellite. Multiple messages may be transmitted, one
        for each satellite in the GPS constellation, up to maximum of 32
        messages.

     $--ALM,x.x,x.x,xx,x.x,hh,hhhh,...
             |   |  |   |  |   |
             |   |  |   |  |   +-------e, eccentricity [3]
             |   |  |   |  +-----------SV health, bits 17-24 of each almanac page [2]
             |   |  |   +--------------GPS week number [1]
             |   |  +------------------Satellite PRN number, 01 to 32
             |   +---------------------Message number
             +-------------------------Total number of messages


        hh,hhhh,hhhh,hhhhhh,hhhhhh,...
        |   |    |     |      |
        |   |    |     |      +--------Omega, argument of perigee [3]
        |   |    |     +---------------SQRT(A), root of semi-major axis [3]
        |   |    +---------------------OMEGADOT, rate of right ascension [3]
        |   +--------------------------(sigma) index i, inclination angle [3]
        +------------------------------t index OA, almanac reference time [3]


        hhhhhh,hhhhhh,hhh,hhh*hh<CR><LF>
          |      |     |   |
          |      |     |   +-----------a index f1, clock parameter [3]
          |      |     +---------------a index f0, clock parameter [3]
          |      +---------------------M index O , mean anomaly [3]
          +----------------------------(OMEGA) index O, longitude of ascension node[3]

    [1] Variable lengh integer, 4-digits maximum. Converted from (10) most
        significant binary bits of Subframe 1, Word 3. Reference Table 20-I,
        ICD-GPS-200, Rev. B.

    [2] Reference paragraph 20.3.3.5.1.3, Table 20-VII and Table 20-VIII, ICD-
        GPS-200, Rev. B.

    [3] Reference Table 20-VI, ICD-GPS-200, Rev. B for scaling factors and
        units.



 APB - Autopilot Sentence "B"

        Commonly used by autopilots this sentence contains navigation
        receiver warning flag status, cross-track-error, waypoint arriv-
        al status, initial bearing from origin waypoint to the destina-
        tion, continuous bearing from present position to destination
        and recommended heading-to-steer to destination waypoint for the
        active navigation leg of the journey.

     $--APB,A,A,x.x,a,N,A,A,x.x,a,c--c,...
            | |  |  | | | |  |  |  |
            | |  |  | | | |  |  |  +---Destination waypoint ID
            | |  |  | | | |  |  +-----\M/T Magnetic or True
            | |  |  | | | |  +--------/Bearing origin to destination
            | |  |  | | | +------------Status: A = perpendicular passed at waypoint
            | |  |  | | +--------------Status: A = arrival circle entered
            | |  |  | +----------------XTE units, nautical miles
            | |  |  +------------------L/R Direction to steer
            | |  +---------------------Magnitude of XTE (cross-track-error)
            | +------------------------Status: V = Loran-C Cycle Lock warning flag
            |                                  A = OK or not used
            +--------------------------Status: V = Loran-C Blink or SNR warning
                                               V = general warning flag for other navigation
                                                   systems when a reliable fix is not available


        x.x,a,x.x,a*hh<CR><LF>
         |  |  |  |
         |  |  |  +-------------------\M/T Magnetic or True
         |  |  +----------------------/Heading-to-steer to destination waypoint
         |  +-------------------------\M/T Magnetic or True
         +----------------------------/Bearing, Present position to destination


*ASD - Autopilot System Data

        I.M.O. Ref. A342 (IX). Autopilot operating parameters, alarm status
        commanded course and vessel heading.

        (TO BE DETERMINED)



 BEC - Bearing & Distance to Waypoint - Dead Reckoning

        Time (UTC) and distance & bearing to, and loacation of, a speci-
        fied waypoint from the dead-reckoned present position.

     $--BEC,hhmmss.ss,llll.ll,a,...
              |        |      |
              |        |      +-------\N/S North or South
              |        +--------------/Waypoint Latitude
              +------------------------UTC of observation


        yyyyy.yy,a,x.x,T,x.x,M,x.x,N,...
          |      |  |  |  |  |  |  |
          |      |  |  |  |  |  |  +--\nautical miles
          |      |  |  |  |  |  +-----/Distance
          |      |  |  |  |  +--------\degrees Magnetic
          |      |  |  |  +-----------/Bearing
          |      |  |  +--------------\E/W East or West
          |      |  +-----------------/Waypoint longitude
          |      +--------------------\N/S North or South
          +---------------------------/Waypoint latitude


        c--c*hh<CR><LF>
         |
         +-----------------------------Waypoint ID


 BOD - Bearing - Origin to Destination

        Bearing angle of the line, calculated at the origin waypoint, extend-
        ing to the destination waypoint from the origin waypoint for the
        active navigation leg of the journey.

     $--BOD,x.x,T,x.x,M,c--c,c--c*hh<CR><LF>
             |  |  |  |  |    |
             |  |  |  |  |    +--------Origin waypoint ID
             |  |  |  |  +-------------Destination waypoint ID
             |  |  |  +---------------\degrees Magnetic
             |  |  +------------------/Bearing
             |  +---------------------\degrees True
             +------------------------/Bearing



 BWC - Bearing & Distance to Waypoint - Great Circle
 BWR - Bearing & Distance to Waypoint - Rhumb Line

        Time (UTC) and distance & bearing to, and location of, a specified
        waypoint from present position. '$--BWR' data is calculated along the
        rhumb line from present position rather than along the great circle
        path.

     $--BWC,hhmmss.ss,llll.ll,a,...
              |        |      |
              |        |      +-------\N/S North or South
              |        +--------------/Waypoint latitude
              +------------------------UTC of observation


        yyyyy.yy,a,x.x,T,x.x,M,x.x,N,...
          |      |  |  |  |  |  |  |
          |      |  |  |  |  |  |  +--\nautical miles
          |      |  |  |  |  |  +-----/Distance
          |      |  |  |  |  +--------\degrees Magnetic
          |      |  |  |  +-----------/Bearing
          |      |  |  +--------------\degrees True
          |      |  +-----------------/Bearing
          |      +--------------------\E/W East or West
          +---------------------------/longitude

        c--c*hh<CR><LF>
         |
         +-----------------------------Waypoint ID



     $--BWR,hhmmss.ss,llll.ll,a,...
              |        |      |
              |        |      +-------\N/S North or South
              |        +--------------/Waypoint latitude
              +------------------------UTC of observation


        yyyyy.yy,a,x.x,T,x.x,M,x.x,N,...
          |      |  |  |  |  |  |  |
          |      |  |  |  |  |  |  +--\nautical miles
          |      |  |  |  |  |  +-----/Distance
          |      |  |  |  |  +--------\degrees Magnetic
          |      |  |  |  +-----------/Bearing
          |      |  |  +--------------\degrees True
          |      |  +-----------------/Bearing
          |      +--------------------\E/W East or West
          +---------------------------/longitude

        c--c*hh<CR><LF>
         |
         +-----------------------------Waypoint ID





Peter Bennett VE7CEI                | Vessels shall be deemed to be in sight
Internet: [email protected]   | of one another only when one can be
Bitnet:   bennett@triumfer          | observed visually from the other
TRIUMF, Vancouver, B.C., Canada     |                          ColRegs 3(k)
2212.4BGSDEV::MORRISTom Morris - Light &amp; Sound EngineeringWed Jun 28 1995 01:2413
    >It's sort of long for
    >decwindows readers, but if folks keep warning them about long
    >notes, they'll never fix their code...
    
    Entirely off the subject, but since it was mentioned...
    
    I thought this was already fixed some time ago.  When I run Notes with
    the DECwindows U/I, it only loads what it needs to view, not the entire
    note.
    
    Are you sure your running current software?
    
    Tom