HOVERCRAFT "SABVABAA"    

     2020 SEISMIC SURVEY

Fig. 1: Starting GNSS/GPS data collection and distribution program. Click to enlarge.

First, a warning: While scanning for GNSS/GPS COM-port, the COM-port attached to Mini-GUNCO will be activated - thus firing airguns, if they are left in Enabled state - which should never happen!

Then listening for NMEA GNSS/GPS telegrams on available COM ports, also determining baud rate.

Next, analyzing the stream of NMEA telegrams that arrives, in order to determine the last telegram in each "batch" (a batch of different NMEA telegrams arrives at each time instance, in our case each second). This is necessary in order to only extract and forward information tied to a specific second, and not mix data that belongs to different time instances. True, it would not be a catastrophe if such mixing occurred since our application is geophysical data collection where location does not change that fast - it's more a matter of principle. And since different models of GNSS/GPS-receivers seem to vary with regard to start- and end NMEA telegrams for block delineation, auto-detecting this property makes software adjustments that was done before, a thing of the past.

Fig. 2: Completing start-up procedure and starting normal acquisition and distribution. Click to enlarge.

Last telegram in batch found - in this case, $GNZDA.

Creating objects and threads.

When attempting to send broadcast UDP telegram on network interface, it was seen that external network interface was not activated, so reverting to only internal network. Should external network interface become active, the program will automatically start using it (providing notification).

At regular intervals, these parameters printed:

• Time.
• Fix (OK or not).
• Latitude and Longitude.
• Number of GPS satellites | Number of GLONASS satllites, used in fix.
• HDOP = Horizontal Dilution of Precision - the smaller, the better (normally less then 1.0).
• Standard deviation, Latitude error. Using $GNGST -- GNSS Pseudo Range Error Statistics telegram (see GNSS receiver documentation below).
• Standard deviation, Longitude error. Using $GNGST -- GNSS Pseudo Range Error Statistics telegram (see GNSS receiver documentation below).

Fig. 3: Two TCP socket clients collecting data from the program. Click to enlarge.

Fig. 4. The two clients have been terminated. Click to enlarge.

Fig. 1. Start of program. Click to enlarge.

Start of program. A warning - if you have left airguns in Enabled state -- which should never happen!

Section [A]:
Ensure there is at least 500 MByte free space on harddisk (C: partition) before proceeding. If not, a warning is provided, before program exits.

Section [B]:
Three required parameters are set. Previous choices are kept and appear as defaults - just press <ENTER> to accept. If new values are entered, they will become the new defaults. This makes is very easy to start new lines that all have identical configuration.

• Alternately shooting two airguns -- "Flip-flop mode" -- or not
• Shooting mode, either distance or time
• Shot interval, either meters or seconds

Section [C]:
Searching for Ashtech DG16 time stamping unit. If found, initialize it.

Fig. 2. Click to enlarge.

Section [D]:
* Searching for UDP broadcast telegrams on network interface, as JSON formatted packages. Source of these UDP telegrams can be on the same machine, or on another machine on the network. If not detected within time-out period, program exits with a warning. You must then verify that UDP emitter is operational (using the test UDP package display program to inspect raw data).

Section [E]:
Searching for COM port that is connected to Mini-GUNCO. The Gunco unit has a loopback on RS232-port RX-and TX-pins, so that serial messages sent to Gunco will be returned on the same COM-port --- in that way, the presence of a Gunco unit can be detected. If Gunco not found, program exits with a warning.

The user can then review all line parameters.

Terminate line and program by pressing <ENTER>.

Fig. 3. Click to enlarge.

After accepting profile parameters the line is started. The log file is created, with name automatically generated by using date and time stamp. The first shotpoint occurs immediately, and its associated data are shown in green text.

For each shotpoint, these parameters are shown (also written to logfile):

• SP = Shotpoint number.
• Kp = Kilometer post. Distance [km] since first shotpoint of this line.
• dDelta = Distance sine last shotpoint.
• Fix: OK, or not.
• N = Number of satellites in fix (GPS and GLONASS combined).
• HDOP = Horizontal Dilution of Precision. The lower, the better. Normally less then 1.0.
• Gun# = Airgun number 1 or 2.
• TS_fix_QC = Time stamp fix QC.
  • For each timestamp, the Ashtech DG16 is asked to provide information on which sat. system used in fix - two characters: First=GPS, Second=GLONASS; A=used, N=not_used. NOTE: The DG16 ONLY has GPS!
  • Number of satellites used in fix.
  • HDOP
  • TDOP = Time Dilution of Precision.

Every 10 seconds, the following parameters are printed:

• Current Time, Latitude and Longitude.
• dDelta = Distance since last shot point.
• tDelta = Time since last shot point.
• Fix: If GNSS/GPS receiver has fix or not.
• NSats = Number of Satellites used in GNSS/GPS fix. Includes both GNS and GLONASS.
• HDOP = Horizontal Dilution of Precision: The less, the better (should be less then 1.0).

The red warnings are generated when GEODE program is terminated (and GEODE hardware is put to sleep), thus removing external network interface. The GNSS/GPS data distributor software automatically detects this, and starts using the internal network interface after a short while.

Fig. x. Click to enlarge.

Fig. 1. Click to enlarge.

• "$P"=Proprietary, in contrast to "official" NMEA telegrams that starts with "$G"
• "UIB" = University of Bergen
• "NAV" = Navigation data

Fig. 2. Click to enlarge.

• Manufacturer: NaviLock
• Model: P/N: 62531 "Navilock NL-8004U USB 2.0 Multi GNSS Receiver u-blox 8 4.5 m"
• Cable length: ca. 4.5 m
• Connector: USB 2.0 Type-A male
• Data sheet: Link -- also local copy
• User Manual --- also local copy
• Driver: https://www.navilock.de/files/39255.download ---- Windows (32/64) 7, 8, 8.1, 10 --- 5.37 MB --- Virtual COM-Port Version 3.10 --- 05.03.2018
• Suppliers:
  • ComputerSalg A/S
  • CDON.no
  • MultiCom
• More detailed telegram information
• Chipset: u-blox 8 UBX-M8030-KT
  • About ubx-m8030-series
  • Listing of Document resources
  • Interface Manual --- u-blox 8 / u-blox M8 Receiver Description, Including Protocol Specification ---- also local copy Δ
  • UBX-M8030 Product Summary --- also local copy.
  • 72-channel u-blox M8 engineGPS/QZSS L1 C/A, GLONASS L10FBeiDou B1, Galileo E1B/CSBAS L1 C/A: WAAS, EGNOS, MSAS, GAGAN

1st record, only at the beginning (when opening COM-port):

$GNTXT,01,01,02,u-blox AG - www.u-blox.com*4E
$GNTXT,01,01,02,HW UBX-M8030 00080000*60
$GNTXT,01,01,02,ROM CORE 3.01 (107888)*2B
$GNTXT,01,01,02,FWVER=SPG 3.01*46
$GNTXT,01,01,02,PROTVER=18.00*11
$GNTXT,01,01,02,GPS;GLO;GAL;BDS*77
$GNTXT,01,01,02,SBAS;IMES;QZSS*49
$GNTXT,01,01,02,GNSS OTP=GPS;GLO*37
$GNTXT,01,01,02,LLC=FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFFF-FFFFFFE9*50
$GNTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*3E
$GNTXT,01,01,02,ANTSTATUS=OK*25
$GNTXT,01,01,02,PF=3FF*4B

Subsequent records:

$GNRMC,120136.00,A,6023.10268,N,00519.78150,E,0.050,,030320,,,A*62
$GNVTG,,T,,M,0.050,N,0.093,K,A*32
$GNGNS,120136.00,6023.10268,N,00519.78150,E,AA,18,0.73,75.0,43.8,,*53
$GNGGA,120136.00,6023.10268,N,00519.78150,E,1,12,0.73,75.0,M,43.8,M,,*73
$GNGSA,A,3,24,17,19,12,15,10,28,20,01,13,,,1.87,0.73,1.72*17
$GNGSA,A,3,75,66,74,84,76,83,67,85,,,,,1.87,0.73,1.72*19
$GPGSV,3,1,12,01,14,011,40,10,25,282,27,12,38,217,25,13,07,153,09*73
$GPGSV,3,2,12,15,26,178,10,17,40,070,41,19,41,102,27,20,10,253,11*78
$GPGSV,3,3,12,24,78,225,21,25,06,230,21,28,16,057,42,32,19,314,06*76
$GLGSV,3,1,10,65,26,211,,66,49,293,25,67,15,342,34,74,33,075,39*6D
$GLGSV,3,2,10,75,84,306,21,76,32,262,16,83,19,006,27,84,36,070,37*66
$GLGSV,3,3,10,85,12,126,20,,,,46*5F
$GNGLL,6023.10268,N,00519.78150,E,120136.00,A,A*7C
$GNGST,120136.00,3326643,,,,4.1,1.9,7.2*73
$GNZDA,120136.00,03,03,2020,00,00*7F

$GNRMC,120137.00,A,6023.10269,N,00519.78144,E,0.061,,030320,,,A*65
$GNVTG,,T,,M,0.061,N,0.113,K,A*39
$GNGNS,120137.00,6023.10269,N,00519.78144,E,AA,16,1.11,74.9,43.8,,*55
$GNGGA,120137.00,6023.10269,N,00519.78144,E,1,12,1.11,74.9,M,43.8,M,,*7B
$GNGSA,A,3,24,17,19,12,10,28,01,13,,,,,2.82,1.11,2.60*12
$GNGSA,A,3,75,66,74,84,76,83,67,85,,,,,2.82,1.11,2.60*1A
$GPGSV,3,1,12,01,14,011,40,10,25,282,27,12,38,217,25,13,07,153,10*7B
$GPGSV,3,2,12,15,26,178,07,17,40,070,41,19,41,102,26,20,10,253,09*76
$GPGSV,3,3,12,24,78,225,22,25,06,230,21,28,16,057,42,32,19,314,12*70
$GLGSV,3,1,10,65,26,211,,66,49,293,26,67,15,342,34,74,33,075,39*6E
$GLGSV,3,2,10,75,84,306,19,76,32,262,18,83,19,006,27,84,36,070,37*63
$GLGSV,3,3,10,85,12,126,21,,,,46*5E
$GNGLL,6023.10269,N,00519.78144,E,120137.00,A,A*79
$GNGST,120137.00,24,,,,4.1,1.9,7.1*42
$GNZDA,120137.00,03,03,2020,00,00*7E

$GNRMC,120138.00,A,6023.10270,N,00519.78142,E,0.053,,030320,,,A*65
$GNVTG,,T,,M,0.053,N,0.098,K,A*3A
$GNGNS,120138.00,6023.10270,N,00519.78142,E,AA,17,0.79,74.8,43.8,,*5B
$GNGGA,120138.00,6023.10270,N,00519.78142,E,1,12,0.79,74.8,M,43.8,M,,*74
$GNGSA,A,3,24,17,19,12,15,10,28,01,13,,,,2.17,0.79,2.02*11
$GNGSA,A,3,75,66,74,84,76,83,67,85,,,,,2.17,0.79,2.02*1D
$GPGSV,3,1,12,01,14,011,40,10,25,282,27,12,38,217,25,13,07,153,12*79
$GPGSV,3,2,12,15,26,178,12,17,40,070,41,19,41,102,25,20,10,253,08*70
$GPGSV,3,3,12,24,78,225,22,25,06,230,21,28,16,057,42,32,19,314,07*74
$GLGSV,3,1,10,65,26,211,,66,49,293,26,67,15,342,34,74,33,075,39*6E
$GLGSV,3,2,10,75,84,306,16,76,32,262,20,83,19,006,27,84,36,070,36*66
$GLGSV,3,3,10,85,12,126,21,,,,45*5D
$GNGLL,6023.10270,N,00519.78142,E,120138.00,A,A*78
$GNGST,120138.00,443098,,,,4.0,1.9,7.1*48
$GNZDA,120138.00,03,03,2020,00,00*71

$xxRMC,time,status,lat,NS,lon,EW,spd,cog,date,mv,mvEW,posMode,navStatus*cs<CR><LF>
where:
  status:  V = Data invalid, A = Data valid
  spd: Speed over ground [knots]
  cog: Course over ground [degrees]
  mv: Magnetic variation value. Only supported in ADR 4.10 and later
  mvEW: Magnetic variation E/W indicator. Only in ADR 4.10 and later
  posMode: Mode Indicator
               N = No fix
               E = Estimated/Dead reckoning fix
               A = Autonomous GNSS fix
               D = Differential GNSS fix
               F = RTK float
               R = RTK fixed
  navStatus: Navigational status indicator
               V = Equipment is not providing navigational status information,
                   fixed field, only available in NMEA 4.10 and later

$GNGNS,120136.00,6023.10268,N,00519.78150,E,AA,18,0.73,75.0,43.8,,*53

$xxGNS,time,lat,NS,lon,EW,posMode,numSV,HDOP,alt,sep,diffAge,diffStation,navStatus*cs<CR><LF>
where:
  posMode: Positioning mode, see position fix flags description.
               1st character for GPS, 2nd character for GLONASS,
               3rd character for Galileo, 4th character for BeiDou
  alt: Altitude above mean sea level
  sep: Geoid separation: difference between ellipsoid and mean sea level
  diffAge: Age of diff corrections [seconds], null when DGPS is not used
  diffStation: ID of station providing diff corrections, null when DGPS is not used
  navStatus: Navigational status indicator
                V (Equipment is not providing navigational status information,
                   fixed field, only available in NMEA 4.10 and later)

$GNGGA,120136.00,6023.10268,N,00519.78150,E,1,12,0.73,75.0,M,43.8,M,,*73

The NMEA specification indicates that the GGA message is GPS specific. However, when the receiver is configured for multi-GNSS, the GGA message contents will be generated from the multi-GNSS solution. For multi-GNSS use, it is recommended that the NMEA-GNS message is used instead.

$xxGGA,time,lat,NS,lon,EW,quality,numSV,HDOP,alt,altUnit,sep,sepUnit,diffAge,diffStation*cs<CR><LF>
where:
  quality: Quality indicator for position fix, see position fix flags description [1]
              0 = No fix
              1 = Autonomous GNSS fix
              2 = Differential GNSS fix
              4 = RTK fixed
              5 = RTK float
              6 = Estimated/Dead reckoning fix

$GNGSA,A,3,24,17,19,12,15,10,28,20,01,13,,,1.87,0.73,1.72*17
$GNGSA,A,3,75,66,74,84,76,83,67,85,,,,,1.87,0.73,1.72*19

• If less than 12 SVs are used for navigation, the remaining fields are left empty. If more than 12 SVs are used for navigation, only the IDs of the first 12 are output.
• The SV numbers (fields 'svid') are in the range of 1 to 32 for GPS satellites, and 33 to 64 for SBAS satellites (33 = SBAS PRN 120, 34 = SBAS PRN 121, and so on).
• In a multi-GNSS system this message will be output multiple times, once for each GNSS.

$xxGSA,opMode,navMode{,svid},PDOP,HDOP,VDOP,systemId*cs<CR><LF>
where:
  opMode: Operation mode:
            M = Manually set to operate in 2D or 3D mode
            A = Automatically switching between 2D or 3D mode
  navMode: Navigation mode, see position fix flags description [1]
           Possible values for navMode:
              1 = No fix
              2 = 2D fix
              3 = 3D fix
  svid: Space Vehicle ID - Start of repeated block (12 times)
  PDOP: Position dilution of precision
  HDOP: Horizontal dilution of precision
  VDOP: Vertical dilution of precision
  systemId: NMEA defined GNSS System ID, see Signal Identifiers table [2]
            Only available in NMEA 4.10 and later

$GNGST,120136.00,3326643,,,,4.1,1.9,7.2*73

This message reports statistical information on the quality of the position solution.

$xxGST,time,rangeRms,stdMajor,stdMinor,orient,stdLat,stdLong,stdAlt*cs<CR><LF>
where:
  rangeRms: RMS value of the standard deviation of the ranges [meter]
  stdMajor: Standard deviation of semi-major axis (only in ADR 4.10 and later)
  stdMinor: Standard deviation of semi-minor axis (only in ADR 4.10 and later)
  orient: Orientation of semi-major axis (only in ADR 4.10 and later)
  stdLat: Standard deviation of latitude error [meter]
  stdLong: Standard deviation of longitude error [meter]
  stdAlt: Standard deviation of altitude error [meter]

$GNZDA,120136.00,03,03,2020,00,00*7F

$xxZDA,time,day,month,year,ltzh,ltzn*cs<CR><LF>
where:
  ltzh: Local time zone hours: 00 (fixed field)
  ltzn: Local time zone minutes: 00 (fixed field)

• Remote Trigger Module 3, or RTM3, made by Seismic Source Company
• Ethernet: The RTM3 has a fixed IP and not a DHCP server. If the RTM has a serial number of 171 the IP address will be, 10.0.1.71. The computer should be set to 10.0.0.101. This link shows a video on setting up the computer IP address: https://www.youtube.com/channel/UCWszOSFMYMt20E-d2CD4xvQ
• FTP server: The unit has an FTP server through which data can be downloaded.
• Data can be exported through WLAN interface.
• Display: The "1" is the GPS indicator value from the NMEA string, $GPGGA, that is being received by the RTM3 and sent by the GPS receiver. The "P" means that the RTM3 is receiving the PPS from the GPS receiver. The "T:OK" means the RTM3 is time synchronized with the GPS receiver’s NMEA messages and PPS.

• ASHTECH ProFlex Lite DG16
• DG16 Manual

• 1-port serial
• Manufacturer: ST Labs

• 4-port serial
• Manufacturer: Aten
• Model: UC2324
• Driver for Windows XP, Windows, Windows Vista, Vista (32 bit), Windows 7, Windows 8, Windows 8.1 -- V2.0.7.0 -- 2014-09-11 -- uc2322_2324_4852_4854_windows_v2.0.7.0.zip

$GPGGA,083901.000,6023.0793,N,00519.7550,E,1,11,0.97,18.5,M,43.7,M,,*5D

ID, UTC, Lat, N/S, Lon, E/W, Pos fix indicator, Nsats, HDOP, MSL alt, units, geoid sep, units, age of diff corr, diff ref station id
where:
   Pos fix indicator: 0 = Fix not available or invalid
                      1 = GPS SPS mode, fix valid
                      2 = Diff GPS, SPS mode, fix valid
                      3-5 not supported
                      6 = Dead reckoning mode, fix valid

$GNRMC,083901.000,A,6023.0793,N,00519.7550,E,0.00,214.26,110220,,,A*70

ID, UTC, status, lat, N/S, lon, E/W, speed o/ground [kt], course o/ground [deg], date, mag variation, E/W, mode
where:
   status: A = data valid
           V = invalid
   mode:   A = autonomous
           D = DGPS

$GNGSA,A,3,09,30,21,07,,,,,,,,,1.32,1.03,0.82*1A
$GNGSA,A,3,65,83,66,82,76,75,,,,,,,1.32,1.03,0.82*15

ID, mode_1, mode_2, SV#_used_ch1, ...,SV#_used_ch12, PDOP, HDOP, VDOP
where:
   mode_1: M = manual; set to operate in 2D or 3D mode
           A = automatic switch between 2D/3D
   mode_2: 1 = fix not available
           2 = 2D (<4SVs used)
           3 = 3D (>3SVs used)

$GPGSV,3,1,12,05,63,251,,07,62,092,35,30,61,174,18,13,32,263,18*72
$GPGSV,3,2,12,09,19,098,29,39,19,157,,21,12,340,36,02,10,223,*73
$GPGSV,3,3,12,16,09,016,,27,08,042,,15,04,275,37,28,01,156,*75

$GLGSV,2,1,08,66,73,300,27,75,63,096,37,65,38,122,23,76,36,174,25*69
$GLGSV,2,2,08,82,25,297,22,83,24,350,36,67,19,300,,81,03,254,18*68

ID, no_of_msg, msg_no, sats_in_view, SV#, elevation, azimuth, S/N_ratio, {repeat 3 sets, each 4 parameters}