DH_SAMPLING_NAV: Text files of the navigation logged with Microsoft HyperTerminal during sampling survey 07003 conducted aboard the R/V Connecticut by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:

What does this data set describe?

Title:
DH_SAMPLING_NAV: Text files of the navigation logged with Microsoft HyperTerminal during sampling survey 07003 conducted aboard the R/V Connecticut by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.
Abstract:
These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Science Center (WHSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of sea-floor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters (5-30 m deep) of Massachusetts between the New Hampshire border and Cape Cod Bay. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (<http://woodshole.er.usgs.gov/project-pages/coastal_mass/html/current_map.html>). This spatial dataset is from the study area located between Duxbury and Hull Massachusetts, and consists of high-resolution geophysics (bathymetry, backscatter intensity, and seismic reflection) and ground validation (sediment samples, video tracklines and bottom photographs). The data were collected during four separate surveys conducted between 2003 and 2007 (NOAA survey H10993 in 2003, USGS-WHSC survey 06012 in 2006, and USGS-WHSC surveys 07001 and 07003 in 2007) and cover more than 200 square kilometers of the inner continental shelf.
  1. How should this data set be cited?

    U.S. Geological Survey, 2010, DH_SAMPLING_NAV: Text files of the navigation logged with Microsoft HyperTerminal during sampling survey 07003 conducted aboard the R/V Connecticut by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.: Open-File Report 2009-1072, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Barnhardt, Walter A. , Ackerman, Seth D. , Andrews, Brian D. , and Baldwin, Wayne E. , 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts.: Open-File Report 2009-1072, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.816437
    East_Bounding_Coordinate: -70.188584
    North_Bounding_Coordinate: 42.329980
    South_Bounding_Coordinate: 41.519287

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 07-Sep-2007
    Ending_Date: 11-Sep-2007
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Point data set.

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The times recorded in the navigation file are in UTC. The (National Marine Electronics Association) NMEA strings $GPGGA, $GPVTG, and $GPZDA are stored in these navigation files. These are defined as follows:

    $GPGGA is GPS fix data in the format "$GPGGA, t, lat, lath, long, longh, q, sat, h, a, M, alt, M, t2, refcheck" where t=time in UTC in the format hhmmss.ss; lat=latitude in the format ddmm.mmmmmm; lath= N or S indicating the latitude hemisphere; long=longitude in the format dddmm.mmmmmm; longh=E or W indicating the hemisphere; q=fix quality where 0=fix not available or invalid; 1=GPS fix; 2=Differential GPS fix; 3=GPS PPS Mode fix; 4=RTK fix; 5=RTK float; sat=number of satellites; h=Horizontal Dilution of Precision (HDOP); a=Antenna altitude above mean sea level (geoid); M= units of antenna altitude in meters; alt=height of geoid above WGS84 ellipsoid; M=units of geoidal height in meters; t2=time since last DGPS update; refcheck=DGPS reference station id and the checksum.

    Example: $GPGGA,173356.00,4204.848996,N,07036.929067,W,4,09,01.1,00003.278,M,-028.888,M,01,0000*56 UTC Time = 173356 Latitude = 4204.848996 N Longitude = 7036.929067 W Fix Quality = 4 Number of satellites = 9 HDOP = 01.1 relative accuracy of horizontal position Altitude = 3.278 meters above mean sea level Height of geoid above WGS84 ellipsoid = -28.888 meters Time since last update = 01 Checksum = *57.

    $GPVTG is track made good and ground speed in the format "$GPCTG, true, T, mag, M, grsp1, N, grsp2, K, mode", where t=true course made good over ground in degrees, T= True, m=magnetic course made good over ground in degrees, M=magnetic, grsp1=ground speed, N=Knots, grsp2=ground speed, K=Kilometers per hour, mode=Mode indicator (A=Autonomous, D=Differential, E=Estimated, N=Data not valid).

    Example: $GPVTG,340.39,T,356.37,M,005.50,N,010.18,K,D*27 True course made good: 340.39 Magnetic course made good: 356.37 Ground speed (knots) = 5.5 Ground speed (kilometers) = 10.18 Mode=Differential

    $GPZDA is UTC Date/Time and Local Time Zone Offset in the format "$GPZDA,hhmmss.ss,xx,xx,xxxx,xx,xx" where hhmmss.ss=UTC, xx=Day, 01 to 31, xx=month, 01 to 12, xxx=Year, xx=Local zone description, 00 to +/- 13 hours, xx=Local zone minutes description (same sign as hours), checksum.

    Example: $GPZDA,173357.00,28,04,2007,,*69 UTC= 173357.00 UTC day = 28 UTC month = 04 UTM year = 2007 Local zone hours = null Local zone minutes = null Checksum = *69

    $PASHR,SAT is GPS satellite tracking status information. This is an Ashtech proprietary format; no additional explanation could be found.

    Entity_and_Attribute_Detail_Citation:
    The definitions of the NMEA strings were obtained from: <http://home.mira.net/~gnb/gps/nmea.html> and <http://www.nps.gov/gis/gps/NMEA_sentences.html>

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

Why was the data set created?

To provide the raw navigation feed files acquired during USGS survey 07003 offshore of Massachusetts, between Duxbury and Hull. Survey 07003 was conducted aboard the R/V Connecticut September 7-11, 2007. A Microsoft HyperTerminal session on a Dell Latitude D820 laptop computer was used to log these raw Global Positioning System (GPS) navigation data.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    Differential Global Positioning System (DGPS) navigation from an Ashtech BR2G GPS unit was logged through a Microsoft HyperTerminal (version 5.1) session on a Dell Latitude D820 laptop computer running Windows XP, SP2 via serial cable. Log files were saved for each sampling watch then reformatted into log files by Julian Day (e.g. nav_sda.251) during post-processing.

    Raw navigation data were saved in ASCII text format. Original navigation file name convention is MMDDYY_XXXXX_watch.txt, where MM is the month, DD is the Gregorian Day, YY is the year and XXXXXXXX is the watch (e.g. day_watch or night_watch). The reformatted log files are named nav_sda.JJJ, where JJJ is the Julian day. No editing was done in the reformatting, just a rearrangement of records into files organized by Julian day. However, included in the WinZip of data is an AWK script (HT_doGPGGA.awk) that can be used to extract the navigation from each log file into the format: latitude (in decimal degrees), longitude (in decimal degrees), hour, minute, seconds, Julian day, year, surveyid

  2. How were the data generated, processed, and modified?

    Date: Sep-2007 (process 1 of 2)
    The raw navigation feed from the Differential Global Positioning System (DGPS) receiver was logged at a one-second interval using Microsoft HyperTerminal on a Dell Latitude D820 laptop computer. Log files were recorded for each sampling watch (noon-midnight, midnight-noon; local time) by Gregorian day.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

    Data sources produced in this process:
    • Original navigation files

    Date: Sep-2007 (process 2 of 2)
    The original log files were reformatted into log files by Julian Day (e.g. nav_sda.250, nav_sda.251, nav_sda.252, nav_sda.253, nav_sda.254). No additional editing was done in this step, the navigation records were simply rearranged into files organized by Julian day.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

    Data sources produced in this process:
    • Navigation files organized by Julian day

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    Navigation for survey 07003 used Differential Global Positioning System (DGPS). The recorded position of each navigation point is the position of the GPS antenna on the survey vessel, not the SEABOSS sampler. A conservative estimate the horizontal accuracy of the DGPS locations is 10 meters. The estimated horizontal accuracy of the sampling data is greater than 10 meters because no layback or offset was applied to the recorded position to account for the position of the SEABOSS sampler.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    These files represent all the navigation recorded by the Microsoft HyperTerminal session during USGS survey 07003.

  5. How consistent are the relationships among the observations, including topology?

    The original files recorded by a Microsoft HyperTerminal session were logged by Gregorian Day. The original files were split and combined to create an individual file for each Julian Day of surveying. These files include navigation data during the transits en-route to, returning from, and between the sampling sites. In general, the navigation feed was continuous, even during breaks in the sampling survey, although some gaps in the navigation data may occur during the transit times. A quality check of these files revealed a total of one-hundred eleven records of garbled or null navigation data; these records were not removed or corrected. Additional records of well-formatted but erroneous navigation fixes may occur but were not checked, removed or corrected.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of this information.

  1. Who distributes the data set? (Distributor 1 of 1)

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    These data are available as a ASCII text files. To utilize these data, the user must have software capable of viewing text files.

Who wrote the metadata?

Dates:
Last modified: 25-Aug-2009
Metadata author:
Seth Ackerman
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598
USA

508-548-8700 x2315 (voice)
508-457-2310 (FAX)
sackerman@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.8.25 on Fri Feb 19 21:43:36 2010