Text files of the navigation logged with during the sampling survey of field activity 2012-024-FA in 2012 by the U.S. Geological Survey in the Connecticut River

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Frequently anticipated questions:


What does this data set describe?

Title:
Text files of the navigation logged with during the sampling survey of field activity 2012-024-FA in 2012 by the U.S. Geological Survey in the Connecticut River
Abstract:
A geophysical and geological survey was conducted at the mouth of the Connecticut River from Old Saybrook to Essex, Connecticut, in September 2012. Approximately 230 linear kilometers of digital Chirp subbottom (seismic-reflection) and 234-kilohertz interferometric sonar (bathymetric and backscatter) data were collected along with sediment samples, riverbed photographs, and (or) video at 88 sites within the geophysical survey area. Sediment grab samples were collected at 72 of the 88 sampling sites, video was acquired at 68 sites, and photographs of the river bottom were taken at 38 sites. These survey data are used to characterize the riverbed by identifying sediment-texture and riverbed morphology. More information can be found on the web page for the Woods Hole Coastal and Marine Science Center field activity: https://cmgds.marine.usgs.gov/fan_info.php?fan=2012-024-FA. Data collected during the 2012 survey can be obtained here: https://doi.org/10.5066/F7PG1Q7V.
Supplemental_Information:
More information can be found on the WHCMSC Field Activity webpage: https://cmgds.marine.usgs.gov/fan_info.php?fan=2012-024-FA. Data collected during the 2012 survey can be obtained here: https://doi.org/10.5066/F7PG1Q7V.
  1. How might this data set be cited?
    U.S. Geological Survey, 2017, Text files of the navigation logged with during the sampling survey of field activity 2012-024-FA in 2012 by the U.S. Geological Survey in the Connecticut River: data release DOI:10.5066/F7PG1Q7V, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Ackerman, Seth D., Foster, David S., Moore, Eric M., Irwin, Barry J., Blackwood, Dann S., and Sherwood, Christopher R., 2017, High-Resolution Geophysical and Sampling Data Collected at the Mouth of the Connecticut River, Old Saybrook to Essex, Connecticut, 2012: data release DOI:10.5066/F7PG1Q7V, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Ackerman S.D., Foster D.S., Moore E.M., Irwin B.J., Blackwood D.S., and Sherwood, C.R., 2017, High-resolution geophysical and sampling data collected at the mouth of the Connecticut River, Old Saybrook to Essex, Connecticut, 2012: U.S. Geological Survey data release, https://doi.org/10.5066/F7PG1Q7V.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -72.4134717
    East_Bounding_Coordinate: -72.3349450
    North_Bounding_Coordinate: 41.3890983
    South_Bounding_Coordinate: 41.2650883
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 21-Sep-2012
    Ending_Date: 23-Sep-2012
    Currentness_Reference:
    ground condition of survey dates: 20120921-20120923
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tabular 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:
    Not all files contain complete NMEA strings. These are the original files, no corrections have been made to these files. The times recorded in the navigation file are in UTC. The NMEA keywords and the information they provide are 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,170003.00,4119.08134,N,07221.00464,W,2,09,1.2,5.5,M,-33.8,M,6.4,0008*70 UTC Time = 170003.00 Latitude Deg = 41 Latitude Min = 19.08134 N Longitude Deg = 072 Longitude Min = 21.00464 W Fix Quality = 2 (indicates Differential GPS) Number of satellites = 09 HDOP = 1.2 relative accuracy of horizontal position Altitude = 5.5 meters above mean sea level Height of geoid above WGS84 ellipsoid = -33.8 meters Time since last update = 6.4 Checksum = 0008*70.
    $GPVTG is track made good and ground speed in the format: $GPVTG, 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,70.98,T,,M,0.09,N,0.17,K,D*01 True course made good: 340.39 Magnetic course made good: 70.98 Ground speed (knots) = 0.09 Ground speed (kilometers) = 0.17 Mode=Differential.
    Entity_and_Attribute_Detail_Citation:
    The definitions of the NMEA strings were obtained from: http://home.mira.net/~gnb/gps/nmea.html, 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)
    • U.S. Geological Survey
  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
    USA

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

Why was the data set created?

These raw navigation data are provided as an archive of the navigation data files acquired during the sampling portion of USGS survey 2012-024-FA in the Connecticut River. Survey 2012-024-FA was conducted aboard the R/V Rafael. These data were logged, via serial port input, at a one-second interval using Microsoft HyperTerminal on a Dell Latitude D820 laptop computer.

How was the data set created?

  1. From what previous works were the data drawn?
    raw navigation data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw navigation data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Raw navigation data from survey 2012-024-FA were logged at a one-second interval using Microsoft HyperTerminal on a Dell Latitude D820 laptop computer. File name convention is vessel_julianday_starttime.TXT.
  2. How were the data generated, processed, and modified?
    Date: 2012 (process 1 of 2)
    The raw navigation feed from the Hemisphere 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 survey day (by Gregorian day). The filenames are in the format of vessel_julianday_starttime.TXT. For example, filename Rafael_JD265_1702.TXT represents the navigation logged on the R/V Rafael on Julian day 265 beginning at 1702. Times are recorded in UTC (Coordinate Universal Time). Person who carried out this activity:
    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov
    Date: 08-Sep-2020 (process 2 of 2)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  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?
    Some lines of navigation data may be empty or incomplete, especially at the beginning of a file when the first bits of data were being received via serial input.
  2. How accurate are the geographic locations?
    Differential GPS (DGPS) navigation data were collected during the sampling portion of USGS survey 2012-024-FA using the Hemisphere DGPS which had an antenna mounted on the aft of the R/V Rafael's cabin just port of the centerline. Positioning data from this receiver were logged at a one-second interval using Microsoft HyperTerminal on a Dell Latitude D820 laptop computer via serial input. These data were incorporated into the sampling data in post-processing. The DGPS horizontal positional accuracy is estimated to be within 3-5 m.
  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 during the sample portion of USGS survey 2012-024-FA in the Connecticut River. Temporal and spatial gaps may occur when the navigation data was not being logged or when the GPS signal was temporarily disrupted.
  5. How consistent are the relationships among the observations, including topology?
    These are the original files recorded during the sampling survey. These data were checked but no modifications or corrections have been made to these files.

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:
These data are NOT to be used for navigation. Mariners should refer to the appropriate nautical chart. 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 originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    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? USGS data release 2012-024-FA contains raw sampling navigation files collected in the Connecticut River (2012-024-FA_SamplingNav.zip). The zip file contains 4 raw navigation files that serve as a navigation archive and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata files (2012-024-FA_SamplingNav.xml) in standard formats.
  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 ASCII text files. To utilize these data, the user must have software capable of unzipping the zip file, viewing text files and parsing the navigation strings.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
Seth Ackerman
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA
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)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/field_activities/2012_024_fa/2012-024-FA_SamplingNav.faq.html>
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