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gps-sem-parser

Example

  import sem from 'gps-sem-parser';
  const almanac = sem( rawAlmanac );
{
  "gpsWeek": 1844,
  "toa": 405504,
  "epoch": 1115656704,
  "satellites": [
    {
      "prn": 1,
      "svn": 63,
      "ura": 0,
      "eccentricity": 0.00419855117797852,
      "inclination": 0.9617664060621093,
      "rightAscensionDot": -8.114623720935037e-9,
      "semimajorAxis": 26559649.327529907,
      "rightAscension": -1.6779199426606246,
      "argumentOfPeriapsis": 0.37559459670255485,
      "meanAnomaly": -2.781213528432701,
      "clockBias": -0.0000057220458984375,
      "clockDrift": 0,
      "health": 0,
      "config": 11
    }
  ]
}

API

sem(file, gpsEpoch)

Parses a string containing a GPS almanac in sem format. Pass gpsEpoch with the number of times the gps week has rolled over. Set gpsEpoch to null and year to the year in which the almanac was issued to try to automatically resolve the gps epoch. (Defaults to current year)

Return an Almanac object.

Parameters

name type description
file string Almanac in SEM format
gpsEpoch number (optional) Number of times the GPS Week index rolled over.
year number (optional) Year in which the Almanac was issued (to resolve gps epoch). )

Almanac

Object representing a GPS almanac

name type description
gpsWeek number GPS Week of the almanac
toa number Time of Applicability of the alamanc
epoch number Epoch of the almanac (seconds since start of GPS time)
satellites [Satellite] Array of satellite element sets

Satellite

Object representing a satellite element set. (For details see IS-GPS-200)

name type description
prn number Assigned PRN
svn number Space Vehicle Number
ura number User Range Accuracy
eccentricity number Eccentricity at epoch
inclination number Inclination at epoch (rad)
rightAscensionDot number First derivative of the right ascension (rad/s)
semimajorAxis number Semimajor Axis at epoch (m)
rightAscension number Right ascension at start of GPS Week (rad)
argumentOfPeriapsis number Argument of periapsis (rad)
meanAnomaly number Mean Anomaly at epoch (rad)
clockBias number Clock bias at epoch (s)
clockDrift number Clock drift at epoch (s/s)
health number Health of satellite
config number Configuration of satellite

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parser for GPS almanac .sem files

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