GPS_PVT

gem 'gps_pvt'

require 'gps_pvt'

receiver = GPS_PVT::Receiver::new
receiver.parse_rinex_nav(rinex_nav_file) # This is required before parsing RINEX obs file (For ubx, skippable)

# For generate solution in CSV format
puts GPS_PVT::Receiver::header
receiver.parse_rinex_obs(rinex_obs_file)
# receiver.parse_ubx(ubx_file) # same as above for ubx file including RXM-RAW(X) and RXM-SFRB(X)

# Or precise control of outputs
receiver.parse_rinex_obs(rinex_obs_file){|pvt, meas| # per epoch
  meas.to_a # => measurement, array of [prn, key, value]; key is represented by GPS_PVT::GPS::Measurement::L1_PSEUDORANGE; instead of .to_a, .to_hash returns {prn => {key => value, ...}, ...}
  
  pvt # => PVT solution, all properties are shown by pvt.methods
  # for example
  if(pvt.position_solved?){
    pvt.receiver_time # receiver time; .to_a => [GPS week, seconds], .c_tm => [year, month, day, hour, min, sec] without leap second consideration
    [:lat, :lng, :alt].collect{|f| pvt.llh.send(f)} # latitude[rad], longitude[rad], WGS-84 altitude[m]
    pvt.receiver_error # receiver clock error in meter
    [:g, :p, :h, :v, :t].collect{|k| pvt.send("#{k}dop".to_sym)} # various DOP, dilution of precision
    if(pvt.velocity_solved?){
      [:north, east, :down].collect{|dir| pvt.velocity.send(dir)} # speed in north/east/down [m/s]
      pvt.receiver_error_rate # clock error rate in m/s
    }
    pvt.used_satellite_list # array of used, i.e., visible and weight>0, satellite
    pvt.azimuth # azimuth angle [rad] to used satellites in Hash {prn => value, ...}
    pvt.elevation # elevation angle [rad]

    pvt.G # design matrix in Earth-centered-Earth-fixed (ECEF); .to_a returns double array converted from matrix. its row corresponds to one of used_satellite_list
    pvt.G_enu # design matrix in East-North-Up (ENU)
    pvt.W # weight for each satellite
    pvt.delta_r # residual of pseudo range
    pvt.S # (delta position) = S * (residual) in last iteration in ECEF
  }
}

## Further customization
# General options
receiver.solver.gps_options.exclude(prn) # Exclude satellite; the default is to use every satellite if visible
receiver.solver.gps_options.include(prn) # Discard previous setting of exclusion
receiver.solver.gps_options.elevation_mask = Math::PI / 180 * 10 # example 10 [deg] elevation mask
# receiver.solver.sbas_options is for SBAS.

# Precise control of properties for each satellite and for each iteration
receiver.solver.hooks[:relative_property] = proc{|prn, rel_prop, meas, rcv_e, t_arv, usr_pos, usr_vel|
  weight_range, range_c, range_r, weight_rate, rate_rel_neg, *los_neg = rel_prop # relative property
  # meas is measurement represented by pseudo range of the selected satellite.
  # rcv_e, t_arv, usr_pos, usr_vel are temporary solution of 
  # receiver clock error [m], time of arrival [s], user position and velocity in ECEF, respectively.
  # Note: weight_rate is added since v0.10.1
  
  weight_range = 1 # quick example: identical weight for each visible satellite
  # or weight based on elevation, for example:
  # elv = GPS_PVT::Coordinate::ENU::relative_rel(GPS_PVT::Coordinate::XYZ::new(*los_neg), usr_pos).elevation
  # weight_range = (Math::sin(elv)/0.8)**2
  
  [weight_range, range_c, range_r, weight_rate, rate_rel_neg] + los_neg # must return relative property
}

# Range correction (since v0.3.0)
receiver.solver.correction = { # provide by using a Hash
  # ionospheric and transpheric models are changeable, and current configuration
  # can be obtained by receiver.solver.correction without assigner.
  :gps_ionospheric => proc{|t, usr_pos_xyz, sat_pos_enu|
    # t, usr_pos_xyz, sat_pos_enu are temporary solution of 
    # time of arrival [s], user position in ECEF, 
    # and satellite position in ENU respectively.
    0 # must return correction value, delaying is negative.
  },
  # combination of (gps or sbas) and (ionospheric or tropospheric) are available
}

# Dynamic customization of weight for each epoch
(class << receiver; self; end).instance_eval{ # do before parse_XXX
  run_orig = instance_method(:run)
  define_method(:run){|meas, t_meas, &b|
    meas # observation, same as the 2nd argument of parse_XXX
    receiver.solver.hooks[:relative_property] = proc{|prn, rel_prop, meas, rcv_e, t_arv, usr_pos, usr_vel|
      # Do something based on meas, t_meas.
      rel_prop
    }
    run_orig.bind(self).call(meas, t_meas, &b)
  }
}