Class: GPS_PVT::UBX

Inherits:
Object
  • Object
show all
Defined in:
lib/gps_pvt/ubx.rb

Constant Summary collapse

GNSS_ID = 
{
  :GPS => 0,
  :SBAS => 1,
  :Galileo => 2,
  :BeiDou => 3,
  :QZSS => 5,
  :GLONASS => 6,
}
SIGNAL_ID = 
{
  :GPS      => {:L1CA => 0, :L2CL => 3, :L2CM => 4},
  :SBAS     => {:L1CA => 0},
  :Galileo  => {:E1C => 0, :E1B => 1, :E5_bI => 5, :E5_bQ => 6},
  :BeiDou   => {:B1I_D1 => 0, :B1I_D2 => 1, :B2I_D1 => 2, :B2I_D2 => 3},
  :QZSS     => {:L1CA => 0, :L2CL => 4, :L2CM => 5},
  :GLONASS  => {:L1OF => 0, :L2OF => 2},
}

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ UBX

Returns a new instance of UBX.



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# File 'lib/gps_pvt/ubx.rb', line 34

def initialize(io)
  @io = io
  @buf = []
end

Class Method Details

.checksum(packet, range = 2..-3)) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 38

def UBX.checksum(packet, range = 2..-3)
  ck_a, ck_b = [0, 0]
  packet[range].each{|b|
    ck_a += b
    ck_b += ck_a
  }
  ck_a &= 0xFF
  ck_b &= 0xFF
  [ck_a, ck_b]
end

.gnss_svid(svid_legacy) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 148

def UBX.gnss_svid(svid_legacy)
  case svid_legacy
  when 1..32;     [:GPS, svid_legacy]
  when 120..158;  [:SBAS, svid_legacy]
  when 211..246;  [:Galileo, svid_legacy - 210]
  when 159..163;  [:Beido, svid_legacy - 158]
  when 33..64;    [:Beido, svid_legacy - 27]
  #when 173..182 # IMES
  when 193..197;  [:QZSS, svid_legacy - 192]
  when 65..96;    [:GLONASS, svid_legacy - 64]
  when 255;       [:GLONASS, nil]
  else; nil
  end
end

.svid(id, gnss = :GPS) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 130

def UBX.svid(id, gnss = :GPS)
  gnss = GNSS_ID[gnss] if gnss.kind_of?(Symbol)
  case gnss
  when GNSS_ID[:GPS], GNSS_ID[:SBAS]
    id
  when GNSS_ID[:Galileo]
    id + 210
  when GNSS_ID[:Beido]
    (id < 6) ? (id + 158) : (id + 27)
  when GNSS_ID[:QZSS]
    id + 192
  when GNSS_ID[:GLONASS]
    id + 64
  else
    nil
  end
end

.update(packet) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 59

def UBX.update(packet)
  [:update_size, :update_checksum].inject(packet){|arg, f|
    UBX.send(f, arg)
  }
end

.update_checksum(packet) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 48

def UBX.update_checksum(packet)
  packet[-2..-1] = checksum(packet)
  packet
end

.update_size(packet, size = nil) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 52

def UBX.update_size(packet, size = nil)
  size ||= packet.size - 8
  size = size.divmod(0x100)
  packet[4] = size[1]
  packet[5] = size[0]
  packet
end

Instance Method Details

#each_packet(&b) ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 99

def each_packet(&b)
  res = Enumerator::new{|y|
    while packet = read_packet
      y << packet
    end
  }
  b ? res.each(&b) : res
end

#read_packet ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 64

def read_packet
  while !@io.eof?
    if @buf.size < 8 then
      @buf += @io.read(8 - @buf.size).unpack('C*')
      return nil if @buf.size < 8
    end
    
    if @buf[0] != 0xB5 then
      @buf.shift
      next
    elsif @buf[1] != 0x62 then
      @buf = @buf[2..-1]
      next
    end
    
    len = (@buf[5] << 8) + @buf[4]
    if @buf.size < len + 8 then
      @buf += @io.read(len + 8 - @buf.size).unpack('C*')
      return nil if @buf.size < len + 8
    end
    
    ck_a, ck_b = UBX::checksum(@buf, 2..(len + 5))
    if (@buf[len + 6] != ck_a) || (@buf[len + 7] != ck_b) then
      @buf = @buf[2..-1]
      next
    end
    
    packet = @buf[0..(len + 7)]
    @buf = @buf[(len + 8)..-1]
    
    return packet
  end
  return nil
end

#read_packets ⇒ Object 



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# File 'lib/gps_pvt/ubx.rb', line 108

def read_packets
  each_packet.to_a
end