Module: PWN::SDR::Decoder::GPS

Defined in:
lib/pwn/sdr/decoder/gps.rb

Overview

Pure-Ruby GNSS / GPS L1-C/A activity detector.

1.023 Mcps BPSK/DSSS spread across 2 MHz ā€” acquisition/tracking of 32 PRNs in real time is not feasible in interpreted Ruby. Native mode reports L1 carrier presence / C/Nā‚€ proxy only. parse_line retained for offline gnss-sdr / NMEA text analysis.

Class Method Summary collapse

Class Method Details

.authors ⇒ Object

Author(s)

0day Inc. support@0dayinc.com



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# File 'lib/pwn/sdr/decoder/gps.rb', line 54

public_class_method def self.authors
  "AUTHOR(S):\n  0day Inc. <support@0dayinc.com>\n"
end

.decode(opts = {}) ⇒ Object

Supported Method Parameters

PWN::SDR::Decoder::GPS.decode( freq_obj: 'required - freq_obj returned from PWN::SDR::GQRX.init_freq' )



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# File 'lib/pwn/sdr/decoder/gps.rb', line 18

public_class_method def self.decode(opts = {})
  freq_obj = opts[:freq_obj]
  PWN::SDR::Decoder::Base.run_detector(
    freq_obj: freq_obj,
    protocol: 'GPS',
    note: 'BPSK/DSSS 1.023 Mcps below thermal noise ā€” native mode reports composite L1 energy only.',
    threshold: 3.0,
    describe: proc { |_b| { modulation: 'BPSK/DSSS', chip_rate: 1_023_000 } }
  )
end

.help ⇒ Object

Display Usage for this Module



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# File 'lib/pwn/sdr/decoder/gps.rb', line 60

public_class_method def self.help
  puts "USAGE (ruby-native detector, no external binaries):
    #{self}.decode(
      freq_obj: 'required - freq_obj returned from PWN::SDR::GQRX.init_freq'
    )

    #{self}.parse_line(line: 'Position ... Lat = 32.7 Long = -97.1 Height = 210')

    #{self}.authors
  "
end

.parse_line(opts = {}) ⇒ Object

Supported Method Parameters

PWN::SDR::Decoder::GPS.parse_line(line: 'Position at ... Lat = 32.7 [deg] ...')



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# File 'lib/pwn/sdr/decoder/gps.rb', line 32

public_class_method def self.parse_line(opts = {})
  line = opts[:line].to_s
  out  = { protocol: 'GPS' }
  out[:prn]  = ::Regexp.last_match(1) if line =~ /PRN[ =]?(\d{1,2})/
  out[:cn0]  = ::Regexp.last_match(1) if line =~ /CN0[ =]?([\d.]+)/i
  out[:lat]  = ::Regexp.last_match(1) if line =~ /Lat(?:itude)?\s*=\s*(-?[\d.]+)/i
  out[:lon]  = ::Regexp.last_match(1) if line =~ /Long(?:itude)?\s*=\s*(-?[\d.]+)/i
  out[:alt]  = ::Regexp.last_match(1) if line =~ /Height\s*=\s*(-?[\d.]+)/i
  out[:utc]  = ::Regexp.last_match(1) if line =~ /UTC\s*=?\s*([\d:.-]+T?[\d:.]*)/
  out[:nmea] = line if line.start_with?('$G')
  out[:summary] = if out[:lat]
                    "GPS FIX #{out[:lat]},#{out[:lon]} alt=#{out[:alt]}m"
                  elsif out[:prn]
                    "GPS PRN#{out[:prn]} CN0=#{out[:cn0]}"
                  else
                    "GPS #{line[0, 100]}"
                  end
  out.compact
end