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

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

Overview

True-air + detector-fallback decoder for GPS. Prefers PWN::FFI I/Q (RTL-SDR / ADALM-Pluto / HackRF / capture file) via Base.run_iq; degrades to Base.run_detector with no hardware.

Defined Under Namespace

Classes: DemodIQ

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 118

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 74

public_class_method def self.decode(opts = {})
  freq_obj = opts[:freq_obj]

  rate  = (opts[:sample_rate] || freq_obj[:iq_rate] || 2_048_000).to_i
  proto = 'GPS'
  demod = DemodIQ.new(
    rate: rate, protocol: proto, modulation: 'BPSK/DSSS',
    extra: { threshold: 3.0 }
  )
  PWN::SDR::Decoder::Base.run_iq(
    freq_obj: freq_obj,
    protocol: proto,
    sample_rate: rate,
    source: opts[:source],
    file: opts[:file],
    demod: demod,
    threshold: 3.0,
    note: 'BPSK/DSSS 1.023 Mcps — true-air I/Q path reports composite L1 energy; PRN acquisition is layered on FFTW when available.',
    describe: proc { |_b| { modulation: 'BPSK/DSSS', chip_rate: 1_023_000 } }
  )
end

.help ⇒ Object 



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# File 'lib/pwn/sdr/decoder/gps.rb', line 122

public_class_method def self.help
  puts "USAGE (true-air I/Q via PWN::FFI + detector fallback):
    #{self}.decode(
      freq_obj: 'required - freq_obj returned from PWN::SDR::GQRX.init_freq',
      source:   'optional - :auto|:rtlsdr|:adalm_pluto|:file',
      file:     'optional - .cu8/.cs16 capture'
    )

    #{self}.authors
  "
end

.parse_line(opts = {}) ⇒ Object 



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# File 'lib/pwn/sdr/decoder/gps.rb', line 96

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