Module: PWN::SDR::Decoder::P25

Defined in:
lib/pwn/sdr/decoder/p25.rb

Overview

Pure-Ruby APCO Project 25 Phase-1 C4FM activity detector.

P25 is 4800 sym/s 4-level FSK with 1/2-rate trellis + RS + IMBE vocoder. Full symbol recovery, deinterleave, FEC and voice decode is out of scope for a portable pure-Ruby implementation; this module instead characterises C4FM keying activity (talkgroup key- ups, control-channel duty cycle) natively via Base.run_detector. parse_line is retained for offline dsd-format log 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/p25.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::P25.decode( freq_obj: 'required - freq_obj returned from PWN::SDR::GQRX.init_freq' )



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# File 'lib/pwn/sdr/decoder/p25.rb', line 20

public_class_method def self.decode(opts = {})
  freq_obj = opts[:freq_obj]
  PWN::SDR::Decoder::Base.run_detector(
    freq_obj: freq_obj,
    protocol: 'P25',
    note: 'C4FM 4-FSK + trellis/RS/IMBE — native mode reports key-up bursts (duration/peak/duty) only. Feed captured dsd text to .parse_line for NAC/TG/RID.',
    threshold: 6.0,
    describe: proc { |b|
      kind = if b[:duration_ms] > 1500 then 'voice-superframe'
             elsif b[:duration_ms] > 150 then 'LDU/HDU'
             else 'TSBK/control'
             end
      { modulation: 'C4FM', symbol_rate: 4800, classification: kind }
    }
  )
end

.help ⇒ Object

Display Usage for this Module



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# File 'lib/pwn/sdr/decoder/p25.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: 'Sync: +P25p1 NAC: 293 src: 1234 tg: 5678')

    #{self}.authors
  "
end

.parse_line(opts = {}) ⇒ Object

Supported Method Parameters

PWN::SDR::Decoder::P25.parse_line(line: 'Sync: +P25p1 NAC: 293 src: 1234 tg: 5678')



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# File 'lib/pwn/sdr/decoder/p25.rb', line 40

public_class_method def self.parse_line(opts = {})
  line = opts[:line].to_s
  out  = { protocol: 'P25' }
  out[:nac]       = ::Regexp.last_match(1) if line =~ /NAC:\s*([0-9A-Fa-f]+)/
  out[:talkgroup] = ::Regexp.last_match(1) if line =~ /(?:TGID|tg[: ])\s*(\d+)/i
  out[:radio_id]  = ::Regexp.last_match(1) if line =~ /(?:RID|src[: ])\s*(\d+)/i
  out[:duid]      = ::Regexp.last_match(1) if line =~ /DUID:\s*(\S+)/
  out[:sync]      = ::Regexp.last_match(1) if line =~ /Sync:\s*(\S+)/
  out[:summary]   = "P25 NAC=#{out[:nac]} TG=#{out[:talkgroup]} RID=#{out[:radio_id]}".squeeze(' ')
  out.compact
end