Enhanced Digital Access Communications System (EDACS)
EDACS logo

HISTORY
  • General Electric Private Radio Systems Division (Lynchburg, Virginia)
    • First system installed in 1988.
  • Ericsson bought GE's Lynchburg operations in 1989, called it Private Radio Systems division but kept it in Lynchburg
  • Com-Net in Pittsburgh bought 80% of PRS in January 2000, called it Critical Radio Systems

    550 employees at this point

  • Tyco bought CRS in April 2001, put it under M/A-COM in Lowell, Massachusetts (under Tyco Electronics in Harrisburg, Pennsylvania)

    • About 400 systems installed as of 2001.
    • 651 employees in April 2001 (M/A-COM had 2,800 employees at that time)

  • Tyco Electronics sells the Wireless System Segment to Harris Corporation in 2009. The new business unit is called "Public Safety and Professional Communications."

  • In 2012, Harris announces end-of-life for EDACS, with support ending in December 2017.

TECHNOLOGY
  • 9600 baud control channel, transmitted as GFSK.
  • Supports analog and three types of digital voice:
    • First Generation (first available in mid-1980's): Voice Guard
      Vocoder uses subband coding, producing 9244 bits per second
      Frame synchronization and signalling adds 356 bits
      Total data rate 9600 bits per second
      Uses a synchronization header and periodic sync updates
      Claimed 25% better range than analog due to error correction
      • Voice Guard with VGE encryption
      • Voice Guard with DES encryption

    • Second Generation (first available in 1990): AEGIS
      Voice quality 10x better than Voice Guard
      Uses Adaptive Multiband Encoding (AME)
      9,600 baud data stream
      • AEGIS without encryption
      • AEGIS with VGE encryption
      • AEGIS with DES encryption

    • Third Generation (first available in 1998): ProVoice (uses IMBE vocoder)
      Voice quality 10x-15x better than AEGIS
      • ProVoice without encryption
      • ProVoice with VGE encryption
      • ProVoice with DES encryption
      • ProVoice (Trunking) with AES encryption

  • Voice Guard Encryption (VGE)
    • G.E. proprietary algorithm
    • 64-bit key (1.8 × 1019 keys)
    • "The encryption algorithm utilizes highly complex nonlinear data spreading and iterative key scheduling to insure the security of encrypted voice data."

      "It [also] utilizes a key scheduling algorithm, bit permutations, and nonlinear product transformations to provide a very high level of bit spreading."

    • Customer Unique Encryption (CUE), additional 64-bit key

  • Data Encryption Standard (DES)
    • U.S. Government standard algorithm
    • 56-bit key (7.2 × 1016 keys)
    • OFB = Output Feedback mode

  • Advanced Encryption Standard (AES)
    • U.S. Government standard algorithm
    • 256-bit key
    • OFB = Output Feedback mode


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    Last revised January 28, 2015

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