EDACS

Enhanced Digital Access Communications System (EDACS)

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.

In 2019, Harris merges with defense contractor L3 to form L3Harris, to be headquartered in Melbourne, Florida.

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 June 26, 2020