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Advanced Extremely High Frequency System

Advanced Extremely High Frequency System

Advanced Extremely High Frequency System

Mission


The Advanced Extremely High Frequency System is a joint service satellite communications system that provides survivable, global, secure, protected, and jam-resistant communications for high-priority military ground, sea and air assets. Advanced EHF enables the National Security Council and Unified Combatant Commanders to control their tactical and strategic forces at all levels of conflict up to and through nuclear war and supports the attainment of information superiority. 

Background

The AEHF System is the follow-on to the Milstar system, augmenting and improving on the capabilities of Milstar, and expanding the MILSATCOM architecture. AEHF provides connectivity across the spectrum of mission areas, including land, air and naval warfare; special operations; strategic nuclear operations; strategic defense; theater missile defense; and space operations and intelligence.

Features

The AEHF system program of record consists of six satellites in geosynchronous earth orbit that provides 10 times the throughput of the 1990s-era Milstar satellites with a substantial increase in coverage for users. AEHF-1 was launched on August 14, 2010 and AEHF-2 was launched on May 4, 2012, AEHF-3 was launched on September 18, 2013, while AEHF-4 is projected to launch sometime in mid-2017. AEHF provides continuous 24-hour coverage between 65 degrees north and 65 degrees south latitude. The AEHF system is composed of three segments: space (the satellites), ground (mission control and associated communications links) and terminals (the users). The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps. The space segment consists of the on-orbit satellite systems utilizing crosslink communications to allow for full AEHF and legacy Milstar constellation integration.  The mission control segment controls satellites on orbit, monitors vehicle health and provides communication system planning and monitoring. This segment is highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks will operate in the extremely high frequency range and downlinks in the super high frequency (SHF) range. A secondary method of command and control uses the Command and Control System-Consolidated (CCS-C) and the Air Force Satellite Control Network (AFSCN). This integrated system provides backup command and control through S-band links for both Milstar and the Advanced EHF satellite systems. The terminal segment includes fixed and ground mobile terminals, ship and submarine terminals, and airborne terminals used by all of the Services and international partners (Canada, Netherlands and UK). MILSATCOM is responsible for acquisition of the space and ground segments as well as the Air Force terminal segments. The Army and Navy will acquire their own terminals.

General Characteristics

Primary Function:
Near-worldwide, secure, survivable satellite communications

Primary Contractor: Lockheed Martin Space Systems Company

Payload: Onboard signal processing, crossbanded EHF/SHF communications

Antennas: 2 SHF Downlink Phased Arrays, 2 Crosslinks, 2 Uplink/Downlink Nulling Antennas, 1 Uplink EHF Phased Array, 6 Uplink/Downlink  Gimbaled Dish Antenna, 1 Each Uplink/downlink earth coverage horns

Capability: Data rates from 75 bps to approximately 8 Mbps

(Current as of Dec 2016)