FM 24-18: Tactical Single-Channel Radio Communications Techniques
EXTENDED FREQUENCY RANGE, MULTIMODE FIELD RADIO SET AN/PRC-70
Radio set AN/PRC-70 (fig C-1) is designed to provide special forces, ranger, and selected engineer units, reliable long- and short-range command and control communications, under all climatic conditions. This radio gives units operating behind enemy lines the capability of providing near real-time, secure tactical and/or strategic intelligence information to corps and theater.
Figure C-1. AN/PRC-70 Manpack.
C-2. Basic Components and Accessories
The AN/PRC-70 system consists of the basic receiver/transmitter, battery, and accessory kit. Additional ancillary/accessory items for use with this system are a mast assembly, retransmission cable, maintenance cable assembly, AC/DC power supply, and G-76 hand-cranked DC generator. A burst-data device, the Digital Message Device Group OA-8990 can also be used with the AN/PRC-70 system.
C-3. System Description
The AN/PRC-70 is an extended frequency range, multimode, manpack receiver/transmitter. It is designed to provide medium-to-long-range communications in CW, FSK, AM, FM, and SSB modes in the frequency range of 2 to 76 MHz. It has power output levels ranging from 1.8 to 5.6 watts in the low-power setting, and 21 to 42 watts in the high-power setting. The radio set is designed to be compatible with all standard Army HF and FM sets when utilizing appropriate modes and frequencies. Compatibility with standard voice security equipment provides the capability of secure communications in the FM mode. Additionally, burst communications can be accomplished in the CW and FSK modes by utilizing appropriate ancillary equipment. (For example, see figure C-2, Coder-Burst Transmission Group AN/GRA-71.) Retransmission capability is provided by using two AN/PRC-70 radio sets in conjunction with an interconnecting cable (Retransmission Cable MK-456) designed for this purpose (fig C-3).
The BB-542/U, a 2 ampere-hour (AH) sealed, fast-rechargeable NICAD battery, is for use with the AN/PRC-70 system. A special battery box is required to contain appropriate lithium batteries.
Power Supply PP-6148.
The PP-6148 is a portable, AC battery charger/power supply providing 0 to 10 amperes at 14 or 28 VDC from 115/230 volts, single phase, 50, 60, or 400 Hz AC power sources. This item is used to power the Radio Set AN/PRC-70 and to recharge NICAD batteries.
Direct Current Generator G-76.
This generator is a lightweight, hand-cranked generator providing 30 to 32 VDC output at a maximum of 200 watts developed at a cranking speed of approximately 80 RPM. This item will power the radio set directly for short-duration burst transmissions and will charge rechargeable NICAD batteries.
Figure C-2. Coder-Burst Transmission Group AN/GRA-71.
Figure C-3. Retransmission configuration.
Digital Message Device Group OA-8990( )/P.
This device, which weighs two to three pounds including self-contained rechargeable batteries, is a hand-held, microprocessor-controlled message terminal designed to originate alphanumeric information in either free or 5-letter format. The device provides storage of 1,000 characters in transmit-partitioned memory, and 2,000 characters in the receive-partitioned memory. Messages may be edited, stored, and transmitted at 300 or 1200 BPS utilizing the American Standard Code for Information Interchange (ASCII) 7 bit code, audio FSK over HF, VHF, or UHF satellite radios. The unit features a 32-key standard typewriter style keyboard and a 16-character liquid crystal display. The device is powered by a rechargeable NICAD battery.
Secure communications may be obtained by use of COMSEC devices when operating in both the VHF and UHF frequency ranges.
The Radio Set AN/PRC-70 is installed and operated by field radio operators in field environments within tactical and strategic communication nets as required by the mission assigned. Special signal operation instructions (SOI) are developed and specifically tailored to support these widely varying missions by type organizations and required net structures Specific installation configurations are dependent upon the specific net requirements of these organizations. Power Supply PP-6148 instead of batteries may be selected to directly power a radio set installed in a semi-fixed installation. In support of special operations (SO) of short duration, lithium batteries may be chosen instead of rechargeable batteries.
The Radio Set AN/PRC-70 is organic to the special forces (SF). Operational detachments employ the radio set to provide command and control communications to the special forces operational base (SFOB)/forward operational base (FOB). These operational bases are normally established in theater rear areas. Operational detachments/elements deploy deep behind enemy lines to conduct unconventional warfare (UW) and special operations missions. Additionally, special forces perform foreign internal defense (FID) missions. Special forces units normally install field wire antenna systems designed around required directional characteristics, and specifically selected to provide maximum gain to support both medium (VHF-FM) and long-range (HF) communications requirements. SF message traffic is normally transmitted in the burst mode between stations operating within SFOB/FOB signal centers to a maximum of 36 deployed operational detachment elements at distances of up to 4000 kilometers. The blind transmission broadcast method of contact is normally employed.
Ranger Battalion and Long Range Reconnaissance Patrol Company.
The Radio Set AN/PRC-70 is organic to each ranger battalion and long range reconnaissance patrol company (LRRP) which are corps assets. These radios are employed to provide both short-range and long-range command and control communications between established headquarters base stations and deployed operational company/platoon/patrol in support of Army corps operations. Ranger and LRRP units normally install antenna systems designed to be erected rapidly and support short- to long-range communications.
Engineer (ADM) Company.
The Radio Set AN/PRC-70 is organic to atomic demolition munitions (ADM) engineer companies to provide near real-time secure command and control communications as required in support of the unique mission requirements of these units. Engineer units normally install antenna systems designed to be rapidly erected and to support their radio network communications.
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