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Military communications equipment may lack the pocket-sized convenience of a modern smart cellular phone, but it must endure punishing operating conditions and deliver secure communications at all times. The need for ruggedness can add size and weight to mobile military radios, which is acceptable if the radio works as designed. Modern mobile military communications equipment come in many forms—from point-to-point terrestrial radios to satellite-based systems for greater range—with the goal always the same: get the message through.

Troops from different branches of the U.S. military have long suffered from incompatibilities in communications equipment. Whether in frequency, bandwidth, modulation scheme, or some other parameter, each branch typically specified gear in such a way that made networking among the different branches difficult (if not impossible). The Army, for example, still relies on high-frequency (HF) terrestrial line-of-sight portable radios in the frequency range from 1.6 to 30.0 MHz and beyond.

Fig. 1

The Joint Tactical Radio Systems (JTRS) program attempted to develop some form of universal tactical radio that could serve all branches of the military, using software-defined-radio (SDR) technology to change the nature of the radio as needed for different applications and operating conditions. If anything, the JTRS program has helped accelerate the adoption of SDR technology in tactical radios and added to their performance levels and flexibility, while pushing the development of smaller, more portable tactical communications equipment that could be used anywhere at any time (Fig. 1).

Newer tactical radios are taking to the sky—for greater range via connections with orbiting satellites—and taking more after their commercial counterpart, the cellular telephone, than ever before.  The Navy’s Mobile User Objective System (MUOS) is a satellite-based communications network that is being developed to provide military personnel with ruggedized, secure versions of cellular telephones. The system is based on five geosynchronous orbiting satellites (four active and one serving as a spare), with the fifth satellite about to be launched in May 2016 (Fig. 2).

Fig. 2The satellites, in orbit about 22,300 miles above the Earth, are managed by Lockheed Martin, while the MUOS ground communications equipment is being manufactured by General Dynamics Mission Systems and others. Satellite launches began in 2012. The satellite communications (satcom) network is expected to serve all branches of the  military and compatriots in support of inter-branch networking.

An example of the system’s mobile radio—the AN/PRC-155 from General Dynamics—was recently validated by the Army for use on the MUOS network during field trials, primarily in the Hawaiian Islands. The two-channel SDRs were used with the MUOS network to connect soldiers in that region (Fig. 3), helping soldiers talk, share data, and maintain communications on board military vehicles. In addition to the MUOS waveforms, the radios support a number of other tactical radio waveforms, including SINCGARS, SRW, WNW, high-frequency (HF) and single-sideband (SSB) communications.

While not quite as compact as a cellular smartphone, the AN/PRC-155 is small as far as traditional tactical radios go, measuring 3 × 10.1 × 7.8 in without battery and 3.0 × 10.1 × 12.5 in. with battery bucket. It weighs 9 lb. without the battery pack and 14 lb. with the battery.

The AN/PRC-155 (Fig. 3) can operate from 2 MHz to 2.5 GHz in bands. It is capable of transmit power levels to 20 W on its own and as much as 5 W transmit power with the addition of external amplifiers. The MUOS network, which provides considerably more capability than the legacy tactical satcom system, employs a secure waveform developed by General Dynamics as an offshoot of wideband-code-division-multiple-access (WCDMA) technology used in Third-Generation (3G) cellular telephone networks.

An AN/PRC-155 works with JTRS APIs and has full JTRS compliance for compatibility with other tactical radios in the field. It is also versatile mechanically, and can be used as a manpack radio or with the appropriate hardware as a vehicular radio. 

Fig. 3It is compatible, for example, with the AN/PRC-154 Rifleman Radio (Fig. 4) produced by General Dynamics C4 Systems (Phoenix, AZ), an SDR capable of transmitting SRW signals. This terrestrial line-of-sight radio operates across frequency ranges of 225 to 400 MHz, 1,250 to 1,390 MHz, and 1,755 to 1,850 MHz. It was designed to create mobile, self-forming networks with similar radios and includes a Global Positioning System (GPS) receiver for precise position location.

As with the AN/PRC-155 (with which it seamlessly communicates), the AN/PRC-154 is software programmable and upgradeable and functions very much like a cellular telephone. It can also be used as a carried, armor-worn, or vehicular radio. With the aid of a satellite, however, it has a communication range limited to about 2 km when operating with about 5 W transmit power. It weighs 0.95 lb. without a battery,1.69 lb. with the rechargeable battery, and measures 7.5 × 2.5 × 1.7 in.

Fig. 4The AN/PRC-154 Rifleman Radio communicates with classified and non-classified networks. It operates over temperatures of -40 to +55°C and features JTRS-compliant APIs. For flexibility, it operates with USB and RS-232 ports for displays and radio control. It will run about 9 h on a battery charge, and can even work with a commercial battery and its associated charger.

In terms of enhancing satcom technology for tactical use, Hughes Network Systems, LLC has devoted a great deal of work to the refinement of its advanced time-division-multiple-access (TDMA) waveform technolog. The company, recently tested its satcom waveforms under a variety of conditions during the biannual Talisman Sabre event with Australian and U.S. military forces.

While satellites provide convenience and long-distance communications, short-distance communications is often all that is needed in tactical situations. Conventional manpack radios, often considered as glorified walkie-talkies, generally provide reliable point-to-point communications in these situations. The Falcon II line of tactical manpack portable tactical radios from Harris Corp. is an example of how SDR technology is providing flexibility and adaptability to battlefield communications—for example, in the AN/PRC-150(C) tactical radios (Fig. 5).

The multiband radio operates SSB at HF and with frequency modulation (FM) at VHF, with a frequency range that runs to 60 MHz for secure frequency-shift-keying (FSK) voice and data rate of 16 kb/s at VHF. The portable radios transmit with as much as 20 W peak envelope power (PEP) and as much as 10 W FM output power.

The radios are certified by the National Security Agency (NSA) for U.S. Type 1 voice and data encryption compatible with ANDVT/KY-99, ANDVT/KY-100, VINSON/KY-57, and KG-84C cryptographic devices, eliminating the need for external encryption. The radios also include a Citadel encryption mode for secure communications with coalition forces.

Fig. 5

Operating at these lower frequencies (1.6 to 60 MHz), an AN/PRC-150(C) tactical radio is considerably larger and heavier than a MUOS satellite radio modeled after a cell phone. The Falcon II radios operate across temperatures from -40 to +70°C and have been long trusted for their durability and reliability. However, they are also built to last, measuring 10.5 × 3.5 × 13.2 in (26.7 × 8.1 × 34.3 cm) with battery case and weighing 10 lb. (4.7 kg) without batteries.

In addition to the Army’s manpack radio needs, Harris has contributed to the advancement of vehicular radios for secure, mobile communications—in particular, the Mid-Tier Networking Vehicular Radios (MNVRs). MNVRs are vehicle-mounted modular radios capable of running SDR waveforms to create a secure wireless network on the battlefield for effective ground communications. They are capable of forming a dynamic, scalable on-the-move (OTM) network architecture to connect soldiers to mission command.

Fig. 6

MNVRs from Harris Corp. (Fig. 6) are based on the Falcon line of manpack radios. They provide ground-level connectivity with rapid exchange of voice messages, images, and videos, enabling the creation of secure, mobile networks on the battlefield.

In terms of exploring new technologies, Silvus Technologies has helped to demonstrate multiple-input, multiple-output (MIMO) radio technology for potential military users in the form of its StreamCaster MIMO radio for tactical applications. The approach, which is meant to boost communications range and capacity, is another example of commercial technology, as used in Fourth-Generation (4G) cellular communications systems, “leaking” over to the military side to the benefit of the warfighter. The technology is designed into the firm’s mission-critical radio.

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