Tactical radios are the communications lifeline of the warfighter, providing invaluable information in the field—often under hostile circumstances—where no failure is acceptable. Whenever a new radio is introduced by one of a handful of proven and trusted suppliers, skepticism is to be expected over whether it will improve upon what came before. For its part, the new SRX 2200 Combat Radio from Motorola Solutions has a rich heritage of military and public-service systems from which to draw technology, functionality, and features. The SRX 2200 has been designed for backward and forward compatibility with all Motorola mission-critical radios, including those based on the Project 25 (P25) public safety and homeland security standard. The SRX 2200 borrows the ease of use of the company’s widely used APX™ series of portable two-way radios and the scalability of a design approach based on commercial-off-the-shelf (COTS) components.

The SRX 2200 (see photo) is billed as the next generation of the AN/PRC-153 Integrated Intra-Squad Radio (IISR) developed by Motorola, which has been employed by the United States Marine Corps. The SRX 2200 features a wide-dynamic-range radio receiver capable of 80-dB performance across its frequency range, allowing for improved coverage and audio quality compared to other P25 radios. The radio is compliant with United States Department of Defense (DoD) standards for waveform structure and encryption capabilities, and meets Federal Information Processing Standard (FIPS) 140-2 Level 3 security requirements for deployment in extremely sensitive environments.

The SRX 2200 radio is powered by a suite of communications applications and features, such as secure encrypted voice and text messaging, over-the-air programming (OTAP), individual location information (ILI), and even biomonitoring of radio users. The radio meets MIL 810 environmental requirements and exceeds IP67 submersion requirements—it will still be usable after having been submerged under 2 m of water for two hours. A multiple-unit charger makes it possible to charge the radio from a vehicle or other power source at extremely high operating temperatures.

Paul Mueller, Vice President for Motorola Solutions’ US Federal Government Markets Division, explains that “The SRX 2200 Combat Radio is an easy-to-use, rugged device that was designed specifically for military operations. The SRX 2200 has a full set of tactical voice and data capabilities, including encrypted voice and texting, which makes it an ideal grab-and-go radio for squads in distributed operations as well as for on-base personnel.”

The SRX 2200 combines the attributes of an AN/PRC-153 radio and a P25 design. For tactical use, an AN/PRC-153 IISR actually consists of two components: the radio and the tactical headset. Based on digital technology, the AN/PRC-153 radio is an ultrahigh-frequency design, developed for voice communications from 380 to 470 MHz. It is capable of analog and digital operation with a maximum transmit distance of 1 km using as much as 5 W transmit power. It ensures security through the use of Advanced Encryption Standard (AES) 256-b encryption. The headset is designed to analyze the surrounding environment and to provide hearing protection based on detected audio. A dual switch connection on the headset provides interoperability with legacy tactical radios.

P25 radios draw upon a set of standards for digital radios in use by federal, state, and local public safety users, ensuring interoperability among different radio platforms from different manufacturers. Since P25 radio designs are used for land mobile radio (LMR) services for government agencies, they must be able to operate in analog mode with legacy radios and in digital or analog mode with other P25 radios. Project 25 came about in 1989 in cooperation with the Association of Public Safety Communications Officials (APCO), the US Department of Defense (DoD), the National Security Agency (NSA), the National Telecommunications and Information Administration (NTIA), and various other national organizations. Their intent was to promote interoperability of the digital two-way radios emerging at that time.

Two-way P25 radios such as the SRX 2200 can operate in different modes, communicating either directly with other radios in the field, or through repeaters when operating as a form of ad hoc network in the field. The radios can communication in a conventional mode, where two radios link through a repeater or base station without trunking, or in a trunked mode where the repeater or base station assigns channels to different users on the network. As one form of security, P25 radios employ a network access code, which is a 12-b prefix code for every packet of data sent by a radio through the network. A radio can be programmed to respond only to specific codes, thus preventing unauthorized users from joining a conversation.

For reliability, the SRX employs one of the waveforms developed for the Joint Tactical Radio System (JTRS), an ambitious program to create a “future-proof” tactical radio system which was cancelled late in 2011 (due to its failure to produce satisfactory results or progress). The advanced waveforms developed as part of that program were designed to make the most efficient use of available bandwidth while also providing secure and reliable communications. Although the JTRS program was cancelled, it provided a great deal of insight into advanced tactical communications waveforms, and essentially paved the way for the emerging development of software-defined radios (SDRs).

Ergonomically, the SRX 2200 Combat Radio has been designed for ease of use under often less-than-ideal operation conditions, whether used for voice or data. When used for data links or for communications to groups, it can be quickly switched to different operating modes through its OTAP capability. In addition, its Over The Air Rekeying (OTAR) functionality makes it possible to quickly command modem or data link capability from any position in the field. The SRX 2200 borrows from lessons learned with the firm’s APX radios, featuring large controls that are well spaced and easy to locate. The radio’s display is easy to read but can also be dimmed for added security.

Will the SRX 2200 be the last radio the military will ever need? Probably not, given the ongoing issues with interoperability, but ease of use is still a key to the effective use of a tactical radio. The SRX 2200 is an attempt to achieve that ease of use.