The Single-Channel Ground and Airborne Radio System (SINCGARS) is a very high-frequency, frequency-modulation combat net radio developed by the Army supporting the Joint Vision 2010 operational concepts of dominant maneuver, precision engagement, focused logistics, and full-dimensional protection. SINCGARS provides secure, jam-resistant communications primarily for units conducting land battle. It enables secure communications by transmitting tactical voice and data using communications security (COMSEC) and frequency-hopping techniques. SINCGARS is also capable of operating in the single-channel (single-frequency) mode for interoperability with older radios.

Recently, the new SINCGARS System Improvement Program (SIP) radio has been used with the Tactical Internet (TI) to support the Army digitization of the battlefield program. The SINCGARS SIP radio is the same physical size as the previous radio, but incorporates forward error correction, higher data rates, packet technology, and the Internet Controller (INC). The TI is the network of radios and routers, which provide connectivity across the battlefield. The TI comprises the Enhanced Position Location Reporting System (EPLRS), SINCGARS SIP radios, and the INC router.

The second major modification to the radio is the current Advanced SIP (ASIP). The ASIP radio is a new manpack radio that has been adapted from the SINCGARS airborne radio. ASIP radios will replace the SIP radios in the Army Force Package 1 and 2 units. The ASIP radio incorporates programmable digital signal processing technology and is significantly smaller than the existing radio. The ASIP radio reduces the weight of a manpack SINCGARS radio from 18 pounds to 8 pounds, improves reliability, and extends the battery life by incorporating low power technology. The ASIP radio incorporates a redesigned and more user-friendly, man-machine interface via flat-panel technology.

The Army began SINCGARS development following approval of a requirements document in December 1974. International Telephone and Telegraph (ITT) was awarded a contract to produce SINCGARS in 1983. ITT produced two versions of the SINCGARS. The current SINCGARS has an integrated communications security (ICOM) module and is designated the SINCGARS ICOM. The original design, the non-ICOM radio, uses existing KY-57 COMSEC devices. The Defense Systems Acquisition Review Council (DSARC) reviewed the program in October 1984 and approved the Army's request to award the first option. The DSARC decision memorandum provided guidance to plan testing of the radio when it was modified for ICOM and to seek a second source. ITT and the second source, General Dynamics, built ICOM radios with different internal designs that are interchangeable in form, fit, and function.

The ITT ICOM IOT&E was conducted in 1990 at Ft. Hood, TX. A SINCGARS Follow-on Operational Experiment was also conducted at Ft. Hood in October 1990. The experiment investigated changes to the ITT radio to improve data message-completion rates during jamming and mutual interference. The IOT&E and Follow-on Operational Experiment data supported Defense Acquisition Board approval of full-rate production for the ITT ICOM radio.

SINCGARS second-source IOT&E was conducted at Ft. Hood between 1992-1993. The results of the second-source IOT&E supported a Milestone-IIIB full-rate production decision for General Dynamics. In April 1995, the Army briefed a SINCGARS SIP to the OSD, C3I Committee. The SIP included several enhancements: (1) improved data performance; (2) position locating and reporting (with an external Global Positioning System); (3) reduced weight; (4) simplified operations; and (5) interface to the common user system.

The SINCGARS SIP radio and INC were part of the TI that supported the Force XXI Advanced Warfighting Experiment (AWE) that began at Ft. Hood in June 1996, and culminated at the National Training Center in March 1997. There were a number of performance problems identified that related to the SINCGARS SIP/INC role in the TI, and resulted in poor message completion rates and speed-of-service. The corrections to these problems include: (1) improvement of the Noisy Channel Avoidance Algorithm. The SINCGARS transmitting radio is capable of detecting a noisy channel, and the radio avoids noisy channels in the hopset; (2) reduced Net Fragmentation. During the Force XXI experiment, it was possible for two SINCGARS SIP radios to sense an open net and transmit at the same time. This rapid response occurred because SINCGARS' receivers require 99 milliseconds to recognize an open net. The ASIP radio has reduced the net capture time to 19 milliseconds; and (3) improved tactical Internet performance. The memory limitation of one megabyte in the original integrated circuit has been increased to eight megabytes, and separate queues have been incorporated for command and control, and situational awareness message traffic. These improvements will be in both the SINCGARS SIP and ASIP variants.

An ASIP Customer Test was conducted during FY98 with a battalion from the 82nd Airborne Division, Ft. Bragg, NC. This test was a two-week event designed to test the SINCGARS ASIP radio in a non-digital environment, and ensure compatibility with legacy systems in the secure-voice, frequency-hopping mode.

The new TI architecture for the Force XXI Battle Command, Brigade and Below (FBCB2) Program was tested in the May 1998 Development Test-1, employing approximately 60 SINCGARS SIP radios. During the August 1998 Limited User Test (LUT) for FBCB2, approximately 200 SINCGARS SIP radios were employed by a Battalion Task Force at Ft. Hood. These two tests were conducted to confirm fixes to many of the TI problems identified during the Force XXI AWE, and assess progress towards the objective capability. The TI will also be tested in the October 1999 FBCB2 IOT&E, in which 1,500 ASIP radios will participate.

The SINCGARS ICOM radio is operationally effective and suitable for combat, based on operational tests employing both the ITT and General Dynamics designs.

In its role as a critical element of the TI, in conjunction with the EPLRS radio, the data for the SINCGARS SIP collected during the 1997 Force XXI AWE indicated that the message completion rate and speed-of-service were below expectations. Development Test-1 results demonstrated significant improvements over AWE results: command and control message completion rates increased from approximately 30-80 percent, and speed of service decreased from approximately three minutes to less than four seconds. Although these results were reflective of performance in a technical environment, similar improvements were also observed during the more operationally realistic LUT. Whether these results are "scalable" from a battalion task force to a brigade task force was another goal of the LUT evaluation. Although the "scalability" evaluation is incomplete, and may not be supported by the data available from the LUT, there are observed trends that indicate the situation awareness message completion rates and speed-of-service were degraded as the number of transmitting platforms increased during this battalion-level test.

Testing and evaluation from FY99-FY00 for the FBCB2 Program will determine whether SINCGARS SIP improvements adequately support the requirements of the digital battlefield.