AN/ALQ-135 Tactical Electronic Warfare System
The AN/ALQ-135 is an internally mounted active jamming system carried on the F-15C and F-15E designed to defeat electronic threats. It is comprised of Bands 1&2 (low-med freq), Band 3 (med-high freq), and (future) Band 1.5 (low-med freq). The system provides low band jamming capability for the F-15E, contributing to increased survivability against low band threats. A Strike Eagle's AN/ALQ-135 tactical electronic warfare system [TEWS] can jam radar systems that operate in high frequencies, such as radar used by short-range surface-to-air missiles, antiaircraft artillery and airborne threats.
TEWS is an integrated countermeasures system. Radar, radar jammer, warning receiver and chaff/flare dispenser all work together to detect, identify and counter threats posed by an enemy. For example, if the warning receiver detects a threat before the radar jammer, the warning receiver will inform the jammer of the threat.
The addition of new hardware and software, known collectively as Band 1.5, will round out the TEWS capability by jamming threats in mid to low frequencies, such as long-range radar systems. Central to the new capability's success are compact computer modules that calculate the best way to jam specific types of detected radar systems. Since computers have become smaller and faster in recent years, there is room for several of these modules in an F-15E, allowing TEWS to jam more targets simultaneously.
The upgraded ALQ-135 is a two-band system, designated as Bands 1.5 and 3, for use on newer models of the F-15. The designations refer to two portions of the radar frequency band covered. The older F-15C aircraft is being equipped with only the Band 3 because the original ALQ-135, which is already installed, covers the frequency band of the Band 1.5. Band 3, therefore, will provide extended frequency coverage for the F-15C. The newer F-15E, which does not have the original ALQ-135, is supposed to be equipped with Band 1.5, as well as Band 3.
A 1990 GAO Report (Electronic Warfare: Need to Strengthen Controls Over Air Force Jammer Programs (GAO/NSIAD-90-168, July 1, 1990)), noted that the Air Force had started production of several jammers, including the upgraded ALQ-135, without adequately testing their performance capability. The report had also noted that the upgraded ALQ-135 units that had been produced were in storage because of software design problems.
A 1994 GAO Report found that the Air Force had continued procurement of the ALQ-135 Band 3 despite its deficient performance, resulting in the premature deployment of systems with limited capability to protect the F-15. While developmental testing showed the Band 3 to have serious performance flaws, the Air Force had already procured most of its total program quantity without demonstrating acceptable operational performance. These performance problems were reported to be compounded by other deficiencies. By the time of that report, the Air Force had deferred further production of the Band 1.5, with information on the impact of this deferral on the F-15E's survivability classified by DOD.
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