series of anti-radiation missiles for Indian Air Force. SIATT with Department of Aerospace Science and Technology of Brazilian Air Force are jointly developing MAR-1. Surface-to-surface Several surface-to-surface missiles, like the P-700 Granit, P-500 Bazalt, MM40 Exocet, B611MR, and Otomat, include a home-on-jam capability wherein the receiver component of their active radar homing is used to home in on enemy radar, ECM or communications. This makes these missiles significantly harder to defeat with ECM and distraction countermeasures, and makes the use of semi-active missiles against them dangerous. Surface-to-air Due to experiences with jamming by US-built aircraft in Vietnam and during Middle Eastern wars in the late 1960s, the Soviet Union designed an alternative tracking mode for their S-75 (SA-2) missiles, which allowed them to track a jamming target without needing to actively send out any radar signals. This was achieved by the SAM site's radar receiver locking on to radio noise emissions generated by an aircraft's jamming pod. In cases of heavy jamming, missiles were often launched exclusively in this mode; this passive tracking meant that SAM sites could track targets without needing to emit any radar signals, and so American anti-radiation missiles could not be fired back in retaliation. Recently, the People's Republic of China developed the FT-2000 system to counter AEW and AWACS targets. This system is based on the HQ-9, which is in turn based on the S-300PMU. These anti-radiation missile systems have been marketed to Pakistan and various other countries. Air-to-air More recently, air-to-air ARM designs have begun to appear, notably the Russian Vympel R-27EP. Such missiles have several advantages over other missile guidance techniques: they do not trigger radar warning receivers (conferring a measure of surprise) and they can have a longer range. In the 1970s, Hughes Aerospace had a project called BRAZO (Spanish for ARM). Based on a Raytheon AIM-7 Sparrow, it was meant to offer an air-to-air capability against proposed Soviet AWACS types and also some other types with extremely powerful radar sets, such as the MiG-25. The project did not proceed. See also DRDO Rudram AGM-88 HARM ALARM Kh-58 TC-2A Hormoz-2 References General references Russian site on the S-75 from Said Aminov "Vestnik PVO" External links Guided missiles by mission Electronic warfare Air-launched missiles Air-to-surface missiles