One of the more powerful electronic counter-measures systems available is the ALQ-162. This system weighs less than 50 pounds (with antennas that are located on various parts of the aircraft). The main unit is a 40 pound 17x8x7 inch box that needs 650 watts of power. The ALQ-162 detects a wide array of radar signals, alerts the pilot to ones that are potentially dangerous, and can jam most of them. This is done using DRFM (Digital Radio Frequency Memory), which transmits back to the enemy radar a distorted return signal (which shows the wrong position of the ALQ-162 equipped aircraft).
The ALQ-162 is easily reprogrammed, to enable it to be updated with new information on enemy radars. Defeating DRFM is largely a matter of having software that can determine which radar return signal is real, and which is generated by DRFM. This is not easy, and the U.S. is careful who they export ALQ-162s equipped with DRFM to, so that potential enemies (like China). For that reason, Pakistan got ALQ-162s without DRFM.