The Maanim is thought to combine the use of radar, UAVs and human observers to detect the rockets, which take about 30 seconds to get from Gaza to their target. The reason for so many different components is to, as much as possible, eliminate false alarms. The more false alarms there are, the more people will ignore the alarms, and be vulnerable when rockets do land. Moreover, the voters get upset if there are a lot of false alarms. So multiple sensors, reporting to an automated system that can count the votes and set off the alarm, wound minimize false alarms.
Israel has developed an early warning system for use against crude Palestinian Kassam rockets being fired at a town two kilometers north of Gaza. The Maanim (Point of Origin) system is a one of a kind, and is thought to combine several different systems. The Israelis are not giving any details, lest the Palestinians have an easier time figuring out a way to fool the system. In its first combat test, on October 13th, Maanim gave the residents of Sderot 20 seconds warning that two rockets were incoming. Everyone hit the ground or scrambled for shelter, and no one was injured as the rockets landed and exploded in fields outside town. The Palestinians have fired over 325 Kassam rockets in the past four years, and the number is increasing. One a day was fired during September. But in the last sixteen weeks, four Israelis have been killed by the rockets. No democracy can stand by and let rockets be fired at its citizens without doing something.