Israel is once more going to try electronic detection systems to guard its borders. In this case, it is installing a new generation of sensors between a number of Palestinian villages and Jerusalem. For over forty years, electronic sensor designers have been promising the military a system that would be accurate, and rugged, enough to actually work. Hasn't really happened yet. But during those decades, new systems have constantly appeared, and been replaced by better ones. While no one was looking, electronic detection systems have become a lot more capable than they were in the 1960s. The Israelis must believe so, because the areas, where they are installing these systems, are popular crossings for Palestinian suicide bombers. If this particular electronic barrier fails the test, there will be quite an uproar. But in the last few years, electronic detection systems along Israel's land and sea borders have apparently been very successful. Israel doesn't talk much about it, lest potential infiltrators gain useful insights on how the system works, and how to defeat it.
The new detections systems, like most electronic devices that have been around for nearly half a century, have gotten more numerous, reliable and sensitive. But the big change has been in the addition of microprocessors and software that enable the devices to, well, "think." Pattern recognition (including video cameras that can make out shapes) makes the devices smart enough take over the tedious task of monitoring themselves, and only alerting human operators when there is a high probability that someone is up to no good out there. The new generation of sensors increase effectiveness with the sheer number of different devices that can be deployed. All small, and hard to spot, they include, besides video and acoustic (microphones), seismic (earth vibrations) and heat sensors. Anyone, or anything, trying to get past such an array of sensors, will have a very difficult time.
Similar systems are sold to commercial users, but because of the need for secrecy (to prevent criminals or terrorists from obtaining information helpful in getting past the systems), little is publicly known about many of these systems. The military versions are even more shielded from public scrutiny, as these are used to guard things like nuclear weapons and top secret projects.