October 23, 2012:
The U.S. Army is finally replacing its older AN PQ-36/37 FireFinder artillery spotting radar systems with the new and improved AN/TPQ-53. Troops in Afghanistan continue to call the new version "FireFinder" or "counterfire radar" even though the new TPQ-53 is a visibly new and different looking system, each consisting of two trucks (one for the radar the other for the control center and backup generator).
Two years ago the U.S. sent the AN/TPQ-53 to Afghanistan for final testing. Earlier this year the army ordered 51 of the AN/TPQ-53 systems. Easier to use and repair, as well as more reliable than its predecessor (the AN/TPQ-36/37), the TPQ-53 can also scan all around (360 degrees), rather than just 90 degrees (as with the older system), and is faster as well. The army wants to buy at least 180 TPQ-53s, for about $9 million each. But so far the army only has money to buy about fifty of them. The older FireFinder is cheaper and still gets the job done. This is why some countries (like Iraqi) want it. Many Iraqis have seen the older FireFinder in action. They know it works.
The older FireFinder (AN/TPQ-36/37) radar had to overcome a bad reputation it acquired when it first came to Iraq. That was often for failing to detect incoming mortar fire. These were problems that were fixed. FireFinder was developed in the 1970s, based on Vietnam experience with enemy mortar and rocket attacks but didn't get a real combat workout until after September 11, 2001.
Both the old and new FireFinders are radar systems which, when they spots an incoming shell, calculates where it came from and transmits the location to a nearby artillery unit, which then fires on where the mortar is (or was). This process takes 3-4 minutes (or less, for experienced troops). FireFinder worked as advertised but got little use until U.S. troops entered Iraq. After that FireFinder was very effective and heavily used. Too heavily used. There were not a lot of spare parts stockpiled for FireFinder and several hundred million dollars-worth had to be quickly ordered. The manufacturer has also introduced new components that are more reliable and easier to maintain.
Some FireFinders failed to catch incoming fire because the enemy was using tactics that fooled the radar. For example, in Iraq American bases were generally on higher ground than the mortars firing at them. Putting bases on the high ground enables you to watch more of the surrounding terrain. But FireFinder needs a line-of-sight to get a good fix on the firing weapon's position. If the mortar was too far below the radar, FireFinder could not accurately spot where the fire was coming from.
Another problem was that if the mortar was too close FireFinder was much less likely to quickly determine where the fire was coming from. So the enemy mortar teams got as close as they could before firing. This still made the mortar teams vulnerable to counterattack by coalition troops but not the immediate (in a few minutes) artillery fire that FireFinder can make happen under the right conditions.
At first, the army was going to halt further upgrades on FireFinder, which, after all, was developed over thirty years ago, and begin developing the TPQ-53, a new system that can better deal with the kinds of problems encountered in Iraq. But FireFinder had been so useful that new upgrades were pursued anyway, while work continued on the TPQ-53. The upgrades have also been made available to other users of FireFinder (including allies in the Middle East, Egypt, Israel, Jordan, Saudi Arabia, and Turkey). FireFinders are still doing most of the work out there, and it will be several years before TPQ-53 replaces a significant number of them.