The U.S. Army has ordered another hundred AN/TPQ-53 artillery spotting radar systems, after having delayed that order until some problems with the first batch were diagnosed and fixed. Back in 2012 the army finally began replacing its older AN PQ-36/37 FireFinder artillery spotting radar with the new and improved AN/TPQ-53. While the new system was an improvement the army began getting more and more reports from users in combat zones of false positives (the radar showing something incoming when there wasn’t anything) as well as difficulty distinguishing between artillery shells, rockets and mortar shells. There were also reports that the new system did not handle multiple incoming shells well, being unable to provide data on where it was all coming from. The army halted distribution after 38 of the new systems went into service and delayed production of another hundred until the problems could be fixed. A series of tests were conducted in 2015 to document the problems so the manufacturer could fix them. These fixes have been completed and verified by more tests so now manufacturing can continue.
Despite the problems the new system was seen as an improvement. Troops in Afghanistan continued 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). For the troops in Afghanistan the TPQ-53 was a success because the most common threat was individual mortar shells being fired at a base. The TPQ-53 was faster and more reliable at dealing with that.
The AN/TPQ-53 had been sent to Afghanistan for final testing in 2010. In early 2012 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 could also scan all around (360 degrees), rather than just 90 degrees (as with the older system), and was faster as well. The army wants to buy at least 180 TPQ-53s, for about $9 million each. The older FireFinder is cheaper and still gets the job done. This is why some countries (like Iraq) 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 spot 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 also introduced some new components that were more reliable and easier to maintain.
There were still problems. 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 back in the 1970s, 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 TPQ-53 won’t replace a significant number of them until the 2020s.