March 27, 2024: NATO has sent the Ukrainians a number of artillery items, including guns, ammunition, and fire location radars. The ammunition included special types of 155mm shells. The most useful and economical accessory for 155mm shells was the PGK (Projectile Guidance Kit) 155mm fuze. The PGK fuze turns an unguided 155mm shell into a GPS/INS guided one. These were found to be exceptionally useful in Syria and Iraq and, in mid-2017, the U.S. Army ordered another 5,600 PGK fuzes and has been building a stockpile. This enabled the U.S. to send Ukraine large numbers of PGK fuzes. While armies still use unguided artillery shells for situations that don’t require precise accuracy, the PGK fuze is available to quickly turn any standard unguided shell into a guided smart shell. Many PGK fuzes were sent to Ukraine. It was found that PGK fuzes worked well particularly with the Zusana-2 8x8 155mm self-propelled artillery systems that western neighbor Slovakia purchased and then sent to Ukraine. Zusana-2 is highly automated with a modern fire control system so it can, in less than a minute, halt, fire one or two PGK equipped shells with the location data provided by FireFinder to destroy Russian artillery, and then move on before being targeted itself. Russia too has counterfire radars and guided shells, but no combination of radar and guided shells quick enough to catch Zuzanna-2s when it is employing such shoot and scoot tactics. The Zuzanna-2 armor offers some protection from shell fragments and blast effects on equipment and its three-man crew.

Ukraine also received Excalibur GPS guided 155mm shells from several NATO countries. Excalibur is more accurate than a shell with a PGK fuze but a lot more expensive. A PGK fuze will give a 50 meter CEP at all ranges a shell can reach versus 170 meters for an unguided shell at maximum range. The Excalibur is dealing 6 to 10 meters at all ranges. For unguided shells, accuracy gets worse the farther you fire it. Excalibur achieved the same results as 40 unguided shells at maximum range. For example, when you fire an unguided 155mm shell as far as 17 kilometers, the shell has a CEP, or circular error probable of up to 170 meters. A shell with a PGK fuze shell has a 50 meter CEP at all ranges. That is a major improvement over unguided shells but still not as precise enough for some missions. Currently the $200,000 GPS guided Excalibur shell will land within ten meters of the target. A shell equipped with a $20,000 PGK fuze can land within 50 meters with a new version being developed that will achieve 30 meter CEP. The GLMLRS missiles fired from Himars vehicles have a three meter CEP.

Ukraine received several older FireFinder (AN/TPQ-36/37) radars that were used to locate enemy artillery that had fired shells at targets within about twenty kilometers of the radar. The location of the enemy artillery was passed to Ukrainian artillery which fired one or two guided shells at the target, or a larger number of unguided shells. The guided shells were much more effective because enemy artillery would quickly move if they were being hit by artillery shells. Soon after the first shell landed, the enemy artillery was gone, unless it was damaged or destroyed by the first shells to land. This tactic of firing back at enemy artillery is called counter-battery fire and is the best way to reduce enemy artillery capabilities.

The key to counter battery fire is the specialized radar that detects the location of enemy artillery. There is a problem, however, in that you cannot realistically test the effectiveness of artillery detection radars. An example of this was the American FireFinder radar. This system has had a lot of problems in the past. These were discovered after the United States went to war after the 2001 terror attacks.

The war initially took place in Afghanistan and Iraq. FireFinder 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 supposed to be 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 2001.

Both the old and new FireFinders are radar systems which, when they spot an incoming shell, calculate where it came from and transmit 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 under combat conditions 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. 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. These 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 end of the decade.

The AN/MPQ-64 Sentinel entered service in 2007 and over 300 of them are currently in use. Sentinel is light and compact enough to be trailer mounted and towed or mounted in the back of a 4x4 truck along with a generator. Sentinel can be ready for action in less than 15 minutes and ready to be moved again in less than ten. Some Sentinel users are East Europe NATO members and Ukraine received Sentinels, which quickly received lots of use in combat.

FireFinder and Sentinel were designed to operate together, merging their data into a single display of all aerial and ground-based threats detected and being tracked, American troops trained Ukrainians personnel on how to use both systems. Ukraine was also using its own joint operation software for the two systems. Ukrainians proved more adept at dealing with systems like this than the Russians, and used FireFinder/Sentinel to establish widespread protection against Russian low-altitude threats. After all, one Sentinel system can monitor a circular area 150 kilometers in diameter.