We’re used to seeing clips and stories of artillery pummeling enemy fortifications or troops. Goodness knows we’ve shown more than a few ourselves.
But one of the major roles of artillery is attacking an enemy’s artillery. This counter artillery role is known as counterbattery (even when engaging formations larger than a battery).
In the days of the American Civil War, counterbattery was directed visually. But in the era of breechloaded guns with smokeless powder and explosive shells firing from over the horizon, locating enemy batteries was infinitely more difficult.
Forward observers could spot some mortar and light artillery batteries. And there were acoustical detection devices. In fact, from about 1916 well into the 1950s, sound location, or MASINT (Measure And Signature INTelligence) was the primary means of locating enemy firing batteries. By measuring the difference in the Time of Arrival (TOA) of a gun blast along a baseline of sensors, the enemy location could be triangulated. Similarly, lines of bearing from multiple points could point to an enemy battery. Calculating the firing point could take as little as three minutes.
Meanwhile, at the beginning of World War II, the US Army was just staring to explore the possibilities of using radar to control anti-aircraft fire. The first Army radars operated with frequencies in the meter range. That was relatively adequate for long range search, but for precise control of gunfire, it was rather disappointing. When the British shared the discovery of the cavity magnetron, the US was able to very quickly develop centimetric wavelength radars. One in particular, the SCR-584, was extremely effective. Not only was it very precise, it was quite versatile as well. It could act as a search radar out to respectable ranges, as much as 35 miles. Incredibly, given the infancy of radar development, it was capable of automatically tracking targets within about 18 miles.
The SCR-584 was so fundamentally sound, during the development of the M1 90mm Anti-Aircraft gun it was intended to work with, the radar was used to confirm the ballistic profiles of the shells fired from the gun. Ballistic tables were normally devised by computers- that is, hundreds of women with slide rules- mathematically. By confirming the calculations with empirical observation provided by the SCR-584, the complete tables were validated more quickly than normally possible. That is, the 584 was precise enough to track a 90mm shell in flight. By measuring the range and angle from the mount to the shell over a handful of times during the flight of the shell, the ballistic parabola could be derived.
It didn’t take long for some bright operators to realized that if you could determine the ballistics of an outgoing shell, you could also determine the ballistics of an incoming shell. And with a map and a little math, you could plot the parabola back to its point of origin, that is, the enemy firing battery.
Having discovered that radars could be used to track artillery fire, it wasn’t long before the service sought out a radar optimized for the mission. Nor was the US Army the only force to develop a dedicated counterbattery radar. Today, almost every army has at least some counterbattery radar capability.
For the past 30 years or so, the US Army and Marines have fielded the TPQ-36 and TPQ-37 Firefinder radars in the Target Acquisition Batteries of their artillery units. Recently, the Army has also fielded the TPQ-46 Lighweight Counter Mortar Radar. While the Q-46 does calculate the firing point of enemy radars, it’s primarily used to warn troops of incoming mortar and rocket fire. It can also cue the Counter Rocket Artillery Mortar (C-RAM) system to intercept mortar rounds.