Serbia Debuts Digital Fire-Control Upgrade for M75/M69 Mortars at Partner 2025.

Serbia unveiled a digital fire-control system for legacy 120mm M75 and 82mm M69 mortars at the Partner 2025 defense expo in Belgrade. The upgrade uses modern sensors and RTK drone cueing to tighten dispersion, cut time-to-first-shot, and reduce crew workload.

At Partner 2025, in September 2025, Serbia presents a mortar fire control system aimed at modernizing existing weapons rather than introducing an entirely new design. The equipment is described as a digital upgrade for two widely used mortars in the region, the 120 mm M75 and the 82 mm M69. The stated goal is to tighten dispersion, reduce the time between detection and the first round, and ease the crews’ workload.
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The system seeks to trim minutes between detection and effects, especially for short missions where speed outweighs volume (Picture source: Army Recognition)

The system starts with sensing. The kit includes an eye safe laser rangefinder rated for a reach of up to 7 kilometers. That figure sets the upper limit for direct distance measurement injected into the fire control chain without relying on external relays. Next to it is a thermal camera with an uncooled detector at 640 by 480 pixels. This level of definition, common in low power modules, simplifies maintenance. The brochure specifies that in a narrow field of view the sensor detects a tank sized target out to 5 kilometers. The claim concerns detection rather than identification, a useful distinction suggesting the supplier targets realistic expectations under varied weather and light.

These sensors feed an application labeled UPAS, for Universal Movement Artillery Station. UPAS manages planning, data reception, and processing for mortar fire, with a ballistic module that computes basic firing elements, applies corrections, and then transmits parameters to the weapons. The intent is to provide a single environment where coordinates arrive, are reconciled with the weapon’s own position, and are converted into elevation and azimuth without manual transcription. To improve location beyond line of sight, the package adds a Matrice 300 RTK drone. Use of RTK refines geolocation through differential positioning, which reduces the error ellipse that often affects dismounted observation.

The weapon end is digitized as well. A directing device based on inertial sensors determines the mortar’s position on the X, Y, and Z axes with a stated precision of up to 5 meters. The same device provides azimuth with an accuracy of 0.2 degree RMS. These two figures define the system’s aims: once the weapon is emplaced and the device is stabilized, the software has a stable reference to compute and repeat lay angles. A 5 meter position error is not survey grade, but combined with RTK target coordinates and internal ballistic tables it remains coherent for rapid setups. The 0.2 degree azimuth figure looks modest on paper yet matters in practice, because even small direction errors compound with range.

Beyond the numbers, the supplier describes a simplification of the sequence of actions. Moving to digital observation tools supported by dedicated applications is designed to remove friction in mortar fire control. In practical terms, this means fewer voice relays, fewer hand calculations, fewer conversions from grid squares scribbled in pencil to sight settings. A crew used to the M75 or M69 keeps familiar motions, with electronics absorbing the repetitive steps. If the tablet running UPAS and the inertial sensors remain synchronized, the section chief can focus on safety and rate of fire rather than arithmetic.

Tactically, the system seeks to trim minutes between detection and effects, especially for short missions where speed outweighs volume. A forward element marks a point, the drone refines it, the section lays the weapon and sends the first rounds with less back and forth. The rangefinder and thermal camera support night work and reduced visibility, which matches typical mortar employment. Because the device provides a consistent azimuth and a stable estimate of own position, displacement and reentry into the fire plan are faster. This does not neutralize counter battery threats, but it reduces exposure time and the number of visible actions, which lowers risk.

In operations, the concept mainly interests units that field several generations of equipment. Rather than retire stocks of M75 or M69, a command can attach the digital kit and move closer to current practice based on rapid targeting and distributed observers. The logistics burden remains contained. Uncooled detectors avoid heavy maintenance cycles associated with cooled cores, and the Matrice 300 RTK is a commercial platform with available spares and training. The hard point is integration discipline. If power supply, data handling, and crew training drift, the gains erode quickly.

Many countries keep large inventories of mortars that remain reliable but are not well adapted to networked targeting and time sensitive missions. Budgets do not always allow full replacement. Industry therefore proposes incremental modernization that avoids changes to caliber, mount, or logistics doctrine. In regions where artillery upgrades progress step by step, a kit of this type addresses a recurring requirement: connect older tubes to newer sensing methods, including accessible drones and tablet based fire control calculators. These are products that circulate quietly because they rely on commercial components and open training pathways.