Precision-guided munitions (PGMs), often referred to as “smart bombs,” have revolutionized modern warfare. They offer significantly improved accuracy compared to traditional unguided bombs, minimizing collateral damage and maximizing the effectiveness of each strike. But How Do Precision Guided Munitions Work? This article explores the technology behind these sophisticated weapons, their vulnerabilities, and potential countermeasures.
PGMs utilize various guidance systems to accurately hit their intended targets. These systems can be broadly categorized into several types, each with its own strengths and weaknesses:
- GPS Guidance: This is one of the most common guidance methods. PGMs equipped with GPS receivers use satellite signals to determine their location and navigate to the target coordinates. The U.S.-provided Ground-Launched Small Diameter Bomb (GLSDB), boasting a range of 90 miles, relies on GPS for navigation, along with an inertial navigation system. However, as recent events in Ukraine have shown, GPS-guided munitions are vulnerable to electronic warfare.
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Inertial Navigation System (INS): INS is a self-contained navigation system that uses accelerometers and gyroscopes to track the munition’s position and orientation. It doesn’t rely on external signals, making it resistant to jamming. However, INS accuracy can drift over time, especially over long distances, which is why it is often used in conjunction with GPS or other guidance systems.
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Laser Guidance: Laser-guided PGMs home in on a laser beam directed at the target. This can be done by ground troops, aircraft, or drones. Laser guidance offers high accuracy, but it requires a clear line of sight to the target and can be affected by weather conditions or smoke.
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Electro-Optical/Infrared (EO/IR) Guidance: These PGMs use cameras to capture images of the target area and compare them to pre-programmed target profiles. EO systems operate in the visible light spectrum, while IR systems detect heat signatures. EO/IR guidance is effective in day and night conditions, but it can be affected by weather and camouflage.
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Radar Guidance: Radar-guided PGMs use radar waves to locate and track targets. They are particularly useful in adverse weather conditions where other guidance systems may be ineffective.
The Impact of Electronic Warfare
The effectiveness of PGMs is increasingly challenged by electronic warfare (EW). Russia, in particular, has demonstrated a sophisticated EW capability in Ukraine. EW tactics aim to disrupt or deceive the guidance systems of PGMs, causing them to miss their targets or even self-destruct.
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GPS Jamming: This involves transmitting high-power radio signals on the same frequencies as GPS satellites, effectively drowning out the real signals. This prevents the PGM from acquiring its position and navigating accurately.
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GPS Spoofing: This is a more sophisticated technique that involves transmitting false GPS signals that mimic the real signals. The PGM locks onto the false signals and navigates to an incorrect location. Bryan Clark, a senior fellow at the Hudson Institute, noted that Russia uses GPS spoofers to throw off munitions by sending false location data. The weak nature of GPS signals makes them susceptible to being overridden by stronger, false signals.
- Jamming Other Guidance Systems: EW can also target other guidance systems, such as laser and radar. For example, smoke or obscurants can be used to block laser beams, while radar jamming techniques can disrupt radar signals.
The impact of Russian EW on PGMs in Ukraine has been significant. Daniel Patt, Senior Fellow at the Hudson Institute, testified that the effectiveness of the GPS-guided Excalibur round dropped from 70% to 6% in a few months due to new EW mechanisms. CNN reported that GMLRS missiles, also GPS-guided, have been directed off course by Russian electronic warfare.
Countermeasures and Future Developments
Despite the challenges posed by electronic warfare, there are several countermeasures and future developments that can improve the resilience of PGMs:
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Anti-Jam GPS Receivers: These receivers use advanced signal processing techniques to filter out jamming signals and maintain a lock on the real GPS signals.
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Inertial Navigation System (INS) Integration: As mentioned earlier, INS is resistant to jamming. Integrating INS with GPS allows the PGM to continue navigating even if GPS signals are lost or jammed.
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Alternative Navigation Systems: Developing alternative navigation systems that don’t rely on GPS is another approach. These could include using celestial navigation, terrain-aided navigation, or visual odometry.
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Electronic Counter-Countermeasures (ECCM): These are techniques used to protect electronic systems from jamming and spoofing. ECCM can include frequency hopping, spread spectrum modulation, and adaptive filtering.
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Enhanced Guidance Algorithms: Advanced algorithms can be used to improve the accuracy and robustness of PGM guidance systems. These algorithms can compensate for errors caused by jamming, spoofing, and other disturbances.
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Utilizing Alternative Munitions: Clark suggests Ukraine could use other U.S. munitions less susceptible to GPS spoofing, such as the Harpoon missile. Furthermore, launching weapons from F-16s could improve accuracy, as these aircraft can pass navigational data to JDAMs, unlike the Soviet planes currently used.
Conclusion
Precision-guided munitions have transformed modern warfare by offering unprecedented accuracy and minimizing collateral damage. They achieve this through a variety of sophisticated guidance systems, including GPS, INS, laser, EO/IR, and radar. However, the increasing prevalence of electronic warfare poses a significant challenge to the effectiveness of PGMs, particularly those that rely on GPS guidance. Countermeasures such as anti-jam receivers, INS integration, alternative navigation systems, ECCM, and enhanced guidance algorithms are being developed to improve the resilience of PGMs. The ongoing battle between PGMs and EW will continue to drive innovation in both areas, shaping the future of warfare.
