This is the only footage currently available of an unusual interception: a Russian FPV drone intercepting a Ukrainian FPV drone that was being controlled via a fiber-optic cable. The Russian drone pursued the Ukrainian one and likely damaged its control cable during the flight. It is also worth noting that this is a rare instance of footage from an FPV drone equipped with a microphone; it is likely a "loitering" (or "waiting") drone.
Ukraine - Russia Conflict
- Thread starter randomradio
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Footage shows the assembly and launch of the new Russian interceptor drone, the "ROI-F1." This "F-1" interceptor drone is operated by personnel from an anti-aircraft missile brigade within Russia’s "Center" grouping of forces. According to the operators, the drone is easy to assemble and launch, and it remains stable even in wind speeds of 15 meters per second. The drone is particularly effective at intercepting UAVs such as the D-2, "Rubaka," "Bliskavka," and "Anubis" models.
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S-PNT / R-MIMO Project: Autonomous Space Illumination and Distributed Passive Radar System for use in the Ukrainian theatre of operations
The Problem: The Limitations of Conventional Air Defence
Modern air defence faces two major challenges: passive stealth (aircraft such as the F-35 or advanced drones, geometrically designed not to reflect waves back to conventional radar) and electronic warfare (jamming of active ground-based radars and GNSS signals such as GPS or Galileo).
To counter jamming, increasing the power of current large navigation satellites is impossible due to their distance (23,000 km) and thermal constraints. Active ground-based radars, for their part, behave like ‘torches’ in the night: as soon as they transmit, they are detected and destroyed.
The Solution: The concept of cross-illumination in low Earth orbit (LEO)
The proposed system completely overturns the paradigm by combining three technological building blocks: a constellation of dedicated and optimised LEO satellites, local knowledge of the perfect replica of their signal, and a network of passive receiver drones close to the ground.
1. The Space Segment: The cross-shaped constellation and energy accumulation
The system is based on a constellation of 12 satellites, each weighing 300 kg, distributed evenly across two specific elliptical orbital planes (400 km perigee / 1,600 km apogee, 105 minutes per orbit):
The angles (63.43° and 116.57°): These critical mathematical inclinations cancel out the Earth’s gravitational perturbations. The satellites’ apogee remains permanently fixed above the Northern Hemisphere.
The slowed-down stroboscopic effect: As they approach their apogee at 1,600 km, the satellites slow down significantly. They thus remain visible for a very long time (over 40 minutes per pass) above the theatre of operations (e.g. Central Europe / Ukraine).
The tactical battery strategy (‘Overpower’ mode): To maximise cost-effectiveness, the satellite reuses the tried-and-tested Galileo FOC service platform (same TT&C command links, same 2.5 kW solar panels and same 3.8 kWh Li-ion batteries). The satellite does not transmit whilst over the Southern Hemisphere: it shuts down its payload to recharge its battery to 100 per cent. When it crosses the equator heading north, it releases this stored energy in the form of a flash via gallium nitride (GaN) amplifiers. It then transmits a phenomenal 1,200 watts of RF power in the S-band, creating a veritable ‘electronic beacon’ on the ground.
2. The Launch Segment: A realistic deployment in three launches
As the laws of space mechanics prevent such a drastic change in inclination with a single rocket, the constellation is deployed autonomously and independently by the European Vega-C launcher in exactly three launches:
Launch 1: One Vega-C places the six satellites into the prograde orbit (63.43°), utilising the Earth’s rotation (~2,100 kg including the adapter).
Launches 2 and 3: Two Vega-C rockets each place three satellites into the retrograde orbit (116.57°), an energy-intensive trajectory that requires the payload to be split into ~1,150 kg per launch to remain within the launcher’s capabilities.
3. The Receiver Segment: The passive MIMO drone network (R-MIMO)
Instead of a single large radar, signal reception is entrusted to a swarm of small, lightweight tactical drones flying over the combat zone. These drones do not transmit any radio signals: they listen exclusively via compact S-band antennas (~25 cm x 25 cm).
Each drone stores in its memory the exact mathematical replica of the codes transmitted by the satellites, enabling it to extract the signals from thermal noise with a massive processing gain, even if the echo is masked below the level of ambient noise.
The 5 Major Advantages of the System
A. Neutralisation of Stealth
Stealth aircraft are designed to deceive monostatic radars (where the transmitter and receiver are in the same location). In our multistatic system, the satellites illuminate the aircraft from above and from the sides. The energy is deflected downwards by the aircraft’s contours, directly into the drones’ sensors. Geometric stealth is neutralised. Furthermore, S-band waves (2.2 GHz) pass through the radar-absorbing coatings (RAM) designed for the X-band, ensuring a maximum Radar Cross-Section (RCS).
B Detection gain vs tracking gain
For a signal to emerge from the parallel correlator and be considered a ‘detection’, it must exceed a certain false alarm probability (FAP) threshold. If we consider a single signal at a given time T (single-shot detection), the echo from the stealth aircraft at a great distance is so weak that it does not exceed this threshold. It remains invisible.
This is where the Kalman filter indirectly influences the system’s ‘energy budget’, via what signal processors refer to as the Track-Before-Detect (TBD) long-term integration gain:
Instead of searching for a strong echo every millisecond, the receiver stores the correlation matrices over time.
The Kalman filter, using its kinematic model (the aircraft is flying in a straight line or initiating a realistic turn), tests possible trajectories across the range and Doppler cells.
By accumulating the signals along the trajectory predicted by the model over a period of 1 second, non-coherent integration is achieved over approximately 100 correlation cycles (if one cycle lasts 10 ms); and if the target’s bistatic radial Doppler is measured, the duration can be extended to 2 seconds, i.e. 200 cycles.
C. A detection range of 170 kilometres
Thanks to the 1,200 W GaN transmitter in the north and the proximity of the satellites, the signal is powerful. By introducing a direct and precise measurement of the bistatic radial Doppler at each cycle, the kinematic Kalman filter stabilises the target’s velocity vector. This observability allows the incoherent integration time to be safely extended to 2 seconds (200 cycles of 10 ms), generating a net processing gain of +11.5 dB. The bistatic radar equation thus locks in a maximum continuous detection range of 170 km against a stealth aircraft travelling at Mach 2.
D. Surgical precision via TDOA (Time Difference)
The dense constellation ensures that at least 4 satellites (2 per plane) are constantly above the horizon. Their ellipses intersect to form a perfect ‘X’-shaped grid over the theatre of operations. By measuring the time difference of arrival (TDOA) of the aircraft’s echo between the various drones in the swarm, the system overcomes the constraints of complex hardware-based interferometry between moving platforms. The intersection of the four ellipsoids of the satellites (transmitters) and the hyperboloids of the drones (receivers) enables the 3D position of the target to be calculated rapidly, to within a metre.
E. Immunity to Jamming and Clutter (Ground clutter)
Stealth aircraft typically fly close to the ground to hide their echo within the clutter of the terrain. Here, the angular diversity of the drone swarm and the constellation breaks through this concealment: if the aircraft is within the clutter blind spot of drone No. 1, its Doppler echo is perfectly visible and detached from the ground to drone No. 2, situated a few kilometres further away. Furthermore, to blind this system, the adversary would have to jam the S-band simultaneously towards the sky and towards the ground over a 360° arc, which would require a colossal amount of energy and turn it into a highly visible opportunistic beacon.
In summary
This system creates a passive, sovereign and invulnerable surveillance dome. For the extremely modest cost (estimated at between 360 and 420 million euros) of 12 small satellites (optimised through the reuse of Galileo FOC components) and three Vega-C launches, it offers the capability to track hypersonic or supersonic stealth threats—a capability beyond the reach of current ground-based radars—whilst ensuring the safety of ground forces, which remain electronically invisible.
The Problem: The Limitations of Conventional Air Defence
Modern air defence faces two major challenges: passive stealth (aircraft such as the F-35 or advanced drones, geometrically designed not to reflect waves back to conventional radar) and electronic warfare (jamming of active ground-based radars and GNSS signals such as GPS or Galileo).
To counter jamming, increasing the power of current large navigation satellites is impossible due to their distance (23,000 km) and thermal constraints. Active ground-based radars, for their part, behave like ‘torches’ in the night: as soon as they transmit, they are detected and destroyed.
The Solution: The concept of cross-illumination in low Earth orbit (LEO)
The proposed system completely overturns the paradigm by combining three technological building blocks: a constellation of dedicated and optimised LEO satellites, local knowledge of the perfect replica of their signal, and a network of passive receiver drones close to the ground.
1. The Space Segment: The cross-shaped constellation and energy accumulation
The system is based on a constellation of 12 satellites, each weighing 300 kg, distributed evenly across two specific elliptical orbital planes (400 km perigee / 1,600 km apogee, 105 minutes per orbit):
The angles (63.43° and 116.57°): These critical mathematical inclinations cancel out the Earth’s gravitational perturbations. The satellites’ apogee remains permanently fixed above the Northern Hemisphere.
The slowed-down stroboscopic effect: As they approach their apogee at 1,600 km, the satellites slow down significantly. They thus remain visible for a very long time (over 40 minutes per pass) above the theatre of operations (e.g. Central Europe / Ukraine).
The tactical battery strategy (‘Overpower’ mode): To maximise cost-effectiveness, the satellite reuses the tried-and-tested Galileo FOC service platform (same TT&C command links, same 2.5 kW solar panels and same 3.8 kWh Li-ion batteries). The satellite does not transmit whilst over the Southern Hemisphere: it shuts down its payload to recharge its battery to 100 per cent. When it crosses the equator heading north, it releases this stored energy in the form of a flash via gallium nitride (GaN) amplifiers. It then transmits a phenomenal 1,200 watts of RF power in the S-band, creating a veritable ‘electronic beacon’ on the ground.
2. The Launch Segment: A realistic deployment in three launches
As the laws of space mechanics prevent such a drastic change in inclination with a single rocket, the constellation is deployed autonomously and independently by the European Vega-C launcher in exactly three launches:
Launch 1: One Vega-C places the six satellites into the prograde orbit (63.43°), utilising the Earth’s rotation (~2,100 kg including the adapter).
Launches 2 and 3: Two Vega-C rockets each place three satellites into the retrograde orbit (116.57°), an energy-intensive trajectory that requires the payload to be split into ~1,150 kg per launch to remain within the launcher’s capabilities.
3. The Receiver Segment: The passive MIMO drone network (R-MIMO)
Instead of a single large radar, signal reception is entrusted to a swarm of small, lightweight tactical drones flying over the combat zone. These drones do not transmit any radio signals: they listen exclusively via compact S-band antennas (~25 cm x 25 cm).
Each drone stores in its memory the exact mathematical replica of the codes transmitted by the satellites, enabling it to extract the signals from thermal noise with a massive processing gain, even if the echo is masked below the level of ambient noise.
The 5 Major Advantages of the System
A. Neutralisation of Stealth
Stealth aircraft are designed to deceive monostatic radars (where the transmitter and receiver are in the same location). In our multistatic system, the satellites illuminate the aircraft from above and from the sides. The energy is deflected downwards by the aircraft’s contours, directly into the drones’ sensors. Geometric stealth is neutralised. Furthermore, S-band waves (2.2 GHz) pass through the radar-absorbing coatings (RAM) designed for the X-band, ensuring a maximum Radar Cross-Section (RCS).
B Detection gain vs tracking gain
For a signal to emerge from the parallel correlator and be considered a ‘detection’, it must exceed a certain false alarm probability (FAP) threshold. If we consider a single signal at a given time T (single-shot detection), the echo from the stealth aircraft at a great distance is so weak that it does not exceed this threshold. It remains invisible.
This is where the Kalman filter indirectly influences the system’s ‘energy budget’, via what signal processors refer to as the Track-Before-Detect (TBD) long-term integration gain:
Instead of searching for a strong echo every millisecond, the receiver stores the correlation matrices over time.
The Kalman filter, using its kinematic model (the aircraft is flying in a straight line or initiating a realistic turn), tests possible trajectories across the range and Doppler cells.
By accumulating the signals along the trajectory predicted by the model over a period of 1 second, non-coherent integration is achieved over approximately 100 correlation cycles (if one cycle lasts 10 ms); and if the target’s bistatic radial Doppler is measured, the duration can be extended to 2 seconds, i.e. 200 cycles.
C. A detection range of 170 kilometres
Thanks to the 1,200 W GaN transmitter in the north and the proximity of the satellites, the signal is powerful. By introducing a direct and precise measurement of the bistatic radial Doppler at each cycle, the kinematic Kalman filter stabilises the target’s velocity vector. This observability allows the incoherent integration time to be safely extended to 2 seconds (200 cycles of 10 ms), generating a net processing gain of +11.5 dB. The bistatic radar equation thus locks in a maximum continuous detection range of 170 km against a stealth aircraft travelling at Mach 2.
D. Surgical precision via TDOA (Time Difference)
The dense constellation ensures that at least 4 satellites (2 per plane) are constantly above the horizon. Their ellipses intersect to form a perfect ‘X’-shaped grid over the theatre of operations. By measuring the time difference of arrival (TDOA) of the aircraft’s echo between the various drones in the swarm, the system overcomes the constraints of complex hardware-based interferometry between moving platforms. The intersection of the four ellipsoids of the satellites (transmitters) and the hyperboloids of the drones (receivers) enables the 3D position of the target to be calculated rapidly, to within a metre.
E. Immunity to Jamming and Clutter (Ground clutter)
Stealth aircraft typically fly close to the ground to hide their echo within the clutter of the terrain. Here, the angular diversity of the drone swarm and the constellation breaks through this concealment: if the aircraft is within the clutter blind spot of drone No. 1, its Doppler echo is perfectly visible and detached from the ground to drone No. 2, situated a few kilometres further away. Furthermore, to blind this system, the adversary would have to jam the S-band simultaneously towards the sky and towards the ground over a 360° arc, which would require a colossal amount of energy and turn it into a highly visible opportunistic beacon.
In summary
This system creates a passive, sovereign and invulnerable surveillance dome. For the extremely modest cost (estimated at between 360 and 420 million euros) of 12 small satellites (optimised through the reuse of Galileo FOC components) and three Vega-C launches, it offers the capability to track hypersonic or supersonic stealth threats—a capability beyond the reach of current ground-based radars—whilst ensuring the safety of ground forces, which remain electronically invisible.
Footage of strikes—presumably by "Dan-T" or "Banderol" missiles—on the DniproHES dam in Zaporizhzhia, Ukraine. The video was filmed by local residents.