In late September, an upgraded version of the RP-377 Lesochek series of electronic attack systems was exhibited at the ADEX international defence exhibition held in Azerbaijan.
Lesochek, meaning ‘little forest’ in Russian, is extensively used by Russian land forces, and has been deployed to Ukraine to support the latter’s ongoing occupation. The upgrade expands the system’s capabilities to attack Uninhabited Aerial Vehicles (UAVs). This modernisation is almost certainly the result of combat experience gained by Russian forces in the Ukrainian theatre.
According to reports, the modifications visited on Lesochek allow it to engage Global Navigation Satellite System (GNSS) Position, Navigation and Timing (PNT) signals. These signals routinely use a waveband of 1.1 gigahertz/GHz to 1.6GHz. Frequencies of 2.4GHz and 5.8GHz are used for civilian pilot-aircraft UAV radio control links. However, the Ukraine war has seen both sides using an increasingly wide waveband of 30 megahertz/MHz to six gigahertz for UAV control. Both Ukraine and Russia regularly change their UAV control frequencies in a bid to outflank channel jamming. While not explicitly mentioned, it is possible that the waveband covered by Lesochek has now been expanded upwards from 400MHz to circa six gigahertz.
It is known that the RP-377 series includes at least three distinct configurations: One is designed to equip vehicles and for static installation, designated the RP-377UVM1L/VM. The difference between these two systems remains unclear. It appears that the RP-377UVM1L variant equips relatively light wheeled armoured vehicles like the BTR-60/82 series. The RP-377VM appears to furnish heavier armoured vehicles including tracked platforms. The RP-377A variant is used by dismounted troops. Russian reports state that the Lesochek version exhibited at ADEX was the RP-377VM1. Does this imply that it is only the RP-377VM variant that has received the modifications?
Capabilities
The RP-377 series commenced delivery to Russian land forces in 2013 with circa 1,500 systems supplied by 2015. Armada has learned that the original RP-377 design covers six wavebands: 20 megahertz/MHz to 30MHz, 30MHz to 50MHz, 50MHz to 80MHz, 80MHz to 120MHz, 120MHz to 220MHz and 220MHz to 400MHz. Lesochek was conceived as a Counter-Improvised Explosive Device (CIED) jammer to equip individual vehicles and dismounted troops. Official Russian Army documents seen by Armada state that the baseline version of the RP-377A could only perform barrage noise jamming. What this would mean in practice is that the system continually sweeps through each waveband. Any hostile signal inhabiting these wavebands will then be jammed as the sweeping occurs. One disadvantage regarding barrage tactics is that the jammer transmits proportionally less power than when performing spot jamming. Spot jamming sees electronic attack target a specific frequency. An analogy would be a garden hose which distributes a stronger jet of water when focused on a particular spot, compared to when spraying across a wider area. The official documents say the RP-377 generates between three and five watts of jamming power. Batteries equipping the RP-377A provide sufficient power for 24 hours’ continuous electronic attack.
The RP-377A can be deployed and operated remotely using a radio link giving up to ten kilometres (6.2 miles) of range. When used in this remote-controlled configuration, Lesochek provides six minutes’ continuous jamming time before automatically deactivating. The RP-377A can be programmed to activate when it detects specific signals. Likewise, the system can be programmed with taboo frequencies, such as those used by friendly forces or civilians. When being controlled directly, the RP-377A provides continuous jamming for a maximum of 30 minutes before switching off. The RP-377 architecture includes six jamming transmitters, an antenna for remote control, a receiving antenna to detect threats, and the system’s processor, control unit and amplifier.
Concept of operations
As Armada has chronicled in the past, each of the Russian Army’s principal unit of tactical manoeuvre, typically its motorised rifle/tank divisions/brigades has an organic EW (Electronic Warfare) company. The company includes three EW jamming platoons. One of the platoons comprises two EW jamming squads with dismounted EW capabilities. One squad targets hostile radio communications, the other remote-controlled IEDs and radio-activated weapons. Each squad will typically each have around 15 RP-377As.
The squads sometime appear to be ‘fragged’ to support individual manoeuvre elements in the formation at the squad/platoon level. The logic appears to be to provide EW support to these units during manoeuvre. Likewise, vehicles are thought to be outfitted with the RP-377UVM1L/VMs to provide platform and small group protection. When attacking hostile communications, the Russian documents state that the RP-377A can target amplitude and frequency modulated signal along with signal sideband modulated transmissions. Alternatively, EW squads can be deployed holistically for jamming support in specific areas during reconnaissance or special forces missions.
Alongside supporting manoeuvre RP-377As can be used for static defence. Several units can be placed remotely across a wide area providing a jamming coverage that the red force will need to manoeuvre through. The latter tactic is also useful for providing an electromagnetic cordon sanitaire. Russian documents say that between two and three RP-377As are sufficient to provide jamming across a one square kilometre (0.38 square mile) area. The documents continue that units should have a minimum spacing of no less than 200 metres/m (656 feet/ft) to be effective. When jammers are deployed remotely, they must not be emplaced more than 24 hours before they are needed. This is to reduce the chances of concealed jammers being discovered by red forces. Russian Army doctrine says that Lesochek must be a maximum of 600m (1,968ft) range from the target to be effective. When operating in undulating terrain, RP-377As should be on a hilltop, or a hill side with a line-of-sight to the target.
It remains to be seen how effective these recent modifications to the Lesochek architecture will be in theatre. The upgrades appear to be relatively new, and their impact may be yet to be felt in Ukraine. Moreover, it is unclear whether the modifications can be retrofitted onto legacy systems.
by Dr. Thomas Withington
