An electronic war of jamming and counter-jamming is being played out in Ukraine with civilian lives in the middle. Two Russian weapons have become crucial, both of which rely on satellite navigation: glide bombs, released at long range, and Shahed drones, both of which kill many civilians. According to President Zelensky, Russia launched some 1,050 attack drones and 1,300 aerial bombs in just one week last month.
Both weapons use the Russian Kometa (“Comet”) satellite guidance system. Ukraine has deployed vast numbers of electronic jamming and spoofing devices to make the weapons to miss their targets. Russia has responded by successively upgrading Kometa, increasing the number of antenna elements from 4 to 8 to 12 and beyond to beat the jammers. What is the end game in this arms race, and can the Russian guided bombs and drones be stopped?
The Legendary Kometa Smart Antenna
The first Shahed drones launched by Russia had a commercial Chinese navigation antennas. In September 2023 Ukrainian analysts found that crashed drones fitted with the Russian-made Kometa, showing the drones were assembled in Russian with an increasing proportion of locally made parts.
Kometa is a military system from St. Petersburg-based maker VNIIR Progress, first unveiled in 2017, with different versions for aircraft, drones and ground vehicles. It is a smart antenna which can plug into any satnav receiver. The selling point is its ability to filter out jamming signals.
A February 2024 piece in Russian news source Zen Novosti gushes over Kometa claiming “There are legends about this development in the West, and for good reason,” and that the Kometa “plunged the NATO command into despair” because “no interference created by electronic warfare can deceive it.”
“Drones that are equipped with this system are not affected by electronic suppression systems,” states an electronic warfare specialist quoted by Zen Novosti.
The article even claims (without evidence) that Kometa are so effective that the Ukrainians are using units salvaged from crashed Shaheds to use in their own drones. This seems unlikely.
Interestingly, the makers still provide technical details of Kometa online to prospective customers . These reveal that as well as handling signals from the Russian GLONASS satellite navigation system it can also use the U.S. GPS and European Galileo navigation systems, and that the broadband noise reduction is 40-50 decibels. This means it can potentially cope with 100,000 times as much radio interference as an unshielded antenna.
But there is an important limitation to this ability.
CRPA: Turning A Deaf Ear To Noise
Kometa is a type known as a Controlled Reception Pattern Antenna or CRPA, pronounced “serper,” also called adaptive antenna, null-steering antenna or beamforming antenna.
A CRPA uses multiple antenna elements and combines their signals in smart ways. The most obvious approach is amplification: adding two signals together to boost the amplification. But it can also be used for subtraction. By shifting the phase of a signal when it is combined, a CRPA can selectively remove one signal from the output, effectively tuning it out. (Noise-cancelling headphones use a similar principle with sound waves).
In technical terms this is known as “null-forming” or “null-steering.” Old-fashioned antennas for TVs were highly directional and had to be set up pointing toward the transmitter; the direction in which the antenna was deaf to the signal was called a null. CRPA allows nulls to be created at will, so a low-power satellite signal can be picked up even though there is a more powerful jamming signal nearby.
The limitation is that it requires an additional antenna element to generate each null. The original Kometa had four elements, meaning it could generate three nulls and so cancel out three jammers. It would have no protection against a fourth jammer.
Ukrainian electronic warfare specialist Serhii Flash noted in September 2023 that overcoming Komet would require four jammers in one area, which was a challenge.
However, Ukraine has been fielding more jammers – lots of them. Unlike jamming drones, satellite navigation jamming only requires a simple, low-power device on a known wavelength. The output from a GPS satellite has been compared to a car headlight 12,000 miles away, making it easy to drown out, and there are lots of phone-sized $30 GPS jammers on the open market. Piling on enough jammers seemed to work.
Element Escalation
“Ukraine was eventually able to overcome the four-antenna CRPAs as they deployed more jammers,” the OSINT analyst who goes by Roy told me.
Roy has documented what happened next on his X/Twitter feed: in 2024 upgraded Kometa started turning up with 8 antenna elements instead of 4.
“When the Russians switched to the 8 antenna Kometa-M. the accuracy of their UMPK glide bomb kits and Shaheds was restored,” says Roy.
However, even the upgraded Komets were not effective for long.
“The Russians reported that accuracy of UMPK bombs was lost in certain areas. Apparently, Ukraine now has enough jammers to concentrate around areas where these bombing attacks are active,” says Roy.
At the start of this year Roy noted another new version: a Komet with 12 antenna elements.
And that is not the end of it. This month Serhii Flash released images of a captured Komet with no less than 16 antenna elements on his Telegram channel.
Joker In The Pack
Adding progressively more elements adds complications, but 16 does not look like the limit.
“The amount of data and data processing increases with each additional antenna element,” DanielR, an OSINT analyst and imaging physicist told me. “The overall size of the array will become a limitation as well since the elements need to be separated by several centimeters. Sixteen antenna elements seems fairly large but that doesn’t stop anyone from adding more if it can be done cheaply. “
Roy concurs, noting that the stakes are high, and the Russian are likely to keep escalating,
“The devices do get bigger and heavier each time, with increasing complexity of the signal processing electronics,” notes Roy. “Russia is likely to keep going to maintain accuracy of their devastating UMPK heavy bombs, as long as the increasingly bigger CRPA devices can still be fitted.”
However, one interesting feature is the accelerating pace of change. The switch from four elements to eight took at least a year, then only a few months to go to twelve, and an even shorter gap to sixteen. This may suggest that more (or more effective) jammers are being deployed faster than the Russians can respond.
There is also the question of spoofing, a joker in the pack.
While the Komet may be effective again noise inference produced by jammers drowning out the signals from satellites, they may be vulnerable to spoofing signals which quietly mimics a satellite with false navigation data. Ukraine’s Pokrova spoofing system was revealed last year and is now likely to be widely deployed.
The Russians may not know why their bombs are missing and simply adding more and more elements in the hope of getting through. If a spoofing signal is present, like a journalist stealthily lurking in a Signal chat, no amount of noise filtering will help.
Beating The Bombs And Drones
Ukraine also has other ways to beat Kometa. Given that the location of VNIIR Progress is known and their production facilities are in St. Petersburg — well within the range of Ukrainian drones and missiles – the supply chain could be targeted.
In addition, as is obvious from VNIIR’s own material, Kometa uses foreign components, most obviously the antenna elements still branded with the name of the Irish makers Taoglas. The Ukrainian group Molfar has traced these units and others to third parties based in Hong Kong .The enforcement of existing sanctions against Russia should prevent them from building weapons using Western components.
The contest is still ongoing. Electronic warfare is obscure field and few are even aware of CRPA and null-forming, but the results are a matter of life and death for the people of Ukraine targeted by Russian bombs and drones. Success means a bomb lands in an empty field instead of hitting a building full of people.
Developers on both sides will be working on new techniques, and the outcome is still far from certain.