Digital Radio Frequency Memory (DRFM) has improved the capability of electronic warfare and anti-missile countermeasure systems

Rajesh Uppal February 20, 2019 Electronics & EW Comments Off on Digital Radio Frequency Memory (DRFM) has improved the capability of electronic warfare and anti-missile countermeasure systems 4,860 Views

All modern forces depend on unimpeded access to, and use of, the EM spectrum in conducting military operations. Therefore, there is a requirement to gain and maintain an advantage in the electromagnetic spectrum by countering adversary’s systems and protecting one’s own systems. Thus the EM spectrum can no longer be viewed as an enabler, but rather as a primary warfighting domain, on par with land, sea, air and space operations. This is leading to race among all Militaries to introduce innovations in sensors and communications, countermeasures, and counter-countermeasures in an attempt to gain an advantage over their enemies.

Electronic warfare provide means to counter adversary’s systems while protecting one’s own systems through Electronic Attack (EA), Electronic Protection (EP) and Electronic Support (ES). EA is the electronic countermeasure which includes jamming and deception of enemy radars, electro-optic and communication systems. It also includes use of anti-radiation missiles (ARM), electromagnetic pulse (EMP) and directed energy weapons (DEW).

In the military, RADAR is one of the primary technologies used for engaging targets with missiles or anti-aircraft fire. The ability to deceive target locking RADAR can keep friendly pilots safe and allow them to carry out their mission.

Radar jamming is a form of electronic countermeasures (ECM), designed to degrade the effectiveness of enemy radar systems. Usually, this is done by emitting radio signals at specific frequencies which impair the ability of radar systems to accurately detect and depict objects in the operational environment. This can generate “noise” in the radio spectrum which will confuse or mislead the enemy and affect their decision-making accordingly.

Techniques like “dumb jamming” are useful for taking a RADAR installation out of commission, but more sophisticated electronic warfare attacks can make the enemy think their RADAR is still working when it is actually reporting incorrect target range and velocity information.

This technique is also called Radar spoofing, Spoofing is not so much about interfering with the functionality of radar systems, but rather tricking them into displaying inaccurate information to deceive enemy forces. Spoofing systems like the Digital Radio Frequency Memory Units (DRFM) can confuse the enemy by replaying captured pulses with a delay, making a target appear to move when it may not be. These units can also trick enemy radars into perceiving more than one target.

The use of DRFM systems in jammers has improved the capability of electronic warfare systems. These systems can store and modify signals, before transmitting them to enemy radars.

Modern radar-guided missiles are able to defeat the traditional chaff countermeasures that have been in use since WW2. BriteCloud was designed to beat 21st century threats, with its innovation centring on the miniaturisation of advanced jamming technology. The final product is a battery-powered Digital Radio Frequency Memory (DRFM) jammer in a completely self-contained unit, reduced to the size of drinks can. The decoy is therefore small enough to be ejected from fighter aircraft in exactly the same way as a flare, allowing pilots to lure even the most up-to-date RF-guided missiles and fire control radars away from their aircraft.

DRFM Technology

The principals behind DRFM take advantage of the assumptions a RADAR system makes when identifying a target. The first assumption a RADAR makes is that the only possible reasons for a shift in frequency, phase, amplitude, or polarization is due to a reflection off of a material with a very different permittivity than air. DRFM defeats this assumption by artificially shifting any or all of those physical wave properties and sending them back to the RADAR. This causes the RADAR to make incorrect deductions about the material, velocity, and range of what it thinks are reflections off of a surface.

Another assumption that RADAR makes is that electronic countermeasures used against it will not be able to keep up with the sliding time slot that it samples in and that the countermeasure won’t be able to find the RADAR’s frequency precisely enough. This was true before 1999, when DRFM systems first came into use. With the proliferation of high dynamic range ADCs, fast FPGAs, and more efficient processors, it is now possible to very quickly and effectively find a RADARs frequency and keep up with its sampling rate.

Electronic warfare systems use different deception techniques, such as multiple false target generation, Range Gate Pull-Off (RGPO), and Velocity Gate Pull-Off (VGPO), among others.

Implementation Methods

RADAR pulses are often very high frequency, so it’s important to have an extremely fast sampling and processing abilities. All RFDM modules have fast ADCs with high dynamic range which feed directly into a large, fast FPGA like a Virtex-5. To actually receive and retransmit the RADAR signal, an RF frontend is necessary.

A typical RF frontend will contain an antenna, filter or filter bank, amplifier, and if the design is superheterodyne, a mixer and LO. DRFM for more advanced RADARs that use techniques like pulse compression involves detecting any additional modulation imparted to the incident waveform and accurately recreating it using Direct Digital Synthesis (DDS) in real time. Handling advanced RADAR signals like pulse compression is active area of research, almost all of which is classified.

On the basis of architecture, the Digital Radio Frequency Memory (DRFM) comprises of processor, modulator, converter, memory, and other components. DRFM systems use various microprocessors, memory blocks, and other components that are embedded on their integrated circuits. The integrated circuit processors in DRFM systems are commonly known as System-on-Chip (SOC). Specific Application Programmable Logic Devices SOCs are programmed using the Hardware Description Language (HDL), such as Verilog or VHDL. The use of Application Specific Integrated Circuit (ASIC) in DRFM systems has offered various advantages, such as low power consumption and faster operation. However, new DRFM systems are using FPGAs over ASICs, as FPGAs have low operating cost and offers re-programmability. Xilinx Virtex-5 is a type of FPGA that is commonly used in DRFM systems.

Available DRFM Modules

Since DRFM modules use bleeding edge techniques, the kinds of modules available and their functions are often classified. However, there are at least two modules that have public details. The first is offered by a British company called Herley and operates from 6-18 GHz. It has a bandwidth of 400 MHz, a built in Doppler modulator, and can be used as flight hardware or by itself as part of a hardware-in-theloop simulator. It is easily controlled using a standard interface to a computer, and is rack mountable. The output power is 0 dBm, so it requires an external amplifier and antenna.

A second module that has public information available is made by an American company called Kor Electronics. It has 1 GHz bandwidth and built in real time Doppler, amplitude, phase, and multiscatter simulation . Kor lets the customer define the range of frequency operation, but it can be as low as 20 MHz or as high as 18 GHz. No public information is available on the exact cost of either the Herley or Kor modules, but according to the Department of Defense, costs for such modules can range from $150,000 to $700,000 per system depending on capability. The mean time to fail of such systems is greater than 500 hours, and all systems cover at least the 7-11 GHz band. Higher end systems cover the 2- 18 GHz band.

Developed by Leonardo over the past five years, BriteCloud is a second-generation expendable digital radio frequency memory (DRFM) jammer device designed to provide fast jet aircraft with effective ‘end game’ protection against advanced radar-guided missile threats and/or tracking radars. The DRFM’s coherent response prevents the threat from detecting the deception as the decoy separates, thereby generating large miss distances and breaking the target lock. Qualified for operational use in conjunction with the RAF’s Rapid Capabilities Office (RCO), the 55 mm diameter BriteCloud device has initially been cleared for the Tornado GR4 aircraft.

Digital Radio Frequency Memory Market worth 1,222.2 Million USD by 2022

The report “Digital Radio Frequency Memory (DRFM) Market by Platform (Defense, Commercial & Civil), Application (Electronic Warfare, Radar Test & Evaluation, Electronic Warfare Training), Architecture (Processor, Modulator, Converter, Memory) – Global Forecast to 2022”, was valued at USD 613.9 Million in 2016, and is projected to reach USD 1,222.2 Million by 2022, at a CAGR of 12.16% from 2016 to 2022

The key factors driving the market growth are increased adoption of military electronic warfare systems, technological advancements in military radars, emergence of cognitive electronic warfare technology and development of DRFM-based jammers for UAV applications.

On the basis of application, the Digital Radio Frequency Memory (DRFM) market has been segmented into electronic warfare, radar test & evaluation, electronic warfare training, and radio & cellular network jamming. The electronic warfare segment accounted for the largest share of the Digital Radio Frequency Memory (DRFM) market in 2016.

North America accounted for the largest share of the Digital Radio Frequency Memory (DRFM) market in 2016, followed by Europe. The growth of the DRFM market in North America is mainly attributed to the increasing investments made by defense forces for the development of technologically advanced DRFM systems.

Key players operating in the Digital Radio Frequency Memory (DRFM) market include Airbus Group (Netherlands), Northrop Grumman Corporation (U.S.), Raytheon Company (U.S.), Elbit Systems Ltd. (Israel), and BAE Systems plc (U.S.), among others.