Smart jammers, commonly referred to as deceptive jammers or digital radio frequency memory (DRFM) jammers, based on their technology, are widely used by the defense industry in electronic attack and defense suites to deceive hostile radars and protect friendly assets.
Test challenges for advanced and integrated jammer designs
The design of advanced jammers plays a central role in providing vital protection for modern military system platforms, as they face a multitude of radar threats spreading over a wide frequency range and are, nowadays, agile in most of their operational parameters. In order to check the correct parameters of the used jamming and deception techniques, interoperability with other subsystems like radar warning receiver systems (RWR) or tactical air navigation systems (TACAN) has to be ensured. In addition, since an imminent threat is often a combination of different emitters (e.g. early warning, target acquisition, target track/illumination and missile guidance radars), different parts of the electromagnetic spectrum have to be tested at the same time.
Moreover, DRFM jammer has become a highly complex key element of the EA suite. It has evolved from a simple repeater with some fading capabilities to a complex electronic attack asset. Some of the more critical tests are verifying proper operation and timing of the deception techniques on the system level, qualifying the individual components, submodules and modules at the RF/IF level, and last but not least making sure that clock jitter and power integrity are addressed early at the design stage.
The art of radar simulation and signal generation
To verify the parameter set of an electronic countermeasure (ECM) technique, multiple-domain analysis is crucial. The threat radar or the full scenario can be simulated with vector signal generators, the R&S®SMW200A. An example for an ECM may be a sophisticated coherent range gate pull-off (RGPO) with range-Doppler matching, which emulates one or more moving false targets and aims at achieving a break lock of the threat radar. The original radar pulse is used as reference for the ECM. To measure the position of the cover pulse, the hook and the dynamic behavior of the RGPO pulse, time domain analysis is necessary. In parallel, in the frequency domain, it needs to be evaluated whether movement of the false target also inherits the corresponding Doppler behavior.
Majority of modern radar systems use matched filtering and pulse compression, so the retransmitted false targets have to maintain coherence with the original signal. Otherwise, they will lose in processing gain compared to the original signal and will be ineffective. For frequency agile radars (pulse-to-pulse or burst-to-burst), the DRFM should follow that agility, so an RF hopper analysis over a relatively wide bandwidth may be necessary. It may be noteworthy that lab testing only verifies the correct settings of an ECM technique, not its effect on a radar system. For that, it is necessary to do an evaluation of a live threat system.
Next generation jammer testing
Test and measurement solutions from Rohde & Schwarz address all challenges during the design phase, system performance validation and production process. The DRFM technique involves sampling the RF signal, digitally storing and recreating the signal while modifying some or all of the signal parameters based on the desired deception technique.
Furthermore, Rohde & Schwarz will organize a webinar to discuss about Testing deceptive jammers and DRFM designs on Tuesday, May 18, 2021. Click here to register for the webinar
The webinar will introduce the concept of Digital RF Memory Jammers, describes their technology and the respective Test and Measurement challenges and solutions from Rohde & Schwarz.
The speaker, Yassen Mikhailov is responsible for the Rohde & Schwarz A&D Test and Measurement Market in Europe. He holds a BS in Systems Engineering from the US Naval Academy and a MS in Telecommunications from the University of Maryland. With over 16 years of experience as an RF engineer Mikhailov has held different engineering and management positions at ARINC and Rohde & Schwarz.