This article looks at spot jamming and barrage jamming and describes how these jammers and electronic counter counter measurres are implemented in SkyRadar's FreeScopes DSP environment.
Jamming is part of electronic warfare. It may be used in attack situations against military or civil sites. SkyRadar's focus - following our mission to make the skies safe and peaceful - is to protect sites against jamming and deception.
We set our focus on training how to "dismantle" jamming signals and to "disguise" targets hidden under jamming signals. In this series we will write about various forms of jamming including noise and deception jamming. This first article focuses on two specific noise jammers implemented in FreeScopes:
- Spot jammers
- Barrage jammers.
In general a radar noise jammer is built to generate a disturbance in a radar receiver. It covers a target's reflection and consequently denies its detection.
iIt does so by masking the target reflections by substantially adding noise to the generally available thermal noise level.
Barrage jamming spreads energy across a wide frequency range. Such a jamming of an attacked radar requires high power to achieve a continuous coverage of various frequencies. Given the jammer's fixed total radiation power, this technique lowers the radars general efficiency as it leads to a low power density. But this technique is efficient when attacking radars which can vary their frequencies or radars which operate with several frequencies concurrently.
The video below shows barrage jamming as generated in SkyRadar's DSP simulator. Alternatively, students might practice with SkyRadar's physical jammer.
A workaround to the barrage jammer's low efficiency is spot jamming. Spot jammers jam in a narrow band, hense with a higher power density. Consequently it can raise the jamming signal power over a narrower frequency spectrum.
Electronic Counter Counter Measures (ECCM) Against Noise Jamming
There are many strategies to defend an attacked radar against noise jamming and FreeScopes offers a range of these ECCM solutions.
The basic defense strategies are to work with varying thresholds and intelligent 2 dimensional Constant False Alarm Rates.
Another technique is to work with multiple radars in several frequency bands or even monitor with a pulse and an FMCW radar in parallel, making it difficult for the jammer to jam both.
Algorithms like MTI or MTD can help to filter out a moving object behind jamming signals. However it has to be applied in an intelligent way, as jammers fixed to attacking aircraft also have a Doppler frequency.
There are more intelligent algorithms like history based solutions e.g., using a Kalman filter or spectrum analysis. In the latter, signals with a spectrum deviating from the radar's signal spectrum are eliminated.
SkyRadar's ECCM, jammers, simulators and Digital Signal Processing
In the subsequent articles we will introduce deception jammers including range, angle and speed deception. And we will introduce more ECCM methods like Kalman based filtering, the CFAR based spectrum analysis, statistical processing and more. We will also introduce SkyRadar's physical jammer, which has been specially developed for training purposes and which can be operated safely indoors.
SkyRadar's DSP radar simulator is able to simulate radar, noise jammer and deception jammers. This allows to apply the simulator in the context of civil and military defence training. The signals can be superimposed on the live raw data stream of SkyRadar's NextGen 8 GHz Pulse radar and thus create a realistic training context of multiple jamming scenarios.
The solution allows for the following 3 scenarios
- Full simulation (radar and jammer are simulated)
- Real radar and simulated jammer
- Real radar and real jammer
References and Further Reading
- Electronic Warfare Fundamentals (2000), Det 8, ACC TRSS