Low Probability of Intercept (LPI) signals is now considered an essential tactical requirement and is being specified by much military personnel using radar today.
LPI radar has specific design features that render it difficult to detect.
LPI is the property of an emitter that, because of its low power, wide bandwidth, frequency variability, or other design attributes, makes it difficult to be detected or identified utilizing passive intercept receiver devices.
The objective of LPI radars is to detect targets at longer ranges than intercept receivers to detect the radar. In other words, the whole point of an LPI radar is “To See and Not Be Seen,” or “To Detect and Not Be Detected.”
Consequently, the DoD advocates the usage of LPI radars under tight “EMCON” conditions to provide an advantage in establishing a recognized maritime picture to the user side.
Examining the technical aspects, low probability of intercept radar that uses frequency hopping techniques changes the transmitting frequency in time over a wide bandwidth in order to prevent an intercept receiver from intercepting the waveform.
The frequency slots used are chosen from a frequency hopping sequence, and it is this unknown sequence that gives the radar the advantage over the intercept receiver in terms of processing gain. The frequency sequence appears random to the intercept receiver, and so the possibility of it following the changes in frequency is remote.
This prevents a jammer from reactively jamming the transmitted frequency.
Frequency hopping radar performance depends only slightly on the code used, given that certain properties are met. This allows for a larger variety of codes, making it more difficult to intercept.
Want to learn more? Tonex offers Fundamentals of Low Probability of Intercept (LPI) Signals Certificate, a 4-day course that is designed for the working professional who is actively engaged in the waveform capture and analysis domain (Subject Matter Expert), as well as the junior engineer who wishes to become more familiar with the basic understanding of LPI principals.
This course could be valuable to a wide variety of individuals, ranging from technicians in commercial industry to higher-level professionals within government agencies as well as SOF operators and other military specialists.
For more information, questions, comments, contact us.