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Smart Utilization: How does passive radar use surrounding wireless signals?
In today's era of rapid development of military and civilian technology, passive radar systems have gradually revealed their unique charm. The potential of this radar technology lies in its ability to detect and track objects using existing wireless signals in the environment, which often come from non-cooperating sources such as broadcast stations, commercial communications signals, etc. Compared with traditional radar systems, passive radar systems do not require a special transmitter, which gives them obvious advantages in terms of cost, efficiency and concealment.
Traditional radar systems have a common transmitter and receiver that measure the position of an object through pulse signals. In a passive radar system, the receiver uses a third party in the environment to emit signals and calculates the object's position information by comparing the direct distance and reflection distance of the emitted signal to the object. This process not only provides the target's range, but also measures multiple parameters such as Doppler frequency shift and direction of arrival to calculate the target's speed and heading.
The advantage of the passive radar system is its low operating cost and concealment, which allows it to quickly update intelligence without the need for special frequency configuration.
Historical background of passive radar
The concept of passive radar systems is not new. As early as 1935, the British Robert Watson Watt used radio waves to detect a bomber for the first time, which laid the foundation for the development of radar technology. With the evolution of technology, many countries have begun to deploy various types of bistatic radar systems to deal with air threats. The UK's CHAIN HOME and France's CW radar are early examples.
During World War II, Germany also used passive bistatic radar to detect aircraft through the British CHAIN HOME radar. Although advances in transmitter and receiver technology allowed monostatic radar to flourish, passive radar systems regained interest in the 1980s as computer technology and digital receiver technology improved.
How passive radar works
In a passive radar system, the receiver needs to accurately receive reflected waves from multiple signal sources. This includes broadcast television signals, FM radio and GPS satellites, among others. The system dynamically samples the signal form by capturing the reference channel of the transmitted signal, and performs multiple processing steps such as digital beam forming and adaptive filtering to ensure that target information can be accurately extracted.
Passive radar systems require receiver designs with low noise, high dynamic range and high linearity to identify extremely small echo signals under strong interference.
Advantages and challenges of passive radar
In terms of advantages, passive radar systems not only reduce procurement costs, but also make operation and maintenance easier. In some missions that require covert operation, passive radar certainly provides an option without transmitting a specific frequency. However, with this technology comes challenges. The biggest challenge is that the system is highly dependent on external signal sources, which makes its availability greatly affected by environmental factors.
In addition, although the performance of passive radar has gradually approached that of traditional short and medium-range radar systems, its positioning accuracy and tracking stability still need to be further improved. Although the use of multi-base radar can improve accuracy, the complexity of the system also increases.
Current research and future prospects
Currently, many commercial and academic institutions around the world are actively conducting research on passive radar and expanding its application fields. Researchers in the United States, the United Kingdom, France and other countries are committed to further developing the possibilities of utilizing modern digital broadcast signals. For example, the HDTV standard is considered an ideal signal source for passive radar because of its excellent ambiguity function, which has gradually made it a hot spot in related research.
Given the low-cost nature of passive radar systems, this technology is particularly attractive to research institutions and other units with limited budgets. Because it requires less hardware facilities, researchers can focus on improving algorithms and computing power. strengthen. With the advancement of digital signal processing technology, we will witness the further development of passive radar technology in the future, and its scope will be further expanded to more application fields. Will this change our basic understanding of wireless signal utilization?
