Secondary Surveillance Radar Illumination Time Extension
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Solution Overview
Problem
Current secondary surveillance radar systems face limitations in illumination time and data exchange due to the constraints of their operational modes, particularly in high-density air traffic scenarios, where increasing antenna rotation speeds reduce the time available for information exchange with aircraft, and the need for longer illumination times to handle more sophisticated interrogations and data transmission.
Innovation Solution
The system modifies existing secondary surveillance radar architecture to utilize the Difference channel for both transmission and reception, allowing interrogation messages to be sent and responses to be detected using both the Sum and Difference channels, depending on the target's position, thereby extending the illumination time without modifying the antenna or channel formation means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the antenna rotation speed is increased to handle high-density air traffic, then the productivity of the radar system is improved, but the illumination time for each target is reduced
Solution Approach 1:
The patent segments the single Sum channel into two functional channels: Sum channel for transmission and Difference channel for reception. This segmentation allows the system to maintain longer illumination times by using the Difference channel for reception over a wider angular sector, while the Sum channel continues rotation for transmission, effectively decoupling the transmission and reception functions to resolve the contradiction between rotation speed and illumination time.
Solution Approach 2:
The Difference channel, traditionally used only for monopulse processing, is given a dual function: it serves both as the error signal source for monopulse and as the reception channel for detecting transponder responses. This multi-functionality allows the system to extend illumination time without adding new hardware, as the existing Difference channel infrastructure is utilized for both precision tracking and extended-range detection.
2Loss of information
If the illumination time is extended to allow more data exchange, then the quantity of information transmitted is improved, but the antenna rotation speed must be reduced
Solution Approach 1:
The patent transitions from a single-channel operation to a dual-channel operation, adding a dimensional aspect to the radar system's functionality. By utilizing both Sum and Difference channels simultaneously for different purposes (transmission and reception), the system expands its operational dimensions, allowing extended illumination and data exchange without compromising rotation speed through more sophisticated channel management.
3Device complexity
If the Sum channel is used exclusively for transmission, then the device complexity is minimized, but the illumination time is limited
Solution Approach 1:
The system makes the Difference channel serve itself for dual purposes: it continues to provide monopulse error signals while simultaneously serving as the reception channel for transponder responses. This self-service approach allows the system to extend illumination time without requiring additional dedicated reception hardware, maintaining device complexity at acceptable levels while achieving the goal of longer illumination.
Data Source
AI summary
A secondary surveillance radar with rotating antenna, configured for transmitting interrogations in S or IFF mode and processing the responses to these interrogations. The radar includes an antenna having a lobe with three channels, a Sum channel, a Difference channel and a Control channel, whose transmission means are configured for transmitting interrogation messages over the Sum and Difference channels and whose reception and processing means are configured so as to carry out, aside from conventional detections by the Sum channel, detections by the Difference channel of the responses from the aircraft having been subjected to interrogation by this same channel. The radar also includes means for Space-Time Management configured for generating interrogation messages and determining whether a given message is to be transmitted by the Sum channel, by the Difference channel or by the two channels simultaneously and controlling its transmission by the corresponding transmission channel.