In drone detection and short-range automotive radar, the detection system should have the ability to monitor a large area and to detect the distances and directions of multiple targets. Suffered from electronic bottleneck, it’s difficult to achieve a high-performance detection via conventional radar system. Microwave photonics has the advantages of low loss, large bandwidth and so on, and greatly improves the performance of radar system. To realize simultaneous distance and direction detection, microwave photonic phased array radar steers the beam for inertialess and squint-free scanning to detect targets from different directions. However, limited by the narrow angle scanning range, its field of view is inadequate. Photonics-assisted AOA (angle-of-arrival) detection method can detect the direction of target in a large-angle range. Nevertheless, it can hardly obtain the distance information of targets. It is a key issue to perform wide-angle simultaneous detection of distances and directions for multiple targets. We introduce a microwave photonic radar for distance and direction measurement of multiple targets. At the transmitter, a linear frequency modulation signal is generated by photonic frequency doubling and transmitted for detection. At the receiver, echo signals are received by a uniform linear array with three antennas. The intermediate antenna supplies overlapped reference spectra by polarization-multiplexing modulation. The de-chirped spectra possess specific symmetry, thus de-chirped frequencies of each antenna are clearly distinguished and distances and directions of multiple targets can be obtained. Two-target proof-of-concept experiments have verified that the average measurement errors of distance and direction are 2.4 cm and 0.6°, respectively.
Compared with traditional electrical methods, radio frequency self-interference cancellation (SIC) based on microwave photonic technology has the advantages of large bandwidth, high precision, low loss and anti-electromagnetic interference. For distributed full-duplex communication system, a SIC method based on cascade modulation is studied. The cancellation depth of the system for single-frequency signals is more than 43 dB, and the cancellation depth for wideband signals is more than 22 dB, and the recovered useful signals is obtained. The system adopts cascade modulation, and the isolation degree of LO and RF signal is high. In this scheme, the signal after SIC can be transmitted to the central office through a long fiber. The proposed approach supplies an architecture for distributed systems with both down-conversion and SIC.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.