vector to actual speed
V.N. Lepin, V.V. Muhin, A.J. Trushchinsky, A.Yu. Frolov, N.F. Chezganov
Currently, the development of miniature synthetic aperture radar (MiniSAR) is one of the priorities. Miniature SAR provide a solution to problems of intelligence, surveillance, target designation for the application of air strikes, search and rescue operations and perform other tactical tasks at any time of day, and adverse weather conditions, the presence of natural and artificial noise. To ensure the long-range mapping requires high average power radiation. Therefore, all known types of MiniSAR are working with continuous emission of the LFM signal.
The paper analyzes the factors influencing the range of MiniSAR with continuous radiation. The analysis shows that because of the influence of penetrating signal transmitter power capacity does not increase the range of MiniSAR with a continuous radiation. Currently, the range of MiniSAR with a continuous radiation is limited to 10 ... 20 km.
The purpose of articles - study the structure of MiniSAR using quasi continuous chirp signal of low duty cycle.
In order to ensure simultaneous operation at high and low range are encouraged to use the block diagram SAR with two antennas, one receiving and transmitting, and the second – just passed. The closest in energy performance (average power) to a continuous signal is quasi continuous signal with low duty cycle. Processing of such signals in MiniSAR may be accomplished by a combination of algorithms for continuous and pulsed signals depending on the distance of observation. The structure of such MiniSAR has two channels: only the receiver and receiver-transmitter, and allows us to observe targets not only small but also at long range.
For a small range of mapping, when the reflected signal enters the receiver at the time of the radiation transmitter, MiniSAR is working on a scheme with a continuous radiation.
With long-range observation, when the reflected signal enters the receivers after the radiation transmitter, MiniSAR is working as usual impulse radar.
Mode control (surveillance zone) is provided by the synchronizer. As a result, it is possible to monitor the area at different distances: from almost zero, which is limited by altitude carrier, to the maximum, which is limited to only an average power of the transmitter.
Conclusion: A sound structure of MiniSAR with quasi-signal low duty cycle provides the opportunity to work at small distances (continuous emission) and at large (pulsed radiation).