A high-resolution vertical detection method for the ionospheric es layer based on cross-spectral analysis

Abstract

The invention relates to ionospheric detection technology, in particular to a high-resolution vertical detection method of the ionospheric Es layer based on cross-spectrum analysis. There is a coded and modulated short-wave detection signal with a narrow bandwidth, and the effective part of the echo is intercepted, and the spectral estimation method is used for each detection of each detection frequency to perform high-resolution imaging, so as to realize the high-resolution imaging of the internal structure and motion process of the Es layer. Precision observation. This method does not require additional equipment and hardware costs, and can greatly improve the range resolution of Es layer observations. Compared with traditional coherent accumulation techniques or high-resolution imaging using multi-frequency interferometry, this method does not require a high number of repeated detections. In order to achieve energy accumulation or use multi-frequency echo data for joint operation, it has a high range resolution and at the same time improves the time resolution, which is convenient to observe the short-term drastic changes in the Es layer.

Description

technical field [0001] The invention belongs to the technical field of ionospheric detection, in particular to a high-resolution vertical detection method of the ionospheric Es layer based on cross-spectrum analysis. Background technique [0002] The ionospheric Es layer is a common thin and uneven structure in the E layer, which mainly occurs at a height of 90-130km. Because its occurrence law is still difficult to grasp and does not appear all the time, it is usually called "sporadic E layer" (Es layer). Existing research results have shown that there is a complex internal structure and motion process inside the Es layer, which may be a thin and dense thin layer in height distribution, or there may be small inhomogeneous bodies embedded in dispersion, and also in the horizontal direction. There may be discontinuities in the electron density distribution. [0003] The formation and movement process of the inner structure of the Es layer can be simultaneously modulated by ...

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Problems solved by technology

[0004] At present, the high-resolution observation of the Es layer mainly relies on incoherent scatter radar or ultra-short wave coherent scatter radar, but both require large antenna arrays and extremely high transmission power, making construction difficult and inconvenient to move

As the most commonly used observation instrument with a long history, the ionospheric dipmeter can be widely deployed and long-term continuous observation due to its low cost and simple structure. Recognizing the characteristics and short-term motion process of the fine structure inside the Es layer

[0005] For the method of improving the distance resolution of the vertical survey instrument, one of the directions is to reduce the pulse width of the vertical survey instrument detection signal, which means that it is difficult to realize the improvement of the system bandwidth requirements and the increase of the transmission power; the other is to use multiple The signal coherence between two adjacent frequencies, multi-frequency coherent technology is used for high-resolution imaging, but it requires a small transmission frequency interval and comprehensive calculation of multiple frequency echo data, and it is also necessary to compare each frequency point. Repeated detection multiple times to obtain a high number of signal snapshots, the time resolution is low; in addition, the multi-carrier technology using frequency division multiplexing is also a feasible method, but the ability to improve the range resolution is limited, and requires Matched filtering is performed on signals in multiple different frequency bands, which requires high hardware and software requirements

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