Ionized layer Es high-resolution vertical detection method based on cross-spectrum analysis

Abstract

The invention relates to an ionosphere detection technology, in particular to an ionosphere Es layer high-resolution vertical detection method based on cross-spectrum analysis, which comprises the following steps of: transmitting a short-wave detection signal which has a narrower bandwidth and is coded and modulated to an Es layer above vertically by using a vertical measurement instrument in a sweep frequency or fixed frequency observation mode, intercepting an effective part of an echo, and carrying out cross-spectrum analysis on the effective part of the echo; and for each detection of each detection frequency, a spectrum estimation method is independently adopted to carry out high-resolution imaging, so that high-precision observation of the internal structure and the motion process of the Es layer is realized. According to the method, extra equipment and hardware cost are not needed, the range resolution of Es layer observation can be greatly improved, and compared with high-resolution imaging conducted through a traditional coherent accumulation technology or a multi-frequency interference technology, the method does not need high-frequency repeated detection to achieve energy accumulation or conduct joint operation through multi-frequency-point echo data; the time resolution is improved while the distance resolution is very high, and the short-time violent change in the Es layer can be observed conveniently.

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 at all times, 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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