36 results about "Ionospheric sounding" patented technology

The invention discloses a non-coherent scattering radar signal processing method based on frequency hopping and multiphase alternate codes. The method mainly solves the problems that existing non-coherent scattering radar is low in height resolution ratio, long in detection period and limited in coding mode. According to the technical scheme, the method comprises the following steps that all sets of the multiphase alternate codes are modulated respectively according to different frequencies, and radar pulses arranged in sequence without any time slot are generated and transmitted through a radar transmitter; radar echo signals are filtered respectively according to transmitting modulation frequencies so as to obtain detection data, corresponding to the same height range, of all the sets of the multiphase alternate codes, post-detection filtering is carried out on each set of coding echo signals, a self-correlation function is worked out, multi-period accumulation and fuzzy revising are carried out, and therefore the power spectral density of scattered signals of an ionized layer is worked out. The method can increase the height resolution ratio of the radar, shorten the detection period of the radar, expand the signal coding modes and be used for detection of the ionized layer.

An MIMO (multiple input multiple output) radar technology can perform beam forming at both a transmitting end and a receiving end, particularly can emit narrow beams in different directions at the same time, and just can meet demands of a sky-wave over-the-horizon radar (OTHR) on multilayer ionospheric sounding and inhibition of relatively strong clutter. A two-ionized-layer structure is applied to an MIMO OTHR system, and aimed at a characteristic of relatively high clutter-noise ratio (CNR) caused by influence of sea clutter and ionized layers on the OTHR, a set of signal processing method is proposed and comprises adaptive optimization of a transmitted waveform with a two-step method of a mutual information theory. Simulation verification discovers that the method remarkably increases the target detection probability and resolution, so that the MIMO-OTHR can utilize multipath echoes to improve target detection and other system performances.

A micro / nano-satellite for ionospheric probing is composed of an external spherical shell, antenna housings, antennas and a modular component, namely the CubeSat, wherein the outer spherical shell and the antenna housings are connected to form a spherical case of the whole satellite; the antennas are fixed to the external spherical shell and covered with the antenna housings; and the CubeSat is fixed to the center of the interior of the whole satellite through supporting rods on the external spherical shell. The micro / nano-satellite for ionospheric probing is a combination of the modular component and the customized components, is convenient to produce and machine, and has the advantages of low cost, simple structure, high universality and short production cycle. The micro / nano-satellite for ionospheric probing can probe ionized layers and the air density of atmosphere, thereby having high practicability. By the adoption of symmetrical distribution of the two omnidirectional antennas, the effect that the satellite can receive and dispatch signals in any posture is ensured, and requirements for a posture control system are reduced.

The invention discloses an ionized layer parametric inversion method based on AIS target indication. The method includes the steps of obtaining the target positions and movement information of offshore ships on the basis of the AIS, detecting suspected ship targets on the basis of a sky wave radar echo spectrum and through the combination with the AIS target indication area, conducting correlation, fusion and matching on the ship targets detected by radar and the ships indicated by the AIS so as to obtain the route of a radar ship target group, detecting a quasi parabolic ionized layer model required for the ship target positioning on the basis of sky wave radar backscatter sounding, establishing a mean square error equation of the route of the radar ship target group, and obtaining the optimal solution of the ionized layer parameter on the basis of the optimization solution algorithm. By means of the method, the ionized layer parameter model can be obtained without more professional ionized layer detection devices, and the number of devices and the device cost are reduced. The static and dynamic information of a large number of offshore ships can be provided through a ship automatic identification system in real time, the amount of the information serving as input data of the parametric inversion algorithm is large, the inversion accuracy and stability of the ionized layer parameter are improved, and the spatial resolution of the ionized layer parametric inversion is improved.

The invention discloses a top ionosphere detection space-borne MIMO radar system which belongs to the field of radar technology and compromises a complete complementary sequence generator, a pulse period delayer, a modulator, emission antennae, reception antennae, a demodulator, a pulse compression system and an electron density distribution generation system. The complete complementary sequence generator simultaneously generates N pairs of complementary sequences. The pulse period delayer alternatively inputs two complementary sequences to the modulator. N pairs of signals are modulated at Ncarrier frequencies respectively and sent out by the N emission antennae, and the echo signals are received by the N reception antennae. The demodulator demodulates signals on the N carrier frequencies. The signals are sent to the electron density distribution generation system after pulse compression to generate a two dimensional ionogram. The space-borne MIMO radar system is used for the top ionosphere detection. Compared with the prior ionosphere detector, the space-borne MIMO radar system of the invention can generate two dimensional ionograms and has very high orientation resolution and high work efficiency.