Abstract: A ship-centric direct communication system and an operation method thereof are proposed. The system includes a data transmission device configured to transmit, to a data reception device through a link channel, a transmission frame composed of a plurality of slots generated according to slot time, a plurality of pilots provided for channel estimation and arranged at respective specific positions in each of the plurality of slots according to a pilot transmission period, and data symbols arranged between each of the plurality of pilots, and the data reception device configured to perform channel compensation for data present between the plurality of pilots by using the plurality of pilots for each of the plurality of slots of the transmission frame when the transmission frame is received from the data transmission device and performing linear interpolation after the channel estimation in a frequency domain, and convert channel-compensated signals back into time domain symbols.

Abstract: In order to solve the problems of a conventional flat surface wave generator which has limitations on being applied to a curved structure due to more than a certain required thickness of a dielectric material, proposed are a flexible surface wave generator and system and method for surface wave communication using the same where the flexible surface wave generator is bendable by removing a third dielectric material and by making a first and a second dielectric material thin and at the same time reaches communication performance applicable to the ISM band by changing a pattern of a surface wave generation member and by forming a slit in a radiator material, so it is possible to easily establish a surface wave communication system even in environments where a conventional flat surface wave generator is difficult to be applied by being tightly attached to the surface of a metal medium with curvature.

Abstract: Disclosed is an automatic switching communication method including: obtaining LTE communication state information of a main communication module for communicating with outside through a directional antenna and a sub-communication module for communicating with the outside through a directional antenna; registering the LTE communication state information of the main communication module and the sub-communication module in a routing table; determining whether the main communication module and the sub-communication module are capable of performing LTE communication; and comparing with pre-specified communication quality coefficients of the main communication module and the sub-communication module to adjust a routing path.

Abstract: A surface wave generator is proposed. The generator may include a radiator configured to generate an electromagnetic field based on a signal externally applied. The generator may also include a first dielectric substrate on a top of the radiator and a second dielectric substrate on a bottom of the radiator. The generator may further include a first surface wave generation member on a bottom of the second dielectric substrate, a first geometric pattern being deposited on a top of the first surface wave generation member. The generator may further include a third dielectric substrate on a bottom of the first surface wave generation member. The generator may also include a second surface wave generation member between the third dielectric substrate and a metal surface, a second geometric pattern different from the first geometric pattern and being deposited on an upper surface of the second surface wave generation member.

Abstract: A ship IoT wireless communication system using metal surface waves is proposed. The ship IoT wireless communication system may include a first access point installed in a first compartment among a plurality of compartments formed in a ship, and a second access point installed in a second compartment among the plurality of compartments. Each of the first access point and the second access point may perform surface wave communication with each other to form a communication network inside the ship. Each of the first and second access points may include a surface wave generator configured to transmit and receive a surface wave through at least one of a floor, a ceiling, or a bulkhead of each of the plurality of compartments.

Abstract: The present invention relates to a system for detecting ambiguities in a satellite signal for the GPS tracking of vessels, which includes: a GNSS receiving unit obtaining a vessel position using a plurality of satellites; a vessel position calculating unit calculating a second vessel position from a first vessel position after a specific amount of time elapses using dead-reckoning; a distance calculating unit calculating prediction distances between each of the satellites and the vessel and an error monitoring unit comparing the calculated prediction distances between the satellites and the vessel, and pseudoranges between the satellites and the GNSS receiving unit at the second vessel position, and monitoring for the occurrence of errors at the satellites on the basis of the existence of an increase in errors at each of the satellites.

Abstract: The present invention relates to a system for detecting ambiguities in a satellite signal for the GPS tracking of vessels, which includes: a GNSS receiving unit obtaining a vessel position using a plurality of satellites; a vessel position calculating unit calculating a second vessel position from a first vessel position after a specific amount of time elapses using dead-reckoning; a distance calculating unit calculating prediction distances between each of the satellites and the vessel and an error monitoring unit comparing the calculated prediction distances between the satellites and the vessel, and pseudoranges between the satellites and the GNSS receiving unit at the second vessel position, and monitoring for the occurrence of errors at the satellites on the basis of the existence of an increase in errors at each of the satellites.