Ulf-Vlf-Lf Bantları için Alıcı Tasarımı ve Geliştirilmesi
Özet
ULF-VLF-LF bands are the frequency range of 300 Hz to 300 kHz, where the low frequency signals with long wavelengths that are emitted from artificial or natural sources propagates. Since the signals observed in this frequency range propagate with very small attenuation over long distances in the earth-ionosphere waveguide, they contain not only the communication data of a nearby source, but also the information of many artificial and natural phenomena observed over the long distance it travels. The sources of the waves that can be seen in the VLF band can be directed to transmit information in the form of time information transmission, military communication, amateur radio communication, submarine communication, or sources using waveform rather than content such as transmitters used for underground analysis. In addition to these, natural events such as lightning, solar flares and earthquakes may cause wave formation and wave shaping in the VLF band.
By examining the signals in this band, studies on ionosphere structure and interactions are made. Another field of study related to natural phenomena is the study of VLF signals in order to investigate and detect changes that occur before and after earthquakes.
Within the scope of this thesis, a receiver system design and application aiming at the reception and processing of signals in VLF (3–30 kHz) and LF (30–300 kHz) communication bands and lower frequency bands has been made.In this study, it is prioritized that the system is able to take accurate measurements as precisely and at high speed as possible in terms of current technological standards. Another important consideration is the easy multiplexing and remote accessibility of this system to obtain data sets that may be needed in more complex studies. The developed system has been firstly passed through the theoretical design stages and the necessary parts have been designed in computer environment, prototyped by means of reference measuring instruments and turned into an embedded system that can work standalone with the printed circuit method in the final product.
