Electromechanical Transmitters For Elf Vlf Radio PDF Download

ELF/VLF radio signals, from approximately 300Hz to 30KHz, are commonly used for submarine communications, ionospheric remote sensing, geophysical prospecting, and studies of the near-Earth space environment. Naturally occurring ELF/VLF emissions caused by nearly every lightning strike can be detected for thousands of miles and provide an abundance of wave-particle interaction possibilities in the radiation belts. Any applied studies of these events, however, require electromagnetic waves in the ELF/VLF band to be amplified, captured, analyzed, and stored. Specific studies often require the placement of receivers in extremely remote locations such as Antarctica or the middle of an ocean, and are almost always located far away from power sources to decrease noise. These scientific requirements drive the creation of new ELF/VLF receiver systems. Two new receiver systems were designed for use in terrestrial, typically Antarctic, locations. Both new systems utilize 10-100 times less power than the lowest-power comparable existing ELF/VLF receivers and were designed for remote unmanned operation in extreme environments without external power. The so called Penguin system, comprised of a hybrid microcontroller and FPGA architecture, removes the overhead of a general purpose CPU to provide the most streamlined processing for data acquisition possible while still maintaining a relatively traditional sampling architecture. The drastically reduced architecture of the Penguin system, compared to traditional receiver systems, on average consumes less power than a typical LED indicator lamp while capturing high fidelity ELF/VLF magnetic field snapshots every fifteen minutes. The low power and thermal requirements of the Penguin system enables low-cost remote studies of medium to large timescale phenomena such as Chorus and Auroral Hiss without the need for local power. The system has been deployed and operated at the United States Amundsen Scott South Pole Station in Antarctica. A second ELF/VLF receiver architecture, the VLF Advanced Technology platform, or "VAT", removes the typical CPU from the sampling and recording loop further reducing power requirements and physical system size while gaining the ability to record continuously. This radically new architecture enables future scientific studies of the fine structure in time and frequency of long-term events, such as the onset mechanisms of natural Chorus emissions, due to the extremely low power requirements. The system architecture is also greatly applicable to any continuous time recording system, including but not limited to acoustic and electromagnetic arrays for subsurface imaging systems, ionospheric remote sensing, and optical sensors.