Measuring the Non-Line-of-Sight Ultra-High-Frequency Channel in Mountainous Terrain: A Spread-Spectrum, Portable Channel Sounder
ERDC-CRREL HANOVER United States
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Very few measurements campaigns have conducted ground-based, radio-frequency propagation field measurement campaigns conducted in deep mountainous terrain, and none have focused on the non-line-of-sight channel in mountain shadow zones. Here, we introduce a versatile, spread-spectrum, portable channel sounder specifically designed to measure the non-line-of-sight, ultra-high-frequency channel in mountainous terrain. The receiver is backpack mounted for ease of transport into remote, mountainous locations that are kilometers from the transmitter and inaccessible to vehicles of any kind. The system uses software-defined radios to transmit and capture a wideband pseudorandom noise waveform and maintains synchronization using reference signals from rubidium clocks trained by global positioning system signals. A clock holdover capability maintains system synchronization within tens of nanoseconds even when global positioning system signals are unavailable. System synchronization allows for coherent captures up to 60 seconds in duration and provides a dynamic range of more than 30 decibels. The system exhibits a timing uncertainty of plus or minus 145 nanoseconds, corresponding to plus or minus 44 meters. Measured channel powerdelay profiles are verified using geospatial analyses. Initial results suggest that local topography strongly affects channel time dispersion characteristics and that a given set of channel conditions cannot be readily generalized to cover an entire mountainous region.
- Radio Communications