We describe a mathematical framework for evaluating timing offset and timing noise in channel sounders based on a second-order deterministic model and a stochastic metric based on the Allan Deviation. Using this framework, we analyze the timing offset and noise for a 1-6 GHz correlation-based channel sounder that uses rubidium clocks to provide a common timebase between the transmitter and receiver. We study timing behavior in three clock-distribution configurations. In the "untethered" configuration, the transmitter and receiver each have a rubidium clock, and no physical timing cable is connected between the clocks. In the "tethered" configuration, a coaxial cable synchronizes timing between the two separate clocks. Finally, a benchmark "single-clock" configuration is used where a single rubidium clock drives the transmitter and receiver.

An efficient procedure for modeling medium frequency (MF) communications in coal mines is introduced. In particular, a hybrid approach is formulated and demonstrated utilizing ideal transmission line equations to model MF propagation in combination with full-wave sections used for accurate simulation of local antenna-line coupling and other near-field effects. This work confirms that the hybrid method accurately models signal propagation from a source to a load for various system geometries and material compositions, while significantly reducing computation time. With such dramatic improvement to solution times, it becomes feasible to perform large-scale optimizations with the primary motivation of improving communications in coal mines both for daily operations and emergency response. Furthermore, it is demonstrated that the hybrid approach is suitable for modeling and optimizing large communication networks in coal mines that may otherwise be intractable to simulate using traditional full-wave techniques such as moment methods or finite-element analysis.