In this work, 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 timing noise for a 1-6 GHz correlation-based channel sounder which uses rubidium clocks to synchronize 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. We analyze the experimental channel-sounder data for timing offset using a second-order clock model. Next, we perform a qualitative analysis of the timing noise processes using Time Deviation, a modified form of the Allan Deviation. From these analyses, we gain insight into the sources of timing offset and timing noise in our correlation-based channel sounder.
, Quimby, J.
, Rezac, J.
and Romisch, S.
Timing Offset and Timing Stability for Dual-Clock Systems, IEEE Antennas and Propagation Magazine, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=929258
(Accessed January 23, 2022)