Preliminary Analysis of WWV Experimental Tone Signals

NIST Time station WWV and WWVH have recently been broadcasting a set of audio modulation signals designed by the WWV/H Scientific Modulation Group as an initial exploration of possibilities for using these powerful and ubiquitous time distribution HF transmissions as remote sensing diagnostics of the terrestrial ionosphere.  Included audio modulations include pseudorandom white noise, swept chirps, controlled amplitude sequences, and single pulses.  The first task in assessing feasibility for remote sensing is to analyze characteristics of the analog WWV transmitters themselves, in order to gauge the transfer function imposed on the original test transmission.  Using ground wave recordings from a GNSS locked receiver station maintained by Glenn Elmore N6GN, we present preliminary transmitter-centric analysis of WWV experimental tone signals, focusing on amplitude fidelity, transmission delay, cross-ambiguity examination of frequency and amplitude stability, and pseudorandom noise determinations of audio passband shape.