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Abstract:
We have developed and demonstrated a time transfer system using high-definition television (HDTV) broadcast signals in common view. The system is comprised of a software defined radio (SDR), a TV antenna, a digitally programmed crystal oscillator (DOCXO) in remote systems that is disciplined to the master system reference clock, and standard servers connected to a network. Data are transferred via a low-bandwidth backchannel and the system is compatible with any HDTV waveform type that has an underlying framing structure. Using the time deviation (TDEV) as a standard metric for charactering stability, the residual noise floor of the master and remote nodes, co-located with a common antenna and receiving a HDTV signal in the ultra-high frequency (UHF) band, is less than 10 ps at all averaging periods of more than 100 s. We also report the results of field demonstrations where the master and remote systems each have their own antenna and are separated by a baseline of 210 m on the National Institute of Standards and Technology (NIST) campus in Boulder, Colorado. Future work is expected to utilize the system to compare the primary UTC(NIST) time scale in Boulder to the secondary UTC(NIST) time scale in Ft. Collins, Colorado, over a 78-km baseline.