Call Sign Specifically Optimized For Fmcw Hf Oceanographic Radars

At the end of 2012, the ITU issued Resolution 612, which allotted designated secondary radio spectral slots to coastal oceanographic radars (3 - 50 MHz). Part of the condition for authorized use of these bands is the requirement that each radar transmit a Morse-coded call sign issued by its national authority. The unique call sign identifies the transmitter. The worldwide process of implementing this has begun. In the absence of ITU recommended rules for conformity, we outline and are implementing an optimized procedure that is described herein. It is meant to follow the intended spirit fairly, of allowing identification by AM radio receivers impacted by the radar's signal, when both occupy different spectral bandwidths. Our design also ensures continuous data capture during call-sign broadcast periods, both the radar as well as neighboring radars on the same frequency. We demonstrate this with radar Doppler spectra spanning periods of call-sign transmission. This is based on the FMCW radar waveform, which all commercially available oceanographic radars employ.