An interference avoidance waveform for the UHF downlink on the new NOAA GOES-R satellite

The Data Collection System, onboard the NOAA GOES satellites, receives environmental data from more than 25,000 meteorological platforms in the western hemisphere using a one-way UHF uplink. There is strong interest in the Data Collection System (DCS) user community to establish a two-way system to permit the remote control and reconfiguration of these platforms. The first of the next generation of NOAA GOES satellites, GOES-R, was launched on November 19, 2016. Onboard, there is a 100 kHz transponder that will permit NOAA and the DCS user community to establish a DCS two-way link with meteorological platforms. The spectrum that must be used for this downlink is at 468.8 MHz. The DCS two-way service has a secondary allocation in this frequency band. The primary user group in this band, for the United States, is the business and industrial, land-mobile, radio community. This paper proposes an interference avoidance waveform that can coexist with the primary user group. The waveform is a coherent slow-hopping PSK waveform that utilizes the narrow interstitial notches between the emission masks of the primary, adjacent 12.5 kHz land mobile radio channels. A shortened Reed Solomon (250,218) code is added to assist with overcoming interference while at the same time providing the potential to use the GPS timing reference on DCS platforms to assist with decoding. Simulation results are included that verify the proposed waveform has the desired interference avoidance capabilities.