The invention relates to a bottom hook block system for a given maximum load, for providing differently portative bottom hook blocks for a crane, especially for a heavy lift crane. This receiver includes an analog front end, a GPS digital front end and a GLONASS DFE for receiving an output of the AFE, and a dual mode interface for receiving outputs of the GPS and GLONASS DFEs. The end seal includes a blade pocket for mating with the end portions of the cleaning blade and a middle portion having an array of ridges thereon. The modem cable is accommodated in an electric cable accommodating device in the state that a part of the modem cable is wound up about a reel. The interpolation module may interpolate a reference image signal with each of the candidate filters.