Review of protection measurements and spectrum efficiencies of ACSB and FM mobile radio systems

Recent measurements of co- and adjacent channel protection ratios of Amplitude Companded Single-Sideband (ACSB) and Frequency Modulated (FM) mobile radio systems are reviewed and evaluated for comparability. It is found that the measurements are not strictly comparable because of differing measurement techniques and interference criteria. Simple definitions of "spectrum efficiency" and "Relative Spectrum Efficiency (RSE)" are developed and it is found that the co-channel protection requirements are much more important in determining spectrum efficiencies than adjacent channel protection. Values of RSE for ACSB and FM systems are calculated using the measured values of co-channel protection. It is found that 5 kHz ACSB systems appear to be about 1.5 to 8.4 times more efficient than 25 kHz FM systems. The large variation arises mainly from the differences in measurement techniques and criteria which tends to hide the real difference between the two systems. This argues for the need to have standard measurement techniques and criteria in future spectrum efficiency measurements.