on effects (multipath fading or nel data modem users. selective fading, rain attenuation, ducting, etc.). In Tables 50.3 and Given similar bandwidth and voice channel capacity: much 50.4 already referred to in the capacity comparison section above, higher System Gain. System Gain was also listed for typical microwave radios of the 4. Given similar System Gain and bandwidth: higher voice chan- various types. nel capacity. In the case of the similar bandwidth, similar voice channel capac- ity comparison (Table 50.3), the System Gain of the analogue FM Though rare exceptions may be found to these conclusions, the type is shown to be superior. This is due to the poorer microwave summary of advantages above will be found to be applicable given receiver threshold of the bandwidth efficient digital microwave the bandwidth restrictions and the traffic requirements of the Private system. This bandwidth efficiency was necessary for the digital Operational Fixed Microwave Services. microwave system to achieve a similar voice channel capacity and bandwidth. In the case of the similar data or T-1 capacity comparison, the System specification and equipment System Gain of the digital microwave type is slightly superior. This is because the digital microwave is a more efficient mode for design transmitting high speed data, and requires less bandwidth for a similar data rate. Less bandwidth equates to less noise in the pass- 50.4.1 The role of microwave in systems band of the digital microwave receiver, and a relatively good re- ceiver threshold. For the owner/user of a microwave system, performance and relia- Table 50.5 adds a new comparison, where similar System Gain bility are of utmost importance. The usual function of a microwave system is to serve as an interconnecting medium for other equip- Table 50.5 Comparison of approximately the same ment which is considered the 'real' communications system. For System Gain analogue and digital microwave (for the same example, microwave is commonly used to convey multiple tele- condit