1.5GHz multipoint system Interference to and from existing systems in the frequency band. 2. A cellular re-use plan must allow for future system growth. Value 3. The use of repeaters must be considered. Transmission direction CS to OSs The available channel frequencies may be allocated to form a Frequency (GHz) cellular pattern of 3,4,7,9,12 cells (Cox, 1982), with perhaps a smaller number of channels forming an overlap pattern for extra (a) Transmitter power (dBm) capacity. In addition a frequency re-use pattern may also be estab- (b) Transmitter antenna gain: omni- lished for repeaters. directional (dBi) The frequency re-use pattern is generally based on geometric (c) Receiver antenna gain yagi (dBi) pattern. However, in practice it is essential to evaluate worst case co-channel interference from cells using similar frequencies in (d) Fixed losses in dB (transmit/receive various clusters. Examples of frequency re-use patterns are given in end feeders filters etc.) CCIR, 1990b. (e) Receiver sensitivity for 1 in 1000 bit error ratio (dBm) 52.3.10 Applications (f) System gain dB (a)+(h)+(c)+(d)-(e) The primary application of these systems is in providing telephony (g) Path loss in dB for 24km hop 123.5 service, often in isolated mountainous villages, deserts or off-shore (h) System fade margin M dB (f)-(g) islands for the very first time. Therefore they are designed to operate in harsh environments over a wide range of temperatures to 55°C) They have found applications in desert areas 52.3.7 Modulation/demodulation methods to provide connections to remote drilling sites with transportable solar powered OSs. Although pulse width modulation of speech channel followed by Transportable OSs have also found applications in providing frequency modulation has been used in an earlier system, most temporary telephony, facsimile and telex services at important systems employ binary frequency shift keying, binary phase shift events and shows (Holm, 1988). Other applications include emer- keying or quarternary phase shift keyi