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A-8 Appendix A: Path Evaluation Information
Moseley SL9003Q 602-12016-01 Revision J
Table A-6. Relationship Between System Reliability & Outage Time
RELIABILITY OUTAGE OUTAGE TIME PER:
(%) TIME (%) YEAR MONTH (Avg.) DAY
0 100 8760 Hr 720 hr 24 hr
50 50 4380 Hr 360 hr 12 hr
80 20 1752 hr 144 hr 4.8 hr
90 10 876 hr 72 hr 2.4 hr
95 5 438 hr 36 hr 1.2 hr
98 2 175 hr 14 hr 29 min
99 1 88 hr 7 hr 14.4 min
99.9 0.1 8.8 hr 43 min 1.44 min
99.99 0.01 53 min 4.3 min 8.6 sec
99.999 0.001 5.3 min 26 sec 0.86 sec
99.9999 0.0001 32 Sec 2.6 sec 0.086 sec
A.2.5 Methods of Improving Reliability
If adequate reliability cannot be achieved by use of a single antenna and frequency, space
diversity or frequency diversity (or both) can be used. To achieve space diversity, two
antennas are used to receive the signal. For frequency diversity, transmission is done on
two different frequencies. For each case the two received signals will not experience fades
at the same time. The exact amount of diversity improvement depends on antenna spacing
and frequency spacing.
A.2.6 Availability Requirements
Table A-7. Fade Margins Required for 99.99% Reliability,
Terrain Factor of 4.0, and Climate Factor of 0.5
DISTANCE 450 MHz BAND 950 MHz BAND
5 Miles (8 km) 7 dB 10 dB
10 Miles (16 km) 17 dB 20 dB
15 Miles (24 km) 22 dB 25 dB
20 Miles (32 km) 27 dB 30 dB
25 Miles (40 km) 29 dB 32 dB
30 Miles (48 km) 32 dB 35 dB