Triple-Play Service Deployment

132
Relative Frequency %
5
4
3
2
1
Home shielding effectiveness in the FM band
Cable Labs® performed a study of digital transmission characteristics
in a home in 1994. This study was performed on multiple
homes served by various cable systems in different geographical
regions. In that study one factor examined was home shielding
effectiveness in the FM band. Table 5.3 presents the results as a
histogram. The study showed that 99% of the homes have a
shielding effectiveness of greater than 27 dB and 90% have a
shielding effectiveness of greater than 42 dB. On the other hand,
10% will attenuate an external signal by less than 42 dB and 5% by
less than 36.
Average 50% 90% 95% 99%
Home Wiring Shielding (dB) 67 58 42 36 27
Table 5.3: Histogram of shielding effectiveness
Probability Distribution Function
Average Shielding (dB) = 67 (dB)
100 80 60 40 20
Shielding (dB)
Relative Frequency %
100
Figure 5.10 Plots of home shielding effectiveness
80
60
40
20
Chapter 5: Troubleshooting the Premises Wiring
Cumulative Distribution Function
Average Shielding (dB) = 67 (dB)
0
100 80 60 40 20
Shielding (dB)