Subjective tests of picture quality have documented the degradation in picture quality seen near threshold. Therefore receiver manufacturers have been motivated to develop methods to "extend" or lower threshold and thus make a weaker signal more watchable. There are a number of approaches to extending receiver threshold. Using the best possible circuit design and components that contribute the lowest amounts of noise to a signal being processed is the starting point. Another simple method underlying most of these techniques is to reduce video bandwidth.e effect of reducing bandwidth is to increase C/N ratio resulting in some loss of picture fidelity. The increase in C/N ratio can be calculated from the link equation. For example, decreasing the bandwidth from 30 to 15 MHz results in a 3 dB increase in C/N ratio. The same result can be obtained by doubling the surface area of the receive dish. This technique can be valuable in out-of-footprint or weak signal areas. For example, reducing the bandwidth from 28 to 18 MHz, a manageable amount, increases the C/N ratio by 1.92 dB. This would be equivalent to replacing a 5 meter dish with an equivalent one that is 6.3 meters in diameter.