Analog modulation techniques such as frequency and phase modulations provide significant noise immunity as known and provide SNR enhancement proportional to the square root of the modulation index and can thus exchange the bandwidth for SNR. Noise as known and provide SNR enhancement proportional to the square root of the modulation index, and thus are able to trade broadband for SNR. However, the SNR enhancement provided by these techniques is much smaller than the ideal performance as shown by the Shannon capacity theorem. On the other hand, the digital transmission techniques can use error correction codes that provide a performance close to the theoretical prediction. However, the main disadvantage of digital transmission techniques is the inherent quantization error introduced, which is imminent for the entire time the signal is retransmitted. This error causes distortion in the original signal being retransmitted and can not be recovered later by any means possible. If we quantify the sampled signal using QAM or any other method, using a fixed number of bits, a fixed digital distortion is introduced into the development stage itself. This distortion is present regardless of the transmission quality of the channel being used. Therefore, the original signal can be considered as permanently damaged. Communication systems are typically built for SNR much higher than the minimum required, to leave room for fading and other effects, which may occasionally reduce the SNR.