30-07-2009, 04:13 PM
This paper seeks to present ways to eliminate the inherent quantization noise component in digital communications, instead of conventionally making it minimal. It deals with a new concept of signaling called the Signal Code Modulation (SCM) Technique. The primary analog signal is represented by: a sample which is quantized and encoded digitally, and an analog component, which is a function of the quantization component of the digital sample.
The advantages of such a system are two sided offering advantages of both analog and digital signaling. The presence of the analog residual allows for the system performance to improve when excess channel SNR is available. The digital component provides increased SNR and makes it possible for coding to be employed to achieve near error-free transmission. we introduce the concept of Signal Code Modulation (SCM) which utilizes both the analog, as well as, digital modulation techniques. The primary analog input signal is sampled at the appropriate rate and quantized. The digital samples are denoted by symbols D. The resulting D symbols are then transmitted using digital transmission techniques (like QAM) optimized for that channel. Those D symbols represent N bits per analog input sample. The quantization residual, which is not left behind, is transmitted over the noisy channel as an analog symbol A, corresponding to the digital symbol D,To produce the quantization error A, the quantized data is converted back into analog form and subtracted from the original analog input signal. This symbol A, for noise immunity, is amplified by a gain of 2N (or any proportional factor that will optimize the voltage swing of the signal with that of the channel).
The advantages of such a system are two sided offering advantages of both analog and digital signaling. The presence of the analog residual allows for the system performance to improve when excess channel SNR is available. The digital component provides increased SNR and makes it possible for coding to be employed to achieve near error-free transmission. we introduce the concept of Signal Code Modulation (SCM) which utilizes both the analog, as well as, digital modulation techniques. The primary analog input signal is sampled at the appropriate rate and quantized. The digital samples are denoted by symbols D. The resulting D symbols are then transmitted using digital transmission techniques (like QAM) optimized for that channel. Those D symbols represent N bits per analog input sample. The quantization residual, which is not left behind, is transmitted over the noisy channel as an analog symbol A, corresponding to the digital symbol D,To produce the quantization error A, the quantized data is converted back into analog form and subtracted from the original analog input signal. This symbol A, for noise immunity, is amplified by a gain of 2N (or any proportional factor that will optimize the voltage swing of the signal with that of the channel).