Communications using a mixed analog-digital modulation technique

We present a mixed analog-digital modulation technique called signal code modulation (SCM). The technique is based on the idea of representing the analog signal by a digital (i.e. quantized) component, and an analog component consisting of the quantization error. The combination of these digital and analog components provides an exact representation of the original signal. Both components are transmitted by the communication system and used to reconstruct an estimate of the signal at the receiver. The presence of the analog residual allows system performance to improve when excess channel SNR is available. The digital component provides an SNR gain and makes it possible to employ coding to achieve near error free transmission.