Performance of 16 kbit/s APC codec with maximum likelihood quantization for low-speed voiceband data

This paper presents an evaluation of the performance, with low-speed voiceband data at 300 bit/s, 1.2 kbit/s and 2.4 kbit/s, of a 16 kbit/s APC (Adaptive Predictive Coding) with maximum likelihood quantization(MLQ). By measuring modem bit error rates, the effect of a long-term predictor and influence of a subscriber line and channel bit errors over the APC-MLQ codec were investigated. The results indicate that the 16 kbit/s APC-MLQ can successfully transmit these low-speed voiceband data and is applicable to digital maritime satellite communication systems which must carry both speech and voiceband data up to 2.4 kbit/s. The performance has also been confirmed through field trials with G-III facsimile transmission at 2.4 kbit/s over a digital maritime satellite transmission system.