The PLC-1 Private Line Voice Concentrator is introduced. This equipment uses the well-known TASI (time assignment speech interpolation) technique to reduce the number of transmission facilities required to transmit a number of trunks by a factor of up to two. In addition to reducing transmission facility requirements, the PLC-1 provides a very high level of management and diagnostic tools to the telecommunications manager.

This paper presents a performance analysis of a PLC-1 private line voice concentrator which uses speech interpolation to increase the capacity of transmission facilities. The PLC-1 employs speech storage. As a result it can be applied to relatively small trunk groups where statistics of loading patterns are particularly unfavorable. Speech impairments can be categorized as delay, gap modulation, and clipping. A mathematical model based on queueing theory is presented for the evaluation of the statistics of these impairments. The model can be used to determine obtainable TASI advantage for various system configurations and loading conditions. It is shown that a TASI advantage of two is achievable with 24 transmission facilities. The veracity of the queueing model is established using simulation techniques.