5.1 Introduction

5.1.1     The first, and most significant part of the digitisation process is the optimisation of signal retrieval from the original carriers. As a general principle, the originals should always be kept for possible future re-consultation. However, for two simple, practical reasons any transfer should attempt to extract the optimal signal from the original. Firstly, the original carrier may deteriorate, and future replay may not achieve the same quality, or may in fact become impossible, and secondly, signal extraction is such a time consuming effort that financial considerations call for an optimisation at the first attempt.