7  Digital Principles

Sampling Rate

The number of times each second that the signal is ‘measured’. A figure of 2.2 times the highest audio frequency is considered to be practical. The sampling rate for standard digital audio such as compact discs is 44.1, giving the highest audio frequency that can be recorded and replayed as 44.1/2.2 or just over 20 kHz. 48 kHz is an alternative ‘professional’ rate.

Bit Rate is the number of 1s and 0s transmitted or recorded per second and is the product of the number of bits in the sample and the sampling frequency. Thus with a 16 bit system and a sampling rate of 44.1 kHz the number of bits per second is 705.6 × 103.

The number of bits/sample is closely related to the number of quantizing levels – the ‘resolution’ ...

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