2.6 Why Digital?

2.6 Why Digital?

There are two main answers to this question, and it is not possible to say which is the most important, as it will depend on one's standpoint:

  1. The quality of reproduction of a well-engineered digital system is independent of the medium and, in the absence of a compression scheme, depends only on the quality of the conversion processes.

  2. The conversion to the digital domain allows tremendous opportunities that were denied to analog signals.

Someone who is only interested in quality will judge the former the most relevant. If good quality convertors can be obtained, all of the shortcomings of analog recording and transmission can be eliminated to great advantage. One's greatest effort is expended in the design of convertors, whereas those parts of the system that handle data need only be workmanlike. Wow, flutter, timebase error, vector jitter, crosstalk, particulate noise, print-through, dropouts, modulation noise, HF squashing, azimuth error and interchannel phase errors are all history. When a digital recording is copied , the same numbers appear on the copy: it is not a dub, it is a clone. If the copy is indistinguishable from the original, there has been no generation loss. Digital recordings can be copied indefinitely without loss of quality through a digital interface.

In the real world everything has a cost, and one of the greatest strengths of digital technology is low cost. If copying causes no quality loss, recorders do not need to be far better than necessary in order to withstand generation loss. They need only be of adequate quality on the first generation if that quality is then maintained . There is no need for the great size and extravagant tape consumption of professional analog recorders . When the information to be recorded is discrete numbers, they can be packed densely on the medium without quality loss. Should some bits be in error because of noise or dropout, error correction can restore the original value. Digital recordings take up less space than analog recordings for the same or better quality. Tape costs are far less and storage costs are reduced.

Digital circuitry costs less to manufacture. Switching circuitry handling binary can be integrated more densely than analog circuitry. More functionality can be put in the same chip. Analog circuits are built from a host of different component types having a variety of shapes and sizes and are costly to assemble and adjust. Digital circuitry uses standardized component outlines and is easier to assemble on automated equipment. Little if any adjustment is needed. Once audio or video signals are in the digital domain, they become data, and apart from the need to be reproduced at the correct sampling rate, are indistinguishable from any other type of data. Systems and techniques developed in other industries for other purposes can be used for audio and video. Computer equipment is available at low cost because the volume of production is far greater than that of professional audio equipment. Disk drives and memories developed for computers can be put to use in audio and video products. A word processor adapted to handle audio samples becomes a workstation. If video data is handled the result is a non-linear editor. Communications networks developed to handle data can happily carry digital audio and video over indefinite distances without quality loss. Digital audio broadcasting (DAB) makes use of these techniques to eliminate the interference, fading and multipath reception problems of analog broadcasting. At the same time, more efficient use is made of available bandwidth. Digital broadcasting techniques are now being applied to television signals, with DVB being used in Europe and other parts of the world.

Digital equipment can have self-diagnosis programs built in. The machine points out its own failures. Routine, mind-numbing adjustment of analog circuits to counteract drift is no longer needed. The cost of maintenance falls . A small operation may not need maintenance staff at all; a service contract is sufficient. A larger organization will still need maintenance staff, but they will be fewer in number and more highly skilled.



Digital Interface Handbook
Digital Interface Handbook, Third Edition
ISBN: 0240519094
EAN: 2147483647
Year: 2004
Pages: 120

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