Prism
Operation Manual Issue 2.00
Page 1.1
1.
Introduction
The DSA-1 is a hand-held instrument for measuring connectivity parameters of stereo
digital audio signals in one of the formats described in AES3-1992 and IEC958
(commonly referred to as AES/EBU or SPDIF). The recently-proposed AES3-ID coaxial
format is also supported. Testing of 110
6
balanced, 75
6
coaxial or TOSLINK optical
media is possible. The DSA-1 can also generate a wide range of test signals, and can
edit signals 'in-line'. The unit may be powered from its internal rechargeable battery
or from an external DC power supply.
The parameters measured and signals generated by the DSA-1 are intended to provide
a means of assessing `connectivity'; i.e. the likelihood of trouble-free interconnection.
There are many factors which have implications for connectivity, for example the
sampling-rate of the sending equipment or the number of bits present in the audio data
word. The level and correctness of the Channel Status implementation is also
important if proper connectivity is to be achieved.
The consequences of failure to meet connectivity requirements can range from
complete failure, as when a source operates at a sample-rate not supported by a
receiver, or the most subtle effects which result from truncation of the audio word, as
when a 20-bit source is connected to a 16-bit device without provision for truncation
processing such as re-dithering or noise-shaping.
Among the most frustrating of connectivity problems are those which lead to intermittent
operation, where infrequent clicks or drop-outs mar audio quality. These may occur at
random, or may be related to program content. Such problems are most often the
result of inadequate operating margin in some electrical or timing parameter of the
interface, due to either equipment or cabling problems.
The DSA-1 is a tool designed to measure connectivity parameters with great accuracy
and simplicity. Its automatic Test Sequences can detect subtle abnormalities in
interface conditions without the need for detailed analysis by the operator.
Although the DSA-1 includes a number of basic audio-data generation and analysis
functions, it does not provide distortion measurements or other sophisticated audio
analyses; the Prism Sound Dscope is a high-performance digital audio test system
(including generator and analyzer) which focuses on signal content, rather than
connectivity.
