DCS Computer Hardware dCS 974 User Manual

dCS 974 User Manual

 Manual for Software Version 1.0x

dCS Ltd 

May 2001

Manual part no: DOC1241121A1

Page 94

Document No: OS-MA-A0124-112.1A1

Contact 

 on + 44 1799 531 999 

email to: more@dcsltd.co.uk

(inside the UK replace + 44 with 0)

web site: www.dcsltd.co.uk

The graphs on the following pages show key performances of the dCS 974.

•  Dither PDFs, showing how the dither types are effectively ideal, including

noise shaped triangular dither

•  FFTs of the dither signals used (excludes truncation, or Q, noise)

•  Raw data for small signal truncated (± 4 lsbs) sinewave, showing source

waveform, no dither, and all dither types.  Shows absence of DC offset, and
behaviour of the various dithers

•  FFTs of truncated small signal (-90 dB0 sine), showing no truncation,

truncation without dither, and the effect of dithers.

•  FFTs of truncated small signal (-90 dB0 sine), with noise shaping, with and

without added dithers.

•  DSD spot Q noise for filter options

•  DSD integrated Q noise for filter options

•  DSD F weighted Q noise for filter options

•  DSD 0 dB0 (full scale) signal

•  48 kS/s to 44.1 kS/s conversion, Filter responses

•  96 kS/s to 44.1 kS/s conversion, Filter responses

•  Noise shaping curves for 32 kS/s

•  Noise shaping curves for 44.1 kS/s

•  Noise shaping curves for 48 kS/s

•  Noise shaping curves for 88.2 kS/s

•  Noise shaping curves for 96 kS/s

•  Noise Shaper noise and weighted noise vs shaper order

Histograms of Dither Types, before Truncation

dCS 972 SW v1.54

0.0%

0.1%

0.2%

0.3%

0.4%

0.5%

-384

-256

-128

0

128

256

384

Code (lsbs)

F

rac

tio

n of

 T

im

e D

ith

er O

cc

up

ies

 B

in

Top Hat
Triangular
Noise Shaped Triangular

2 million data points

Word length reduced by 8 bits

Figure 31 – Dither PDFs

                                                     

27

  Note that many aspects of the dCS 974 are identical to those of the dCS 972.