Specifications

2.38
Applications Manual
© 2003-2005 Prism Media Products Ltd
Revision 1.11Prism Sound dScope Series III
Description
This test ensures that the
EUT
can properly downmix a 5.1-channel bitstream into 2-channel output.
All DVD players are required to implement an Lt/Rt downmix. A Lo/Ro downmix may be provided as a
user-selectable option. An Lt/Rt downmix is essentially a surround compatible stereo output (Track
42). An Lo/Ro downmix is for standard stereo output (Track 41).
Since most DVD players only support an Lt/Rt downmix, the scripted version of
this test only exercises Lt/Rt mode, using Track 42.
Method
Play Track 42 and then immediately click the
[OK]
button to start the test.
The Dolby Digital test tracks are such that when the correct downmix is performed, the signals in the
L,R,C,LS & RS channels cancel producing very little output. The dScope measures the outputs of
each channel using a 400Hz band-pass filter to eliminate the effects of noise.
Specification
If the correct downmix is being performed, the output should be less than –60dBr for both channels.
4.2.1.6 Separation
dScope Configuration:
Separation L Track 26.dsc
Separation R Track 27.dsc
Track Number:
26 and 27
Corresponding AP Test File:
2_997L.at2 & 2_997_R.at2
.ac3 Test File:
2_997L.ac3 & 2_997_R.ac3
Duration:
30 sec
Test Signal Description:
997Hz at 0dBFS (left and right)
Description
This test measures the left-to-right and right-to-left cross-talk between the
EUT
outputs at
full-
scale amplitude
.
Method
Play Track 26 and then click the
[OK]
button to start the test; when prompted, play Track 27 and click
the
[OK]
button to resume.
The dScope measures the amplitude of the non-driven channel, via a 997Hz band-pass filter to
exclude noise, and reports the result for each channel.