Specifications

2.25
Applications Manual
© 2003-2005 Prism Media Products Ltd
Revision 1.11Prism Sound dScope Series III
3.2.8.2 Non-linear inter-channel cross-talk
Applies to:
EUTs with analogue or digital inputs and analogue or digital outputs.
Aim:
To measure the non-linear inter-channel cross-talk between the channels of the
EUT
at HF and
LF.
Method
High-frequency non-linear cross-talk
This is measured by driving the input of the EUT with a –20
dBFS
sinusoidal stimulus at the
upper band-edge frequency
on the channel to be measured, and a +3dBFS sinusoidal stimulus at
3kHz below that frequency on the other channel.
At the output of the measured channel of the EUT, the ratio of the second-order difference frequency
component at 3kHz to the overall signal amplitude is measured. Also, the ratio of the third-order IM
component at 6kHz to the overall signal amplitude is measured. These are reported as the even-
order non-linear cross-talk and odd-order non-linear cross-talk, in dB, for each channel.
Low-frequency non-linear cross-talk
This is measured by driving the input of the EUT with a –20
dBFS
sinusoidal stimulus at HALF the
upper band-edge frequency
on the channel to be measured, and a +3dBFS sinusoidal stimulus at
40Hz on the other channel.
At the output of the measured channel of the EUT, the ratio of the amplitude of the modulation
sidebands (introduced on the high-frequency tone by the low-frequency tone in the hostile channel) to
the overall signal amplitude is measured. This is reported in dB for each channel.
3.2.8.3 Input-to-output leakage
Applies to:
EUTs with analogue or digital inputs and analogue or digital outputs.
Aim:
To measure the input-to-output leakage ('feed-through') of the
EUT
at a range of frequencies.
Method
Both inputs of the EUT are driven with a sinusoidal stimulus at 0
dBFS
which is swept in octave steps
from 10Hz to the
upper band-edge frequency
. The EUT is put into a mode where all its outputs are
muted.
At each frequency, the RMS amplitudes of the EUT's outputs are measured through a 1/3 octave
band-pass filter at the stimulus frequency. The results are expressed in dBFS, and displayed
graphically against frequency for both channels. The two channels are overlaid on the same axes so
that worst-case leakage can be easily seen.