Specifications
2.19
Applications Manual
© 2003-2005 Prism Media Products Ltd
Revision 1.11Prism Sound dScope Series III
3.2.5.2.1 Phase response
This test is not currently implemented.
3.2.5.2.2 Group delay
This test is not currently implemented.
3.2.5.2.3 Inter-channel phase response
Applies to:
EUTs with analogue or digital inputs and analogue or digital outputs.
Aim:
To measure the variation in the
EUT
's inter-channel phase with applied frequency.
Method
The EUT is stimulated with a sine stimulus swept from 10Hz to the
upper band-edge frequency
in
third-octave steps. In order t
o prevent overload in systems that use emphasis, the inter-channel phase
response is measured at –20dBFS. The inter-channel phase of the EUT is graphed against
frequency, expressed in degrees.
If emphasis is used in the device, then the results should be reported both with and without emphasis.
3.2.5.3 Delay through a device
Applies to:
EUTs with analogue inputs and analogue outputs only.
Aim:
To measure the delay through the
EUT
.
Method
The delay is measured by applying a 50Hz sinusoidal signal with an amplitude of –20
dBFS
and
measuring the time difference between the input and the output of the EUT. This frequency gives a
maximum useful reading of 5ms. The delay through each channel of the EUT is displayed.
This test currently has two limitations: firstly, it does not use the method specified
in AES17 (a pulse-delay or PRBS correlation method); secondly, the test can only
be made for an EUT with analogue inputs and outputs and not for a cross-domain
or digital-to-digital case.
3.2.5.4 Polarity
Applies to:
EUTs with analogue or digital inputs and analogue or digital outputs.
Aim:
To determine whether the
EUT
inverts the absolute phase of the signal.
Method
The test stimulus is a single-cycle 1kHz burst which is gated on the FALLING edge. The dScope's
FFT Analyzer is used to examine the burst after passing through the EUT and to determine its polarity
(for precise details of how this is done, please see the "AES17 Tests.dss" script). Each channel is
reported as 'non-inverting' or 'inverting'.