Specifications

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2.9

Applications Manual

Revision 1.11Prism Sound dScope Series III

EUT input (dScope output):

This is used to select the type of input that is being measured on the

EUT. Depending on the selection here, the tests available in the menus will change. Some tests are

available for both digital and analogue inputs, but give different results depending on which is

selected. If an analogue input is specified, whether it is balanced or unbalanced must also be

specified.

Input D/A Line-up:

This is used to enable the dScope signal generator analogue output amplitude to

be set in terms of dBFS for the EUT. The figure specified here should be the analogue level at the

EUT input that causes the digital signal within the EUT to go

full scale

. This parameter is measured

in the

Input for full_scale amplitude test

in the

Input Characteristics

menu, but an approximate value

should be entered here before commencing with the test in order to protect the EUT from excessive

levels. The test also searches within a pre-defined range around the level set by this parameter, so it

is important that it is of the right order of magnitude before commencing with the test or it will not

complete successfully. The unit for this parameter can be changed by selecting from the drop list at

the bottom of this dialogue box. The same unit is used for both input and output D/A Line-up settings.

For equipment with input gain controls, this value will not remain valid if the gain

is changed. It is important to make sure it is correct for the test being undertaken.

EUT output (dScope input):

This is used to select the type of output being measured on the EUT.

Depending on the selection here, the tests available in the menus will change. Some tests are

available for both digital and analogue outputs, but give different results depending on which is

selected. If a digital output is specified, which type of connector must also be specified. The selected

digital output connector will also determine which digital input on the dScope will be used for

measurement.

Output D/A Line-up:

This is used to enable the measuring of analogue output parameters in terms of

dBFS for the EUT. The figure specified here should be the analogue level on the EUT outputs that is

caused by a 997Hz 0dBFS digital signal within the EUT. This parameter is measured in the

Output Amplitude at Full Scale

in the

Output Characteristics

menu, but an approximate value should

be entered here in order to protect the EUT from excessive levels. The test also searches within a

pre-defined range around the level set by this parameter, so it is important that it is of the right order

of magnitude before commencing with the test or it will not complete successfully. The unit for this

parameter can be changed by selecting from the drop list at the bottom of this dialogue box. The

same unit is used for both input and output D/A Line-up settings.

For equipment with output gain controls, this value will not remain valid if the gain

is changed. It is important to make sure it is correct for the test being undertaken.

EUT Sample rate:

The sample rate of the EUT is selected here. For EUTs with digital inputs, this

will set the digital output sample rate of the dScope. For equipment that only has analogue inputs and

outputs, but is digitally sampled internally, enter the internal sample rate if known. For equipment

incorporating sample rate conversion, the appropriate sample rate should be selected depending on

whether the parameter being measured is on the input or output side.

OK and Cancel:

Selecting the OK button exits this dialogue and uses the values and settings as

selected. Selecting Cancel exits the dialogue but retains previously set parameters

UNLESS

the units

for the D/A Line-up have been changed, in which case the values in the D/A Line-up boxes have

already been updated and will not revert to previously stored values.

3.2.2 Level Search Routines

For several of the tests in the AES17 standard, the level that causes a particular condition is required.

These are automated within the dScope AES17 tests. The below explains how the search routines

work, where they are used and what errors may occur.

Find the maximum input amplitude