dScope Series III Applications Manual by Rachel Wilkinson, Ian Heaton, Liam Elliott This manual is also available as 'on-line help' from the dScope software. You can access the on-line help from the 'Help' menu. The on-line version is context-sensitive: by pressing F1, you can get immediate help for whichever menu or dialogue box you are currently using.
Table of Contents Part 1 General information 1 Part 2 Applications introduction 5 1 About ................................................................................................................................. this manual 5 Part 3 AES17 1 Overview ................................................................................................................................. 7 2 AES17 .....................................................................................................
Idle ................................................................................................................................................ channel noise spectrum 23 Signal-to-noise ................................................................................................................................................ ratio or noise in the presence of signal 23 Power-line ........................................................................................................................
Index 82
Part 1 General information
Prism Sound dScope Series III 1 Applications Manual Revision 1.11 General information Manual revision history Rev Date Author Notes 1.00 28th January 2003 R.Wilkinson To accompany software 1.00 1.10 10th June 2004 I.A.Heaton To accompany software 1.10 1.11 14th July 2005 L.R.Elliott To accompany software 1.
Prism Sound dScope Series III Applications Manual Revision 1.11 Statements of conformity This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against interference in a residential area. This device generates and uses radio frequency energy and, if not installed and used in accordance with the instructions, may cause interference to radio or TV reception.
Part 2 Applications introduction
Prism Sound dScope Series III 2 Applications Manual Revision 1.11 Applications introduction This volume of the dScope Operation Manual describes how dScope can be used in a variety of applications. For a description of AES17 testing, see the AES17 section. For a description of Dolby Digital 2-channel testing, see the Dolby Digital 2-channel section. For a description of Dolby Digital 5.1-channel testing, see the Dolby Digital 5.1-channel section. 2.
Part 3 AES17
Prism Sound dScope Series III 3 Applications Manual Revision 1.11 AES17 The dScope can perform conformity testing of digital audio products (such as A-D or D-A converters), according to the AES17 standard, quickly and easily. A set of simple-to-follow scripts and accompanying configurations are provided that guide you through each test. These are installed automatically from the dScope's installation CD; updates may be obtained from www.prismsound.
Prism Sound dScope Series III Applications Manual Revision 1.11 Directory structure On installation, the AES17 test files are contained in four directories as follows: Configurations are in \Configurations\AES17 Scripts are in \Scripts\Automation\AES17 Filter definitions are in \FFT Detector Weighting Filters\AES17 Sweep Data Tables are in \Sweep Data Tables\AES17 The launcher script, "AES17 Tests.dss" is in \Scripts\Automation 3.
Prism Sound dScope Series III Applications Manual Revision 1.11 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.
Prism Sound dScope Series III Applications Manual Revision 1.11 Used in Input for full-scale amplitude and Maximum input amplitude tests. This search routine looks for the input amplitude that causes one of three conditions: For systems where the digital signal is accessible, it finds the input level that causes 0dBFS at 997Hz. For systems where the digital signal is not accessible or cannot be made to reach 0dBFS, it looks for the level that causes 1% distortion or 0.
Prism Sound dScope Series III 3.2.3.1 Applications Manual Revision 1.11 Suppression of alias components Applies to: EUTs with analogue inputs. Aim: To measure the alias components in the EUT when presented with out-of-band HF components at its analogue input. Method The suppression of alias components is measured using a sinusoidal stimulus with amplitude –20dBFS. The frequency of the signal is first set to 997Hz in order to establish an output reference level.
Prism Sound dScope Series III 3.2.3.4 Applications Manual Revision 1.11 Input for full-scale amplitude Applies to: EUTs with analogue inputs. Aim: To determine the maximum input amplitude before digital clipping with normal device settings. Method The input gain controls are set to the reference position supplied by manufacturer or to the normal operating position if no reference position is specified. Other controls should be adjusted to minimise the potential for overload in the output circuitry.
Prism Sound dScope Series III 3.2.3.6 Applications Manual Revision 1.11 Input logarithmic-gain stability Applies to: EUTs with analogue inputs. Aim: To determine the long-term gain stability of the EUT input. Method The test signal for the input logarithmic-gain stability test is a 997Hz sinusoid 6dB below fullscale amplitude. The output amplitude of the EUT is measured for at least one hour. The user is invited to confirm that the EUT has been adequately warmed-up prior to starting the test.
Prism Sound dScope Series III 3.2.3.8.1 Applications Manual Revision 1.11 Analogue-to-digital jitter susceptibility Applies to: EUTs with analogue inputs and digital audio outputs. Aim: To measure the jitter susceptibility of the EUT when presented with jitter of varying frequency at its Reference Sync input. Method This test can only be performed if the EUT has an AES11 Reference Sync input.
Prism Sound dScope Series III 3.2.3.8.3 Applications Manual Revision 1.11 Digital-to-digital jitter susceptibility Applies to: EUTs with digital audio inputs and outputs. Aim: To measure the jitter susceptibility of the EUT when presented with jitter of varying frequency at its digital or reference input. Method The digital input of the EUT is driven with a –3dBFS sinusoidal stimulus at fs/4 (where fs is the sample rate of the EUT).
Prism Sound dScope Series III 3.2.4.2 Applications Manual Revision 1.11 Suppression of imaging components Applies to: EUTs with analogue outputs. Aim: To measure the total of HF imaging components beyond the audio band which are output from the EUT's D/A converter, as a result of applied audio-band signals. Method The analogue output of the EUT is measured with a –20dBFS sinusoidal stimulus applied, swept from 10Hz to the upper band-edge frequency or 10kHz (whichever is the lower).
Prism Sound dScope Series III Applications Manual Revision 1.11 If the EUT input is being driven in the analogue domain, the result is obtained by driving the analogue input with a 997Hz sinusoidal stimulus whose amplitude is the maximum which produces an undistorted output, and recording the RMS output amplitude. The result is displayed in dBu and volts for both channels. See also: Level Search Routines for fault finding with this test. 3.2.4.
Prism Sound dScope Series III 3.2.5.1 Applications Manual Revision 1.11 Amplitude vs frequency The Amplitude vs frequency tests are arranged in the following subsections, which correspond to the equivalent subsections of the AES17 standard: Frequency response Maximum signal level vs frequency 3.2.5.1.1 Frequency response Applies to: EUTs with analogue or digital inputs and analogue or digital outputs. Aim: To measure the variation in the EUT's gain with applied frequency.
Prism Sound dScope Series III 3.2.5.2.1 Applications Manual Revision 1.11 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.
Prism Sound dScope Series III 3.2.6 Applications Manual Revision 1.11 Amplitude non-linearity The Amplitude non-linearity tests are arranged in the following subsections, which correspond to the equivalent subsections of the AES17 standard: Level-dependent logarithmic gain Intermodulation distortion (IMD) Signal modulation noise Low-level noise modulation Total harmonic distortion and noise (THD+N) 3.2.6.
Prism Sound dScope Series III 3.2.6.3 Applications Manual Revision 1.11 Signal modulation noise Applies to: EUTs with analogue or digital inputs and analogue or digital outputs. Aim: To measure signal modulation components produced by gain modulation in the EUT. Method A sinusoidal stimulus is applied at –5dBFS with a frequency of 0.4999 times the upper bandedge frequency.
Prism Sound dScope Series III 3.2.6.5.1 Applications Manual Revision 1.11 Total harmonic distortion and noise vs frequency Applies to: EUTs with analogue or digital inputs and analogue or digital outputs. Aim: To measure the THD+N of the EUT against frequency. Method A –1dBFS sinusoidal stimulus is applied to the EUT, successively at each octave frequency between 20Hz and half the upper band-edge frequency.
Prism Sound dScope Series III 3.2.7.1 Applications Manual Revision 1.11 Idle channel noise Applies to: EUTs with analogue or digital inputs and analogue or digital outputs. Aim: To measure the output noise of the EUT with no signal present. Method If the EUT has a digital input, it is fed with a digital-zero signal; if the EUT has an analogue input it is terminated with 50R (or 25R if unbalanced). The RMS amplitude of the output noise of the EUT is measured via the standard weighting filter.
Prism Sound dScope Series III 3.2.7.4 Applications Manual Revision 1.11 Power-line (mains) related products Applies to: EUTs with analogue or digital inputs and analogue or digital outputs. Aim: To measure power-line (mains) related products in the output noise of the EUT. Method If the EUT has a digital input, it is fed with a digital-zero signal; if the EUT has an analogue input it is terminated with 50R (or 25R if unbalanced). The operator nominates either 50Hz or 60Hz power-line frequency.
Prism Sound dScope Series III 3.2.8.2 Applications Manual Revision 1.11 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.
Prism Sound dScope Series III 3.3 Applications Manual Revision 1.11 Glossary The following definitions are used in the AES17 standard and in the dScope implementation of the AES17 tests: Aliasing components - Aliasing can take place when a frequency above the folding frequency of an EUT is applied to its analogue input (or where internal down-sampling occurs).
Prism Sound dScope Series III Applications Manual Revision 1.11 Standard notch filter - A band-reject filter with a Q between 1 and 5, for example the dScope's band-reject filter at the '1/3 octave' setting. Standard weighting filter - A weighting filter with a response according to CCIR468, but normalised to have unity gain at 2kHz, for example the dScope's 'CCIR468–2k' weighting filter.
Part 4 Dolby Digital 2-channel
Prism Sound dScope Series III 4 Applications Manual Revision 1.11 Dolby Digital 2-channel The dScope can perform conformance testing of Dolby Digital 2-channel replay devices such as DVD players (in conjunction with the Dolby DVD Test DVD), or set-top-boxes (in conjunction with the equivalent .ac3 test files). An easy-to-use script and accompanying Configurations are provided which provides a menu of all available tests, and guides you through each test.
Prism Sound dScope Series III Applications Manual Revision 1.11 Collection of results When a test from the test menu has been executed, its button becomes italicised in the test menu to indicate that it has been completed. Results of completed tests are retained by the script, and any graphical results are automatically exported to .EMF files in the 'Dolby Exports' folder within the main dScope program folder.
Prism Sound dScope Series III Applications Manual Revision 1.11 Dolby accreditation This document does NOT describe all the requirements that must be met in order to achieve accreditation from Dolby Laboratories. Please refer to Dolby documentation for full details. Note that to comply with the Dolby Laboratories' requirements, additional tests outlined in the Dolby procedure (such as listening and functional tests) must also be completed and documented.
Prism Sound dScope Series III 4.2.1 Applications Manual Revision 1.
Prism Sound dScope Series III Applications Manual Revision 1.11 Method Play Track 8 and then click the [OK] button to start the test. The test track contains a –20dBFS sinusoidal stimulus at 997Hz. The measured amplitude at the output of the EUT is increased by 20dB and entered as the dScope's dBr reference amplitude. This value is used as the 0dBFS reference amplitude in all subsequent tests unless otherwise noted.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification No precise specification is provided. A tolerance of ±1dB from the design norm is a reasonable guideline of acceptability. Note: A 20dB imbalance between the channels is expected when an Lt/Rt downmix is performed. 4.2.1.3 Dialog Normalization dScope Configuration: Dialog Normalization Track 23.dsc Track Number: 23 Corresponding AP Test File: 2_dnswp.at2 .ac3 Test File: 2_dnswp.
Prism Sound dScope Series III Applications Manual Revision 1.11 The test track contains a full-scale signal that is stepped down by 1dB every two seconds using Dialog Normalization attenuation. The test plots the output amplitude for both channels every 500ms for 64s, measured through a 1kHz band-pass filter. Specification The sweep should show that output level dropping by 1dB every 2 seconds over a 30dB range.
Prism Sound dScope Series III Applications Manual Revision 1.11 Description This test checks for proper functionality of EUT's dynamic range control in both 2-channel and 5.1channel modes. Method If the EUT offers compression ON and compression OFF modes, the test should be repeated for each mode. Play Track 22 and immediately click the [OK] button to start the test; when prompted, play Track 61 and immediately click the [OK] button to resume.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification Results should be: Track Compression mode Result 22 OFF Output decreases linearly from 0dBFS to –60dBFS. 22 ON Output flat (–3dBr) for 3s then decreases linearly. 61 BOTH Output flat for 11s then decreases linearly. May note a 20dB difference in level depending on type of downmixing in EUT.
Prism Sound dScope Series III Applications Manual Revision 1.11 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).
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification No precise specification is provided. As a guide, separation should generally be better than 85dB at 997Hz. 4.2.1.7 Frequency Response dScope Configuration: Frequency Response Track 19.dsc Track Number: 19 Corresponding AP Test File: 2_frqswp.at2 .ac3 Test File: 2fstplr.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification For line outputs, the response should be within +0.5/–1dB of the 1kHz level from 20Hz to 20kHz; for headphone and speaker outputs, the response should be within +0.5/–1dB of the 1kHz level from 30Hz to 20kHz. 4.2.1.8 THD vs Frequency dScope Configuration: THD vs Frequency Track 19.dsc Track Number: 19 Corresponding AP Test File: 2_thdfreq.at2 .ac3 Test File: 2fstplr.
Prism Sound dScope Series III Applications Manual Revision 1.11 THD+N at each, and produces a plot of the results for both channels. Specification Across the frequency range, the THD+N for line outputs should be less than –60dBr and for headphone or speaker outputs, less than –57dBr. 4.2.1.9 THD vs Level dScope Configuration: THD vs Track 24.dsc Track Number: 24 Corresponding AP Test File: 2_thdlvl.at2 .ac3 Test File: 2_aswp4ka.
Prism Sound dScope Series III Applications Manual Revision 1.11 corresponds to a sweep from 0dBFS to –120dBFS. Specification Across the amplitude range, the THD+N for line outputs should be less than –60dBr and for headphone or speaker outputs, less than –57dBr. 4.2.1.10 Signal-to-noise dScope Configuration: Signal to Noise Ratio Track 13.dsc Track Number: 13 Corresponding AP Test File: 2_dnr.at2 .ac3 Test File: 2_200a60.
Prism Sound dScope Series III Applications Manual Revision 1.11 The dScope measures the residual amplitude of both EUT output channels, after a 200Hz notch filter, band-limited between 22Hz and 22kHz, and using a CCIR–2k weighting filter. Note that this test is performed as a sweep against track time (even though it could actually be a single spot measurement) for consistency with the Dolby test procedure.
Prism Sound dScope Series III Applications Manual Revision 1.11 Method Click the [OK] button to start the test, and then play Track 19. The dScope senses the 60 logarithmically-spaced frequencies on the test track, measures the interchannel phase at each, and produces a plot of the results. Specification No precise specification is provided. As a guide, phase matching well within 1 degree should be preserved over the frequency range. 4.2.
Prism Sound dScope Series III Applications Manual Revision 1.11 Setting up The digital domain tests are measured at the digital outputs of the EUT. Please make sure that the following connection has been made: l Digital Output of the EUT to the dScope's Digital Input BNC, using the provided RCA/PHONO–BNC adapter. 4.2.2.1 Eye Pattern dScope Configuration: Eye Pattern Track 19.dsc Track Number: (any) Corresponding AP Test File: Digeye.at2 .
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification Dolby Laboratories does not provide a precise specification, however the red box on the plot shows the minimum eye region specified by the IEC60958 standard, into which the eye pattern should not transgress if reliable reception is to be guaranteed. 4.2.2.2 Jitter Spectrum dScope Configuration: Jitter Spectrum Track 19.dsc Track Number: (any) Corresponding AP Test File: Digjitn.at2 .
Prism Sound dScope Series III Applications Manual Revision 1.11 The dScope can measure various types of jitter in a variety of different ways. In this case, the data jitter from the EUT's digital output carrier is demodulated and fed to the dScope's analogue Signal Analyzer. An FFT is calculated to show the spectrum of the jitter, and the peak level of the jitter is also measured. Specification Dolby Laboratories does not provide a precise specification, however a peak jitter limit of 0.
Prism Sound dScope Series III Applications Manual Revision 1.11 Method Play Track 19 and then click the [OK] button to start the test. The Category Code field of the Channel Status is read from the EUT's digital output carrier. The value is shown both as a binary value, and also decoded. The example below shows the results for DVD playback.
Prism Sound dScope Series III Applications Manual Revision 1.11 Note that during this test, the dScope's Digital Inputs dialogue box is open to enable the operator to note other parameters of the EUT's digital output, for example wordlength, sample rate and valid bits. Specification The 'non-audio' bit should be set to 0 ('audio', i.e. linear PCM) when outputting PCM, and 1 ('nonaudio', or at least not linear PCM) when outputting undecoded Dolby Digital bitstreams.
Prism Sound dScope Series III Applications Manual Revision 1.11 Data jitter - A type of interface jitter. Data jitter is that part of the interface jitter which is caused by variations in the duty cycle of the AES3 or IEC60958 carrier acting with high-frequency losses in the transmission medium (e.g. cable capacitance) such that edge timing in the carrier is modulated by the activity of the data bits. This is distinct from fs jitter, which is inherent in the carrier source.
Part 5 Dolby Digital 5.
Prism Sound dScope Series III 5 Applications Manual Revision 1.11 Dolby Digital 5.1-channel The dScope can perform conformance testing of Dolby Digital 5.1-channel replay devices such as DVD players (in conjunction with the Dolby DVD Test DVD), when operating in 5.1-channel and twochannel modes. An easy-to-use script and accompanying Configurations are provided which shows a menu of all available tests, and guides you through each test.
Prism Sound dScope Series III Applications Manual Revision 1.11 Additional help during testing When starting the launcher script, the operator will be prompted to select whether additional help is required in either (or both) of the following areas: l Test methods; l Test specifications (pass/fail limits); If either of these is selected, then additional message boxes are generated during running of each test which describe the selected parameter(s) for that test.
Prism Sound dScope Series III Applications Manual Revision 1.11 Dolby Test Procedure document and Test DVD The following reference document and test DVD are relevant to these tests, and are available from Dolby Laboratories: l Dolby Digital 5.1-Channel DVD Player Test Procedure, Issue 3 l Dolby Digital Test DVD, version 1.0 or 1.5 l Dolby Digital AutoTest DVD, version 2.
Prism Sound dScope Series III Applications Manual Revision 1.11 The following Configurations are used during Dolby Digital 5.1-channel testing: Ref Level Track 30.dsc Rel Output Level Track 28_2.dsc Max Output Level Track 65-69.dsc Max Output Level Track 70-73.dsc Dialog Normalization Track 62.dsc Dynamic Range Compression Track 61.dsc Frequency Response Track 43-48.dsc THD vs Frequency Track 43-47.dsc THD vs Level Track 63.dsc Signal to Noise Ratio Track 35.dsc DownMix Track 41-42.
Prism Sound dScope Series III Applications Manual Revision 1.11 Dolby Digital Centre Channel Delay Dolby Digital Surround Channel Delay Noise Sequencer The following Pro Logic tests are not currently implemented in the Dolby Digital 5.1-channel test scripts: · Pro Logic Functionality · Pro Logic Centre Channel Evaluation · Pro Logic Surround Channel Delay Setting up The analogue domain tests are measured at the analogue line outputs of the EUT.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification No specification is provided. A Reference Level of around 2V (RMS) might be typical for all channels except the Sub, which will probably be around 400mV. 5.2.1.2 Relative Output Level dScope Configuration: Rel Output Level Track 28_2.dsc Track Number: 28 (AutoTest DVD v2.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification With the trim/balance controls set to their nominal positions, any individual output (except the Sub) should be within 1.0dB of any other output. 5.2.1.3 Maximum Output Level Track Number: Max Output Level Track 65-69.dsc Max Output Level Track 70-73.
Prism Sound dScope Series III Applications Manual Revision 1.11 Description This test measures the worst-case maximum output of the EUT with a 5-channel signal. Since compression can affect the level of a 5.1-channel full-scale signal, this test involves playing a 0dBFS sine wave for each channel separately. Method Turn compression Off, and set all trim/balance controls to their maximum positions. Part 1 of this test involves measuring the maximum output amplitude for the Sub.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification The DVD player should operate within a maximum RMS level of 2.0V ±10% at any output. 5.2.1.4 Dialog Normalization dScope Configuration: Dialog Normalization Track 62.dsc Track Number: 62 Corresponding AP Test File: 5_dnsweep Duration: 64 sec Test Signal Description: 1kHz at 0dBFS Channels: L, C, R, Ls, Rs Description This test ensures that dialog normalization is turned on and functioning.
Prism Sound dScope Series III Applications Manual Revision 1.11 Normalization attenuation. The test plots the output amplitude for the left channel every 500ms for 64s, measured through a 1kHz band-pass filter. Specification The sweep should show the output level dropping by 1dB every 2 seconds over a 30dB range. If compression is turned on, the output level should be flat for 3 seconds before beginning to drop. 5.2.1.
Prism Sound dScope Series III Applications Manual Revision 1.11 Method The test is firstly performed with the Sub ON and all the pother speakers set to "small". The other parts of the test have the Sub turned OFF, the left and right speakers set to "large", and all combinations of "large"/"small" for the other speakers. For each test, play track 61 and when the track has started playing, immediately click the [OK] button to start the test.
Prism Sound dScope Series III 5.2.1.6 Applications Manual Revision 1.11 Frequency Response, Bass Redirection dScope Configuration: Frequency Response Track 43-48.
Prism Sound dScope Series III Applications Manual Revision 1.11 For Test 2, the Left and Right outputs will show a flat frequency response with no redirected bass present at the Sub output. © 2003-2005 Prism Media Products Ltd 2.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification For the first test, all the main channel signals should have very similar frequency response curves, rolling off at lower frequencies. The Sub signal redirected from the front speakers should be distinct and around 10dB higher than the other channels at low frequencies. If Simplified Bass Management is used, the Left and Right outputs will show a flat response and no bass will be redirected to the Sub.
Prism Sound dScope Series III Applications Manual Revision 1.11 Description This test produces a plot of the THD+N of the EUT against frequency, at 20dB below fullscale amplitude. Method If possible, set all speakers to "large". The script will perform sweeps for each pair of channels in turn. For each test, you will be asked to play track Click the [OK] button to start the test, and then play track 49.
Prism Sound dScope Series III 5.2.1.8 Applications Manual Revision 1.11 THD vs Level dScope Configuration: THD vs Level Track 63.dsc Track Number: 63 Corresponding AP Test File: 5_thdlvl Duration: 120 sec Test Signal Description: 4kHz sweep, 0 to -120dBFS Channels: L, C, R, Ls, Rs Description This test produces a plot of the THD+N of the EUT against level, from 0dBFS to –120dBFS, at 4kHz. Method If possible, set all speakers to "large".
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification Across the amplitude range, the THD+N for line outputs should be less than –60dBr and for headphone or speaker outputs, less than –57dBr. Typically, the THD+N will decrease slightly for the first 10 or 20dB and then reach a low, constant level. 5.2.1.9 Signal-to-Noise dScope Configuration: Signal to Noise Ratio Track 35.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification No specification is given. 5.2.1.10 Downmix dScope Configuration: Downmix Track 41-42.dsc Track Number: 41-42 Corresponding AP Test File: 2_dwnmix Duration: 30 sec (each track) Test Signal Description: 400Hz; level and phase vary depending on the channel. L, C, R, Ls, Rs Channels: Description This test ensures that the EUT can properly downmix a 5.1-channel bitstream into 2-channel output.
Prism Sound dScope Series III Applications Manual Revision 1.11 Method Play track 41 and then click the [OK] button to start the test. When prompted, play track 42 and then click the [OK] button. 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.
Prism Sound dScope Series III 5.2.1.11 Applications Manual Revision 1.11 Downmix Overload dScope Configuration: Downmix Overload Track 60.dsc Track Number: 60 Corresponding AP Test File: N/A Duration: 30 sec Test Signal Description: 2kHz; 0dBFS Channels: L, C, R, Ls, Rs Description This test ensures that channel levels are adjusted correctly during Downmix situations by checking for distorted output in the presence of a full-scale tone in all five channels.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification The distortion should be less than 3% THD+N for all conditions measured. 5.2.1.12 Low Frequency Overload dScope Configuration: Low Frequency Overload Track 70-73.
Prism Sound dScope Series III Applications Manual Revision 1.11 channels are measured with bass redirection on (i.e. the Left and Right channels set to "large" with the Sub turned off). If the Low Frequency Overload test passes on one of the tracks, subsequent testing is not necessary. The script will detect this and will only prompt for the next track if the previous track caused the overload test to fail. Specification The distortion should be less than 3% THD+N for the Sub and the Left channel. 5.2.
Prism Sound dScope Series III Applications Manual Revision 1.11 Description This test confirms that relative phase is preserved at the line outputs of the DVD player. Track 55 is the best track for this test since it contains a signal in the Sub channel; track 56 can be used to check the results from track 55 if necessary. Method Set all speakers to "large" and play track 55. When the track has started, click [OK] to start the test.
Prism Sound dScope Series III 5.2.1.14 Applications Manual Revision 1.11 Level Trim Controls dScope Configuration: Level Trim Controls Track 30.dsc Track Number: 30 Corresponding AP Test File: N/A Duration: 30 sec Test Signal Description: 997Hz, -20dBFS Channels: L, C, R, Ls, Rs Description This test verifies the operation of level trim and/or balance controls, if provided. Method Set all level trim/balance controls to their nominal positions.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification Each trim control should have a range of at least 10dB and should be adjustable in steps of 1dB or smaller. 5.2.1.15 Dolby Digital Centre Channel Delay dScope Configuration: Centre Channel Delay Track 56.dsc Track Number: 56 Corresponding AP Test File: N/A Duration: 60 sec Test Signal Description: 1ms, -20dBFS pulse with 40ms cycle.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification If the Centre channel delay is variable, it should range from 0 to 5ms and increment in steps of 1ms or less. 5.2.1.16 Dolby Digital Surround Channel Delay dScope Configuration: Centre Channel Delay Track 56.dsc Track Number: 56 Corresponding AP Test File: N/A Duration: 60 sec Test Signal Description: 1ms, -20dBFS pulse with 40ms cycle.
Prism Sound dScope Series III Applications Manual Revision 1.11 Specification If the Surround channel delay is variable, it should range from 0 to 15ms and increment in steps of 5ms or less. 5.2.1.17 Noise Sequencer dScope Configuration: Noise Sequencer.
Prism Sound dScope Series III 5.3 Applications Manual Revision 1.11 Glossary The following definitions are used in the Dolby Digital test procedure and in the dScope implementation of the Dolby Digital tests: Channel Status - status information embedded in an AES3 or S/PDIF digital interface, one bit per channel per sample-period, which accumulate into a 192-bit frame for each channel every 192 sample-periods.
Prism Sound dScope Series III Applications Manual Revision 1.11 IEC60958 - A two-channel digital audio interface standard, as provided at the dScope's Digital Output and Input. Also known as S/PDIF this format is used in consumer applications usually with an unbalanced phono/RCA copper or TOSLINK optical connection. It carries audio wordlengths up to 24 bits, plus Valid bit, User bit, Channel Status and Parity bit per channel. IMD - Intermodulation Distortion.
Dialog Normalization 34, 61 Digital audio input format 13 Digital audio output format 17 Digital domain tests 44, 79 Dolby 29, 53 Accreditation 29, 53 Index -..ac3 files Dolby 2-channel tests 29, 31 Dolby 5.
IMD 20, 49, 80 Input characteristics 10 Input D/A Line-up 8 Input for full-scale amplitude 12 Input logarithmic-gain stability 13 Input-to-output leakage 25 Inter-channel cross-talk and separation Inter-channel Phase 43 Inter-channel phase response 19 Intermodulation distortion 20 Peak jitter 46 Phase 43 Phase response Interchannel Jitter 46, 49, 80 Jitter Spectrum 46 Jitter susceptibility 13, 26 Analogue-to-digital 14 Digital-to-analogue 14 Digital-to-digital 15 15 19 19 Phase vs frequency 18 Polarity
-TTHD vs Frequency 40, 66 THD vs Level 41, 68 THD+N 21, 40, 41, 66, 68 vs frequency 22 vs level 22 Total harmonic distortion and noise vs frequency 22 vs level 22 -UUI 46, 49, 80 Unbalanced input 8 Unit interval 46, 49, 80 Upper band-edge frequency 26 21
