cd signal guide

DaTARIUS Technologies GmbH. The DaTARIUS CD Signal Guide (1st edition).

05-2004 - © DaTARIUS Technologies GmbH. All rights reserved.

DISCLAIMER

Whilst every effort is made to ensure that the contents of this Guide are complete and comprehensive as at the date of publication, DaTARIUS gives no warranty and makes no representation or promise that the contents of and statements and representations in this Guide are true, accurate and/or complete. The reader of this Guide will be responsible for making its own evaluation of the contents of this Guide and DaTARIUS will not be liable to the reader or anyone to whom the reader discloses the guide if any statement or representation set out in the guide is subsequently relied upon.

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About DaTARIUS and the Signal Guide

DaTARIUS is a world-leading supplier of test equipment, not only proving the quality of media during the manufacturing process, but helping to improve quality through comprehensive products and services that embrace process optimization. We also offer extensive training through our service centres worldwide, and for 20 years we have been at the forefront of this technology, consistently committed to the future of our customers and of the industry overall.

DaTARIUS produces quality control systems for all formats: pre-recorded, recordable, and rewritable, and our revolutionary DaTABANK technology is fully enabled for Blu-ray (BD) and HD DVD testing. While our test systems come under the general heading of measuring equipment, incorporating Analyzers and Evaluators, our product family extends into two further areas: process optimization, with our MF DisCo temperature optimization system; and inspection, with print label, disc orientation and ident code validation.

The DaTARIUS position in the optical media marketplace enables us to collect important information on the entire manufacturing process, from mastering to packaging. We receive valuable input from major global media manufacturers, which gives us a clear picture of manufacturing issues and challenges, and enables us to answer a wide range of questions such as:

• What are the main challenges of media manufacturing?

• What are the important parameters for each format, and how are they achieved? • How can the manufacturing process be optimized for maximum productivity?

This DVD Recordables Signal Guide, companion to the DaTARIUS DVD Signal Guide, is one of the many ways in which DaTARIUS provides valuable information and resources not only for its customers but also for the industry as a whole. It contains every significant parameter for recordable DVD media, along with reasons for disc failure, and suggestions on how to optimize the manufacturing process.. It has been written by experts in the fields of media manufacturing, quality control, and process optimization – in conjunction with input from DaTARIUS customers and partners.

DaTARIUS Group The quality people – measurement, inspection, and process optimization solutions

We welcome your comments and feedback on this Signal Guide. To contact us with your input, or to order more copies of this or other DaTARIUS publications, please email:

[email protected]

mailto:[email protected]


Contents 1 HF SIGNALS.....................................................................................................................................- 1 -

1.1 SNP – HF SNAPSHOT ................................................................................................................. - 3 - 1.2 ITP – ITOP .................................................................................................................................. - 5 - 1.3 I1L – I11 LOW, IBOTTOM ........................................................................................................... - 7 - 1.4 I1T – I11 TOP ............................................................................................................................. - 9 - 1.5 I3H, I3L – I3 HIGH, I3 LOW ..................................................................................................... - 11 - 1.6 I3T – I3 TOP ............................................................................................................................. - 13 - 1.7 ASY – ASYMMETRY................................................................................................................. - 15 - 1.8 HF – HIGH FREQUENCY SIGNAL............................................................................................... - 17 - 1.9 HFV – HF VARIATION ............................................................................................................. - 19 - 1.10 ITN, IBN – ITOP NOISE, IBOTTOM NOISE .................................................................................. - 21 - 1.11 ITV, IBV – ITOP VARIATION, IBOTTOM VARIATION ................................................................. - 23 - 1.12 I3U, I1U – UN-NORMALIZED I3 AND I11................................................................................... - 25 - 1.13 XT – CROSS TALK.................................................................................................................... - 27 -

2 TIME-BASED ERROR PARAMETERS .....................................................................................- 31 - 2.1 THP, THL – TBE HISTOGRAM PIT & LAND.............................................................................. - 33 - 2.2 TAL, TAP – TBE ANALYSIS LAND & PIT................................................................................. - 35 - 2.3 JPX, JLX – JITTER PIT X, JITTER LAND X .................................................................................. - 37 - 2.4 DPX, DLX – DEVIATION PIT X, DEVIATION LAND X................................................................. - 39 -

3 ANALOGUE SIGNALS .................................................................................................................- 41 - 3.1 PP – PUSH PULL ....................................................................................................................... - 43 - 3.2 PPC – PUSH PULL CIRCULAR ................................................................................................... - 45 - 3.3 RN1 – RADIAL NOISE............................................................................................................... - 47 - 3.4 FC1, FC2 – FOCUS NOISE......................................................................................................... - 49 - 3.5 RAC – RADIAL ACCELERATION ............................................................................................... - 51 - 3.6 VAC – VERTICAL ACCELERATION ........................................................................................... - 53 -

4 DIGITAL ERROR PARAMETERS .............................................................................................- 55 - 4.1 E32, E22, E12, E31, E21, E11 – ERROR FLAGS........................................................................ - 57 - 4.2 E22R – ERROR FLAG ................................................................................................................ - 61 - 4.3 BLE – BLOCK ERROR RATE ..................................................................................................... - 63 - 4.4 BLER – BLOCK ERROR RATE ................................................................................................... - 65 - 4.5 FBL – FRAME BURST ERROR LENGTH ..................................................................................... - 67 - 4.6 TBR, PBR – SUBCODE BLOCK ERROR RATE............................................................................ - 69 -

5 MECHANICAL PARAMETERS..................................................................................................- 71 - 5.1 ECC – ECCENTRICITY .............................................................................................................. - 73 - 5.2 BLI – BEGIN OF LEAD-IN ......................................................................................................... - 75 - 5.3 BPL – BEGIN OF PROGRAM LOCATION..................................................................................... - 77 - 5.4 BLO – BEGIN OF LEAD-OUT .................................................................................................... - 79 - 5.5 SVY – SCANNING VELOCITY ................................................................................................... - 81 - 5.6 ASV – AVERAGE SCANNING VELOCITY................................................................................... - 83 - 5.7 TRP – TRACK PITCH ................................................................................................................ - 85 - 5.8 ATP – AVERAGE TRACK PITCH................................................................................................ - 87 -

GLOSSARY ..............................................................................................................................................- 89 -

CD Signal Guide 1


1 HF Signals HF signals reflect the quality of the modulation of the digital EFM data on the CD. They are obtained from the sum of all signals coming from the four photodiode-quadrants.

With CD and DVD, the data structure is based on a time period “T”. On the High-Frequency (HF) signal of the CD, we can find pits and lands whose length ranges from T3 to T11. It means that the shortest information element (T3) has a length three times the length of one period “T”, where T has a length of 231 nanoseconds (ns).

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CD Signal Guide 3

1.1 SNP – HF Snapshot

1.1.1 DVD equivalent

SNP

1.1.2 Description

SNP is an actual sample of the HF signal coming from the pickup during readout. It reflects the Pits and Lands along the track. There is no valid scaling for this graph, but it can help to trace problems.

Figure : HF Snapshot

1.1.3 Interpretation

An abnormal SNP sample means that there is a problem with one or more of the following parameters:


Pit-forming

Metallization layer

Laser power

Polycarbonate properties

4 CD Signal Guide


Personal Notes

CD Signal Guide 5

1.2 ITP – Itop


I14H

1.2.2 Description

This continuously measured signal, reported for every second,

Is the highest possible reflection measured on a T11 land

Is the highest voltage level the HF signal can reach during readout, where the focused laser beam tracks along a T11 land

Figure : Eye-pattern, ITP

ITP displays the maximum signal level from the optical photodiode, measured from DC zero (zero level) to the peak of the I11 land. A result of 1.0 would mean that 100% of the emitted light was reflected back into the photodiodes.


6 CD Signal Guide


The ITP signal is proportional to:

The reflection of the information level

The transmission of the substrate

The optical laser power influences the absolute ITP value

Due to differences in pit geometry, there can be influences from adjacent tracks. Reasons are diffraction appearances and the fact that the optics are also able to capture the 1st order. ITP, therefore, does not measure the real reflectivity of a disc. To find out about the real reflectivity, the optical parameter (REF) has to be measured.


The signal value has to be within specification, otherwise there can be read-out difficulties. A low or abnormal HF level means that there is a problem with one or more of the following parameters:

Pit-forming

Metallization layer

Laser power

Polycarbonate properties

1.2.4 Specifications

RED BOOK DaTARIUS CS-4 Limits Min / 0.70 Max / / Measured From / 0 To / 1.0 Resolution / 0.004 Decimal places shown / 2 Unit / /

CD Signal Guide 7

1.3 I1L – I11 Low, Ibottom


I14L

1.3.2 Description

This continuously measured signal, reported for every second,

Is the lowest possible reflection measured on a T11 pit

Is the lowest voltage level the HF signal can reach during readout, where the focused laser beam tracks along a T11 pit

Figure : Eye-pattern, I1L


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CD Signal Guide 9

1.4 I1T – I11 Top


I14N

1.4.2 Description

Formula : ITPITI 111 =

( )ITP

LIITP 1−=

This continuously measured value, reported for every second, represents the normalized I11 amplitude.

Figure : Eye-pattern, I11 - ITP - I1L


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The I11 amplitude is detected by measuring the level difference of the HF signal in the moment the laser beam passes a T11 land and a T11 pit. Due to normalizing, influences from the drive (different laser power) are being compensated and the value becomes dimensionless.

The formulas for the signals HF (Chapter 1.8) and I1T look equal, but I1T is determined through a much more sophisticated method, where all data not belonging to the analogue EFM signal are eliminated mathematically and electronically.


The amount of the signal ratio reveals information about the shape of pits and subsequently of the quality of the pit replication on the substrate. Values below or above the required level would lead to high error rates.

Possible causes for abnormal I1T results are poor stampers due to problems in glass mastering (unequal application of layer, wrong laser power), or deviations of the moulding process parameters such as pressure, mould and melt temperature.

See also ITP.


RED BOOK DaTARIUS CS-4 Limits Min 0.60 0.60 Max / / Measured From / 0 To / 1.0 Resolution / 0.004 Decimal places shown / 2 Unit / /

CD Signal Guide 11

1.5 I3H, I3L – I3 High, I3 Low


I3H, I3L

1.5.2 Description

These continuously measured values, reported for every second, represent the maximum (I3H) and minimum (I3L) signal levels of the HF signal in the moment the laser beam passes a T3 land or T3 pit.

Figure : Eye-pattern, I3


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Personal Notes

CD Signal Guide 13

1.6 I3T – I3 Top


I3N

1.6.2 Description

Formula : ITPITI 33 = ( )

ITPLIHI 33 −

=

This continuously measured value, reported for every second, represents the normalized I3 amplitude.

The I3 amplitude corresponds to the level difference of the HF signal at the moment where the laser beam passes a T3 land and a T3 pit.

The normalizing of the signal has the same reasons as for I1T.

Figure : Eye-pattern, I3



I3T should not be:

Too low = low resolution

Too high = the I3 signal could have an amplitude similar to the next higher signal (I4). Jitter problems could also occur.

Possible causes for abnormal I3T results are poor stampers due to problems in glass mastering (unequal application of layer, wrong laser power), or deviations

14 CD Signal Guide


of the moulding process parameters such as pressure, mould and melt temperature.


RED BOOK DaTARIUS CS-4 Limits Min 0.30 0.30 Max 0.70 0.70 Measured From / 0 To / 1.0 Resolution / 0.004 Decimal places shown / 2 Unit / /

CD Signal Guide 15

1.7 ASY – Asymmetry


ASYd

DaTARIUS Group

1.7.2 Description

The asymmetry signal reflects the relation of the positions of I3-signal centre to the I11-signal centre. The I3-signal centre, for example, lies on (I3H+I3L) / 2.

Formula: ( ) ( )

( )LIITPLIHILIITPASY

12331

−⋅

+−+=

Figure : Eye-pattern, I3 – I11 (ITP = Itop, I1L = I bottom)

Figure : Eye-pattern asymmetry

The quality people – measurement, inspection, and process optimization solutions

16 CD Signal Guide


This signal is a continuously measured value, and reported for every second.

In CS4win, the sign of ASY can be changed if necessary.


In theory, the decision level of I3 and I11 should coincide. In practice, a deviation is tolerated.

I3 Centre Level > I11 Centre Level ASY < 0. I3 Centre Level < I11 Centre Level ASY > 0.

Possible causes for abnormal ASY results are poor stampers due to problems in glass mastering (unequal application of layer, wrong laser power), or deviations of the moulding process parameters such as pressure, mould and melt temperature.


RED BOOK DaTARIUS CS-4 Limits Min -20 -15 Max 20 5 Measured From / -25 To / 25 Resolution / 0.2 Decimal places shown / 1 Unit % %

CD Signal Guide 17

1.8 HF – High Frequency Signal


None

1.8.2 Description

Formula: ItopIHF 11

=

This continuously measured value, reported for every second, reflects the maximum actual degree of modulation relative to the maximum HF signal level. It is determined by a much simpler method than I1T. It still gives you I11/Itop, but there is no mathematical operation on the HF signal before measuring to eliminate noise contributions.


See I1T.


RED BOOK DaTARIUS CS-4 Limits Min 0.60 / Max / / Measured From / 0 To / 1.0 Resolution / 0.004 Decimal places shown / 2 Unit / /


18 CD Signal Guide


Personal Notes

CD Signal Guide 19

1.9 HFV – HF Variation


HFVd

1.9.2 Description

The HFV signal is the variation of the amplitude of I11 within one second.

Figure : HFV


This parameter should be constant, otherwise it means there are abnormal variations in the HF top and/or bottom signals. Reasons are the pit structure or metallization layer.


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CD Signal Guide 21

1.10 ITN, IBN – Itop noise, Ibottom noise


None

1.10.2 Description

These continuously measured values, reported for every second, show the amount of noise where the HF signal (Itop and Ibottom) is expected to be constant. The value is normalized to Itop again, so the displayed numbers are % of Itop.

Figure : HF Snapshot



This kind of noise happens on long lands and pits. The signals were introduced to verify the reflection of the long effects more closely.

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Personal Notes

CD Signal Guide 23

1.11 ITV, IBV – Itop variation, Ibottom variation


I14V, IBVd

DaTARIUS Group

1.11.2 Description

These continuously measured values, reported for every second, show the variation of Itop and Ibottom.

Figure : Eye-pattern, ITV

Figure : Eye-pattern, IBV


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ITV reflects changes in the level of maximum reflection. The maximum reflection can suddenly drop due to problems with the metallization layer or the substrate.

The IBV signal gives information about the pit structure to find out whether the pits are too deep or too shallow. When the pit depth changes, light is not reflected with enough phase shift to result in low intensity of the reflected beam and a low signal coming out of the photo-detectors.

CD Signal Guide 25

1.12 I3U, I1U – un-normalized I3 and I11


I3Ud, I1Ud

1.12.2 Description

These continuously measured values, reported for every second, tell us the amount of modulation of the total light which was transmitted. Normally, I11 and I3 make sense only if they are measured relatively to Itop, that means, relative to the total light that could be reflected. So I1T actually means I11/Itop. But in some cases you may want to see its value directly, before normalization. So the un-normalized I11 can be seen as I1U. I3U is used equally.

Figure : Eye-pattern, I3U (I3), I11U (I11)



Low signal values mean that the laser is ageing, or that the reflection has dropped due to other reasons.

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CD Signal Guide 27

1.13 XT – Cross Talk


TCS

1.13.2 Description

The pit pattern on the disc can be seen as a grating structure in both radial and tangential directions. Most conventional CD and DVD players are equipped with a four-quadrant photo-detector, on which an image of the spot on the disc is formed, including the 0th orders and partially the 1st orders. The overlap of the 1st and 0th order generates the operational signal, so neighbouring tracks will have small influences on the readout.

Laser light intensity distribution :

Figure : Intensity Distribution Figure : 3d diagram of an actual measurement


28 CD Signal Guide

The XT signal is evaluated in the "open loop mode". Open loop means that the CD is spinning and the focused laser beam passes the track at a right-angle, in radial direction. The HF signal is fed through a low pass filter. The modulation of this picked up signal is detected. The modulation results in the fact that the average reflection between the tracks is higher than the average reflection on the track.

This means that the modulation of the open loop signal is a value for the cross talk of adjacent tracks.

Figure : Pick-up movement during open loop XT measurement

Figure : Measuring XT open loop Figure : Actual Open Loop measurement

The maximum voltage level remains the same both on and between the tracks, which is why the top is flat. The HF amplitude is greater when the pickup is above the tracks and smaller when between.


CD Signal Guide 29

XT is the amount of HF-Signal found by the pick-up between the tracks, compared to the amount exactly on the track.

Formula: axinXT

ImIm

=

Imin = Hf amplitude if pickup is between tracks. Small. Imax = Hf amplitude if pickup is on track. High.

Figure : Measuring XT XT is also referred to as radial contrast.



Since the XT result is very dependent on the distance between the tracks (TRP) and on the reflectivity of the metallization layer (reflected in ITP, I1T), these parameters should be observed closely in case of problems with XT.

If the tracks are too close to each other, there is a risk that the pick-up head will get too much interference from the neighbouring track into the read-out signal, or in severe cases, even follow the wrong track. The same cases can happen if the pits on the disc are too wide due to too strong laser power in the mastering process.

Possible causes for abnormal XT results are poor stampers due to problems in glass mastering (track pitch, pit shape), or deviations of the moulding process parameters such as pressure, mould and melt temperature.

Reason for bad reflection or I1T could be a poor metallization layer… (Also see ITP and I1T)

30 CD Signal Guide



RED BOOK DaTARIUS CS-4 Limits Min / / Max 50 0.50 Measured From / 0 To / 1.0 Resolution / 0.004 Decimal places shown / 2 Unit % 100-1%

CD Signal Guide 31


2 Time-Based Error parameters

Figure : Count length of effects and add up to single histograms for each effect length

The information on CDs is coded in different effect lengths T3 – T11. The timebase T in CD technology is 231,4ns. A T3 effect therefore lasts for 694,2 (= 3 x 231,4) ns.

In theory, pits and lands have a specific length. Due to technical imperfections, these specific lengths cannot be physically represented, and we can observe deviations. Pits/lands are shorter or longer than their specified lengths. If these deviations are above a specified level, read-out failures will be generated because of a wrong decision on the nature of a pit/land. Jitter is the expression of these deviations.

The Tbe (Time based error) signals Jitter and Deviation describe timing errors that occur at transitions in the digitized EFM data stream. If the timing errors become bigger than a certain limit, the decoder has trouble distinguishing between the single effect lengths. I.e. the decoder could confuse a T5 with a T6 effect.

Analyzing the absolute length of individual pits and lands on a CD results in 18 groups of values, 9 for pit and 9 for land. Theoretically, the distance between neighbouring groups is 231,4 ns.

32 CD Signal Guide


Personal Notes

CD Signal Guide 33

2.1 THP, THL – Tbe Histogram Pit & Land


None

2.1.2 Description

The measured effect lengths are grouped. This results in separate diagrams for T3 Pit, T4 Pit ... T11Pit, T3 Land, T4 Land ... T11 Land. All different lengths of one group (T3 Pit for example) add up to a length-deviation distribution diagram, called a histogram.

Figure : Adding up T3 Pit effects to a Histogram


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Figure : THP, Tbe Histogram Pit Figure : THL, Tbe Histogram Land


Jitter is related to the width of the histogram of one effect length. Deviation can be seen in the distance between the maximum value of the histogram and the specified values for this effect length. The specified effect lengths are marked with dotted lines in the THL and THP histograms.

A high jitter value means that pits/lands are shorter or longer than their specified length. If these deviations are above a specified tolerance, read-out failures will be generated because of a wrong decision on the nature of a pit/land. BLE, the digital Signal Block Error Rate, will start to rise quickly from that point.

High Jitter values in the Histogram can be detected by taking a look at the width of the single histograms. If the single distribution diagrams increase in width, they will start to touch each other at some point. This is the critical area, where the decoder can confuse the two different effect lengths.

Figure : Jitter on the disc is worse than above


CD Signal Guide 35

2.2 TAL, TAP – Tbe Analysis Land & Pit


None

2.2.2 Description

The Tbe Analysis diagrams TAL and TAP are different approaches for displaying the same results as in the histograms.

TAL and TAP are divided into sections for T3, T4, T5,…,T11. For each Tbe measurement that was done one bar, representing the result, is added to each section. Jitter is reflected in the length of the bars. Deviation can be seen in the distance between the centre of the bars and the zero-level line.

Figure : TAP Diagram Figure : TAL Diagram

DaTARIUS Group


See THP, THL.

Figure : Example of bad Jitter on a disc


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Personal Notes

CD Signal Guide 37

2.3 JPx, JLx – Jitter Pit x, Jitter Land x


None

2.3.2 Description

The actual Jitter value is the width of the area which contains 2/3 of all samples in a single histogram. The results for JP3, JP4, .. JP11, .. JL11 are displayed in nanoseconds [ ns ].

Figure : Measuring Jitter If the timing errors for a specific effect length are big, the histogram gets wider. In that case of course the area which contains 2/3 of the samples also gets wider, meaning the Jitter value rises.


38 CD Signal Guide



A high jitter value means that pits/lands are shorter or longer than their specified length. If these deviations are above a specified tolerance, read-out failures will be generated because of a wrong decision on the nature of a pit/land. BLE, the digital Signal Block Error Rate, will start to rise quickly from that point.

Possible causes for abnormal Jitter results are poor stampers due to problems in glass mastering (unequal application of layer, wrong laser power), or deviations of the moulding process parameters such as pressure, mould and melt temperature.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 35 35 Measured From / 0 To / 250 Resolution / 1 Unit ns ns

CD Signal Guide 39

2.4 DPx, DLx – Deviation Pit x, Deviation Land x

2.4.1 CD equivalent

None

2.4.2 Description

Deviation describes the distance between specified length for an effect (theoretical) and average effect-length measured on the disc. The results for DP3, DP4, .. DP11, .. DL11 are displayed in nanoseconds [ ns ].

Figure : Measuring Deviation The deviation of the maximum (highest point in a single histogram) from the specified value can be measured when the largest number of effects with an equal length are counted for effects, shorter or longer than the specified length.


40 CD Signal Guide



A high deviation value means that most counted pits/lands of this sample are much shorter or longer than their specified length. If these deviations are above a specific tolerance, read-out failures will be generated because of a wrong decision on the nature of a pit/land. BLE, the digital Signal Block Error Rate, will start to rise swiftly from that point.


RED BOOK DaTARIUS CS-4 Limits Dx3 (T3) ±40.0 ±40 Dx4 (T4) ±42.5 ±43 Dx5 (T5) ±45.0 ±45 Dx6 (T6) ±47.5 ±48 Dx7 (T7) ±50.0 ±50 Dx8 (T8) ±52.5 ±53 Dx9 (T9) ±55.0 ±55 Dx10 (T10) ±57.5 ±58 Dx11 (T11) ±60.0 ±60 Measured From / -125 To / 125 Resolution / 1 Unit ns ns

CD Signal Guide 41


3 Analogue Signals The task of the servo electronics is to ensure that the laser spot follows, and is centred on the middle of the track. Analogue signals are necessary for the servo circuits to keep track and obtain the recorded data. They do not contain information about the quality of the information carrier itself, as do the HF-parameters.

Tracking is based on the following principles: the two signals from the pair of photodiodes to the left of the track, and the two signals from the pair of photodiodes to the right of the track are added. The result is one signal for the left side and one signal for the right side.

If both signals are equal, so that the same amount of reflected light hits left and right sides (A and B), the resulting tracking error signal (e) is zero. This happens exactly on and between the tracks.

Figure : Spot on track centre Figure : Spot between the tracks

If the readout spot drifts off, meaning that one side of the photodiodes gets more reflection than the other, the resulting tracking error signal (e) is fed back into the servo control circuit that will bring the pickup back on the centre of the track.

Figures : Spots drifting off, leading to difference in light intensity

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Personal Notes

CD Signal Guide 43

3.1 PP – Push Pull


RPP – Radial Push Pull

DaTARIUS Group

3.1.2 Description

PP is obtained by crossing the tracks radial in open loop servo condition, where the focusing circuits are active and the tracking circuits are switched off.

PP tells you the difference in intensity of reflected light between the left and the right half of photodiodes (A – B), relative to the maximum amount of light obtainable within the recorded area (Itop).

Since this difference in intensity of the light depends on the position of the pickup, the position for the PP measurement had to be specified :

The measurement has to be done at a radial distance of 100nm between the track centre and the laser spot (pickup).

Figure : PP measurement on 100nm displacement


44 CD Signal Guide

The photo detector is split into two halves, A and B, that are parallel to the track.

ItopBAPP −

=


Since the drives use PP-based tracking, PP is an indication for the tracking ability of the disc under the pickup system. Any value too low/high might cause tracking problems.

The signal contains information about the symmetry of the pit geometry over the track.

When PP is high, the pits’ flanks have a steep slope, which can cause tracking problems.

When PP is low, the pits’ flanks have a gentle slope, which can cause tracking problems.

The conditions are optimized for tracking, when the pits’ flanks have a specific angle.

Flanks that are too steep or too gentle flanks do not offer better tracking. There is an optimal slope for pits. To get as close as possible to the optimum, PP has to stay between the specified limits.

Possible causes for abnormal PP results during mastering are unequal application of the layer or wrong laser power. Possible causes during the moulding process are the temperatures of mould and melt, injection parameters or disc cooling.



RED BOOK DaTARIUS CS-4 Limits Min 0.040 0.046 Max 0.090 0.095 Measured From / 0 To / 0.125 Resolution / 0.005 Decimal places shown / 3 Unit / /

CD Signal Guide 45


3.2 PPC – Push Pull Circular


None.

3.2.2 Description

Originally, the Push Pull measurement was specified for a circular polarized light beam to compensate the influence of the birefringence of the PC.

Since none of the testers use circular polarized light beams, PPC has to be calculated.

Measurement sequences showed that, within the PP range that is used when measuring the disc, the following rule can be applied :

PPC = f(PP) = a + b * PP

PPC and PP are related to each other over a linear function, so the PPC result can be calculated after measuring PP.


See PP.

46 CD Signal Guide


Personal Notes

CD Signal Guide 47

3.3 RN1 – Radial Noise


RNSd

3.3.2 Description

This continuously measured signal, reported for every second, reports the radial deviations of the track, which lie in a frequency spectrum of 1.1 to 10 kHz.

The centre of the pits on a track is not really on the same line. The PUH has to move (to the left or to the right) to centre itself and follow the pits. The radial movements from nominal positions of the pick-up head are expressed in nanometres [ nm ].

Figure : Radial noise


48 CD Signal Guide

RN1 is a tracking signal that reflects the deviations of the pickup from the track centre in [ nm ]. Tracking errors introduce an error signal (e), with polarity and amplitude depending on position and distance between light spot and the centre of the track. Due to the stochastic character of tracking errors the signal is called noise.

Figure : RN1


Peaks in the radial noise signal mean that the PUH has to make an abnormal radial deviation to stay on the track.

Such local effects can be caused by mechanical defects on the stamper, spots (dots) on the stamper, black spots (random specks or inclusions), grey spots (inclusions of particles from the environment) or silver streaks.

High radial noise results over the whole disc often indicate problems with the stamper. Either the glass master was poor or the preparation in plating was not ideal. Another reason could be a dirty or worn mirror of the moulding machine.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 30 30 Measured From / 0 To / 50 Resolution / 0.02 Unit nm nm


CD Signal Guide 49


3.4 FC1, FC2 – Focus Noise


None.

3.4.2 Description

Very similar to Radial Noise, the Focus Noise signal shows deviations from the ideal, smooth movement without any noise. This time the vertical deviations are considered.

FC1 and FC2 are scaled in internal units and measured uncalibrated, as there are no references available.

Low and high corner frequency and integration time for both signal circuits can be adjusted in CS4win.


Peaks in the Focus Noise signal mean that the focus servo has to make an abnormal vertical deviation to keep the laser focused on the track.

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Personal Notes

CD Signal Guide 51

3.5 RAC – Radial Acceleration


None.

DaTARIUS Group

3.5.2 Description

The continuously measured RAC signal contains information on the acceleration required by the radial servo to follow the track. This parameter has gained importance since multi-speed CD ROM drives have been included in computers.

Figures : RAC Figure : RAC graph on a bump


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Radial deviation and acceleration of a pickup are related in a square function of the time. Since the time is constant in this case (defined by the effect that is causing radial deviations), the acceleration of the radial servo at higher readout speeds has to rise exponentially for the pickup to follow radial deviations.


If there is any radial deviation caused by a bump on the stamper, or a deflection of the readout laser due to the PC or track layout, the radial servo (pickup head) has to be fast enough to compensate for this. If the pickup head is not fast enough, the track will be lost.

Discs with a high RAC will show performance and playability problems in high speed CD ROM drives.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 0.4 0.40 Measured From / 0 To / 1.25 Resolution / / Decimal places shown / 2 Unit m/s² m/s²

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3.6 VAC – Vertical Acceleration


None

3.6.2 Description

The continuously measured VAC signal contains information on the acceleration required by the focus servo to keep the laser focused on the track. This parameter has gained importance since multi-speed CD ROM drives have been included in computers.

The player’s laser beam must stay focused on the disc’s information layer within a small tolerance. As a disc is not perfectly flat, the player’s auto-tracking system has to refocus continuously in order to compensate the varying distance between the disc’s surface and the player’s optical pick-up.

Vertical deviation and acceleration of a focus servo are related in a square function of the time. Since the time is constant in this case (defined by the effect that is causing vertical deviations), the acceleration of the focus servo at higher readout speeds has to rise exponentially for the pickup to follow vertical deviations.


In the event there is any vertical deviation caused by a bump in the stamper or skewed discs, the focusing mechanism has to be fast enough to keep the laser properly focused. With a high VAC, the spot is not optimally focused on the track and may result in read-out/tracking problems. Discs with a high VAC will show performance and playability problems in high speed CD ROM drives. Problems with VAC are usually related to skewed discs. The carton packaging often causes additional skew on the discs.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 10 10.0 Measured From / 0 To / 12.5 Resolution / / Decimal places shown / 1 Unit m/s² m/s²

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4 Digital Error Parameters To be able to correct errors, redundant data has to be added to the user data. This enables the read-out hardware to correct defective symbols in the stream.

The error detection is done exactly the same way that became an early worldwide standard. Error correction is much more sophisticated nowadays, but to maintain compatibility, it is necessary to reuse the method, which can correct two only defective symbols per correction stage.

For the evaluation of the following error flags a summary over eight matrix or ECC blocks is used.

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4.1 E32, E22, E12, E31, E21, E11 – Error Flags


E32 ≈ POF, E31 ≈ PIE


4.1.2 Description

E-flags are generated by the hardware error correction stages C1 & C2 during EFM signal decoding. Displayed E-Flag results are counter values for 1 second. Each one of the error correction stages is capable of ‘repairing’/restoring up to a maximum of two defective symbols. Exy : y reflects the correction stage, x the number of erroneous symbols detected and possibly corrected in the stage. E22 for instance means, that two symbols were corrected in stage C2, which is the maximum the decoder is able to rebuild. E31 means that three3 or more symbols were defective in stage C1 and therefore it was not possible to correct them. It will be necessary to process them in stage C2. If E32 occurs, correction of this block was not successful and data in this block is not available at all. E32 flags are not allowed on any CD.

Figure : Error Correction Stages

Error correction stage C1 : E11 : 1 symbol out of a frame was defective and has been corrected E21 : 2 symbols out of a frame were defective and have been corrected E31 : more than 2 symbols out of a frame are defective and cannot be corrected; the whole frame is marked as erroneous

Error correction stage C2 : E12 : 1 symbol in the 2nd stage was defective and has been corrected E22 : 2 symbols in 2nd stage were defective and have been corrected E32 : more than 2 symbols in the 2nd stage were defective; uncorrectable error

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If an E32 occurs, correction of this frame was not successful and the data in this frame can not be read from the disc.

E32 flags are not allowed on any manufactured CD! Such errors can be caused by all optical defects that interfere with the normal data read-out (scratches, dots, black spots, pinholes, bubbles, etc). Local defects can corrupt the data content. Other causes for E32 can be jitter problems, stamper defects or a bad HF signal.


E32 RED BOOK DaTARIUS CS-4 Limits Min / / Max 0 0 Measured From / 0 To / 250 Resolution / 1 Unit / /

E11, E21, E31, E12, E22 RED BOOK DaTARIUS CS-4 Limits Min / / Max / / Measured From / 0 To / 500 Resolution / 2 Unit / /

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4.2 E22r – Error Flag

4.2.1 Description:

E22r is a ‘new’ signal in addition to E22. It uses the same signal specification, but is valid only for mixed CDs, which are CDs with audio and non-audio tracks, or CD-ROMs.

E22 values that originate from non-audio tracks (data tracks) are copied to E22r.

That means that the limit settings for data tracks can be different to the limit settings for audio tracks.

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4.3 BLE – Block Error Rate


)2111( EEPIE +=≈

4.3.2 Description:

Formula: 312111 EEEBLE ++=

BLE reflects the number of blocks within one second, where error corrections were made in the first correction stage of the decoder. Therefore BLE is a good overall indicator of the disc quality.

Only 3% of all frames within one second are allowed to be erroneous; this results in an error rate of 220 frames per second.


BLE counts all blocks where error correction is necessary. Therefore BLE is a good overall indicator of the disc quality. Digital errors in general can be caused by all optical defects that interfere with the normal data read-out (scratches, dots, black spots, pinholes, bubbles, etc). Local defects can corrupt the data content. Other causes for BLE can be jitter problems, stamper defects or a bad HF signal.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 220 (10 sec avg.) 220 Measured From / 0 To / 500 Resolution / 2 Unit / /


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4.4 BLEr – Block Error Rate

4.4.1 Description:

BLEr is a ‘new’ signal in addition to BLE. It uses the same signal specification, but is valid only for mixed CDs, which are CDs with audio and non-audio tracks, or CD-ROMs.

BLE values that originate from non-audio tracks (data tracks) are copied to BLEr.

That means that the limit settings for data tracks can be different to the limit settings for audio tracks.

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4.5 FBL – Frame Burst Error Length


None.

4.5.2 Description:

Each second, FBL shows the maximum number of consecutive blocks containing two or more defective symbols detected in the first correction stage. E11 is ignored, E21 and E31 are counted.

Examples : FBL = 3, meaning that 3 consecutive blocks with more than 1 symbol error occurred in that second.

Figures : FBL – consecutive errors


Digital errors in general can be caused by all optical defects that interfere with the normal data read-out (scratches, dots, black spots, pinholes, bubbles, etc). Local defects can corrupt the data content. Other causes for FBL can be jitter problems, stamper defects or a bad HF signal.



RED BOOK DaTARIUS CS-4 Limits Min / / Max < 7 6 Measured From / 0 To / 250 Resolution / 1 Unit / /

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4.6 TBR, PBR – Subcode Block Error Rate


None.

4.6.2 Description:

These continuously measured signals are reported for every second.

TBR (TOC block error rate) is reported only in the lead-in area. In the program area and in the lead-out area this signal is always zero.

PBR (Program subcode block error rate) is reported only in the program area and in the lead-out area. In the lead-in area this signal is always zero.


Both signals reflect the number of defective Subcode frames in SC-Channel "Q". Subcode data cannot be corrected in the two correction stages like the user data, and, therefore, it cannot be used if defective. But this information is very often present, so redundancy is provided by repetition.

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5 Mechanical Parameters Mechanical parameters are obtained from a device that reads the radial position of the pickup.

All static parameters can be directly read with the radial position detection.

By knowing the radius at any time it is possible to calculate track pitch and scanning velocity.

Figure : Mechanical layout of a CD


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5.1 ECC – Eccentricity


ECC


5.1.2 Description

The static ECC value reported once per disc reflects the CD’s eccentricity in micrometers.

Eccentricity is defined as the offset of the physical centre of the disc from the centre of the circular tracks on the disc.

The ECC result is obtained by detecting how far the pickup has to travel in radial direction during readout.

Figure : Eccentricity

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Basically the eccentricity value has to be low for good performance in high-speed drives. The better the eccentricity, the less the pick-up has to move in radial direction and the better the playability of the disc.

In the case of high eccentricity, the servo and pick-up have to move quickly. The inertia of the pick-up can limit the reaction speed of the servo and then cause problems to follow the track.

Abnormal ECC results can be caused by wrong punching of the stamper’s centre hole, or by the tools of the moulding machine (centre, punch unit).

In case of high ECC, turn the stamper on the mould until ECC is ok. If this does not improve the result, make sure that the stamper’s centre hole is centric. If this is the case, the punch or the punching unit might have to be removed.


RED BOOK DaTARIUS CS-4 Limits Min / / Max 70 70 Measured From / 0 To / 60000 Resolution / 1 Unit µm µm

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5.2 BLI – Begin of Lead-In


BLI

5.2.2 Description

This signal reflects the begin radius of the lead-in area. BLI is the smallest diameter on the disc for the analyzer to find readable TOC information.

Figure : BLI


The electronics of consumer CD drives are designed to expect to find data at specified positions. If the data are not at the right location, playability problems can occur. Consumer drives start reading at 24mm, approximately. So even if there were slight tolerances with these drives, they will still detect the TOC.

The cause of abnormal BLI results can be :

Wrong cutting in glass mastering


Problems with moulding parameters – the disc is shrinking too much.

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RED BOOK DaTARIUS CS-4 Limits Min / / Max 23.00±0.05 23.00 Measured From / 22.80 To / > 60 Resolution / / Decimal places shown / 2 Unit mm mm

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5.3 BPL – Begin of Program Location


BPL

5.3.2 Description

The static value BPL is the location where the actual information, that means the pause of track one, starts. It is the transition from index 0 (lead-in) to index 1 (track 1).

Figure : BPL


The electronics of consumer CD drives are designed to expect to find data at specified positions. If the data are not at the right location, playability problems can occur.

The cause of abnormal BPL results can be :



Problem with moulding parameters – the disc is shrinking too much.

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RED BOOK DaTARIUS CS-4 Limits Min / 24.80 Max 25.00±0.02 25.00 Measured From / 22.80 To / > 60 Resolution / / Decimal places shown / 2 Unit mm mm

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5.4 BLO – Begin of Lead-Out


BLO

5.4.2 Description

This static BLO value is the location where the program information ends and the lead-out area starts. It is the transition from the index XX (last track) to index AA (lead-out). The lead-out has to be present for at least one additional millimetre. Figure : BLO


The electronics of consumer CD drives are designed to expect to find data at specified positions. If the data are not at the right location, playability problems can occur.

The cause of abnormal BLO results can be :


Problems with moulding parameters – the disc is shrinking too much.



RED BOOK DaTARIUS CS-4 Limits Min / / Max 58±0.02 58.00 Measured From / 22.80 To / > 60 Resolution / / Decimal places shown / 2 Unit mm mm

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5.5 SVY – Scanning Velocity


SVYd

5.5.2 Description

The continuously measured SVY shows the readout speed of the system in metres per second. This corresponds to the speed at which the laser’s pick-up head travels along the spiral track of the disc.

The turntable is controlled in such a way that the data comes from the CD at an exact rate of 4.32 MHz. The resulting speed of the CD seen by the pick-up is SVY. This is the reason why the CD turns faster when reading out at inner, and slower when reading on the outer radius, where one revolution has space for much more information at the same speed. The result is calculated by measuring the radius and the exact time for one revolution.


Abnormal SVY values are caused during the mastering process.


RED BOOK DaTARIUS CS-4 Limits Min 1.2 1.20 Max 1.4 1.40 Measured From / 1.00 To / 1.50 Resolution / 0.002 Decimal places shown / 2 Unit m/sec m/sec

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5.6 ASV – Average Scanning Velocity


ASVd

5.6.2 Description

ASV is a static parameter, measured once per CD. As soon as BPL and BLO are measured, the CD’s average scanning velocity ASV can be calculated. It makes sense to check ASV instead of the SVY-average, because it is always accurate, even if the whole CD was not tested.

SVY is measured continuously to indicate if there are any significant changes on the CD. Different from this signal, ASV is measured at the beginning of the test sequence to have a very early, general result on the scanning velocity.


See SVY.


RED BOOK DaTARIUS CS-4 Limits Min 1.2 1.20 Max 1.4 1.40 Measured From / 1.00 To / 1.50 Resolution / 0.002 Decimal places shown / 2 Unit m/sec m/sec

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5.7 TRP – Track Pitch


TRPd

5.7.2 Description

The continuously measured value of TRP reflects the distance between adjacent physical track centre lines in the radial direction in micrometres [ µm ].

Figure : Track Pitch



When the laser spot is on one track, the returned signal also reflects information from the adjacent track. This phenomenon can disturb the correct read-out of the disc. Therefore, the space between the tracks should be large enough so that the laser spot highlights the information from one track and a minimum from adjacent tracks.

Abnormal TRP values are either caused during the mastering process, or by the moulding parameters in case the disc shrinks too much.

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RED BOOK DaTARIUS CS-4 Limits Min 1.5 1.50 Max 1.7 1.70 Measured From / 1.30 To / 1.80 Resolution / 0.002 Decimal places shown / 2 Unit µm µm

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5.8 ATP – Average Track Pitch


ATPd

5.8.2 Description

ATP is a static parameter, measured once per CD if the basic sequence was done. As soon as BPL and BLO are measured, the CD’s average track pitch ATP can be calculated. It makes sense to check ATP instead of the TRP-average, because it is always accurate, even if the whole CD was not tested.

TRP is measured continuously to indicate if there are any significant changes on the CD. Different from this signal, ATP is measured at the beginning of the test sequence to have a very early, general result on the track-pitch.


See TRP.


RED BOOK DaTARIUS CS-4 Limits Min 1.5 1.50 Max 1.7 1.70 Measured From / 1.30 To / 1.80 Resolution / 0.002 Decimal places shown / 2 Unit µm µm

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Glossary Basic sequence: This is a test mode in the DaTARIUS CS-4/WIN Software. Up to eight

positions are measured on the disc during a user-defined time length (the standard configuration is 10 sec).

EFM: Eight-to-fourteen modulation.

Lands: During encoding of the glass master disc, a high power laser beam burns pits in a spiral track onto the specially prepared recording surface. The 'lands' are the clear spaces between those pits. When reading a replicated disc, the laser light reflects at a higher intensity from the lands than from the pits, and the transitions between lands and pits make the reading of the contents possible.

Open Loop: Two systems are used to read out information from a CD/DVD:

• Focus = Focus is always needed,

• Tracking = Tracking can be switched on and off.

ON: the pick-up’s laser spot will be corrected to follow the track. This mode is called CONTROL LOOP.

OFF: the pick-up’s laser spot can jump across the tracks (radial jump). This mode is called OPEN LOOP. (Used to measure the basic sequence).

Pits: During optical encoding, pulses of a high power laser beam 'burn' microscopic 'pits' onto the recording layer. The untouched spaces between such pits are called 'lands.' During the read process, the laser light focuses on the spinning spiral track and, as the pits reflect light less intensely, the read head detects the changes in reflectivity, and those transitions are processed as 1s to produce a binary data stream. In DVD, the track pitch is 0.74 microns, and the pits are 0.4 microns wide. Maximum pit lengths are 10 times pit width

PLL clock: The Phase Locked Loop clock is a pulse signal, whose period length is equal to one T or 38.2 nanoseconds. This pulse signal is regenerated from the data stream and used in time based evaluations.

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