|
 |
 Glossary |
|
| Master |
|
| The glass original from which copies of CDs can be created. |
| Mastering |
|
| Recording the data from a CD onto a photosensitive surface
on a glass disc (the master) used for continuous CD production. |
| Metalizing |
|
| A process which applies a thin metallic layer to the
surface of the plastic disc after molding. The process takes place
under a vacuum. |
| MID (Maximum Information Diameter) |
|
| Must be lower than 116mm. The MID parameter is an important
measure because molding and processing result in very high probability
of problems at the end of the track. The MID signal indicates the
end of the disc. If the MID does not meet specifications, there is
a danger that high frequencies in the track following signal will
be weakened owing to birefringence, to scratches, or fingerprints
left when handling. |
| Mixed Mode |
|
| A CD containing several tracks that are not the same
type. |
| MO (Magneto-optical) |
|
| An optical disc recordable and erasable at will. |
| Mb |
|
| Approximately one million bytes. |
| NWA (Normalized Wobble Amplitude) |
|
| Relationship between the wobble signal and the Push Pull.
The Orange Book specifies a NWA of between 0,035 and 0,05. |
| Orange Book |
|
| The standard for recordable CDs. It has two parts, one
for CD-Rs and one for CD-RWs. |
| OS-9 |
|
| Real-time operating system used by the CD-Is. |
| PCM (Pulse Code Modulation) |
|
| Standard method for coding audio. |
| Photo-CD |
|
| Recordable CD specially developed by Kodak to store photos
and view them on CD-ROM/XA, Photo - CD or CDI readers. One CD can
contain 100 photos. |
| Pit |
|
| Areas of the CD burnt by the laser beam in order to create
a change in reflectivity. |
| Post-Gap |
|
| An area at the end of a track with a minimum length of
two seconds. |
| Pre-Gap |
|
| Area at the beginning of a track. |
| Premastering |
|
| Preparing data to be recorded onto CD before continuous
production. |
| Programm Area |
|
| Area of a disc where data is kept. |
| Proof Disc |
|
| Protective coating |
|
| Protective layer of lacquer or polymer applied with a
nozzle and baked under UV rays to protect the layers of dye and gold
(or silver). |
| Push Pull |
|
The Push Pull (PP) parameter is a measure of how easily
the reader is able to follow the spiral. The PPa is the PP value after
recording, which is compared to the reflective value of the spiral
after recording (IGa). The same applies to the PPb (before recording
with IGb). Particularly significant is the normalised Push - Pull
ratio (NPPR) given by the following formula :
The NPPR must fall between 0.5 and 1. The Push-Pull is measured at
10 points in the data area of the disc. In CD-Cats system, the PP
is measured with a linear polarized light. A measurement system using
polarized light can modify results in a linear direction. |
| RC (Radial Contrast) |
|
| The radial contrast is the difference in reflectivity
of spirals and the areas parts between spirals. According to the Orange
Book, RC must be over 20% on a recorded disc and over 5% on a blank
disc. The RC is measured at 10 points across the disc's surface. It
is calculated as follows : |
| Red Book |
|
| REF (Reflectivity) |
|
| Reflectivity is adjusted according to a reference disc
and is used to detect and normalize variations in reflection. |
| RIFF (Resource Interchange File Format) |
|
| File format for storing diagrams, sounds, and animations. |
| RN (Radial Noise) |
|
| Radial noise may be present when tracks are damaged.
It is found in a frequency range of between 500 and 2500 Hz. |
| SVY (Scanning Velocity) |
|
| This is between 1.2 m/sec and 1.4 m/sec. If it falls
below 1.2 m/sec I3 length information is affected. The SVY parameter
represents the speed at which the reading light passes. If the speed
is too high, the I3 level will be too weak. SVY is measured as vertical
information at 10 points across the data area on the disc. The result
is returned as a minimum, maximum and average. SVY variations on the
disc must be be lower than ± 0.01 m/sec (CD-CATS). |
| SLD (Start Lead In) |
|
| The beginning of the lead-in area must be to the radius
23,1 mms. The reader uses this surface to identify the table of contents
(TOC). If the SLD is outside specification the reader will not be
able to identify where the TOC is. |
| SPD (Start of Program Diameter) |
|
| This must be located between the radius 24.8 mms and
25.04 mms. The SPD parameter is used by the reader to find the beginning
of a track. If the SPD parameter is outside specification, the reader
will take more time to find the first track. |
| Stamper |
|
| A metal tool which creates the spiral (groove)
and is held in the injection mold. |
| Substrate |
|
| The main polycarbonate body of a CD to which are applied
several other layers. |
| TIFF (Tagged Image File Format) |
|
| When a picture is scanned, it is saved as a TIFF. |
| TOC (Table Of Contents) |
|
| Information located in the lead-in area. It specifies
the location of the beginning of every track and the type of disc. |
Track
|
|
| In audio, each song is represented by a track. Computerized
data sees this only as one track. If the CD-ROM is mixed format, it
holds both a data and sound track. A CD can hold up to 99 tracks. |
| Track Pitch |
|
| Physical distance between two curves of a spiral, equivalent
to between 1,5 to 1,7µ. |
| Turnaround Time |
|
| Time needed to manufacture a CD. |
| Volume description |
|
| The area at the beginning of the disc reserved for recording
such information as the origin, the copyright, etc. |
| W-O (Write Once) |
|
| Optical disc writable once only. |
| WORM (Write Once, Read Many) |
|
| Yellow Book |
|
| When Philips and Sony created the CD standard, it was
published in a book with a yellow cover. Hence the name. |
| XT (Cross Talk) |
|
| Measure of the quantity of noise present in high-frequency
signals. The XT must be lower than 50%. Excessive XT disturbs HF signals,
which in turn increases BLER. |
|
|
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