Writing Quality - Page 27

Tests after recording

In general there are three types of tests. For detailed explanation visit Quantized (http://www.quantized.com).

Data Channel tests

Those tests are concerned with the integrity of the decoded data from the disc in terms of the amount of and severity of errors on the disc. This is a good overall indication of disc quality, however, when there are underlying problems causing high error rate the root of the problem can be found by looking at other tests. In that category there is only the BLER measurement.

Servo tests

Those tests are generally indicating the trackability of the target disc. This indicates whether there are any problems with the overall track geometry which are likely to cause playability problems. In that category we can find the following measurements:

• Push Pull
• Radial Noise
• Radial Acceleration

High Frequency tests

Those tests examine the read signals form the test player laser pickup. The nature of these signals indicates the overall pit structure on the disc is usually a good indicator of disc playability. In that category we can find the following measurements:

• Reflectivity
• I3/Itop
• I11/ITOP
• Asymmetry
• Beta
• CrossTalk
• Radial Contrast
• EccentricityJitter

Below are listed the initial and the explanation of various measurement tests for written CD-R/RW media. Note that not all measurements are described in the CD specifications. Several testing equipment manufacturers, using the standard standards, created new measurements that describe in a better way, according to them, the condition of a written disc:

• Iga: Signal Level of Groove
• Ila: Signal Level of Land
• RCa: Radial Contrast
• TEa: Push Pull Amplitude
• Push-Pull a: 0.1µm Offset Push-Pull
• RNa: Radial Noise of Push-Pull
• WNRa: Wobble CNR
• Cross Talk
• Itop
• I3/Itop
• I11/Itop
• I3/I11
• Asymmetry
• Beta (?)
• NPPR: Normalised Push-Pull Ratio
• Rtop: Reflectivity from Itop
• Rga: Reflectivity of Groove
• Rla: Reflectivity of Land
• C1: Error rate/sec
• C2: Error rate/sec
• CU: Total Number of CU Errors
• Jitter
• ATER: ATIP Error rate
• ATBEL: Maximum ATIP Errors
• ATIP Jitter