Frequently Asked Questions About Compact Discs

Please contact Media Sciences if your questions are not answered on these pages.

I do not obtain the same CD test results using test equipment from various vendors or even with different testers from the same manufacturer. Why cannot CD test equipment manufacturers achieve correlation?

Although correlation should be supported by all test equipment vendors, calibration and maintenance is normally the responsibility of the testing organization. The Philips 5B disc has been available for many years, and supports single point calibration of Itop, I3, I11, parallel and circular push pull, cross talk, radial contrast, asymmetry, jitter, and length deviation. A multi-point test set newly developed by Philips and Sony is now available to establish correlation over the full range of many parameters.

This three disc Philips Multi-Point Correlation Set is available from Philips Consumer Electronics, Co-ordination Office Optical and Magnetic Media Systems, Building SWA-112, PO Box 80002, 5600 JB Eindhoven, The Netherlands (fax +31 40 2732113). Cost of the complete set is US$750, Disc 1 only is available for US$275, Disc 2 costs US$325, and the price of Disc 3 is US$300, plus shipping charges. Payment can be made by American Express credit card or by bank cheque. Current information is posted on the Philips web site.

Each disc contains multiple test points recorded on a dedicated track. Tracks are separated by gaps. Disc 1, RCD-BH.1, contains multi-point tracks for BLER, E32, burst error length, I11/Itop, I3/Itop, Itop, push pull, cross talk, radial contrast, and asymmetry. Stable errors are created by irregular pit patterns. Disc 2, RCD-RA.1, provides multi-point radial noise and radial acceleration values that are generated by deviated tracks. Disc 3, RCD-JT.1, supports multi-point correlation for jitter and effect length (length deviation) that are controlled by modulated pit and land patterns.

Disc 1 is accompanied by Philips test data that includes strip-chart plots for BLER, E32, and burst errors. One normal track from 00:00 to 01:30 is followed by five 01:30 BLER tracks from 01:30 to 13:30. Each of the five tracks contain 90 seconds of continuous errors with an E11 range of 30-200 per sec. and zero E21, E31, E12, E22, E32, and burst errors. Use these tracks for ten second average error tests. An additional four 00:58 BLER tracks extend from 13:30 to 17:58. Each contains three 2-4 second duration error bursts, E11 range 60-200 per sec., separated by 6-8 seconds of very low error rates. Use these tracks for one second average BLER and E11 tests with zero E21, E31, E12, E22, E32, and burst errors. Ten second averages are not valid on these tracks.

Disc 1 also contains three 01:00 E32 tracks from 17:58 to 20:00 that have an E32 range of 1-25 per sec. Each track has three 2-4 second E32 bursts separated by 6-8 seconds of very low error rates. These tracks provide accurate one second average E32 error rates with zero E22 and burst errors. Ten second average values are not valid on these tracks. Five 01:00 burst length tracks extend from 17:58 to 25:58. Each contains three 2-4 second burst errors with burst lengths of 4-7 frames containing two error bytes per frame, separated by 6-8 seconds of very low error rates. Use these tracks for one second burst length measurements with zero E22 and E32. The fifth track has only one error per frame for five consecutive frames, and should not indicate a five frame burst length.

Disc 1 ends with one normal track from 25:58 to 27:00 followed by ten 02:00 tracks from 27:00 to 57:00. These ten tracks provide an I11/Itop range of 0.45-0.85, an I3/Itop range of 0.25-0.60, a push pull circular range of 0.035-0.068, a push pull parallel range of 0.045-0.070, a cross talk range of 0.3-0.7, a radial contrast range of 0.15-0.50, an asymmetry range from -20% to +11%, and an Itop range from 73% to 80%.

Disc 2 is accompanied by complete data including strip-chart BLER, E22, E32, and burst values. One normal track from 00:00 to 00:58 is followed by one 01:00 inter-track cross-talk signal from 00:58 to 01:58 that contains two 24 second bursts of 20 nm/1 kHz and 40 nm/4 kHz radial noise separated by 6 seconds of low noise. Thirty 01:00 radial noise tracks extend from 01:58 to 31:58. Each track has 58 seconds of quasi-continuous radial noise having an amplitude range of 10-40 nm covering a frequency range of 0.5-10 kHz. Each 58 second region consists of three parts separated by five seconds. The first part contains 108 msec. regions of radial noise separated by 240 ms. The second part contains 20 msec. regions of radial noise separated by four seconds. The third part contains 2 msec. regions of radial noise separated by four seconds. Radial noise test results should agree with the theoretical values provided by Philips within the test bandwidth specified by the standards.

Disc 2 also contains eight 00:30-01:00 radial noise tracks from 31:58 to 36:58, each with FM bursts of radial noise, amplitude range 10-40 nm, sweep ranges 0.8-1.4 kHz and 1.0-5.0 kHz. Radial noise test results should be the same as the theoretical values provided by Philips within the test bandwidth specified by the standards. Twelve 00:15 radial noise tracks from 36:58 to 39:58, each with three one-period (one-cycle) bursts of radial noise, amplitude range 5-45 nm, frequency range 0.5-10 kHz, are separated by about four seconds. Radial noise test results should be the same as the theoretical values provided by Philips within the test bandwidth specified by the standards.

Disc 2 has one normal track from 39:58 to 40:30 is followed by fifteen 01:00-01:30 radial acceleration tracks from 40:30 to 57:30 having an amplitude range of 0.1-0.8 m/s/s and a frequency range of 80-500 Hz. Radial acceleration is present in bursts separated by approximately one second. The highest amplitude bursts may cause loss of lock in the radial tracking loop and associated data errors. Disc 2 ends with one normal track from 57:30 to 58:30.

Disc 3 contains one normal track from 00:00 to 02:00 followed by 03:00 jitter tracks from 02:00 to 14:00 having pit and land jitter ranges of 20-50 ns. One normal track from 14:00 to 17:00 is followed by thirty-six 01:00 effect length tracks from 17:00 to 53:00 having effect length (length deviation) values from -60 ns to +60 ns. Disc 3 ends with one normal track from 53:00 to 56:00.

Equipment manufacturers should support their testers, but you are responsible for initial acceptance testing and for ongoing calibration and maintenance. Media Sciences can provide test data for correlation purposes using our equipment that closely agrees with results of Philips. The 5B and RCD discs from Philips can be supplemented by training available either from your equipment manufacturer or from Media Sciences. All necessary tools are in place for you to fulfill your responsibilities.