Common error of an audio CD-Player is, that the drive not recognise CDs or several tracks won´t play-back.
The quality of every laser in a CD-Player gets worse with the uptime of the device.
With the LASER-CD not only seasoned technicians can check and adjust CD-Players, everybody can use this disc to check and adjust the laser of a CD-Player
Special test signals in the actual information track and on the surface of the LASER-CD act as reference from 0 to 3 mm width. You can directly choose the according references on the disc like tracks on a Audio-CD. The LASER-CD contains 30 different Tracks (from 0 to 3mm).
With the increasing width of the test signal, you can check every CD-Player and for sure adjsuted the laser device.
With an oscilloscope the eye pattern is visible and you can adjust the laser.
Please see the manual for further informations.
Laser CD Booklett
Pioneer CD-Player Adjustment
Sharp CD-Player Adjustment
BUROSCH Audio-Video-Technik has developed an Test-CD to check the quality of in error corrections, built-in to the CD-Player devices. For the realisation of these Test-CD extensive mathematical research was necessary. Now we can assure, that every measurement sector (or track) on the disc is about a specific coefficient widther then the track before.
This means, with increasing track number the error area gets widther, like you can see on the picture above. The widther error area attends to a longer runtime of the simulated error and so the error correction of the device has to do more work.
The first track doesn´t include any errors. The second track includes an error area with a width of 0,1 mm and so on...
To evaluate the error-width (in mm) for a given track you can use this formula:
F/mm = 0.1 + (S-1) x 4.4/29, F is the error-width in mm and S the number of the according track.
This Test-CD gives you the big advantage, to check every CD-Player, even if the result isn´t an absolute result in the form of a common numerical value with a common physic unit.
The error correction works like explained below.
After an error detection, the CD-Player device copies the data into a buffer and interpolate the missing data. This cause an observable delay and sometimes even artifacts and mosaics can be visible or hearable. After the error correction (interpolation) the data stream will further play back. The CD-Player will play the data from the buffer and copy new data from the disc into the buffer. The buffer level has to stay constant all the time. If a new error appear, the CD-Player will play-back the data stream new data maybe won´t be copied (or only very slowly) into the buffer. So again a delay, mosaics and artifacts will appear, while the device tries to interpolate the missing data.
For a good error handling, the laser (reading the signal form the disc) and the buffer have to work together very accurate and with a good timing.
You can check the cooperation between the laser and the buffer easily with the Burosch LASER-Disc.
With the LASER-Disc you can easily evaluate the interpolation quality of the built-in error detection. The main quality criterion of the built-in error detection is the buffer size, because the buffer has to be big enough to save the variable data stream and it has to work well with all the possible different transfer rates for CDs.
To challenge the built-in error detection of a CD-Player device the LASER-Disc use the maximum data rate 9,8 Mbit/s.
This product is also available as a DVD to check the error correction of DVD-Players. Just contact us to get further informations about the LASER-DVD.
