This is true for three out of the four discs that had BLER above 200. A closer look at the E32 error, which means an uncorrectable error, is in the following table. Discs 57 and 64 had acceptable BLER levels, but exhibited E32 errors. For Disc 57, the pit jitters were out of specification and for disc 64 both the land and pit jitters was out of specification. There are many other parameters to investigate, but is out of the scope of this short paper.
Reflectivity is a critical factor and varies by types of substrates and reflective layers.
Noise is also an important key parameters that will be later investigated. The monitoring and investigation of the CD collection will be an ongoing, low level, low priority, and low budget operation. Eventually, the entire collection should be monitored, not just a small sample. First of all, it is probably desirable to increase the size of the sample, since certain assumptions were made to come up with a small sample size of only 125 discs as the first effort. The size should be increased to 1000 discs, for starts.