NEC ND-3500A Recorder - Page 4

DVD Error Correction Tests

In the following tests we examined the DVD reading capabilities of the NEC ND-3500A drive with scratched / defective DVD media. For the tests, we used CDVD Benchmark and Nero CDSpeed . The reference test media comes from ALMEDIO.

- Single Layer media

ABEX TDR-821

This is a single sided, single layer DVD-ROM with a 4.7GB capacity, and its surface has an artificial scratch of dimensions varying from 0.4 to 3.0 mm.

The following transfer rate picture comes from the CDVD Benchmark v1.21 transfer rate test.

The ND-3500A needed to lower its speed to read over the scratched area. However, no errors were reported, and the maximum 16X reading speed was achieved near the end of the reading process.

ABEX TDR-825

This is also a single sided, single layer DVD-ROM of 4.7GB capacity. The data structure of the disc is exactly the same as that of the TDR-821, with the difference that there are no scratches on it but instead, defective areas of dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized from 65 to 75 micrometers.

The ND-3500A read this disc as if there were no defects and fingerprints at all. A continuous line was produced, and the drive once again reached its highest 16X reading speed.

- Dual Layer media

ABEX TDR-841

This is an 8.5GB dual layer, single sided DVD-ROM disc with artificial scratches of dimensions ranging from 0.4 to 3.0mm, on both layers.

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Most NEC based drives have problems reading this type of disc. As seen above, the NEC has improved DVD error correction capabilities over former drives. The ND-3500A gave no errors during reading. The test was completed successfully. Excellent performance at this point!

ABEX TDR-845

The disc is a single sided, dual layer DVD-ROM disc with a capacity of 8.5GB. The only difference between the TDR-845 and the TDR-841 is that the first includes defective areas and fingerprints. The dimensions of the defective areas range from 0.5 to 1.1 mm and the fingerprints are sized from 65 to 75 micrometers.

Again, the drive had no problems reading this disc.

ABEX TDV-541

The TDV-541 is a single sided, dual layer DVD-VIDEO disc, with a capacity of 8.5GB. The disc is based on the TDV-540 series which is designed for inspection and adjustment of DVD-VIDEO players. The disc checks the layer switch operation from layer 0 to layer 1 and also includes test pictures and test signals for DVD sound files.

The current TDV-541 also checks the error correcting capabilities of the drive and includes scratches from 0.4 to 3.0 mm.

According to this reading behavior, the drive could read the disc with no problems. It started to read at a speed of 1.92X, reached a highest reading speed of 4.61X at the end of the first layer, lowered the reading speed just after the start of the second layer and produced an average speed of 3.24X (similar results were reported by the TDK 1616N, as would be expected).

ABEX TDV-545

The TDV-545 disc is based on the TDV-540 series. It is a single sided, dual layer DVD-VIDEO disc with a capacity of 8.5GB. The TDV-545 includes artificial black dots on the data surface, sized from 0.4 to 1.0 mm. It has also 65 - 75 micro meter fingerprints.

Not even this disc was a problem for the ND-3500A model.

- Summary

NEC drives were known to be bad readers, and their DVD error correction capabilities were limited. We were happy to see that NEC improved DVD error correction with their new ND-3500A, making it a very good reader for problematic media.