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Home > Hardware Reviews > Optical Storage

Friday, July 06, 2007
Blu-Ray Writing Quality Tests

5. Measurements - LG GBW-H10N 2x & Memorex BD-R

Pass 1 : Discs out of the box

The Memorex BD-R disc was tested as is. It is very likely that dust particles and signs of handling such as minor scratches and fingerprints are present. Note, that no defects, scratches, fingerprints, etc., were caused on purpose, but were due (if present), to the normal handling of the disc during our burning and testing process.

Blu-Ray burner LG GBW-H10N vGL02

Memorex BD-R 25GB

Media ID
MEI (001)
Writing speed

2x CLV

- Measurements

Digital errors (BEL, UNC, RSER)

Both Burst Error Length (BEL) and UNC (Uncorrectable) signals produced a spike at around the 47mm radius on the disc's surface. The specific issue is attributed to a possible defect on the disc surface. The average BEL is low, but there are points which rise to slightly higher than the specification limit for a Blu-Ray disc, which is less than 600 bytes.

The Random Error Symbol Rate (RSER) signal is beyond the limits for the complete area of the disc. The limit for this signal, which is calculated over 10,000 LDC blocks (see page with definitions), is set to 2 x 10-4. Such errors can be caused by optical defects that interfere with the data read-out procedure.


Both JFli and JRli signals exceed the limits (6.5%).

Reflectivity modulation

The I8/I8H signal actually shows information about the shape of the pits, and a value lower than the specified limit, could lead to digital errors and jitter.


Reflectivity is generally good and stable over the disc .

Servo & Tracking parameters - RADIAL2

As in the case with CD and DVD, RADIAL2 indicates whether the head of a reader loses track due to extreme displacement of the track in the radial direction. In our case, the signal stayed below the 6.4nm limit.

Summary of signals

The diagram on the left, could be very useful in providing a view of the condition of a disc at a glance.

Each signal indicated in red has exceeded the Blu-Ray Disc limits.

The summary of the signals indicate that the Burst Error Count (BEC) is low. However, the BE L signal is high, and the existence of uncorrectable digital errors ( UNC) could be puzzling. The high UNC signal was reported at a specific disc position, and it should be attributed to a local defect as we previously mentioned.

The specific disc was readable by Blu-Ray players.


Pass 2 : Disc cleaned

The specific disc was cleaned using (professional) air spray and special tissues. The disc was measured again, and the results are given below.

Digital errors

All signals

Cleaning the disc surface completely changed the picture of the quality of the disc. The maximum BEL signal fell from 5148 to 849, while the Uncorrectable errors dramatically decreased to just 8. The disc was readable.

The results underline the importance of keeping your Blu-Ray discs in perfect condition, away from dust and defect free. The nature of the Blu-Ray Disc format (NA 0.85) makes the read-out process a very delicate procedure, and the existence of any kind of particles on the disc's surface could make your disc unreliable.

Rest of the measurements:

Jitter - JFli, JRLi
Reflectivity - I8/I8H
Reflectivity Modulation R8H, R8Hrv

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