Sharp RX-P1H Technisches Handbuch Seite 20

RX-P1H
®
2. DAT ERROR CORRECTION
The reason why sound is outputted even when one of
heads is inoperative
R-DAT error correction is completed within one track. As shown
in Fig. 2-1(a), the PCM data is divided into odd and even number
groups and distributed to the tracks for A head and tracks for B
head. That is, the sampled data, as shown in Fig. 2-1(b), is
formated so that data is read alternately by the A head and B
head. Consequently, even when the B head is disabled as shown
in Fig. 2-1(c), approximately corrected data is obtained by the
average interpolation (namely adjacent two data are summed,
and the sum is divided by 2) if data located alternately are valid.
Therefore R-DAT can output sound even when one of heads is
disabled. As shown in Fig. 2-1(a), even number data (of L and
R) and the odd number data are recorded at lower and upper
sides of tape, respectively. Therefore even when data in the half
of widthwise area of tape cannot be read owing to the reason
mentioned above, error correction is possible.
INTERLEAVE FORMAT
<— TAPE TRAVEL DIRECTION
TOW TRACKS
ARE PAIRED.
+AZIMUTH
TRACK
(FOR A HEAD)
LEVEL
€c) WHEN B HEAD IS INOPERATIVE TIME
Drop-out correcting capacity
CD employs the CIRC (Cross Interleave Reed-Solomon code)
error correction system, whereas R-DAT adopts the double
Reed-Solomon code system where two tracks are interleaved.
Therefore even when in 16-bit mode the tape is damaged by
scratch and longitudinal continuous drop-out appears, as shown
in Fig. 2-2(a), correction (complete correction) is possible,
covering 22 blocks, 792 symbols, or tape width of 0.29 mm, and
approximate correction is possible for 74 blocks, 2,664 symbols,
and tape width of 0.99 mm.
Upon occurrence of widthwise continuous drop-out complete
correction (tape width up to about 2.6 mm) and approximate
correction (tape width up to 8.8 mm) are possible.(See Fig.2-2(b))
When drop-out exceeding these correction ranges occurs,
noise occurs, or sound is interrupted by muting.
LEVEL
€b) NORMAL STATE TIME
LEVEL
(ad) WHEN B HEAD IS INOPERATIVE TIME
(AFTER AVERAGE INTERPOLATION)
Figure 2-1 Interleave and its effect
INTERPOLATION AREA
Ve oe CORRECT ION)
]
LALO,
TR \
— | SEP E AE
0. 99mm
TAPE TRAVEL
DIRECTION
€a) CONTINUOUS DROP-OUT IN
LONGITUDINAL DIRECTION
8. 8mm
INTERPOLATION AREA
CAPPROX IMATE CORRECTION)
CORRECTABLE AREA
TAPE TRAVEL
CCOMPLATE CORRECTION)
DIRECTION
(b) CONTINUOUS DROP-OUT IN
LATERAL DIRECTION
Figure 2-2 Error correction capacity of R-DAT
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