V. Braun et al., ON THE APPLICATION OF SEQUENCE ESTIMATION ALGORITHMS IN THE DIGITAL COMPACT CASSETTE (DCC), IEEE transactions on consumer electronics, 40(4), 1994, pp. 992-998
In the current Digital Compact Cassette (DCC) recorder, a straightforw
ard threshold detection scheme is applied which does not exploit the d
istance properties of the 8-to-10 modulation (ETM) code. More advanced
detection schemes are investigated to see if they Improve system perf
ormance. Two soft decision sequence estimation algorithms are consider
ed: a fully-fledged Viterbi algorithm realizing Maximum Likelihood Seq
uence Estimation (MLSE) and a suboptimal trellis detection algorithm.
With either of the algorithms, an asymptotic gain of 3 dB versus thres
hold detection level in the presence of additive white Gaussian noise
(AWGN) is expected. The suboptimal detection algorithm is based on the
sunning Digital Sum (RDS) trellis underlying the ETM code. Performing
the suboptimal algorithm requires a minimum of 48 additions, 19 compa
risons, and a single table look-up for both detection and decoding of
an ETM codeword, versus a minimum of 4234 additions, 421 comparisons,
and 423 table look-ups for the fully-hedged algorithm. Compared to the
fully-hedged scheme, the suboptimal algorithm leads to a large reduct
ion in computational complexity. The performance of either of the algo
rithms in the presence of AWGN is determined by means of a computer si
mulation, The fully-fledged Viterbi algorithm achieves a gain of about
2.3 dB versus threshold detection level for symbol error rates in the
order of 10(-4)...10(-5) In this range of the symbol error rate, the
suboptimal algorithm shows a loss of less than a quarter of a dB compa
red to the fully-fledged scheme. The suboptimal trellis detection algo
rithm thus results in only a slight degradation in error late performa
nce compared to the fully-Hedged scheme. The examination of experiment
al data showed the feasibility of both sequence estimation algorithms
on the auxiliary data track of the DCC system.