| 摘要 |
<p>A DVB-T receiver includes a channel equaliser (110), a metric assignment and demapping circuit (112), an inner interleaver (122), a Viterbi decoder (124), an outer interleaver (126) and an outer or Reed-Solomon decoder (128). The metric assignment and demapping circuit (112) includes a soft-decision quantising arrangement (224, 226) which provides confidence values for the Viterbi decoder. The quantising arrangement receives a control input from channel state indication (CSI) measurement circuitry (240, 260, 280). In such an arrangement, measures are included to improve operation in the presence of impulsive interference: (i) A further channel state indication is obtained on a symbol-by-symbol basis (240,302). This is compared (318) with an average obtained (316) over a few symbols, to detect impulsive interference, and applied (320, 294) as part of the control for the soft-decision quantiser. (ii) Erasures information is provided from the Viterbi decoder (124) to an erasures input of the Reed-Solomon decoder (128). (iii) The erasures information from the Viterbi decoder (124) is dependent upon the error rate over a small number of bytes. (iv) A signal derived from the further channel state indication is also applied to the erasures input of the Reed-Solomon decoder (128). (v) To assist the operation deeper symbol deinterleaving is used in the outer deinterleaver (126), over a block of size of e.g. four symbols. <IMAGE></p> |
