{'fraction_non_alphanumeric': 0.01743406347787215, 'fraction_numerical': 0.007599463567277604, 'mean_word_length': 5.081521739130435, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Error control for data communication

Why Error Control? The data communication system designer, who must weigh the advantages of error control against its costs, will form a decision based on the nature and quality of the channel and of the other terminal equipment already present. Yet with the dramatic improvement in error control techniques and greater reliance on satellite and terrestrial microwave links for broadband data transmission, decisions in favor of error control are becoming ever more frequent. For satellite communication channels the most effective forward error correction techniques can reduce the received signal-to-noise required for a given desired bit error rate by 5 to 6 dB, or more, compared to a system without error control. This translates directly into an equivalent reduction in required satellite effective radiated power, with consequently reduced satellite weight and potentially remarkable reductions in satellite booster costs. For a satellite system with many ground stations an even greater cost savings may be possible by reducing the receiving antenna area by a factor of 4 which is compensated for by the error control savings of 6 dB. The cost of error control is twofold: the equipment which may be more than compensated by savings which it makes possible in other terminal equipment; and the redundancy required by the error control code. This redundancy need not, however, reduce throughput if additional bandwidth is available on the channel. Satellite channels, in particular, are often not nearly as much bandwidth limited as they are power limited. An error control technique which employs a rate 1/2 code (100% redundancy) will require double the bandwidth of an uncoded system; on the other hand if a rate 3/4 code is used, the redundancy is 33% and the bandwidth expansion only 4/3. Terrestrial channels such as microwave links, HF and tropospheric propagation links can also be improved by error control techniques. For these channels which are subject to fading and multipath phenomena, the errors tend to occur in bursts, and thus corrupt long strings of data, rather than as single randomly distributed bit errors. A very effective error control technique for these channels 27