Again the unit of accountability is the frame often

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Unformatted text preview: h as SEC) cause reduced performance on undetected errors, and vice versa. Therefore an acceptable balance must be found between these two objectives. Reference [8] shows that the required undetected error performance will be met by the prescribed system using either TED or SEC decoding in a channel operating at a BER of 10-5 without extra precautions. However, if a greater margin of safety against undetected errors is desired, the cyclic redundancy code specified in Reference [8] may be added to each frame. For an overhead of 16 bits per frame and the same channel BER of 10-5, this will provide an undetected frame error rate of 10-19 when using SEC decoding; with TED decoding, the performance is better. Figure D-7 shows curves comparing undetected error performance (with and without the added CRC) as a function of number of codeblocks in a frame for channel BER of 10-5. These curves are from Reference [8]. Issue 6 Page D-23 January 1987 CCSDS REPORT CONCERNING TELECOMMAND: SUMMARY OF CONCEPT AND SERVICE 10 -09 (SEC DECODING) PROBABILITY OF UNDETECTED FRAME ERROR 10 -10 10 -11 BCH CODEBLOCKS ALONE 10 -14 10 -15 (TED DECODING) 10 -16 10 -19 10 -20 BCH CODEBLOCKS CONCATENATED WITH FRAME CRC (SEC DECODING) 10 -21 10 -22 0 10 20 30 40 50 60 NUMBER OF CODEBLOCKS PER FRAME Figure D-7: Undetected Error Performance, With and Without Cyclic Redundancy Code END OF DOCUMENT. o Issue 6 Page D-24 January 1987...
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This document was uploaded on 03/06/2014.

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