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All the different data words a transmitter can send and a receiver can detect can be imagined as dots arranged in a large space. Selecting a data encoding for error detection and correction is about keeping valid code words at a certain distance from each other. As a result, a slight change ("movement") of a valid word doesn't make it look like ...


12

Though what's in the Voyager remains to be seen, the Performance Study of Viterbi Decoding as Related to Space Communications1 gives a description of such a system implemented on Earth for the ground station: It is not the prototype, it is the final version. The prototype may have required about 4 to 8 times the volume. Not a real monster, but filling a ...


3

Question: If the Voyagers' lowest playback speed is 7200 bits per second, how does it transmit to Earth at only 160 bps? It doesn't. The 160 bps transmission is real-time data rather than playback data. The playback data is rather infrequent and was at 1400 bps. (It may be at 600 bps now.) From https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--...


2

Question: Did the Voyager spacecraft use a Golay, a Reed-Solomon and/or a Hamming code for data transmission encoding for error correction? Yes! And there's a convolutional coder in there as well. From DESCANSO Design and Performance Summary Series, Voyager Telecommunications, (2002): The TMU [telemetry modulation unit] encodes the high rate data stream ...


1

The RS encoder is similar to Golay and Hamming encoders (shift-register based). For example, this resource gives a schematic diagram. In principle, it is as "simple" as binary encoders (check bits calculated from info bits). The main difference (and complication) is that additions and multiplications now operate on bytes (check bytes calculated ...


1

The Apollo Guidance Computer used a plus/minus sign and 5 decimal digits. This can be seen in the "List of Nouns Used in Program Colossus" of the AGC manual as well as the number of digits on the DSKY user interface: There are various data types used by the nouns. A table in the source file PINBALL_NOUN_TABLES.agc controls how each noun is ...


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