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Serial or parallel buses are widely used to communicate information in most electronic devices. The energy consumed by bus interconnects may comprise a significant portion of the overall energy consumption of the device. Hence, techniques to reduce the energy consumption of bus interconnects have become an important area of research. One common method adopted to reduce energy is Bus Encoding, where redundant bits are added to the original data stream either in time or space to reduce the energy consumption. In this thesis, a novel bus encoding technique, called the Multiple Codebook Approach (MCA), is presented to reduce the Energy-Delay-Product (EDP) and Energy for data transmission over serial buses. For any symbol that is to be transmitted on the bus, the best code is selected (from an EDP or energy minimization standpoint) from among a set of codebooks. In particular, the implementation utilizes 3 codebooks. To minimize EDP, the codeword for each symbol is selected based on the product of the number of transitions resulting from its transmission in a serial manner, and the codeword length. To minimize energy, the codeword for each symbol is selected based on the number of transitions alone. The MCA is compared with other reported techniques in the literature, and the results are quite promising. The MCA achieves a 11% improvement in EDP and 3% improvement iv in Energy over the best approach known for serial data transmission, which was reported by Macii and others.

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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / An artifact of QPSK modems is ambiguity of the recovered data. There are four variations of the output data for a given input data stream. All are equally probable. To resolve this ambiguity, the QPSK data streams can be differentially encoded before modulation and differentially decoded after demodulation. The encoder maps each input data pair to a phase angle change of the QPSK carrier. In the demodulator, the inverse is performed - each phase change of the input QPSK carrier is mapped to an output data pair. This paper discusses a very simple and unique differential encoder/decoder that handles all possible data pair/phase change permutations.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / The Space Ground Link Subsystem (SGLS) provides full duplex communications for commanding, tracking, telemetry and ranging between spacecraft and ground stations. The up-link command signal is an S-Band carrier phase modulated with the frequency shift keyed (FSK) command data. The command data format is a ternary (S, 1, 0) signal. Command data rates of 1, 2, and 10 Kbps are used. The method presented uses direct digital synthesis (DDS) to generate the SGLS command data and clock signals. The ternary command data and clock signals are input to the encoder, and an FSK subcarrier with an amplitude modulated clock is digitally generated. The command data rate determines the frequencies of the S, 1, 0 tones. DDS ensures that phase continuity will be maintained, and frequency stability will be determined by the microprocessor crystal accuracy. Frequency resolution can be maintained to within a few Hz from DC to over 2 MHZ. This allows for the generation of the 1 and 2 Kbps command data formats as well as the newer 10 Kbps format. Additional formats could be accommodated through software modifications. The use of digital technology provides for encoder self-testing and more comprehensive error reporting.

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the design considerations and methodology applied to solve the practical problems posed in the creation of a high bit rate telemetry relay system and specifically the techniques implemented to enhance signal to noise performance under adverse operational conditions.

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