This thesis explores the integration of (Frequency Shift) Chirp Spread Spectrum Modulation (FSCSSM) in Body Coupled Communication (BCC) using the Galvanic Coupling (GC) method. The goal is to provide a method of private communication in a noisy channel for devices in and around the human body. Various parameters, including frequency, electrode dimensions, electrode inter-distances, and noise levels, are evaluated. Results demonstrate that FSCSSM allows reliable communication in highly noisy channels, achieving a data rate of 9.6 kbps at a Signal-to-Noise Ratio (SNR) of -9dB. The impact of body composition is highlighted, showing its significance in single-body communication. The communication in single-body is extended by evaluating body-to-body communication, enabled by touch, as well. This research provides valuable insights for designing robust BCC-FSCSSM systems.

This thesis report focuses on possible methods of digital implementation of motional feedback in a bass loudspeaker. In this thesis, the control system will be created for a monopole and a dipole speaker specifically. It does so by sketching the outlines of such a system and examining possible designs for the components required to suppress distortion which is mainly created by the speaker. This thesis shows that the digital implementation indeed allows filtering with very little latency but there are limitations in accuracy due to the conversion from the analogue to the digital domain. It is shown in this thesis that a partly analogue and partly digital system is desired for better error correction. A desired input-output gain of 30=29.54dB is achieved. The controller that is suggested is a controller based on the transfer function of the speaker. By transforming the input signal with the inverse of this open-loop transfer, the closed-loop transfer will be flattened. The instrumentation amplifier used to subtract the feedback signal from the input signal is designed such that the influence of the quantization noise is minimized. Loop-gain is added by the instrumentation amplifier, the controller and voltage-to-current amplifier. By creating loop-gain as much as possible using the digital implementation, noise is suppressed from 30dB up to 90dB within the range of frequencies of interest. The designed components in the motional feedback system allow a loop-gain up to 70dB and an input to output voltage gain of 30dB before instability occurs.