Laryngectomised people (LP) have many problems with speaking in terms of intelligibility, volume and effort it takes. This thesis describes the design and simulation of a voice enhancement device which will improve the speech of LP with respect to intelligibility and volume. It only describes the chosen hardware peripherals in order to record, process, amplify, and output the modified speech.
The recorded audio could be processed using a digital signal processor (DSP) that could be programmed such that it will filter the undesired noise and shift the pitch of the speaker's voice in real-time.
This thesis focuses on the real-time pitch shifting of the voice, the hardware choices and implementation of the sound output of the system, and the implementation of DSP of the Tracheo-Esophageal Speech Signal Amplifier (TESSA).
The real-time pitch shifting makes use of the Ocean algorithm, of which the principle is described, implemented and tested. Intelligibility tests are performed in order to find the optimal shifting parameters.

Many countries in the world face the problem of fruit frost during spring, which results in the loss of harvested crops. Solutions exist to prevent the fruit to freeze, however this requires that the temperature is known. Therefore, a smart autonomous temperature sensor network is designed that is capable of acquiring a 3D temperature profile of a fruit orchard to detect fruit frost. This thesis discusses the design of the energy harvesting and control module, which is one of the three sub-modules of the system. The goal is to sustain the energy demands of the sensor in a durable way, in order to operate for 20 years without requiring maintenance. To achieve this, several ambient energy sources and their harvesting techniques are investigated and simulated to examine the energy that can be harvested. This resulted in the use of solar energy, harvested by a solar cell and controlled by a maximum power point tracking module. Next, different energy storage implementations are considered to store the harvested energy temporarily. The use of a 5 F supercapacitor is concluded. Furthermore, an energy monitoring circuit is designed to measure the energy stored in the supercapacitor. Full system reliability simulations are done to verify the complete design by utilising the solar irradiance and temperature data of the past ten years. From these simulations is concluded that the design can sustain the energy demands of the sensor at all times.

Fruit-frost during spring is one of the main causes of damage to the harvest of fruit in orchards. Various systems using different methods of preventing spring-frost are available on the market. To determine when these systems should be activated, the temperature in the orchard needs to be determined. In this project, a self-sustaining autonomous temperature sensor network is designed, which is capable of making a 3D temperature map of the orchard. The system is used to warn farmers when the threat of fruit-frost occurs and to gather data on the spatial variation of the temperature in the orchard. In this thesis, the focus is put on designing the smart measurement and control system. This includes choosing an appropriate control unit and temperature sensors. Also, the software for the control unit is designed, which allows for a smart measurement scheme that balances energy usage and measurement frequency. Finally, an estimation of the energy usage of the subsystem is given based on theoretical analysis.

In this thesis, the design and implementation of a wireless communication module and an accompanying network are discussed. This wireless communication module is used in a device which communicates frost temperatures measured at orchards. The goal is to gather data on how fruit frost develops on orchards, and to warn a fruit farmer if it starts freezing. First, several wireless communication protocols are discussed and the one best suited for the application is chosen. It is decided to use the LoRaWAN communication protocol. Then, the off-the-shelf hardware components which are required to implement the LoRaWAN communication protocol are chosen. Furthermore, LoRa communication parameters and the LoRaWAN network structure are discussed. A scheduling system is designed and proposed to increase the reliability of the network. At last, network simulations are performed to verify the chosen implementation.

Every year an unfortunate part of the population lose their larynx, often due to the consequences of cancer. The laryngectomy removes the possibility to speak. Fortunately several speech reinstatement techniques have been found. However, all current speech reinstatement techniques do not produce a lot of volume. As a result the laryngectomised person will have difficulties speaking in busy environments, up to the point were the condition can lead to isolation because of the inability to communicate. Moreover with the current methods it costs a lot of energy to speak, the produced speech is less stable and the fundamental frequency has become lower. In this thesis a device is designed to improve the speech produced by a laryngectomised person realtime. The speech is recorded with an electret microphone. The resulting signal is prepared to be quantified to then be processed by a digital signal processing unit. Then the signal is adaptively filtered using the dynamically determined fundamental frequency. By tracking the fundamental frequency some instability from the voice is removed. The fundamental frequency will be determined using the cepstrum, a technique separating the fundamental regency of a voice from the high frequency components added by the oral and nasal cavities during speech. In another thesis a system is designed to amplify the signal to make sure that speaking takes less energy \cite{shiftgroep}. Furthermore a suitable power source is determined for the system. As the system is designed for Tracheo-Esophageal Speech Signal Amplification, the system will be referred to as TESSA.