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.

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.