The number of applications of low-power wide-area networs (LPWANs) has been growing quite considerably in the past few years and so has the number of protocol stacks. Despite this fact, there's still no fully open LPWAN protocol stack available to the public, which limits the flexibility and ease-of-integration of the existing ones. The closest to being fully open is LoRa, however only its medium acess control (MAC) layer, know as LoRaWAN, is open and its physical and logical link control layers, also known as LoRa PHY, are still only partially understood. In this thesis, the essential missing aspects of LoRa PHY are not only reverse-engineered, but also a new design of the transceiver and its sub-components is proposed and implemented in a modular and flexible way using GNU Radio.