ABSTRACT
The Canadian Advanced Digital Ionosonde (CADI) is used to study and investigate the structure and motion o f the ionosphere.
The main components of CADI are implemented in microcontroller based digital logic. Due to the increased speed and reconfiguration capability of modem FPGAs (Field Programmable Gate Arrays) and ADCs (Analog-Digital Converters), this project is aimed to develop an ionosonde based on an open source radio software platform, GNU Radio, in conjunction with its hardware support, the Universal Software Radio Peripheral (USRP). The lowest cost FPGA, Cyclone EP1C12Q240C8 is selected to control Analog Digital Converter to transmit a HF (High Frequency) signal and to decimate and down convert the signal at the receiver side, which is controlled by a USB controller, and to load the FPGA configuration image through GNU radio platform. To obtain a good range resolution and low noise level, the signal is modulated by a 113-bit Legendre sequence with a preamble packed at front for synchronization. Based on the experimental results, the discussion and conclusion are included
