A Software Defined Radio Experimental Platform for GPS/GNSS Signal Reception Analysis

GPS is becoming a crucial element in daily life and in global information infrastructure. GPS nowadays is becoming more reliable thanks to the technology of A-GPS and D-GPS which uses the Internet and cellular network to enhance the accuracy. However, there is still plenty of room for improvement in the GPS operations. A versatile experimental platform that allows researchers to directly receive raw data from satellites is critical to advance further research. We use a software defined radio (USRP) platform with open source GNSS software to perform the related experiments. We choose the USRP N200 as the software defined radio (SDR) for our work, because of its very good signal processing performance at an affordable price. Unlike mobile phones, or even most GPS chip evaluation kits. The GPS data received from USRP can be utilized to compute pseudo ranges based different satellites. And the pseudo range can be valuable when analyzing the accuracy of computing the locations. With the open source software, the users can easily access and customize their own software development to target the specific application. We built a portable experimental environment based the USRP to carry out field tests at various locations. Two additional limitations of GPS chip evaluation kits are their low quality clocks, and very limited computing resources for more sophisticated experiments. This thesis will talk about this portable software platform and the project which was conducted on it to explore and investigate some crucial problems existing in today’s GNSS technology, for example, multipath problem and hybrid GNSS system problem. By investigating into these problems using SDR GNSS receiver, the benefits of adopting this software oriented approach will be talked about and how this approach in the future can save valuable research and experiment time will also be demonstrated

Software Defined Radio Implementation of Carrier and Timing Synchronization for Distributed Arrays

The communication range of wireless networks can be greatly improved by using distributed beamforming from a set of independent radio nodes. One of the key challenges in establishing a beamformed communication link from separate radios is achieving carrier frequency and sample timing synchronization. This paper describes an implementation that addresses both carrier frequency and sample timing synchronization simultaneously using RF signaling between designated master and slave nodes. By using a pilot signal transmitted by the master node, each slave estimates and tracks the frequency and timing offset and digitally compensates for them. A real-time implementation of the proposed system was developed in GNU Radio and tested with Ettus USRP N210 software defined radios. The measurements show that the distributed array can reach a residual frequency error of 5 Hz and a residual timing offset of 1/16 the sample duration for 70 percent of the time. This performance enables distributed beamforming for range extension applications.Comment: Submitted to 2019 IEEE Aerospace Conferenc

Studies in Software-Defined Radio System Implementation

Over the past decade, software-defined radios (SDRs) have an increasingly prevalent aspect of wireless communication systems. Different than traditional hardware radios which implement radio protocols using static electrical circuit, SDRs implement significant aspects of physical radio protocol using software programs running on a host processor. Because they use software to implement most of the radio functionality, SDRs are much more easily modified, edited, and upgraded than their hardware-defined counterparts. Consequently, researchers and developers have been developing previously hardware-defined radio systems within software. Thus, communication standards can be tested under different conditions or swapped out entirely by simply changing some code. Additionally, developers hope to implement more advanced functionality with SDRs such as cognitive radios that can sense the conditions of the environment and change parameters or protocol accordingly. This paper will outline the major aspects of SDRs including their explanation, advantages, and architecture. As SDRs have become more commonplace, many companies and organizations have developed hardware front-ends and software packages to help develop software radios. The most prominent hardware front-ends to date have been the USRP hardware boards. Additionally, many software packages exist for SDR development, including the open source GNU Radio and OSSIE and the closed source Simulink and Labview SDR packages. Using these development tools, researchers have developed many of the most relevant radio standards. This paper will explain the major hardware and software development tools for creating SDRs, and it will explain some of the most important SDR projects that have been implemented to date

A Multi-Purpose Aerial Software Defined Radio Platform

This project focuses on incorporating two new technologies, drones and software defined radios, to detect and localize relevant wireless signals with increased maneuverability. The objective lies in building a platform for wireless signal mapping for search and rescue purposes. The platform prototype will be a baseline for future development through the recommendations provided in this report

Development of a Nanosatellite Software Defined Radio Communications System

Communications systems designed with application-specific integrated circuit (ASIC) technology suffer from one very significant disadvantage - the integrated circuits do not possess the ability of programmability. However, Software Defined Radio’s (SDR’s) integrated with Field Programmable Gate Arrays (FPGA) provide an opportunity to update the communication system on nanosatellites (which are physically difficult to access) due to their capability of performing signal processing in software. SDR signal processing is performed in software on reprogrammable elements such as FPGA’s. Applying this technique to nanosatellite communications systems will optimize the operations of the hardware, and increase the flexibility of the system. In this research a transceiver algorithm for a nanosatellite software defined radio communications is designed. The developed design is capable of modulation of data to transmit information and demodulation of data to receive information. The transceiver algorithm also works at different baud rates. The design implementation was successfully tested with FPGA-based hardware to demonstrate feasibility of the transceiver design with a hardware platform suitable for SDR implementation