We report on different addressing mechanisms for quasi-distributed absorption sensors based on the frequency modulated continuous wave (FMCW) method. The sensor units consist of open-path micro-optic cells constructed from GRIN lenses, each of differing lengths. Guided by initial simulations, two approaches are experimentally investigated and evaluated, namely reference arm addressing and coherence addressing. Reference arm addressing is accomplished by the selection of different length reference arms in a Michelson configuration where each reference arm corresponds to a certain sensing unit. Coherence addressing is achieved by the interferometric mixing of two signals originating from each cell (from the glass/air interfaces). For each method, we show theoretically and experimentally how individual cells can be addressed and the measured signals obtained by suitable choice of cell length, proper modulation of the source and appropriate signal processing. In order to improve sensitivity we present the theoretical analysis of a new scheme based on combining the (FMCW) technique with frequency modulation spectroscopy (FMS). Here we arrange for only one sideband of the rf-modulation to be attenuated by the absorption feature and a new signal, proportional to the absorbance, appears in the output spectrum at a frequency corresponding to the difference between the rf-modulation frequency and the beat frequency of a cell. The method is highly sensitive and applicable to a variety of chemical species with narrow absorption lines, such as in trace gas analysis. We present the mathematical analysis of the proposed method for single and multiple cell systems, using methane detection as an example.

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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / This paper describes the development and test results of a Frequency Modulated Continuous Wave (FMCW) L-Band radar testbed designed to detect obstacles in the proximity of an Unmanned Aerial Vehicle (UAV). From laboratory loopback tests, it was calculated that with pulse compression and a transmit power of 150 mW (22 dBm), the radar is capable of detecting an object with a 0.014-m2 radar cross-sectional area at ranges between 500 ft to 1 mi. Analysis shows that post processing of the collected data would reveal information about the obstacle such as its range and location relative to the aircraft. Design and testing procedures are discussed.

This thesis follows the design process of a back end. The purpose of this back end is to interface a radar front end, developed by Acreo Swedish ICT, and stream it’s digitalized output to a PC using Universal Serial Bus (USB) 3.0. The front end, which acts as a basis for this project, is a Frequency Modulated Continuous Wave (FMCW) radar which is connected to the back end by a header. The header connects the digitalized radar signals, together with two SPI-buses and a few GPIO pins. Thus, enabling configuration and set up of the front end board via a PC. The result of the thesis is a data acquisition board that can be used to interface with the front end. The implemented back end features an FPGA to handle the ADC data from the front end, so the board has DSP capabilities, but can also stream the raw radar data. The FPGA is connected to a USB 3.0 controller through a 32-bit parallel interface. The configuration of the front end, via the produced board, is verified in it’s functionality and can be controlled by a PC using a simple GUI. Commands are sent through the USB 3.0 controller to a front end controller which handles the communication. Since getting the hardware functional has been the main objective of the thesis, the project has been deemed to be successful. The final result is a back end radar prototype, which has the requested core hardware functionalities. In addition to this, the prototype has the capacity to act as a platform for further expanding its functionality after a hand over of the project to Acreo Swedish ICT.

A 50 MHz Frequency Modulated Continuous Wave (FMCW) radar system, developed at the University of Saskatchewan to provide improved spatial and temporal resolution measurements of auroral E-region plasma processes, introduces ambiguous spectral information, due to spectral ghosting, for scattering events in which multiple radar echoes are detected. This thesis identifies two Linearly Frequency Modulated (LFM) radar waveforms used by the FMCW system as the source of the ghosting. An analysis procedure designed to counteract the spectral ghosting problem is developed but is not an ideal solution, and therefore replacement of the LFM waveforms is recommended.<p> A detailed investigation of alternative radar waveforms using the Ambiguity Function and Ambiguity Diagram techniques is performed. A frequency coded continuous wave radar waveform based on a composite Costas sequence is proposed as a successor to the LFM waveforms. The composite Costas radar waveform will conserve the spatial and temporal resolutions extended by the LFM waveforms and preclude any spectral ghosting. Implementing the proposed radar waveform and avoiding receiver saturation issues with the mono-static FMCW radar system in which both the transmitting and receiving antenna arrays are simultaneously and continuously active and geographically co-located is also discussed.<p> In addition to this, two 50 MHz backscatter events are presented in this thesis to demonstrate the effectiveness of the FMCW system, notwithstanding the spectral ghosting complication. The first event from November 21, 2009 is identified as a Type 1 instability and the second from September 13, 2009 is identified as a Type 2 instability which lasted for ~ 16 minutes. Linear plasma fluid theory is used to provide a brief interpretation of both scattering events.

A 50 MHz Frequency Modulated Continuous Wave (FMCW) radar system, developed at the University of Saskatchewan to provide improved spatial and temporal resolution measurements of auroral E-region plasma processes, introduces ambiguous spectral information, due to spectral ghosting, for scattering events in which multiple radar echoes are detected. This thesis identifies two Linearly Frequency Modulated (LFM) radar waveforms used by the FMCW system as the source of the ghosting. An analysis procedure designed to counteract the spectral ghosting problem is developed but is not an ideal solution, and therefore replacement of the LFM waveforms is recommended.<p> A detailed investigation of alternative radar waveforms using the Ambiguity Function and Ambiguity Diagram techniques is performed. A frequency coded continuous wave radar waveform based on a composite Costas sequence is proposed as a successor to the LFM waveforms. The composite Costas radar waveform will conserve the spatial and temporal resolutions extended by the LFM waveforms and preclude any spectral ghosting. Implementing the proposed radar waveform and avoiding receiver saturation issues with the mono-static FMCW radar system in which both the transmitting and receiving antenna arrays are simultaneously and continuously active and geographically co-located is also discussed.<p> In addition to this, two 50 MHz backscatter events are presented in this thesis to demonstrate the effectiveness of the FMCW system, notwithstanding the spectral ghosting complication. The first event from November 21, 2009 is identified as a Type 1 instability and the second from September 13, 2009 is identified as a Type 2 instability which lasted for ~ 16 minutes. Linear plasma fluid theory is used to provide a brief interpretation of both scattering events.

With the population aging worldwide, new solutions for non-invasive health monitoring are required. Radar systems have been proposed as a promising technology for monitoring vital signs in ambient assisted living (AAL) applications. Monitoring vital signs such as breathing rate, heart rate, and pulse rate can provide crucial insights into human well-being and detect a wide range of medical problems. The main focus of mm-wave radar applications is currently geared towards the automotive market; however, several potential application areas within the broad industrial and healthcare domain are also under active investigation. Their major advantage is that, without the need for any cable or electrode, it is possible, at first, to locate the patient inside the room and, then, to measure their respiratory rate and heartbeat. A contactless detection method offers the simple and fast monitoring of vital signs without the disadvantages of current practices. One very promising approach is the use of radar technology. This thesis focuses on finding the safe way of using mm-Wave propagation in a hospital's real-world scenario and finding the safe range of frequency and power dissipation that won’t be harmful to the human body.  Objective: In this thesis, we investigate the optimum range of frequency and power of mm-Wave propagation, which can be considered safe for usage in an environment like hospitals. Also, the range of power with respect to the power density which can be considered safe for implementation in E-health systems.  Methods: Simulation is considered the method to find various range brackets for different parameters like frequencies, distances, bandwidths, and power. The simulation also helps to get a large number of results for a closer approximation. The received signal is observed to get the desired results, and using the available data, the ranges are found for safe usage of the forementioned technologies.  Results: The results obtained are tabulated to show the relation of received signal strength with all the other parameters like frequency, distance, and power. Then using the power and received signal relation, the safe range of power is calculated, which can be used in a closed environment like hospitals.

Inspection methods for satellites post-launch are currently expensive and/or dangerous. To address this, BYU, in conjunction with NASA, is designing a series of small satellites called CubeSATs. These small satellites are designed to be launched from a satellite and to visually inspect the launching body. The current satellite revision passively tumbles through space and is appropriately named the passive inspection cube satellite (PICS). The next revision actively maintains translation and rotation relative to the launching satellite and is named the translation, rotation inspection cube satellite (TRICS). One of the necessary sensors aboard this next revision is the means to detect distance. This work explores the feasibility of using a software defined radio as a small, low-cost front end for a ranging radar to fulfill this need. For this work, the LimeSDR-Mini is selected due to its low-cost, small form factor, full duplex operation, and open-source hardware/software. Additionally, due to the the channel characteristics of space, the linear frequency modulated continuous-wave (LFMCW) radar is selected as the radar architecture due to its ranging capabilities and simplicity. The LFMCW radar theory and simulation are presented. Two programming methods for the LimeSDR-Mini are considered: GNU Radio Companion and the pyLMS7002Soapy API. GNU Radio Companion is used for initial exploration of the LimeSDR-Mini and confirms its data streaming (RX and TX) and full duplex capabilities. The pyLMS7002Soapy API demonstrates further refined control over the LimeSDR-Mini while providing platform independence and deployability. This work concludes that the LimeSDR-Mini is capable of acting as the front end for a ranging radar aboard a small satellite provided the pyLMS7002Soapy API is used for configuration and control. GNU Radio Companion is not recommended as a programming platform for the LimeSDR-Mini and the pyLMS7002Soapy API requires further research to fine tune the SDR's performance.

Radar is an acronym for RAdio Detection And Ranging. In general terms, it is a machine that uses radio waves for object-detection in its near periphery. It transmits radio waves in a known direction, which when intercepted by an obstruction/object are reflected by its surface and are received back at the radar system. The round trip delay time along with the known velocity of radio waves gives an accurate measurement of the distance of the object from the radar system. In a somewhat similar fashion, some radars are even capable of measuring the velocity of this object. Frequency-modulated continuous-wave (FMCW) radar is one such radar system, which is a subclass of continuous wave (CW) radars, where a continuous sinusoidal radio energy is transmitted, reflected, and received back at the radar system. These radar systems are widely used in vehicle automation technologies such as adaptive cruise control (ACC) and collision avoidance systems (CAS) to measure the distance from the nearest vehicles and maintain a safe following distance. But in designing these systems, little attention has been given to security, and these systems have vulnerabilities that are capable of compromising the whole purpose of making such systems. In this work one such vulnerability in FMCW radar was exploited to design an attack that was capable of decreasing the apparent distance, as measured by a radar system. The attack was designed in such a way that there was no tampering with the radar system being attacked. Instead, false distance information was introduced in the return path of the transmitted radio wave by absorbing the original victim transmission and sending out a modified radio wave on the It was shown that the distance could be decreased to alarming values, which at the level of the vehicle automation system results in decreasing the speed of the automobile when actually it should have increased.

High cost is a current problem with modern radar systems. Software-defined radios (SDRs) offer a possible solution for low-cost customizable radar systems. An SDR is a radio communi- cation system where, instead of the traditional radio components implemented in hardware, many of the components are implemented in software on a computer or embedded system. Although SDRs were originally designed for wireless communication systems, the firmware of an SDR can be configured into a radar system. With new companies entering the market, various types of low- cost SDRs have emerged. This thesis explores the use of a LimeSDR-Mini in a short-range radar through open software tools and custom code. The LimeSDR-Mini is successfully shown to detect targets at a short range. However, due to the instability of the LimeSDR-Mini, the consistent detection of a target is not possible. This thesis shows how the LimeSDR is characterized and how timing synchronization and instability issues are mitigated. The LimeSDR-Mini falls short of operating reliable in a radar system and other SDR boards need to be explored as viable options. Test setups using coaxial cables and test setups using antennas in an outdoor environment show the instability of the LimeSDR-Mini. The transmitter and the receiver are asynchronous. The timing difference varies slightly from run to run, which results in issues that are exacerbated in a short-range radar. The bleed-through signal is the signal leakage from the transmitter to the receiver. The bleed-through signal prevents the detection of targets at a short-range. Feed-through nulling is a signal processing technique used to eliminate the bleed-through signal so that short- range targets can be detected. The instability of the LimeSDR-Mini reduces the effectiveness of feed-through nulling techniques.