M.Ing. (Electrical and Electronic Engineering) / The feasibility of modulation and demodulation of speech signals within a microprocessor is invertigated in the following study. Existing modulation and demodulation techniques are investigated and new techniques. suitable for microprocessor implementation, described. Finally a single sideband demodulator was built using the TMS32010 microprocessor with results being better or comparable than existing analog techniques.

This thesis deals with designing and implementing autonomous decoder for RTTY communication. Theoretical part of the thesis deals with researching the RTTY technology and FSK modulation, which it uses, focusing mainly on the methods of demodulation. Next part of the thesis compares suitability of available platforms. Practical part of the thesis describes the design and implementation of circuit board, firmware and computer application. The device is using STM32 microcontroller. Firmware was developed in C++ using Arduino. The computer application was created by using C\# and WPF. 3 methods of FSK demodulations were implmented. One is using a FFT algorithm. Other two calculate frequency based on the period of square signal.

One consequence of the increasing number of small satellite missions is an increasing demand for high data rate downlinks. As the satellites transmit at high data rates, ground-side receivers need to demodulate the transmitted data as quickly as possible. While application specific hardware can be designed, software defined radio solutions for ground stations are attractive for their flexibility, adaptability, and portability. Another industry trend is the increasing use of Graphics Processing Units (GPUs) in general-purpose processing. By performing many operations simultaneously, GPUs are capable of accelerating processing when given a problem that can be implemented in a parallel manner. Furthermore, once a parallel algorithm is implemented, further speedups are possible by increasing hardware resources without need for any revision in the algorithm. This project combines the above ideas by implementing a software defined radio algorithm to quickly demodulate high-speed data on a GPU. It demonstrates the viability of the GPU in software defined radio applications and particularly in the area of fast demodulation.

Temperature sensing in harsh environment is desired in many areas, such as coal gasification, aerospace, etc. Single crystal sapphire is an excellent candidate for construction of harsh environment sensors due to its superior mechanical and optical properties even at temperature beyond 1600°C. The temperature inside a coal gasifier can be as high as 1200°C. And there is dramatic temperature gradient between the inner and outer layers of the gasifier refractory. Previous work has been done at Virginia Tech's Center for Photonics Technology to design and fabricate a sapphire wafer based Fabry-Perot interferometer (FPI) sensor for temperature sensing in coal gasifiers. The sensor head is based on the use of sapphire wafer which is attached to a lead-in sapphire fiber to be applied in the ultrahigh temperature region; and the sapphire fiber is spliced to a multi-mode fused silica fiber for quality signal transmission in lower temperature areas. One of the challenges encountered by this approach is the shear force to the sapphire fiber, which is caused by the differential thermal expansion between the inner and outer layers of the gasifier refractory. This shear force may be so significant to break the sensor probe. This thesis proposed a free space based interrogation sensing system to address that problem. In this free space based interrogation sensing system, only the sensor head is placed in the inner refractory wall, while all the other parts of the system are placed in the outer refractory or outside the gasifier at the ambient room temperature. An optical frequency domain reflectometry (OFDR) based multiplexed technique is applied in the sensor design to realize temperature measurement at multiple locations along the optical path. In this work, three sapphire wafers based multiplexed temperature sensor is fabricated and calibrated in laboratory. This multiplexed high temperature sensor shows linear response in the range of 20°C ~ 1000°C, with a sensitivity of 1.602?10??/°C and a resolution of 1.3°C. / Master of Science

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / A Synthetic Beamforming antenna was built for Airborne Telemetry. Low-Noise Block-converters translated RF to IF suitable for direct analog-to-digital conversion. Then all telemetry functions were performed digitally via parallel FPGAs for 10 independent sources. Monopulse tracking and optimal diversity combination was performed using 4 antenna quadrants at two orthogonal polarizations. Novel estimation approaches drove digital demodulation, symbol- and bit- synchronization. Final telemetry outputs include: digital, analog (video), and analog IF (e.g., for downlink relay). This program has incubated several concepts that we believe have the combined potential to significantly improve the future of telemetry.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / This paper discusses the design and performance of the FM/PM/BPSK "personal computer card-based" receiver. In PSK, a carrier recovery technique must be used for signal demodulation. Costas loop is a well known method and is the basis in the design of the BPSK demodulation. A new design approach employing digital Box Car arm filters is used to improve receiver performance and flexibility. Detail design and performance of the digital Costas loop will be explored in a later section. A classical technique is employed for Phase demodulation with the use of tracking Phase Lock Loop. Frequency demodulation is designed around a simple, single FM discriminator IC.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The telemetry and aerospace communities require communications equipment providing various modulation and demodulation formats. One format, with application in Space Ground Link Subsystems (SGLS), utilizes a Ternary (tri-tone) Frequency Shift-Keyed (FSK) signal Amplitude Modulated (AM) by a triangle waveform. Historically, SGLS equipment has operated with a fixed tri-tone frequency set (e.g., 65 kHz, 76 kHz and 95 kHz). The need for additional transmission channels and increased bandwidth efficiency creates the requirement for equipment with the flexibility to generate and receive varied and higher frequency tone sets. Combining analog and digital techniques, GDP Space Systems has developed the FDT001. It is an FSK/AM detector which recovers a bit rate clock at one of four selectable bit rates and reproduces ternary FSK modulation data over a widely tunable range of tone frequencies. The tuning range is expanded by using two methods of digital frequency discrimination. The following paper describes the design of the FDT001.

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 / Multi-H Continuous Phase Modulation is a highly bandwidth efficient constant amplitude modulation scheme. Because of these qualities it was selected as the Advanced Range Telemetry (ARTM) tier II waveform. In the past, two demodulation techniques have widely been proposed, coherent detection and non-coherent detection. This paper presents a receiver design that implements a hybrid, partially coherent detection scheme that takes advantage of the positive aspects of both coherent and non-coherent detection. Because complete phase recovery is not required, the hybrid receiver performs better in environments with fast fading, strong phase noise, and multi path when compared to the traditional coherent receiver. The hybrid receiver can also acquire and reacquire signals much faster than conventional coherent receivers. The hybrid receiver design implements a partial carrier detection scheme that utilizes phase information that performs much better in AWGN environments than typical non-coherent receivers. Simulation results show that the hybrid receiver has low implementation loss compared to the optimal Maximum Likelihood Sequence Estimation (MLSE) receiver.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Bibliography: leaf 86. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 215-218. / by Leon K. Ekchian. / M.S.