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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Examination of Spatial Diversity Combining Using Commercial Off the Shelf Equipment in Missile Telemetry

Graham, Richard A., Jr. 10 1900 (has links)
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / This experiment has two purposes. One, to determine if a modern diversity combiner normally used in missile telemetry for polarization diversity can be used for spatial diversity to obtain a gain in the signal quality. Two, to determine if a simple test can be designed such that a non-laboratory test can be performed by the average telemetry operator in order to assess the first purpose.
2

Performance Analysis of Minimum Selection GSC with Channel Estimation Errors in Rayleigh Fading Channels

Zhu, Chao January 2007 (has links)
No description available.
3

A Study on Diversity Combining for Fast Frequency Hopping Systems

Dai, Cyuan-Li 28 November 2007 (has links)
In frequency-hopping (FH) system, the signal is not only impaired by receiver thermal noise, but also impaired by jamming, interference or multipath fading. Therefore, diversity techniques are used to reduce these impairments. Two systems are considered in this thesis, the first one is fast frequency-hopping/M-ary frequency-shift-keying (FFH/MFSK) System and the second one is fast frequency-hopping multiple access/M-ary frequency-shift-keying system (FFHMA/MFSK) System. In the first system, we consider three cases, multitone jamming (MTJ), broad-band noise jamming (BBN) and partial-band noise jamming (PBN).In the second system, we consider multiuser cases with multiple access interference, frequency-selective fading, and AWGN channels. In this thesis, two modified diversity combining methods are proposed. These methods are modified product and Order Statistics-Normalized Envelope Detection (OSNED) methods by adding the reliable order statistics. From simulation results, these methods can effectively combat multitone jamming and partial-band noise jamming. When comparing with product and OSNED in multiple access interference channel and frequency-selective fading channels, the proposed methods have better performance at high SNR. The proposed methods also do not need the additional side information as hard limiting majority vote (HLMV) and soft limiting combiner (SLC) needed.
4

ANTI-JAM PERFORMANCE OF SEVERAL DIVERSITY COMBINERS

Eng, Thomas 10 1900 (has links)
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The relative anti-jam (AJ) performance of several diversity combiners are investigated. The modulation is 8-ary frequency-shift-keying (FSK), the demodulation process consists of energy detection of the eight frequency bins at each hop and the subsequent combining of detector outputs. Three combiners are considered : the linear combiner, where the detector outputs of each hop (corresponding to the same frequency bin) are summed without any processing; the self-normalized combiner, where the eight detector outputs of any particular hop are normalized so that they add to unity; and the max-normalized combiner, where the eight detector outputs of any hop are divided by the maximum value among those eight outputs. Results indicate that under worst-case tone jamming, the selfnormalized combiner performs the best, the max-normalized combiner second best, and the linear combiner performs the worst among the three.
5

Control of a Remote Receiving Station and Data Processing at RA Range Hebrides

Mackenzie, Donald, Fielding, Richard 10 1900 (has links)
International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / The Royal Artillery Range (RA Range) is the British Army's weapons practice range in the Outer Hebrides of Scotland. The large sea range is also used by the Royal Air Force and Royal Navy for new weapons system evaluation and in service practice firing. This paper describes the telemetry facility comprising of two prime sites separated by 40 miles of open sea. Tracking antennas and receivers are at the remote island site of St Kilda with data processing and control at the Range Control Base (RCB), Benbecula. To improve operational capabilities and effectiveness, full remote control and monitoring of the multiple receivers and combiners has been installed. Radar tracking outputs are processed in the telemetry computer to produce individual antenna pointing demands.
6

A spatial diversity scheme for fixed point indoor wireless communication

Gerein, Neil 09 January 2004
The ease with which indoor wireless systems can be installed has become their main selling feature. A desirable application for wireless systems is the transmission of compressed digital music in an indoor shopping mall environment. The indoor environment, with its many walls and highly reflective surfaces, has a high level of multipath. High levels of slowly changing multipath can cause deep fades, and therefore reduce the reliability of the system. <p> The proper use of multiple receiving elements is one way to mitigate the deep fades caused by multipath. The main objective of this thesis is to study a simple and cost effective approach to combining the signals from several receiving elements. A novel diversity combining approach using 2 receiving elements is presented. The novel diversity combining approach consists of periodically changing the phase of one of the two received signals. <p> A set of simulations was developed to study the effectiveness of the novel diversity combining method in mitigating deep multipath fades. The relative performances of two different implementations of the diversity combining were compared to a baseline test case that did not include diversity combining. In both of the simulated implementations, the diversity combining approach proved to be an effective means of mitigating the multipath fading phenomenon. <p> A proof-of-concept, bench-top hardware prototype was also developed. The transmitter and receiver were implemented in Field Programmable Gate Arrays (FPGAs). The laboratory testing of the hardware successfully illustrated the feasibility of the proof-of-concept system.
7

A spatial diversity scheme for fixed point indoor wireless communication

Gerein, Neil 09 January 2004 (has links)
The ease with which indoor wireless systems can be installed has become their main selling feature. A desirable application for wireless systems is the transmission of compressed digital music in an indoor shopping mall environment. The indoor environment, with its many walls and highly reflective surfaces, has a high level of multipath. High levels of slowly changing multipath can cause deep fades, and therefore reduce the reliability of the system. <p> The proper use of multiple receiving elements is one way to mitigate the deep fades caused by multipath. The main objective of this thesis is to study a simple and cost effective approach to combining the signals from several receiving elements. A novel diversity combining approach using 2 receiving elements is presented. The novel diversity combining approach consists of periodically changing the phase of one of the two received signals. <p> A set of simulations was developed to study the effectiveness of the novel diversity combining method in mitigating deep multipath fades. The relative performances of two different implementations of the diversity combining were compared to a baseline test case that did not include diversity combining. In both of the simulated implementations, the diversity combining approach proved to be an effective means of mitigating the multipath fading phenomenon. <p> A proof-of-concept, bench-top hardware prototype was also developed. The transmitter and receiver were implemented in Field Programmable Gate Arrays (FPGAs). The laboratory testing of the hardware successfully illustrated the feasibility of the proof-of-concept system.
8

Low Complexity PSP-MLSE receiver for H-CPM with receive diversity.

Zhou, Li January 2009 (has links)
This thesis is a study of harmonized continuous phase modulation (H-CPM) coupled with receive diversity as applied to mobile radio communication applications. H-CPM is the modulation technique specified by the American Public Safety Communication Official Project 25 (APCO P25) Phase 2 standards, which is focused on public safety applications. Practical implementation of an H-CPM maximum likelihood sequence estimator (MLSE) receiver requires complex reduction techniques to ensure a cost effective form. In addition, it must be able to handle a fast fading environment, which is often encountered in public safety applications. Here, the reduction of receiver complexity and the combating of fast fading situations are investigated via MATLAB simulation. By using tilted phase and frequency pulse truncation techniques, the complexity of an H-CPM MLSE receiver is successfully reduced. In particular, the original 384-state receiver is first reduced to a 192-state receiver through the use of tilted phase. Then it is further reduced to 48-states and finally to 12-states by applying frequency pulse truncation. Simulation, assuming static channels, shows that the bit error rate (BER) performance of a 12-state receiver is essentially identical to that of a 384-state receiver, despite a 97% reduction in computational complexity. To take into account the effects of fading, channel gain estimation via persurvivor processing (PSP) is incorporated into the reduced complexity MLSE receiver. Using a weighted-sum approach to the PSP gain estimates, it was found that at Doppler shifts of 5 Hz, 40 Hz and 80 Hz, the receiver performance was comparable to that obtainable by rival techniques. To further reduce the effect of fading, receive diversity combining was investigated, where a three-antenna diversity scheme is applied to the reduced state PSP-based MLSE receiver. Three different combining techniques, namely selective combining (SC), equal gain combining (EGC) and maximum ratio combining (MRC) were compared. It was found via simulation that the best performance is achieved using MRC, with as much as 14dB improvement achieved by applying triple diversity MRC.
9

ENCRYPTED CORRELATING SOURCE SELECTOR

Reid, Eric 10 1900 (has links)
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 / Modern telemetry and data streams are often encrypted. The majority of range testing activities require multiple ground stations to collect these streams and send them to a central processing location. Each of these streams currently needs to be individually decrypted before best source selection, processing and analysis. Using innovative techniques, it is possible to time correlate these encrypted streams, compare them with each other and create an output stream of better quality than any of the individual streams. This stream can then be decrypted by a single decryption device, greatly reducing cost and complexity.
10

Quantifying Coding Gain from Telemetry Data Combining

Forman, Michael A., Condreva, Ken, Kirchner, Gary, Lam, Kevin 10 1900 (has links)
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / A method for combining telemetry data and quantifying the resulting coding gain for a ballistic missile test flight is presented. Data received from five ground stations in 54 data files with 18 million intermittent frames is combined, to create a single file with 1.5 million continuous frames. Coding gain provided by data combining is as high as 30 dB, with a useful improvement of 5 dB at boost and terminal stages. With frame reconstruction techniques, erroneous words in a frame are reduced from 2.1% to 0.12 %.

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