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Development and saw device implementation of a new weighted stepped chirp code signal for direct sequence spread spectrum communications systems
Title
Development and saw device implementation of a new weighted stepped chirp code signal for direct sequence spread spectrum communications systems.
Creator
Carter, Scott Edward, Malocha, Donald C., Engineering
Abstract / Description
University of Central Florida College of Engineering Thesis; This work introduces the new weighted stepped chirp code signal for direct sequence spread spectrum (DS/SS) communications systems. This code signal uses the truncated cosine series functions as the chip functions. This code signal is the result of discretizing a continuous wave (CW) chirp which results in enhanced performance versus a pseudonoise (PN) cose and equivalent performance and easier implementation than a CW chirp. This...
Show moreUniversity of Central Florida College of Engineering Thesis; This work introduces the new weighted stepped chirp code signal for direct sequence spread spectrum (DS/SS) communications systems. This code signal uses the truncated cosine series functions as the chip functions. This code signal is the result of discretizing a continuous wave (CW) chirp which results in enhanced performance versus a pseudonoise (PN) cose and equivalent performance and easier implementation than a CW chirp. This code signal will be shown to possess improved compression ratio (CR), peak sidelobe level (PSL), integrated sidelobe level (ISL), and bit error rate (BER) when compared to a PN code of identical code length and chip length. It also will be shown to have a similar CR, PSL, ISL, and loss in processing gain (LPG) when compared to a CW chirp with identical pulse length and frequency deviation. The code signal is implemented on surface acoustic wave (SAW) devices which can be used as the code signal generator at the transmitter and the correlator at the receiver in a DS/SS communication system. SAW design considerations for the weighted stepped chirp signal are discussed. Experimental data is presented and compared to the predicted CR, PSL, ISL, LPG, and BER.
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Date Issued
1998
Identifier
CFR0008153, ucf:52944
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFR0008153
ULTRA-WIDEBAND ORTHOGONAL FREQUENCY CODED SAW CORRELATORS
Title
ULTRA-WIDEBAND ORTHOGONAL FREQUENCY CODED SAW CORRELATORS.
Creator
Gallagher, Daniel, Malocha, Donald, University of Central Florida
Abstract / Description
Ultra–wideband (UWB) communication new technology with ability to share the FCC allocated frequency spectrum, large channel capacity and data rate, simple transceiver architecture and high performance in noisy environments. Such communication advantages have paved the way for emerging wireless technologies such as wireless high definition video streaming, wireless sensor networks and more. This thesis examines orthogonal frequency coded surface acoustic wave (SAW) correlators for use in...
Show moreUltra–wideband (UWB) communication new technology with ability to share the FCC allocated frequency spectrum, large channel capacity and data rate, simple transceiver architecture and high performance in noisy environments. Such communication advantages have paved the way for emerging wireless technologies such as wireless high definition video streaming, wireless sensor networks and more. This thesis examines orthogonal frequency coded surface acoustic wave (SAW) correlators for use in advanced UWB communication systems. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for UWB spreading of data. The use of OFC spectrally spreads a PN sequence beyond that of CDMA because of the increased bandwidth; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are needed in the IF block in the transmitter and receiver, and reduces much of the signal processing requirements. The OFC SAW correlator device consists of a dispersive OFC transducer and a wideband output transducer. The dispersive filter was designed using seven contiguous chip frequencies within the transducer. Each chip is weighted in the transducer to account for the varying conductance of the chips and to compensate for the output transducer apodization. Experimental correlator results of an OFC SAW correlation filter are presented. The dispersive filter is designed using seven contiguous chip frequencies within the transducer. SAW correlators with fractional bandwidth of approximately 29% were fabricated on lithium niobate (LiNbO3) having a center frequency of 250 MHz and the filter has a processing gain of 49. A coupling of modes (COM) model is used to predict the experimental SAW filter response. Discussion of the filter design, analysis and measurements are presented. Results are shown for operation in a matched filter correlator for use in an UWB communication system and compared to predictions.
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Date Issued
2007
Identifier
CFE0001820, ucf:47338
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001820
MODELING, DESIGN AND FABRICATION OF ORTHOGONAL AND PSUEDO-ORTHOGONAL FREQUENCY CODED SAW WIRELESS SPREAD SPECTRUM RFID SENSOR TAGS
Title
MODELING, DESIGN AND FABRICATION OF ORTHOGONAL AND PSUEDO-ORTHOGONAL FREQUENCY CODED SAW WIRELESS SPREAD SPECTRUM RFID SENSOR TAGS.
Creator
Saldanha, Nancy, Malcoha, Donald, University of Central Florida
Abstract / Description
Surface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor...
Show moreSurface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor environment and provides simultaneous sensing and sensor identification. The SAW device is encoded via proper design of multiple Bragg reflectors at differing frequencies. To enable accurate device design, a model to predict reflectivity over a wide range of electrode metallization ratios and metal thicknesses has been developed and implemented in a coupling of modes (COM) model. The high coupling coefficient, reflectivity and temperature coefficient of delay (TCD) of YZ LiNbO3 makes it an ideal substrate material for a temperature sensor, and the reflectivity model has been developed and verified for this substrate. A new concept of pseudo-orthogonal frequency coded (POFC) SAW sensor tags has been investigated, and with proper design, the POFC SAW reduces device insertion loss and fractional bandwidth compared to OFC. OFC and POFC sensor devices have been fabricated at 250 MHz and 915 MHz using fundamental operation, and 500 MHz and 1.6 GHz using second harmonic operation. Measured device results are shown and compared with the COM simulations using the enhanced reflectivity model. Additionally, the first OFC devices at 1.05 GHz were fabricated on 128o YX LiNbO3 to explore feasibility of the material for future use in OFC sensor applications. Devices at 915 MHz have been fabricated on YZ LiNbO3 and integrated with an antenna, and have then been used in a transceiver system built by Mnemonics, Inc. to wirelessly sense temperature. The first experimental wireless POFC SAW sensor device results and predictions will be presented.
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Date Issued
2011
Identifier
CFE0003594, ucf:48888
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003594
Ultra-wideband Spread Spectrum Communications using Software Defined Radio and Surface Acoustic Wave Correlators
Title
Ultra-wideband Spread Spectrum Communications using Software Defined Radio and Surface Acoustic Wave Correlators.
Creator
Gallagher, Daniel, Malocha, Donald, Delfyett, Peter, Richie, Samuel, Weeks, Arthur, Youngquist, Robert, University of Central Florida
Abstract / Description
Ultra-wideband (UWB) communication technology offers inherent advantages such as the ability to coexist with previously allocated Federal Communications Commission (FCC) frequencies, simple transceiver architecture, and high performance in noisy environments. Spread spectrum techniques offer additional improvements beyond the conventional pulse-based UWB communications. This dissertation implements a multiple-access UWB communication system using a surface acoustic wave (SAW) correlator...
Show moreUltra-wideband (UWB) communication technology offers inherent advantages such as the ability to coexist with previously allocated Federal Communications Commission (FCC) frequencies, simple transceiver architecture, and high performance in noisy environments. Spread spectrum techniques offer additional improvements beyond the conventional pulse-based UWB communications. This dissertation implements a multiple-access UWB communication system using a surface acoustic wave (SAW) correlator receiver with orthogonal frequency coding and software defined radio (SDR) base station transmitter.Orthogonal frequency coding (OFC) and pseudorandom noise (PN) coding provide a means for spreading of the UWB data. The use of orthogonal frequency coding (OFC) increases the correlator processing gain (PG) beyond that of code division multiple access (CDMA); providing added code diversity, improved pulse ambiguity, and superior performance in noisy environments. Use of SAW correlators reduces the complexity and power requirements of the receiver architecture by eliminating many of the components needed and reducing the signal processing and timing requirements necessary for digital matched filtering of the complex spreading signal.The OFC receiver correlator code sequence is hard-coded in the device due to the physical SAW implementation. The use of modern SDR forms a dynamic base station architecture which is able to programmatically generate a digitally modulated transmit signal. An embedded Xilinx Zynq (TM) system on chip (SoC) technology was used to implement the SDR system; taking advantage of recent advances in digital-to-analog converter (DAC) sampling rates. SDR waveform samples are generated in baseband in-phase and quadrature (I (&) Q) pairs and upconverted to a 491.52 MHz operational frequency.The development of the OFC SAW correlator ultimately used in the receiver is presented along with a variety of advanced SAW correlator device embodiments. Each SAW correlator device was fabricated on lithium niobate (LiNbO3) with fractional bandwidths in excess of 20%. The SAW correlator device presented for use in system was implemented with a center frequency of 491.52 MHz; matching SDR transmit frequency. Parasitic electromagnetic feedthrough becomes problematic in the packaged SAW correlator after packaging and fixturing due to the wide bandwidths and high operational frequency. The techniques for reduction of parasitic feedthrough are discussedwith before and after results showing approximately 10:1 improvement.Correlation and demodulation results are presented using the SAW correlator receiver under operation in an UWB communication system. Bipolar phase shift keying (BPSK) techniques demonstrate OFC modulation and demodulation for a test binary bit sequence. Matched OFC code reception is compared to a mismatched, or cross-correlated, sequence after correlation and demodulation. Finally, the signal-to-noise power ratio (SNR) performance results for the SAW correlator under corruption of a wideband noise source are presented.
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Date Issued
2015
Identifier
CFE0005794, ucf:50054
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005794