International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The basic building blocks for implementing complex waveform generators using a look-up table approach are random access memory (RAM) and read only memory (ROM) devices. Due to technological advancements in field programmable gate array (FPGA) development, these devices have the ability to allocate large amounts of memory elements within the same structure. The self containment property makes the FPGA a suitable topology for complex waveform generation applications. In addition, this self containment property significantly reduces implementation costs by reducing the number of external components required to support many applications. This paper examines the use of FPGA’s in various complex waveform generation applications. In particular, a discussion will ensue examining possible mappings of the time domain response of the complex waveform into memory elements of the FPGA. The analyses and examples contained in the sequel are from existing waveform generation applications, developed for Gauissian Minimum Shift Keying (GMSK) and Unbalanced Quadriphase Shift Keying (UQPSK) modulation formats.

Coherent transmission system has been extensively studied in recent years, and it can use different modulation formats and different detection techniques. The modulation formats are ASK (Amplitude shift keying), PSK (Phase shift keying), and FSK (Frequency shift keying). The detection techniques are Homodyne detection and Heterodyne detection, and they need a laser in the receiver called as the LO (Local oscillator). In the previous study, the BPSK (Binary phase shift keying) modulation format was investigated, and the pilot carrier method realized the Homodyne Detection. The merit of the pilot carrier is that it do not need the LO in the receiver. In this master thesis, the QPSK (Quadrature phase shift keying) modulation format is investigated using the pilot carrier method, The BER is calculated using the matlab program. The performance of 20G bit/s, 50 km transmission system using the BPSK and the QPSK is compared to clarify the merits and demerits of the QPSK modulation.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / An artifact of QPSK modems is ambiguity of the recovered data. There are four variations of the output data for a given input data stream. All are equally probable. To resolve this ambiguity, the QPSK data streams can be differentially encoded before modulation and differentially decoded after demodulation. The encoder maps each input data pair to a phase angle change of the QPSK carrier. In the demodulator, the inverse is performed - each phase change of the input QPSK carrier is mapped to an output data pair. This paper discusses a very simple and unique differential encoder/decoder that handles all possible data pair/phase change permutations.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The impact of multipath fading parameters on the probability of error for Offset QPSK (OQPSK) is derived. The multipath fading channel is modeled using the aeronautical telemetry channel model [1-2]. Expressions for the probability of bit error are derived that are a function of the multipath model parameters. The expressions are shown to agree with computer simulations and show that a strong multipath reflection with a short delay causes much more degradation than a weak multipath reflection with a long delay.

The coherent system has been extensively studied in recent years. The reasons are that receiver sensitivity is better than Intensity Modulation with Direct Detection (IM/DD) and the spectral efficiency of wavelength division multiplexing (WDM) is increased. The modulation formats of the coherent system are Amplitude shift keying (ASK), Phase shift keying (PSK), and Frequency shift keying (FSK). The detection techniques are Homodyne detection and Heterodyne detection, both of them need a laser light source in the receiver called as the Local oscillator (LO). In the previous study, the Quadrature phase shift keying (QPSK) modulation format with Pseudo Random Binary Sequence (PRBS) 27-1 to transmit 51km was investigated, and the pilot carrier method realized the Homodyne Detection. The merit of the pilot carrier is that the LO is not necessary in the receiver. In this master thesis, the optical signal of the QPSK modulation format with PRBS 215-1 is transmitted over 500km using the pilot carrier method. A WDM system demonstration is also conducted to increase the system capacity. The Bit error rate (BER) is calculated by the MATLAB program. The BER performance of 20G bit/s, 500 km transmission system using the QPSK with single channel and multiplexed channels were measured.

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In this thesis, novel direct-digital Quadrature Phase Shift Keying (QPSK) modulators are proposed in low-cost Complimentary Metal Oxide Semiconductor (CMOS) technology for radio frequency (RF) wireless applications. Direct-digital architectures have attracted much attention recently as they potentially offer significant cost savings and performance benefits. A new direct-digital QPSK modulator concept is introduced where the carrier is modulated directly by digital data using Pass-Transistor Logic (PTL) circuits for a small size and low power consumption. The concept is demonstrated through the design of an L-band modulator followed by an enhanced tunable S-band version. The proposed L-band modulator first generates all four quadrature phases of the carrier by using a 90° resistor-capacitor, capacitor-resistor (RC-CR) phase shifter followed by two 180° active baluns. One signal from the in-phase components and another from the quadrature-phase components are later selected by two PTL circuits according to the in-phase (I) and quadrature-phase (Q) digital data respectively. Finally the chosen signals are subtracted by a differential amplifier. The circuit has been experimentally demonstrated in a standard 0.18μm CMOS process, showing good performance at 1.7GHz with the data transmission rate and carrier rejection exceeding 20Mbps and 40dB respectively. The integrated circuit (IC) measures only 425μm by 850μm and consumes less than 43mW of power. A new S-band direct-digital QPSK modulator is introduced that offers even better performance and requires fewer components. An active balun first splits the carrier into a pair of balanced signals, which are then fed to a 90° RC polyphase network generating all four differential quadrature signals. Voltage-controlled NMOS resistors are used in the RC polyphase network to fine-tune it after fabrication for the lowest possible phase error. Finally, only one of the four differential quadrature signals is selected by a PTL circuit consisting of six NMOS switches, according to both I and Q digital data values. The circuit has been experimentally demonstrated in a standard 0.18μm CMOS process showing very good performance at 2.4GHz, with the data transmission rate exceeding 56Mbps. The IC measures 720μm by 888μm with an active area of only 505μm by 610μm, and consumes less than 33mW of power. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-09-26 15:42:15.243

This thesis examines the design of a QPSK demodulator frontend for GPON transceiver at end user's side. Since lowering the cost of the terminal transceivers in an access network like GPON is a key requirement, CMOS technology is used and several area-saving design techniques are applied. The designed frontend circuit saved more than 80% area of the key components like the mixers and the QVCO than some published designs which can also fit the application. A measurement in frequency domain and a simulation in time domain verified that this frontend is able to demodulate a QPSK signal with a data rate as high as 5 Gbit/s. Two structures of quadrature oscillators are firstly presented and compared. One is an LC QVCO centered at 5 GHz, which has a tuning range of 3 GHz, a phase noise of -100.8 dBc/Hz at 1 MHz offset, and an area of 0.15 mm2 excluding pads. The other is a ring QVCO which only takes an area of 0.019 mm2. But it has a higher phase noise of -81 dBc/Hz at 1 MHz offset. Then two broadband mixers are described separately. The first one provides a high conversion gain, but its input linearity is insufficient to meet the input power requirement. The second mixer obtains required input linearity but with a trade-off of conversion gain. Both mixers have a broadband input impedance match from 2 GHz to 8 GHz. The first mixer has a conversion gain of 8.5 dB and an input 1 dB compresion point at -17 dBm. The second mixer has a conversion gain of -7 dB with an on-chip buffer or -2.1 dB without buffer, but an input 1 dB compresion point at -5 dBm. A frontend circuit is lastly presented. It integrates the compact ring QVCO, two broadband mixers with high input linearity, and two second-order LC ladder low pass filters. A Frequency domain measurement shows the expected spectrum down conversion of a 2.5 Gsym/s QPSK signal centered at 5 GHz. The whole frontend circuit including pads takes 1 mm2 area, and consumed 157 mW power. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-06-29 10:59:45.312

Thesis deals with problems PLC (Power Line Communication) communication. It is aimed at drawing up a suitable model for testing power network PLC communication. The reader is aware of at the beginning of work with the basic principles of PLC systems, distribution and use in communication networks. Another part of the work deals with different types of interference, which occur in power networks and ways to defend against such interference. For example, an appropriate choice of modulation and coding relevant. As a source of interference in the proposed model is used AWGN channel (Additive White Gaussian Noise). Conclusion of work is dedicated to design and build a model for PLC communication. There are three models designed with different OFDM technology. Models therefore vary between different levels of key mapping in OFDM (QPSK, 16-QAM, 64-QAM). It made a detailed description of a set of blocks that were used to build models. The behavior and functionality of the proposed models for broadband PLC communication was verified in the simulation program Matlab Simulink. Finally, it is shown the comparison and evaluation of results of each modulation.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The impact of frequency selective multipath fading on the bit error rate performance of ARTM Tier-1 waveforms (FQPSK and SOQPSK) is derived and analyzed. In the presence of a strong specular reflection with relative magnitude |Γ1|, the ARTM Tier-1 waveforms suffer a loss in performance of (1 - |Γ1)^(-4√(|Γ1|)) for |Γ1| < 0:5 and a relatively high error floor at approximately 10^(-2) for |Γ1| ≥ 0.5. The ARTM Tier-1 waveforms possess twice the spectral efficiency of PCM/FM, but exhibit a greater loss and higher error floors than PCM/FM for the same multipath conditions and signal-to-noise ratio.