Derivative Gaussian Pulse Research Articles

An Integrated Primary Impulse Radio Ultra-Wideband Radar for Short-Range Real-Time Localization

This paper presents a primary impulse-radio ultra-wideband (IR-UWB) radar system for real-time short-range localization, e.g., for smart traffic and automotive applications. The radar system consisting of an integrated radar transceiver (TRx) using 45-nm SOI CMOS technology and an FPGA-based signal processing. The efficient transmitter (Tx), which complies with the regulations for both indoor and outdoor applications, modulates and emits a seventh derivative Gaussian pulse. In the receiver (Rx), echo signals will be amplified and sampled in real-time. The echo pulses are recovered by signal processing hardware on the FPGA, which is also used to perform simple classification tasks like user warning. The radar system is compact, portable, and power efficient. The Tx has a high-energy efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {11~ \text {p} \text {J} /pulse}$ </tex-math></inline-formula> . The proposed radar system achieves very high signal-to-noise ratio (SNR) and range precision. It has a maximum detection range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {15~m }$ </tex-math></inline-formula> and a range resolution down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {3~ \text {cm}}$ </tex-math></inline-formula> . Moreover, a target of interest can be warned with a latency as fast as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {16~\mu s }$ </tex-math></inline-formula> by using 1-bit real-time sampling.

A High-Performance UWB Gaussian Pulse Generator: Analysis and Design

This article aims to investigate the limitations on the amplitude of the conventional step recovery diode (SRD)-based Gaussian pulse transmitter and techniques to overcome the limits. The operation of the modified design is examined and compared with a conventional configuration. The results show a considerable increase in the pulse amplitude. The high pulse amplitude of the modified configuration represents an increase in the transmitter’s output power and its improved probing range. The Gaussian pulse is converted into the first derivative Gaussian pulse using a 90° broadband coupler as a differentiator and a semi-differentiator delay line circuit with balanced stubs. The output monopulse generated using the balanced stub delay line has more symmetric sidelobes with narrower pulsewidth than the 90° couplers. Experimental results have shown the high performance of the proposed transmitter over the conventional designs in terms of pulse amplitude and symmetry.

Design and Development of a High-Power Pulse Transmitter for Underground Environmental Perception

This article represents a design for a high-power pulse transmitter for high-depth imaging applications. The pulse transmitter consists of an avalanche transistor-based pulse-shaping network, an improved step recovery diode (SRD)-based configuration, and a pulse-shifting circuit with a broadband combiner to generate a first derivative Gaussian pulse for high-power applications. The output pulse of the transistor-based circuit is fed to a balun, which produces two opposite polarity pulses and then feeds two parallel SRD pulse-shaping circuits that produce ultrashort pulses. The SRD-based part of the circuit was developed to have a high amplitude output pulse. Moreover, using a technique based on pulse shifting, a higher power monopulse was achieved without using a balun and a differentiator. This design achieved a monopulse of 169-ps pulsewidth with a peak power of <inline-formula> <tex-math notation="LaTeX">$P =5.78$ </tex-math></inline-formula> W. In order to check the validity of the transmitter for imaging applications, several experiments for buried objects in the sand are conducted, including metal objects, water pipe, rock, and copper veins. All reconstructed 3-D images clearly represent the target shape and dimension, confirming the functionality of the designed transmitter for sensing and imaging applications.

Tunable Subnanosecond Gaussian Pulse Radar Transmitter: Theory and Analysis

This article presents a design methodology and steps to fabricate a tunable step recovery diode (SRD)-based Gaussian pulse transmitter for ultra-wideband (UWB) radar systems. The method exploits a parallel and series combination of two SRDs which are excited using a transistor-based square pulse generator with an amplitude of 9 V. A turning point control circuit is used to control the forward-to-reverse current ratio of the diodes and tune the pulsewidth and magnitude of the Gaussian output pulse. The ringing level of the pulse is reduced using an output diode network. The interconnect between the diodes is designed and optimized to improve the amplitude and pulsewidth. A Gaussian pulse of variable pulsewidth from 60 ps with an amplitude of 1 V to 220 ps with a 6.8 V amplitude and ringing level of less than 11% is achieved. A 90° coupler with broad bandwidth is fabricated to differentiate the Gaussian pulse and extract a dc-free monopulse. Vivaldi antennas with suitable bandwidth are used as transmitting antennas to radiate the monopulses with variable pulse widths. The measured second derivative Gaussian pulses at the receiver end demonstrated pulse widths of 41 and 173 ps for the Gaussian input pulses of 60 and 220 ps, respectively.

Elliptical Ring Antenna Excited by Circular Disc Monopole for UWB Communications

This research proposes a compact elliptical ring antenna excited by a circular disc monopole (CDM) for ultra-wideband (UWB) communications. In the study, time- and frequency-domain pulse distortions of the antenna in the transmission mode were characterized by magnitude and phase of the antenna transfer function (Hrad). The results showed that the gain and magnitude of Hrad in the boresight direction are sufficiently flat with linear phase response. The average antenna gain is 3.9 dBi over the UWB spectrum. The antenna also exhibits low pulse distortion with the correlation factors (ρ) of 0.98 and 0.93 for the fifth-order derivative Gaussian pulse and modulated Gaussian pulse with 6 GHz band rejection. The CDM-excited elliptical ring antenna possesses several attractive features, including wide bandwidth, flat gain, compactness, low cost, and low distortion.

An all-digital frequency tunable IR-UWB transmitter with an approximate 15th derivative Gaussian pulse generator

This work presents a new frequency-tunable, OOK–modulated, impulse-radio ultra-wideband (IR-UWB) transmitter, where approximate 15th derivative Gaussian pulses are produced by a monopulse-synthesis pulse generator. The center frequency of our output UWB pulses can be easily adjusted between 4 and 9 GHz by controlling delay time. Thus, the whole UWB frequency band from 3.1 to 10.6 GHz can be covered and utilized. Since the proposed monopulse-synthesis pulse generator already includes a pulse shaping function, RF bandpass filters are not required, thus realizing the extremely low complexity and small circuit area. The proposed IR-UWB transmitter has been implemented and fabricated in a standard 0.18 μm CMOS 1p6m process. The power supply voltage is 1.8 V and the targeted data rate is 31.25 Mbps. Chip measurement results show that the power spectrum density conforms to the FCC spectrum masks, and the peak-to-peak voltage of output UWB pulses is 56 mV. In addition, the core area of the chip is 0.02 mm2, the measured frequency tuning range is 3.1–10.6 GHz, and the measured energy dissipation is only 12.5 pJ/bit. Compared to the state-of-the-art designs in the literature, the chip area and tunable frequency range are improved by at least 33% and 53%, respectively.

Design and Development of an Inexpensive Sub-Nanosecond Gaussian Pulse Transmitter

A design of a hybrid Gaussian pulse transmitter using a transistor-based pulse generator and two pulse-shaping networks, a shorted stub delay circuit and a 90° hybrid coupler, is presented. A transistor-based pulse generator drives the pulse-forming network to achieve a sub-nanosecond pulsewidth. The shorted stub delay line was modified to optimize the frequency response and phase linearity. The transistor-based pulse generator is an inexpensive way of producing a square pulse of sharp rise time; this design achieved 280-ps rise time. A Schottky diode was used to eliminate the negative part of the output pulse as well as to reduce the ringing. Multiple simulations and measurements were performed to study the circuit behavior. The measurement results demonstrated a pulsewidth as sharp as 153 ps with 0.83-V amplitude and a low ringing on the order of 10%. The Gaussian monopulse was obtained by feeding the Gaussian pulse to a broadband 90° hybrid, which acts as a differentiator in the time domain. The pulse has a width on the order of 100 ps. The transmitter circuit was completed by connecting the monopulse circuit with an antenna. The measured radiated pulse in the far field of the transmitter is a second derivative Gaussian pulse with 85 ps of pulsewidth.

Manipulation of Gaussian derivative pulses and vector solitons in fiber lasers with analytic modeling by the coupled complex Ginzburg–Landau equations

Both positive- and negative-polarity Gaussian monocycle and doublet pulses, for which the pulse shapes are the first and second derivatives of Gaussian functions plus some continuous-wave backgrounds respectively, are generated in a ring-cavity erbium-doped fiber laser from polarization-locked vector solitons by using passive optical technology. The pulse states are switchable and are found to be the superposition of bright and dark solitons with different widths, amplitudes, time delays, polarizations, and wavelengths. Qualitative analysis of the properties of vector solitons are performed by solving coupled complex Ginzburg–Landau equations, and analytic modeling of the fiber laser is presented. By representing the envelopes of bright soliton by sech- and dark soliton by tanh-based functions, the incoherent superposition of these two soliton components have simulated the experimental observations, and the underlying mechanisms for the formation of monocycle and doublet pulses are attributed to the polarization locking of bright and dark solitons. The theoretical modeling is used to calculate the pulse parameters of the fiber laser, and the intracavity birefringence can be estimated. The results of tunable optical vector solitons are compared with atomic solitons in the system of Bose–Einstein condensation. Since the governing equations for soliton generation in fiber lasers and Bose–Einstein condensation have many properties in common, thus the simulation and propagation of pulsating waves may open a new route to explore the classical solitary dynamics in nonlinear optics and its quantum analogy in ultracold fields.

Detection and parameter estimation of weak pulse signal based on strongly coupled Duffing oscillators

Pulse signal detection is widely used in nuclear explosion electromagnetic pulse detection, lightning signal detection, power system partial discharge detection, electrostatic discharge detection, and other fields. The signal strength becomes weak with the increase of the detection distance and may be submerged in strong Gaussian noise for remote detection. Therefore, the detection and recovery of the weak signals, especially the weak pulse signals, have important applications in signal processing area. Some methods have been reported to detect and estimate weak pulse signals in strong background noise. Coupled Duffing oscillators are usually used in processing periodic signals, though it is still in an exploration stage for aperiodic transient signals. There remain some problems to be solved, for example, the system performance depends on some initial values, results are valid only for the period-doubling bifurcation state, the waveform time domain information cannot be accurately estimated, etc. In this paper, we explain the reasons why there exist these inherent defects in the current weakly coupled Duffing oscillators. In order to solve the above-mentioned problems, a new signal detection and recovery model is constructed, which is characterized by coupling the restoring force and damping force of the two oscillators simultaneously. A large coupling coefficient is applied to the two Duffing oscillators, and a generalized " in-well out-of-synchronization”phenomenon arises between the oscillators which conduces to detecting and recovering the weak pulse signals, and also overcoming the defects mentioned above. Using the metrics of signal-to-noise ratio improvement (SNRI) and waveform similarity, the effects of amplitude and period of periodic driving force, coupling coefficient, step size and damping coefficient on signal detection and waveform recovery are studied. Finally, experiments are performed to detect and recover the following three kinds of pulses: square wave pulses, double exponential pulses, and Gaussian derivative pulses. The input SNR thresholds of these three waveforms are –15, –12, and –16 dB, respectively, under the detection probabilities and waveform similarity all being greater than 0.9 simultaneously. The maximum error of the pulse amplitude and pulse width are both less than 5% of their corresponding true values. In summary, the strongly coupled Duffing system has advantages of being able to operate in any phase-space state and being no longer limited by the initial values. Especially, the time domain waveform of weak pulse signals can be well recovered in the low SNR case, and the error and the minimum mean square error are both very low.

QPSK Modulation Scheme Based on Orthogonal Gaussian Pulses for IR-UWB Communication Systems

A new impulse radio-ultra wideband (IR-UWB) communication system with quadrature phase shift keying (QPSK) modulation scheme was presented in this research. The system utilized orthogonal property of fourth- and fifth-order derivatives of Gaussian pulses for modulation and time hopping (TH) multiple-access scheme. This system was compared with conventional TH-PPM and TH-BPSK systems at the same condition. The simulation results in multipath channel showed that the proposed system can provide better bit rate performance compared with the conventional IR-UWB system. A very low power and low complexity circuit for generation of the fourth-order derivative of Gaussian pulse was also proposed. The circuits of fourth- and fifth-order derivatives of Gaussian pulses were simulated using a 0.18[Formula: see text][Formula: see text]m CMOS technology. The core chip size was only 0.015[Formula: see text]mm2. The output amplitude pulse yielded 135[Formula: see text]mV peak to peak under a supply voltage of 1.8[Formula: see text]V. The energy consumption of the fourth- and fifth-order derivatives of Gaussian pulses circuits were 8[Formula: see text]pJ/pulse for 200[Formula: see text]MHz pulse-repeating frequency (PRF).

Improving ultra wideband (UWB) system by modified random combination of pulses

Ultra-Wideband (UWB) technology uses very narrow pulses of nano-seconds duration to provide very high data rates. The pulses to be used for the UWB are very important and should meet the emission mask regulatory requirements to get good performance when transmitted over the channel. To meet these requirements, a combination of higher order derivatives of Gaussian pulses can be considered to form a combined pulse instead of transmitting them separately. The main aim of this paper is to improve the performance of Ultra Wideband (UWB) multiple access modulation system with a newly Proposed combined pulse, generated using a modified random pulse combining of the first five Gaussian derivative pulses with optimal shaping factors as basic functions. In order to meet the UWB power spectrum regulations, the power spectral utilization of the newly designed pulse is calculated and the bit error rate performance of the pulse position modulation time hopping system using the newly proposed pulse is analyzed in a multi-path channel environment using RAKE receiver. The simulation results carried out in MATLAB software shows that the new proposed combined pulse has higher pulse energy matching the spectral limits of UWB and an improved bit error rate performance as compared to the previous literature results.

UWB pulse design using constraint convex sets method

SummaryIn this paper, we propose a constrained convex sets–based method for designing ultra‐wideband (UWB) pulse. The UWB pulses designed using earlier proposed methods either do not fit well in UWB spectral mask or require extra processing circuitry for pulses to fit in the UWB spectral mask. The proposed constraint sets–based method is flexible and optimum for the UWB mask. The pulse designed by the proposed method is Federal Communication Commission compliant and has an autocorrelation function similar to the Gaussian pulse. The bit error rate performance of time hopping binary phase shift keying using the proposed method and some of the existing methods such as Norman and Lee pulses and sixth derivative Gaussian pulse is analyzed in additive white Gaussian noise and Saleh‐Valenzuela channels. Pulse designed using the proposed method outperforms existing pulse design, and the same is verified through simulations. The proposed algorithm is flexible and can also be used to mitigate narrow band interference, multiband UWB pulse generation and any other Federal Communication Commission (or other regulatory body) compliant spectrum mask by modifying the parameter of the proposed constraint set(s).

Analytical and Experimental Investigations on Ultrawideband Pulse Width and Shape Effect on the Accuracy of 3-D Localization

This letter presents analytical and experimental investigation of three-dimensional indoor localization accuracy using different subbands of the Ultrawideband (UWB) spectrum. Combined effect of ranging errors of each base station (due to change in pulse width, bandwidth, and UWB source pulse) on 3-D localization using a compact tapered slot antenna is studied. Higher-order Gaussian derivative source pulses (3rd and 7th) are compared to first-order Gaussian derivative theoretically and analyzed in terms of the fidelity of the UWB source pulses; localization accuracy and Cramer–Rao lower bounds have also been calculated to validate the experimental findings. It is observed that 5-GHz bandwidth gives sufficiently high localization accuracy results with an average error of 2–3 cm. Results related to the different UWB source pulse show that the third-order Gaussian derivative signal can be used to enhance (30% increase) the localization accuracy and also preserve a good tradeoff between accuracy and complexity of the UWB system.

DS-UWB pulse design in IEEE802.15.3a multipath fading channel for cognitive radio applications

This paper presents a novel spectrum shaping technique in direct sequence ultra-wideband (DS-UWB) communication systems. This proposed pulse introduces spectral nulls to limit the interference impact of high power coexisting narrowband signals and to elevate the applications of cognitive radio. The idea depends on the addition and subtraction of several UWB Gaussian derivative pulses in order to design a new pulse that has spectral null at the operating frequency of the narrowband interference (NBI) signal. The use of the Gaussian derivative ensures that the UWB spectrum mask established by the Federal Communications Commission (FCC) is met. The NBI signals are modelled as either the wireless local area network (WLAN) IEEE802.11n which operates in the 5 GHz frequency band or multi tone signals. The power spectral density of the proposed transmitted UWB pulse is derived analytically. The bit error rate performance of the proposed pulse is derived in the multi-path IEEE802.15.3a UWB fading channel models and validated with simulations. Results show that the impact of either the IEEE802.11n interference signal or the multi tone interference signals can be effectively suppressed by transmitting and matched filtering the new pulse with a single or multiple spectral nulls at the interference operating frequencies.

Timed Vivaldi arrays for steerable energy pattern with low side lobes

A novel design of timed Vivaldi antenna arrays for steerable energy patterns is presented in this work. Three geometries are studied and designed in order to obtain an optimum energy pattern with low side lobe level (SLL) during beam steering: equally antenna array, unequally antenna array, and concentric ring array. The antenna elements are fed with the fifth derivative Gaussian pulse. The design process is carried out by the well-known sequential quadratic programming. Three design examples with 16 antenna elements are studied by considering different distribution of antenna positions. The mutual coupling phenomenon is considered by full wave simulations of Vivaldi antenna elements in the design examples. The results show a good performance of the steerable energy pattern with low SLL with ultra wideband operation.

Designing an ultra-wideband electromagnetic waves receiver with new architecture for RF and wireless applications

This paper demonstrates an electromagnetic waves receiver (EMWR) with new architecture for finding the good performances at the very wide frequency range of 2.8 to 10.8 GHz. The proposed device applies conventional pulse position modulation (PPM) scheme for modulation. The combination of 8th–8th-order derivative of Gaussian pulse is used as impulse received signal. The EMW receiver circuit with core chip dimension of 32 × 10−3 mm2 was modeled in a 90 nm CMOS technology. The output amplitude pulse yielded 200 mV peak-to-peak under a supply voltage of 2.2 V. This circuit consumes 12 pJ/pulse at 0.5 GHz pulse-repeating frequency. The designed device can be employed in the transceiver systems in presence the multipath channel for 2.8 GHz to 10.8 GHz. Results express that the proposed system not only decrease the interference with narrowband (NB) systems, but is also robust against NB interference at the operating frequency of 7 GHz. Regarding to results, the EMWR can be used in radio frequency (RF) and wireless receiver applications.

Single Link Performance of UWB Systems Based on Cognitive Radio in the AWGN UWB Channel

 Abstract—The single link performance of UWB systems in the AWGN UWB channel is investigated. Based on Cognitive Radio(CR) spectrum allocation and the restriction of Federal Communications Commission (FCC) emission mask, the second derivative Gaussian pulse with the diverse shaping factors and the diverse spectral moving factors act as basis functions. The iterative combination pulse method is put to use to design pulses. The time domain waveform of iterative combination pulse based on FCC signed as UWB system 1. The time domain waveform based on cognitive radio signed as UWB system 2 and UWB system 3. The single link bit error probability (BER) of three different pulse (UWB system 1, UWB system 2 and UWB system 3) for UWB system in Additive White Gaussian Noise (AWGN) channel are simulated and compared. The better performance and stability are validated based on cognitive radio UWB pulse for UWB system.

Very small inductorless 2nd derivative Gaussian IR-UWB transmitter module using n/p-latches as PDs

In this paper, a new design for an impulse radar Ultra-wideband (UWB) module transmitter using a 180 nm CMOS TSMC process is presented. A 2nd order derivative Gaussian pulse is generated using two phase detectors, which consist of an n-latch and a p-latch to generate a single UWB pulse without any filtering and matches the FCC mask. The Gaussian impulse achieves a very small pulse of 259 ps width, ~104 mVpp amplitude, and consumes about 23.3 µW/pulse. The circuit occupies only 36 × 42 μm2 without PADs.

Integration of IR-UWB Services into Single- and Multi-Channel Optical Coherent OFDM Network

Distribution of wireless communication signals over implemented optical networks is a challenged task since the presence of wireless services may affect the performance of the existing wired ones. This paper addresses the possibility of integrating impulse radio-ultrawideband (IR-UWB) wireless services into implemented coherent optical orthogonal frequency division multiplexing (CO-OFDM) network. Simulation results are presented for the transmission of a 625Mb/s UWB  signal with either 50Gb/s single-channel or three-channel OFDM system. Both Gaussian monocycle and 5th-order derivative Gaussian pulses are used to implement  the UWB system with two modulation formats, namely ON-OFF keying (OOK) and biphase modulation (BPM). The simulation results reveal that the performance of the CO-OFDM channels is not affected in the presence of UWB signals.

A CMOS UWB transmitter with Vivaldi Array for Ultra-fast Beam steering microwave radar

This work presents a new Ultra Wide Band (UWB) beamforming fifth-order derivative Gaussian pulse transmitter with dual small Vivaldi antennas for remote acquisition of vital signals in impulse radar applications. The system consists of a programmable delay circuit (PDC or τ), a UWB pulse generator (PG) circuit and an array of two Vivaldi planar antennas. The circuits is designed using the 0.18µm CMOS IBM process. Spice simulations show the pulse generation with 90mVpp amplitude and 300ps width. The average power consumption is 120µW per pulse, using a 2V power supply at a pulse repetition rate (PRR) of 100MHz. Full tridimensional electromagnetic simulations, using CST MWS, show the main lobe radiation with a gain of 5.5dB, and a beam steering between 20º and -17.5º for azimuthal (θ) angles at the center frequency of 7.5GHz.