Optical arbitrary waveform generator for radar applications

Comprehensive waveform generation is an important functional component of automated test equipment (ATE). Waveform generators synthesize signal stimuli to be applied to a device under test (DUT). As military and commercial electronics become increasingly complex, more sophisticated signal stimuli are required. ATE requires signal stimuli varying from advanced communication signals to the playback of captured real-world analog signals. Waveform generators can synthesize signals that can be broadly categorized into four types: standard functions, advanced functions, arbitrary waveforms, and waveform sequences. Standard functions include the simple sine, square, triangle, pulse, and ramp waveforms. Advanced functions include complex signals such as multi-tone, AM, FM, sinc pulse, haversine, half-cycle sine, Gaussian pulse, Lorentz pulse, noise and others. Arbitrary waveforms involve the point-by-point user-defined waveform synthesis. Waveform sequences provide a mechanism to piece together standard or arbitrary waveforms in stages to create a user-defined compound waveform. Example applications for each of these four waveform categories are described in this paper. Modern waveform generators are extremely powerful, but can also add significant complexity for the user. The arbitrary waveform generator, an instrument found in most ATE systems, is a very powerful signal synthesis tool. Unfortunately, many users take advantage of only a small fraction of the powerful features available to them in an arbitrary waveform generator. Also, selecting the right arbitrary waveform generator can be daunting when comparing specifications such as DAC resolution, clock rates and topology, memory depth, sequencing, sweeping, triggering and synchronization. This paper describes the technical differences between various signal generation techniques, presents the signal fidelity impact of clock topology, discusses dynamic range limitations due to noise, accuracy and resolution, and provides typical applications to illustrate signal generation usage. Ultimately, this information should help the user avoid common pitfalls in applying waveform generators within ATE.

DAC-board based X-band EPR spectrometer with arbitrary waveform control

We demonstrate fast optical arbitrary waveform generation by using the MEMS digital micromirror arrays. The desired radio-frequency waveforms are achieved by properly shaping the spectrum of the broadband optical source via using micromirror arrays as a digital spatial light modulator preceded by wavelength-to-time mapping through the dispersive medium. We obtain up to 280-MHz sawtooth and 200-MHz square waveforms that can be controlled by using 1024 × 768 mirror arrays in the preliminary experimental results. Based on currently available digital mirror technologies, we estimate that arbitrary waveforms up to 1-GHz rate and reconfigurable in ~ 30 μs are achievable by using the proposed approach.

An optoelectronic arbitrary-waveform generator has been proposed and experimentally developed for radar applications. It permits generating predefined waveforms by driving the amplitudes and phases of optically carried microwave signals. The optical architecture combines a high- resolution frequency shifter (for the heterodyne generation of the microwave signal) with spatial light modulators (for the parallel control of amplitudes and phases). Such a waveform generator can be attractive for target recognition or for target simulation.

The paper design a good performance arbitrary waveform generator with AD’s digital-analog chip AD760 as the core. Thesis mainly research hardware and software design of computer-controlled arbitrary waveform generator for the corresponding. Hardware part of the arbitrary waveform generator take Cygnal’s high-speed micro-controller C8051F310 micro-controller as the controller and AD760 circuit components of the design. We carried out anti-jamming design when hardware design, Including filtering, spare part handling of input pin, grounded, the power handling. The paper also describes a total distortion of periodic arbitrary waveform definition and evaluation process and methods, the energy is calculated using the time domain distortion, and the influence of the measurement system itself is compensated. This method can be used for arbitrary waveform generator arbitrary waveform distortion for accurate measurement and measurement calibration.

The arbitrary waveform generator plays a very important role in the design and testing of electronic products, and the virtual instrument provides a new direction for the development of arbitrary waveform generator. The traditional waveform generator is improved by LabVIEW in the paper, and the virtual arbitrary waveform generator is designed by the graphical programming.The system can generate the common basic function signals, generate arbitrary waveform signal through superposition of signal and addition of noise signal, and realize the signal storage and transmission. It can easily realize the continuous upgrading and improvement of the system function and output of the customized signal waveform, and provide convenience for design and measurement.

We propose and demonstrate a silicon-on-insulator (SOI) on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for all taps are controlled by an external thermal source, resulting in an optical pulse shaper. We further demonstrate optical arbitrary waveform generation based on the optical pulse shaper assisted by an optical frequency comb injection. Four different optical waveforms are generated when setting the central wavelengths at 1533.78 nm and 1547.1 nm and setting the thermal source temperatures at 23 °C and 33 °C, respectively. Our scheme has distinct advantages of compactness, capability for integrating with electronics since the integrated silicon waveguide is employed.

: By combing the ultra-fast ( 100 GHz) near-ballistic uni-traveling carrier photodiode (NBUTC-PD) and advanced optical pulse shaper system, we demonstrate the photonic generation and detection of (near) real-time arbitrary waveform at W-band with ultra-high time-bandwidth product. By use of such setup, remote-ranging (5 meters) at Wband with fine resolution ( 5 mm), has also been successfully achieved.

Photonic generation and processing of microwave arbitrary waveforms has been a topic of interest recently. Compared with the electronic techniques, photonics techniques provide the capabilities of generating and processing high-frequency and large-bandwidth microwave waveforms which cannot be fulfilled by the electronic techniques, In this paper, techniques to generate and process microwave arbitrary waveforms in the optical domain using advanced fiber Bragg gratings (FBGs) are reviewed, with an emphasis on the system architectures in which FBGs are employed as spectral shapers or optical filters. The challenges in using FBGs for microwave arbitrary waveform generation and processing are also discussed.

Based on the detailed analysis of the Virtual instrument technology and Arbitrary Waveform Generator technology, Arbitrary Waveform Generator module based on VXI bus is discussed. The design principle and realization method of Arbitrary Waveform Generator based on VXI bus are given, which involved in VXI bus register based interface and Direct Digital Synthesis, furthermore, Arbitrary Waveform Generator module based on VXI bus is developed successfully. The experiment shows that the developed Arbitrary Waveform Generator based on VXI bus can generate the normal waveform and the arbitrary waveform, and can implement the adjustment of frequency, amplitude and phase.

Benefitting from a large bandwidth and compact configuration, a time-domain pulse-shaping (TPS) system provides possibilities for generating broadband radio frequency (RF) arbitrary waveforms based on the Fourier transform relationship between the input–output waveform pair. However, limited by the relatively low sampling rate and bit resolution of an electronic arbitrary-waveform generator (EAWG), the diversity and fidelity of the output waveform as well as its reconfiguration rate are constrained. To remove the EAWG’s limitation and realize dynamic real-time reconfiguration of RF waveforms, we propose and demonstrate a novel approach of RF arbitrary-waveform generation based on an improved TPS system with an integrated dual parallel Mach–Zehnder modulator (DPMZM) and multi-tone inputs. By appropriately adjusting the DC bias voltages of DPMZM and the power values, as well as the center frequencies of the multi-tone inputs, any desired RF arbitrary waveform can be generated and reconfigured in real time. Proof-of-concept experiments on the generation of different user-defined waveforms with a sampling rate up to 27 GSa/s have been successfully carried out. Furthermore, the impact of modulation modes and higher-order dispersion on waveform fidelity is also discussed in detail.

Optical arbitrary waveform generation (OAWG) plays a critical role in many applications, such as generating optical ultra-wide band (UWB) signal, optical pulse radar, all-optical temporal differentiator, and test of optical communication system. Although lots of OAWG schemes were reported using mature fiber grating techniques, one of the most promising solutions is prone to be the miniaturization and integration with photonic integrated circuits, such as using indium phosphide (InP) platform, silica on silicon, silicon nitride or silicon platform. In this talk, we review our recent progress on some OAWG schemes using silicon platform and their applications in photonic computing. First, we report an OAWG and high-order photonic differentiator based on a four-tap FIR silicon integrated circuit. By thermally controlling the amplitude and phase of each tap, we obtain several typical waveforms such as triangular waveform, sawtooth waveform, square waveform and Gaussian waveform, etc. Furthermore, we demonstrate first-, second- and third-order differentiation based on the optical pulse shaper, whose spectra were tailored to the transfer functions of temporal differentiators. Especially, our scheme can switch the differentiator patterns from first- to third-order freely on a fixed photonic chip, and this is unable in our previous works such as cascaded microrings or cascaded Mach-Zehnder interferometers (MZIs). Second, we demonstrate radio-frequency arbitrary waveform generation using temporal synthesis. We compare two schemes of cascaded microring resonators and finite impulse response. There functional photnic chip has only millmeter size, low power consumption, and high frequency response. Third, we will demonstrate an OAWG scheme based on superposition of differentiated waveforms. Compared to the first two schemes, this one shows a more compact size and a more flexible operation.

Today a growing number of applications in design engineering, production and environmental testing, and system service require specific analog waveforms and digital patterns. Such requirements are neither satisfactorily nor easily met by the use of standard function or single purpose, custom generators. Traditional methods of waveform generation suffer from undesirable complexity or mediocre performance and are otherwise limited. For the majority of arbitrary waveform generation applications, including medical engineering, modal analysis and electronic engineering, direct digital synthesis techniques are satisfactory. Direct digital synthesis, based generally on periodic retrieval of predetermined amplitude values, may be used to 2 generate such waveforms. Within the limits imposed by the system's maximum sample rate and the Nyquist criteria, any waveform may be produced using these techniques. The objective of this inquiry, within a particular set of constraints, is to extend the cost/performance envelope of direct digital synthesis techniques for the generation of arbitrary waveforms. Performance is enhanced, particularly in the areas of output bandwidth and signal purity.

The Arbitrary Waveform Generator (AWG) is an important instrument that is widely used in automatic test equipment, radar system, and other fields for generating complex signals. The increasing demand for waveform's complexity is consisted of repeatable segments and advanced-segments, where each segment or segments group could be repeated multiple times. Those requirements make the existing design, implemented by an address generator, complex. The software defined technology can separate the instruction sequence processing from the Data plane to the Controller where the complex logic is defined by software, which lead to a simplified data plane. This paper proposes a design that will generate complex arbitrary waveform by decoupling the waveform composing logic in address generator out from the data plane as an instruction controller. The controller support instruction sequence defined by segment and a jump instruction, which can implement the repeatable segments and the advanced-segments, respectively. We built an AWG based on this design and made the implementation in a field programmable gate array with a required clock frequency of 125 MHz. The design has a high sampling rate of 4 gigabit samples per second and can generate complex arbitrary waveform consisting of repeatable segments and advanced-segments.

We are developing an arbitrary waveform generator (AWG) to provide enhanced capability for radar applications. The current design accommodates two waveform generators on a single unit for dual frequency operation. The basic architecture of this unit employs a field programmable gate array (FPGA) and a high speed and high precision digital to analog converter (DAC) for direct digital synthesis. This AWG is capable of up to 450 MHz bandwidth with ability for frequency notching. Phase fidelity of better than 1.2/spl deg/ deviation RMS is also achievable. This AWG operates with lower power consumption as compared with other waveform generators, which is advantageous for future spaceborne applications. This will enable radars to return higher precision data, to be reduced in complexity, and to operate in any band without interfering with dedicated bandwidths.