Direct Digital Synthesis Technology Research Articles

FPGA-based Serial Port-controlled Frequency Adjustable Waveform Generator

This article explores the design, optimization, and applications of FPGA-based Direct Digital Synthesis (DDS) waveform generators. The DDS technology is widely used in signal generation and processing and is favored for its flexibility and precision. The paper discusses performance optimization strategies, focusing on enhancing frequency resolution, waveform quality, and phase accumulation speed. Suggestions include increasing phase accumulator’s bit width, optimizing the size of the phase lookup table, introducing frequency interpolation, and employing fast accumulation algorithms. Additionally, it delves into more applications such as high-precision testing, high-speed communication systems, multi-channel data synchronization, and multi-waveform outputs. The conclusion emphasizes the ongoing need for performance improvements and application advancements. Future directions include exploring higher-precision phase lookup table designs, sophisticated filtering, efficient accumulation algorithms, and leveraging advanced FPGA chips for broader application scope. Overall, FPGA-based DDS waveform generators exhibit significant potential across various domains, promising enhanced signal accuracy and adaptability.

The Design of High Precision Arbitrary Waveform Generator Based on DDS Technology and FPGA

Combining with the IP core advantage of FPGA, a signal generator which can generate arbitrary waveform is designed on the basis of direct digital synthesis technology in this paper. The INTEL company’s Cyclone IV series EP4CE6F17C8N is used as the control core and the front-end interface design is carried out by XMAL. The software control operation of the logical processing interface is realized through C#. The signal generator has the characteristics of single cycle waveform with 256 sampling points, clear spectrum analysis, higher purity and high precision. The arbitrary waveform displayed on oscilloscope is wonderful after filtering out high frequency signal by seven order butter worth filter.

Design and Experiments of a Waveform Generator Based on DDS Technology

Background: Signal generator plays a crucial role in the field of automatic measurement. However, Domestic signal generator usually uses a number of discrete phases locked loop components, whose circuits are usually complex with low precision and are easily affected by the external environment. Objective: Based on direct digital synthesis (DDS) technology, a small sized high precision economic waveform generator with a simple structure and operational convenience is developed. Methodology: The hardware circuit is designed with an AT89S52 controller, and the corresponding peripheral circuit. A DDS integrated chip AD9834 is employed as a signal source, and the modular programming principle with C and assembly language is used to accomplish the software design, through which the sine wave, square wave, triangular wave signals with adjustable amplitude, frequency, and TTL signal with adjustable duty ratio can be generated. Conclusion: The whole system is advantageous with several aspects such as high frequency precision, wide frequency range, and operational convenience. The experimental results show that the stability and reliability of the waveform generator are good with a simple hardware circuit structure.

Fast Chirp Frequency-Modulated Continuous-Wave Reflectometer for Monitoring Fast Varying Discontinuities on Transmission Lines

A portable fast chirp frequency-modulated continuous-wave (FMCW) reflectometer is presented to locate and monitor fast varying discontinuities or faults on transmission lines. This frequency-domain reflectometry (FDR) approach exploits and adapts the advantages of the closely related and frequently employed FMCW radar principle to transmission line reflectometry and overcomes the limitations of commonly used time-domain reflectometry (TDR) methods. The signal generation is based on direct digital synthesis (DDS) and frequency multiplication in order to exploit the advantages of DDS technology, e.g., fast and agile sweep time, and to overcome the drawbacks of analog signal sources related to nonlinearities, temperature sensitivity, or phase noise. By this means, the presented reflectometer provides highly linear, broadband, and fast swept chirp pulses with a duration on the order of microseconds with an initial frequency in the lower UHF-band and a bandwidth of 5.2 GHz. The system concept, its hardware realization, and performance specifications are introduced. The first laboratory test results for static transmission lines and a dynamic measurement setup are presented. The results demonstrate the effectiveness, versatility, and fine ranging capabilities on the order of 2 cm of this approach.

Digitally-controlled driving power supply for dual-active-valve piezoelectric pump

The dual-active-valve piezoelectric pump (DAVPP) can achieve a precise and bidirectional delivery of liquid with flexibility through multiple control methods. Compared with the unidirectional piezoelectric pump, DAVPP has broader application prospects. For instance, for medical applications, DAVPP is promising to complete blood sample collection as well as drug injection in minute and accurate quantities, further to realize the integration between automatic diagnosis and disease treatment. The objective of this work is to keep DAVPP in operation with an innovative newly developed digitally-controlled driving power supply. First, a direct digital synthesis technology was adopted to generate two sine signals with an adjustable frequency and a phase difference. Then, a T-type resistor network was applied to regulate the voltage. Finally, high-voltage and power amplifying unit was utilized to achieve a sufficient driving ability. A prototype of the supply was made and its driving characteristics were tested in experiments. Experimental results demonstrate that the sine waveform output is satisfactory, the maximum voltage is up to 175 V, the frequency range is 5–500 Hz with a minimum resolution of 1 Hz, and the phase difference can be regulated from 0° to 360° with a minimum resolution of 11.25°, which perfectly matches the driving requirements of DAVPP. Control variables of DAVPP (namely driving voltage, frequency and phase difference) can be adjusted independently and continuously. By adjusting the driving phase difference, the direction of a liquid delivery can be changed, meanwhile, the output flow rate and output pressure can also be modulated smoothly.

UHF Band High-Speed CP-2FSK Modulator’s Design

Aimed at requirements of signal transmission rate in the UAV data link, the UHF band CP-2FSK modulator design method based on Direct Digital Synthesis technology is given, and hardware circuit implementation of the UHF band CP-2FSK functions, get UHF band modulation signal CP-2FSK of code rate up to 67.2 Mbps baseband signal. The transmission experiments of the image signal in UAV data link had been achieved. It suggested the modulator has many advantages such as low power consumption, high output frequency, high transmission rate, occupied channel bandwidth. It meets the design requirements of the UAV data link telemetry data transmission and achieve high-speed transmission UAV telemetry data downlink.

Design of Dual High Precision Power Signal Generator Based on AD9854

To obtain the dual high-precision numerical control signal source, and could be accurately adjusted the dual signals frequency and phase and increase the output signal power, the paper presented a method based on direct digital synthesis technology and parallel push-pull output, designed and implemented the dual channel high-precision and high power signal generator. MSP430 controlled AD9854 registers to realize frequency and phase modulation, after low-pass filter to adjust the square wave duty cycle by the DAC7612, amplitude was integrated optimization adjustment by AD9854 AD603 and power amplifier. Consideration the anti-jamming measures, the system is stable and reliable, and can output high-precision and high power sine and square wave in the 5-150kHz frequency band, signal frequency, phase, amplitude and duty cycle can numerical control. In addition, it has sweep output mode.

Design and Implementation of Signal Generator Based on DDS

A signal generator with adjustable frequency, phase and duty cycle is designed in this paper. The design of this signal generator is based on the technology of direct digital synthesis (DDS).The classic structure of DDS is presented and its principles are introduced in detail. The key modules of the design such as phase accumulator and pulse width processing are implemented by verilog HDL language. With suitable FPGA, the designed signal generator and all modules of the design are simulated successfully in Quartus II.

Design and Simulation of 2PSK Modem

Based on the principle of the modulation and demodulation of Binary Phase Shift Keying(2PSK),a mathematical model for the modulation and demodulation of the 2PSK was built and the carrier signal was designed using the technology of Direct Digital Synthesis (DDS).Then,a model to simulate the hardware circuit of the modulation and demodulation of 2PSK was built,and then analyzed in Matlab and Modelsim.Simulation results show that the model not only properly realizes the function of 2PSK modulator-demodulator,but it also simplifies the hardware circuit and reduces the programming time.

Driver Design of the Piezoelectric Ultrasonic Transducer for Wire Bonding Based on Direct Digital Synthesis Technology

In order to design a driver of piezoelectric ultrasonic transducer which can provide high quality ultrasonic signal and be able to realize the frequency tracking rapidly, accurately and intelligently during the bonding process, the ATmega128 microcontroller and AD9851 synthesizer are selected as core components to build an ultrasonic generator and frequency tracking system. The basic circuit units including low pass filter, power amplifier, signal detection and conversion circuits are also established. The test results of the system shows that, based on DDS technology, high quality ultrasonic signal for transducer can be achieved. By combining the two kinds of frequency tracking methods, the system can realize the frequency tracking during the bonding process. It also indicates that the design significantly improve the precision and flexibility of the ultrasonic generator system.

A Novel Method to Calculate Frequency Control Word of Direct Digital Synthesizer

When designing signal generator with adjustable frequency based on direct digital synthesis technology (DDS), it is very important to calculate the frequency control word. To address the shortcoming of large computation, low efficiency of frequency setting, more storage space occupied or significant cumulative errors of frequency setting when calculating frequency control word with traditional methods, a novel calculation way for frequency control word is researched in this paper. This new method does not need large computation and more space and simultaneously it can decrease the error greatly, which plays an important role in improving the frequency setting speed and precision in signal generator.

Design and implement of the signal generator in the magnetic focused conductivity tomography system

To improve stability and performance of the signal source and sweeping detection, as well as to extract abundant and reliable signal, the direct digital synthesis technology was employed to design the generator of the source which formed sweeping frequencies of sine wave output from 1 to 20 MHz. The planar spiral coil was connected as an amplitude modulation circuit. The same coil adopted differential architecture for signal detection and extraction. The MC1595 was utilized to compose a phase detector in which difference of phases varies with the change of frequencies. A low pass filter was designed to filter the carry waves of the sweeping source. Thereby the system gained abundant data and its stability was improved. Further, the spatial resolution of the system was enhanced. All of the above favors the use of software in the magnetic focused conductivity tomography system (MFCT) to reconstruct the image of conductivity within the human body.

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