PLL wrap function for synchronization in phase jump disturbances

Synchrony plays a major role in the interconnection process between local electric power generation systems and the electrical grid. Grid phase disturbances prevent the generation system from maintaining synchrony. Therefore, an efficient phase tracking method is necessary in order to detect phase jumps and abrupt changes in amplitude. In this paper, we propose a software-designed method to strengthen phase tracking based on the wrap process of a second-level Phase Locked Loop (PLL). The term ‘wrap’ means establishing the phase values of the reference signal in intervals of π to match it with the values obtained from the PLL output (sync pulse). To quantify phase error, a mathematical transformation of the time domain to the frequency domain is implemented. The validity of the proposed wrap function is verified using electrical disturbances.

FPGA implementation of power on self-test towards combo card

The Combo Card is a legacy trunk and subscriber card which provides loop dialing, MAGNETO, FXS, FXO, E&M and SHDSL two wire ports. The Purpose of this Card is to Facilitate Voice and Data Services for the User in Small Deployment. This Module is going to be plugged into Line Card V3 and used in TDM Router. As an FPGA Engineers, Our main Focus is on FPGA part on this SERVICES CARD. We are Using Spartan-6 FPGA in this Project. The Name COMBO CARD isCame into Existence as we are Combining Many Interfaces viz., FXS, FXO, LD, E & M, Magneto, and SHDSL. In this study We are Dealing With Respect to FPGA by Using VHDL and Generating Clock and Sync Pulse 8.192 M Hz Generation for FXO and FXS, SHDSL Control Pin Mapping, Power on Self-Test With Respect to Clock Monitor and Generation of Reset Pulse 300us For all the Devices Connected to FPGA, So, that the Title FPGA Implementation of Power on Self-Test On Services Card Justifies.

RESEARCH OF RELATION OF SAMPLERS FREQUENCY CHARACTERISTICS / STROBAVIMO ĮTAISO DAŽNINIŲ CHARAKTERISTIKŲ SĄRYŠIO TYRIMAS

This paper proposes an algorithm to reduce limitations in band-width measurements of sampling oscilloscopes then using a swept sine-wave measurement method. The traditional swept sine-wave method allow measure only magnitude response. Phase response can be computed only if a sampler is a minimal phase circuit. In this paper alternative bandwidth measurement algorithm using the nose-to-nose method with measurements corrections for the non-idle properties of oscilloscope is de-scribed. Algorithm includes for noise, time base distortions and jitter in measurement signals corrections methods. Proposed algorithm allows to measure phase and magnitude responses when only two similar oscilloscopes and the source of sync pulse are used. Algorithm performs as well as the swept sine-wave method in case when both samplers have the same frequency characteristics. Stroboskopiniai osciloskopai skirti matuoti sparčius periodinius signalus naudojant sąlyginai nesparčius didelio skiltiškumo analoginius-skaitmeninius keitiklius. Vienas iš pagrindinių stroboskopinio osciloskopo mazgų, užtikrinančių, kad osciloskopo charakteristikos atitiktų metrologinius reikalavimus, ir kuriame vyksta matuojamo aukštadažnio signalo spektro transformacija į žemų dažnių sritį, yra strobavimo įtaisas. Šiame darbe pateikiamas strobavimo įtaiso veikimo principas, nagrinėjami įtaiso dažninių charakteristikų matavimo būdai taikant pastovios amplitudės, kintančio dažnio harmoninio virpesio ir priešpriešiais sujungtų strobavimo grandinių metodus. Gauti rezultatai rodo, kad nagrinėjamas strobavimo įtaisas nepriklauso minimalios fazės grandinių klasei ir apskaičiuoti įtaiso dažninę fazės charakteristiką (DFCh) iš dažninės amplitudės charakteristikos (DACh) neįmanoma, tačiau taikant priešpriešiais sujungtų strobavimo grandinių matavimo metodą galima gauti įtaiso DACh ir DFCh nenaudojant papildomos aukštadažnės matavimo įrangos ir mažinant matavimo proceso trukmę.

EWR Research on PZT Excited Discharge Channel Compression Micro-EDM

In micro-EDM machining process, the debris of materials is difficult to be removed form the discharging gap. This problem leads the instability of discharge state, and reduces the efficiency of discharge machining. A new method of PZT incentive synchronous compression discharge channel micro-EDM is developed based on the inverse piezoelectric effect of PZT ceramics, driving by a spark discharge and PZT sync pulse power. The composition of the system is described and many experiments have been done and the effects of parameters on electrode wear ratio (EWR) have been analyzed in this paper. The results indicated that increasing the voltage and width of pulse can lower the rate of electrode wear, increase the efficiency of electric-machining, while increasing the frequency of discharge pulse can lead the increasing of EWR.

Study on Timing Recovery Loop Filter of the Digital Communication System

The digital communication system; timing recovery loop for research, is mainly directed against the application performance and design. Through a variety of different loop filter test were carried out and positioning. The invention of a universal filter, and the filter and the original combined to form a new loop filter. The timing recovery loop searching and positioning performance is passed through the filter in the sync pulse and conversion. The experimental results show, as long as certain conditions, the new loop filter in 64 symbols within the time to achieve the positioning, and a good effect on. The filter has the advantages of simple structure. In a digital receiver demodulation, the A / D converter timing recovery can achieve the best state of digital receiver demodulation performance. When the timing recovery frequency is low, the bit error rate performance has certain effect. [ Through the analog-digital hybrid timing recovery circuit and digital timing recovery circuit is studied. Digital timing recovery circuit is compared with the mixed analog digital timing recovery circuit is easy to design, and little noise when running. Therefore the digital timing recovery circuit is studied.

Research of PZT Excited Discharge Channel Compression Micro-EDM Techniques

In micro-EDM, the debris generated in machining process is difficult to be moved from the discharging gap, the discharge state is instability, and the material removal rate is low. A new method of PZT incentive synchronous compression discharge channel micro-EDM is presented based on the inverse piezoelectric effect of PZT piezoelectric ceramics, using a spark discharge and PZT sync pulse power. In this paper, the system composition and machining principles are described in detail, and its machining mechanism is analyzed in terms of the experiments. By the experiments, it is certificated that on the process of PZT sync compressing discharge channel machining, the state of discharge gap, the machining efficiency and quality can be improved, the throw out of debris makes easier, and then the stability of micro-EDM process is raised, which indicated that this new technology has wide application prospect in the field of micro manufacturing.