便攜式信號采集在機器健康診斷系統中有較高的應用價值。機器健康診斷的信號特點是包括低頻信號。本文研究是為了實現簡易而且低成本的低頻便攜式信號采集。以Microchip公司單片機PIC18F1320為核心設計信號采集電路，實現了信號的采集和保存。系統采用串行電可擦除芯片24LC32A保存數據，經過有線通信，信號數據由串行口通過MAX232芯片輸送到微型計算機接收和保存，最后繪制出信號波形。 微型計算機程序采用Visual Basic編程。研究成功采樣頻率為3 kHz的復雜信號，證明該方案符合設計要求。
Abstract:
Portable signal acquisition is useful in machine health monitoring systems. The signal characteristics of machine health monitoring includes low frequency signals. The goal of this study is to realize simple, inexpensive and portable low frequency signal sampling. This paper provides the project of signal acquisition system design based on PIC18F1320 microcontroller manufactured by the Microchip Technology Incorporation to achieve signal sampling and storage. The system adopted EEPROM 24LC32A to store the signal data. The microcomputer received data via wired link with the MAX232 IC through the serial port. The microcomputer program, programmed in Visual Basic, received the data, stored it and plotted the signal. The study successfully samples 3kHz complicated signals and thus meets the design requirement.
Abstract: While many questions still surround the creation and deployment of the smart grid, the need for a reliablecommunications infrastructure is indisputable. Developers of the IEEE 1901.2 standard identified difficult channel conditionscharacteristic of Low-frequency powerline communications and implemented an orthogonal frequency division multiplexing (OFDM)architecture using advanced modulation and channel-coding techniques. This strategy helped to ensure a robust communicationsnetwork for the smart grid.
Random Number Generators（隨機數生成）包括gaussian random number generator、uniform random number generator、Low-frequency hold generator、1/f noise generator等5種隨機信號生成的c源代碼
his project was built and tested with WinAVR-20060125.
Make sure the MCU target define in the Makefiles corresponds to the AVR you are using!!
To build the code, just install WinAVR and run "make" from the console in echomaster and
echoslave subdirs.
"make program" will program the device if you have a AVRISP attached.
Remember to set the AVR device to at least 8MHz. The AVR may use the programmable clock
from MC1319x, just remember to check if the MC1319x and SPI communication is working FIRST!
Otherwise you wont get any clock signal to the AVR and then you can t program it or reset
the fuses!
The MC1319x has default clock output of 32kHz so you will have to set your programmer to
a very low frequency (<=32kHz/4) to be able to program it while it is running on that!
摘要：本系統以ICL8038集成塊為核心器件，制作一種函數信號發生器，制作成本較低。適合學生學習電子技術測量使用。ICL8038是一種具有多種波形輸出的精密振蕩集成電路，只需要個別的外部元件就能產生從0.001Hz~30KlHz的低失真正弦波、三角波、矩形波等脈沖信號。輸出波形的頻率和占空比還可以由電流或電阻控制。另外由于該芯片具有調制信號輸入端，所以可以用來對低頻信號進行頻率調制。關鍵詞：函數信號發生器頻率調制Abstract：The system ICL8038 integrated block as the core device，producing a kind of function signal generator，producing low cost.Suitable for students to learn the use of electronic technology measurement.ICL8038 is a kind of multi-precision oscillator waveform output integrated circuits，a separate external components only need to be able to generate from the 0.001Hz ~30KHz low-distortion sine wave，triangle wave，square wave pulse signal，etc..Output waveform of the frequency and duty cycle can also be controlled by a currentor resistance.In addition，as the chip has a modulated signal input terminal，it can be used to Low-frequency signal is frequency modulation.
Image enhancement in frequency domain using Fourier center frequency, Gaussian lowpass filter, Low pass filter, high pass filter. Image restoration using medean filter, weiner filter with noise generator such as Gaussian noise, Salt and Pepper noise
The LM158 series consists of two independent, high gain,
internally frequency compensated operational amplifiers
which were designed specifically to operate from a single
power supply over a wide range of voltages. Operation from
split power supplies is also possible and the low power
supply current drain is independent of the magnitude of the
power supply voltage.
We address the problem of blind carrier frequency-offset (CFO) estimation in quadrature amplitude modulation,
phase-shift keying, and pulse amplitude modulation
communications systems.We study the performance of a standard
CFO estimate, which consists of first raising the received signal to
the Mth power, where M is an integer depending on the type and
size of the symbol constellation, and then applying the nonlinear
least squares (NLLS) estimation approach. At low signal-to noise
ratio (SNR), the NLLS method fails to provide an accurate CFO
estimate because of the presence of outliers. In this letter, we derive
an approximate closed-form expression for the outlier probability.
This enables us to predict the mean-square error (MSE) on CFO
estimation for all SNR values. For a given SNR, the new results
also give insight into the minimum number of samples required in
the CFO estimation procedure, in order to ensure that the MSE
on estimation is not significantly affected by the outliers.
The MAX2691 low-noise amplifier (LNA) is designed forGPS L2 applications. Designed in Maxim’s advancedSiGe process, the device achieves high gain andlow noise figure while maximizing the input-referred 1dBcompression point and the 3rd-order intercept point. TheMAX2691 provides a high gain of 17.5dB and sub 1dBnoise figure.
