Delta-sigma ADCs, with their high accuracy and high noiseimmunity, are ideal for directly measuring many typesof sensors. Nevertheless, input sampling currents canoverwhelm high source impedances or low-bandwidth,micropower signal conditioning circuits. The LTC®2484family of delta sigma converters solves this problem bybalancing the input currents, thussimplifying or eliminatingthe need for signal conditioning circuits.
在Multisim 10軟件環(huán)境下，設(shè)計(jì)一種由運(yùn)算放大器構(gòu)成的精確可控矩形波信號(hào)發(fā)生器，結(jié)合系統(tǒng)電路原理圖重點(diǎn)闡述了各參數(shù)指標(biāo)的實(shí)現(xiàn)與測試方法。通過改變RC電路的電容充、放電路徑和時(shí)間常數(shù)實(shí)現(xiàn)了占空比和頻率的調(diào)節(jié)，通過多路開關(guān)投入不同數(shù)值的電容實(shí)現(xiàn)了頻段的調(diào)節(jié)，通過電壓取樣和同相放大電路實(shí)現(xiàn)了輸出電壓幅值的調(diào)節(jié)并提高了電路的帶負(fù)載能力，可作為頻率和幅值可調(diào)的方波信號(hào)發(fā)生器。Multisim 10仿真分析及應(yīng)用電路測試結(jié)果表明，電路性能指標(biāo)達(dá)到了設(shè)計(jì)要求。
Abstract:
Based on Multisim 10， this paper designed a kind of rectangular-wave signal generator which could be controlled exactly composed of operational amplifier， the key point was how to implement and test the parameter indicators based on the circuit diagram. The duty and the frequency were adjusted by changing the time constant and the way of charging and discharging of the capacitor， the width of frequency was adjusted by using different capacitors provided with multiple switch， the amplitude of output voltage was adjusted by sampling voltage and using in-phase amplifier circuit，the ability of driving loads was raised， the circuit can be used as squarewave signal generator whose frequency and amplitude can be adjusted. The final simulation results of Multisim 10 and the tests of applicable circuit show that the performance indicators of the circuit meets the design requirements.
內(nèi)容如下：
1.The history of the computerized database
2.SQL Data Statements--those used to create, manipulate, and retrieve data stored in your database example statements include select, update, insert, and delete
3.SQL Schema Statements--those used to create database objects, such as tables, indexes, and constraints
4.How data sets can interact with queries
5.The importance of subqueries
6.Data conversion and manipulation via SQL s built-in functions
7.How conditional logic can be used in Data Statements
to show the waveform of audio file and play it on computer
Purpose: Familiar with WAV file format and UI design
It should have the following functions:
Provide a Graphic User Interface for user to browse the file system and select one WAV file
Show the waveform of input audio signal
Play the selected WAV file
Print the parameters of WAV file such as sampling rate, bit-depth, etc
Routine mampres: To obtain amplitude response from h(exp(jw)).
input parameters:
h :n dimensioned complex array. the frequency response is stored
in h(0) to h(n-1).
n :the dimension of h and amp.
fs :sampling frequency (Hz).
iamp:If iamp=0: The Amplitude Res. amp(k)=abs(h(k))
If iamp=1: The Amplitude Res. amp(k)=20.*alog10(abs(h(k))).
output parameters:
amp :n dimensioned real array. the amplitude-frequency response is
stored in amp(0) to amp(n-1).
Note:
this program will generate a data file "filename.dat" .
in chapter 2
The EM algorithm is short for Expectation-Maximization algorithm. It is based on an iterative optimization of the centers and widths of the kernels. The aim is to optimize the likelihood that the given data points are generated by a mixture of Gaussians. The numbers next to the Gaussians give the relative importance (amplitude) of each component.
Rotating shafts experience a an elliptical motion called whirl. It is important to decompose this motion into a forward and backward whil orbits. The current function makes use of two sensors to generate a bi-directional spectrogram. The method can be extended to any time-frequency distribution
％
％ compute the forward/backward Campbell/specgtrogram
％
％ INPUT:
％ y (n x 2) each column is measured from a different sensor
％ ///////
％ __
％ |s1| y(:,1)
％ |__|
％ __
％ / \ ________|/
％ | | | s2 |/ y(:,2)
％ \____/ --------|/
％
％ Fs Sampling frequnecy
％
％ OUTPUT:
％ B spectrogram/Campbel diagram
％ x x-axis coordinate vector (time or Speed)
％ y y-axis coordinate vector (frequency [Hz])
Surface profile measurement by noncontact optical methods has been extensively studied because of its importance in automated manufacturing, component quality control, medicine, and robotics. In most of these methods a known periodic pattern,
To estimate the input-output mapping with inputs x
％ and outputs y generated by the following nonlinear,
％ nonstationary state space model:
％ x(t+1) = 0.5x(t) + [25x(t)]/[(1+x(t))^(2)]
％ + 8cos(1.2t) + process noise
％ y(t) = x(t)^(2) / 20 + 6 squareWave(0.05(t-1)) + 3
％ + time varying measurement noise
％ using a multi-layer perceptron (MLP) and both the EKF and
％ the hybrid importance-samping resampling (SIR) algorithm.
Easy-to-Use, Ultra-Tiny, Differential, 16-Bit Delta Sigma ADC With I2C Interface
The LTC2453 is an ultra-tiny, fully differential, 16-bit, analog-to-digital converter. The LTC2453 uses a single 2.7V to 5.5V supply and communicates through an I2C interface. The ADC is available in an 8-pin, 3mm x 2mm DFN package. It includes an integrated oscillator that does not require any external components. It uses a delta-sigma modulator as a converter core and has no latency for multiplexed applications. The LTC2453 includes a proprietary input sampling scheme that reduces the average input sampling current several orders of magnitude lower than conventional delta-sigma converters. Additionally, due to its architecture, there is negligible current leakage between the input pins.
