This simulation script set allows for an OFDM transmission to be
simulated. Imagetx.m generates the OFDM signal, saving it as a
windows WAV file. This allows the OFDM signal to be played out a sound
card and recorded back. Imagerx.m decodes the WAV to extract the
data.
A wireless communication network can be viewed as a collection of nodes, located in some domain, which
can in turn be transmitters or receivers (depending on the network considered, nodes may be mobile users,
base stations in a cellular network, access points of a WiFi mesh etc.). At a given time, several nodes
transmit simultaneously, each toward its own receiver. Each transmitter–receiver pair requires its own
wireless link. The signal received from the link transmitter may be jammed by the signals received from
the other transmitters. Even in the simplest model where the signal power radiated from a point decays in
an isotropic way with Euclidean distance, the geometry of the locations of the nodes plays a key role since
it determines the signal to interference and noise ratio (SINR) at each receiver and hence the possibility of
establishing simultaneously this collection of links at a given bit rate. The interference seen by a receiver is
the sum of the signal powers received from all transmitters, except its own transmitter.
·詳細(xì)說明：雙音多頻的DTMF信號(hào)編碼程序，產(chǎn)生DTMF信號(hào)進(jìn)行編碼。- The double sound multi- frequencies DTMF signal coded program, produces the DTMF signal to carry on the code.
Many applications require a clock signal to be synchronous, phase-locked, or derived fromanother signal, such as a data signal or another clock. This type of clock circuit is important in
Photodiodes can be broken into two categories: largearea photodiodes with their attendant high capacitance(30pF to 3000pF) and smaller area photodiodes withrelatively low capacitance (10pF or less). For optimalsignal-to-noise performance, a transimpedance amplifi erconsisting of an inverting op amp and a feedback resistoris most commonly used to convert the photodiode currentinto voltage. In low noise amplifi er design, large areaphotodiode amplifi ers require more attention to reducingop amp input voltage noise, while small area photodiodeamplifi ers require more attention to reducing op amp inputcurrent noise and parasitic capacitances.
A fully differential amplifi er is often used to converta single-ended signal to a differential signal, a designwhich requires three signifi cant considerations: theimpedance of the single-ended source must match thesingle-ended impedance of the differential amplifi er,the amplifi er’s inputs must remain within the commonmode voltage limits and the input signal must be levelshifted to a signal that is centered at the desired outputcommon mode voltage.
為了使音頻信號(hào)分析儀小巧可靠，成本低廉，設(shè)計(jì)了以2片MSP430F1611單片機(jī)為核心的系統(tǒng)。該系統(tǒng)將音頻信號(hào)送入八階巴特沃茲低通濾波器，對(duì)信號(hào)進(jìn)行限幅放大、衰減、電平位移、緩沖，并利用一單片機(jī)負(fù)責(zé)對(duì)前級(jí)處理后的模擬信號(hào)進(jìn)行采樣，將采集得到的音頻信號(hào)進(jìn)行4 096點(diǎn)基2的FFT計(jì)算，并對(duì)信號(hào)加窗函數(shù)提高分辨率，另一單片機(jī)負(fù)責(zé)對(duì)信號(hào)的分析及控制顯示設(shè)備。此設(shè)計(jì)精確的測(cè)量了音頻信號(hào)的功率譜、周期性、失真度指標(biāo)，達(dá)到較高的頻率分辨率，并能將測(cè)量結(jié)果通過紅外遙控器顯示在液晶屏上。
Abstract:
o make the audio signal analyzer cheaper， smaller and more reliable， this system sends the audio signal to the eight-order butterworth filter， and then amplifies， attenuates， buffers it in a limiting range， transfers the voltage level of the signal before utilizing two MSP430F1611 MCU to realize the audio analysis. One is charged for sampling and dealing with the processed audio signal collected by the 4096 point radix-2 FFT calculation and imposes the window function to improve the frequency resolution. The other one controls the display and realizes the spectrum， periodicity， power distortion analysis in high resolution which is displayed in the LCD screen through the infrared remote control.
介紹一種以Atmel公司的Attiny13為處理器的投影儀防盜器設(shè)計(jì)方案。該防盜器具有功耗低，功能完整，防盜效果良好等特點(diǎn)，除具有報(bào)警功能外，防盜器還具有以無線方式向主機(jī)發(fā)送報(bào)警信號(hào)的功能。采用315MHz發(fā)射模塊實(shí)現(xiàn)無線信號(hào)發(fā)送。該投影儀防盜器可適應(yīng)眾多廠家生產(chǎn)的防盜器主機(jī)。
Abstract:
This paper introduces the design scheme of overhead projector's anti-theft device which users ATMEL company’s Attiny13as processor.This anti-theft device features low powerloss，functional integrity，good effect of anti-theft.In addition to its own with alarm functions，the anti-theft device also has alarm function which can send alarm signal to the host through wireless way.It sends wireless signal using315MHz transmitting module，so this overhead projector’s anti-theft device is adapted to anti-theft device host produced by many manufacturers.
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!
This code was used for making the practical measurements in section 2.3 of my thesis. This Matlab code allows an OFDM signal to be generated based on an input data file. The data can be random data, a grey scale image, a wave file, or any type of file. The generated OFDM signal is stored as a windows wave file, allowing it to be viewed, listened to and manipulated in other programs. The modified wave file can then be decoded by the receiver software to extract the original data. This code was developed for the experiments that I performed in my honours thesis, and thus has not been fully debugged.
This is the original code developed for the thesis and so has several problems with it. The BER performance given by the simulations is infact Symbol Error Rate.
