為了在CDMA系統(tǒng)中更好地應(yīng)用QDPSK數(shù)字調(diào)制方式,在分析四相相對(duì)移相(QDPSK)信號(hào)調(diào)制解調(diào)原理的基礎(chǔ)上,設(shè)計(jì)了一種QDPSK調(diào)制解調(diào)電路,它包括串并轉(zhuǎn)換、差分編碼、四相載波產(chǎn)生和選相、相干解調(diào)、差分譯碼和并串轉(zhuǎn)換電路。在MAX+PLUSⅡ軟件平臺(tái)上,進(jìn)行了編譯和波形仿真。綜合后下載到復(fù)雜可編程邏輯器件EPM7128SLC84-15中,測(cè)試結(jié)果表明,調(diào)制電路能正確選相,解調(diào)電路輸出數(shù)據(jù)與QDPSK調(diào)制輸入數(shù)據(jù)完全一致,達(dá)到了預(yù)期的設(shè)計(jì)要求。
Abstract:
In order to realize the better application of digital modulation mode QDPSK in the CDMA system, a sort of QDPSK modulation-demodulation circuit was designed based on the analysis of QDPSK signal modulation-demodulation principles. It included serial/parallel conversion circuit, differential encoding circuit, four-phase carrier wave produced and phase chosen circuit, coherent demodulation circuit, difference decoding circuit and parallel/serial conversion circuit. And it was compiled and simulated on the MAX+PLUSⅡ software platform,and downloaded into the CPLD of EPM7128SLC84-15.The test result shows that the modulation circuit can exactly choose the phase,and the output data of the demodulator circuit is the same as the input data of the QDPSK modulate. The circuit achieves the prospective requirement of the design.
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(cè)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(cè)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.
簡(jiǎn)單混合衰落信道
This mfile inputs an unmodulated sinewave through a simple Rayleigh two path fading channel and shows the output with phase, gain, and attenuation characteristics via animation.
The Hopfield model is a distributed model of an associative memory. Neurons are pixels and can take the values of -1 (off) or +1 (on). The network has stored a certain number of pixel patterns. During a retrieval phase, the network is started with some initial configuration and the network dynamics evolves towards the stored pattern which is closest to the initial configuration.
The same two-stage decoder as above. However, when transforming the symbols prior to Viterbi decoding, the amplitude information is ignored and only the phase of the received symbol is employed in the metric computation stage.
This mfile illustrates a simple two path Rayleigh multipath fading channel
This mfile inputs an unmodulated sinewave through a simple Rayleigh two path fading channel and shows the output with phase, gain, and attenuation characteristics via animation