frequency modulated carrier 中文意思是什麼
frequency modulated carrier
解釋
調頻載波-
The carrier wave is modulated directly by the baseband signal at several frequency point in l band and s band. firstly, this paper clarifies the theory of i / q modulation, elaborates evm and acpl, and analyzes the effect of amplitude and phase unbalance and dc offset on evm. secondly we review the basic principle of phase locked loop and it ’ s composing parts, including the basic conception and design method of pll frequency synthesizer, especially introduce the charge pump pll frequency synthesizer in detail
首先，在闡述i / q正交調制基本原理的基礎上，通過對誤差矢量和鄰近通道功率泄漏的詳細分析，定性、定量地討論了各種非理想電路因素（如相位不平衡、幅度不平衡、直流偏差等）對調制器性能的影響;其次，介紹了鎖相環的工作原理和基本組成部分，包括鎖相環的設計和環路濾波器的設計，特別詳述了電荷泵鎖相頻率源;第三，介紹了採用直接調制技術模擬衛星信號的射頻前端的設計;最後，對整個直接射頻調制系統進行測試，結果基本上達到了課題要求。 -
This waveform library not only contains those typical radar signals like single - carrier frequency signal, encoded signal, lfm etc, but also include many hybrid modulated signals, like fsk / psk signal, fsk / ppm signal, psk / ppm signal, pseudo - random fsk / psk signal, etc. we use visual c + + 6. 0 to implement this software program, this makes it easy in control operation and provides a nice human - machine interactive interface
波形庫中既包含了傳統的雷達波形，如單載頻脈沖信號、 lfm 、編碼信號等，又包括了復合調制波形，如fsk / psk信號、 fsk / ppm信號、 psk / ppm信號、偽隨機fsk / psk信號等。採用vc編程實現，使其具有友好的人機界面和靈活的控制操作。 -
There are five parts are as follows : in part one, the concept of switching function is introduced first to establish the nonlinear mathematical model of the induction motor variable frequency speed adjustment system which is fed by a sine pulse width modulated ( spwm ) inverter and takes the effect of the main magnetic circuit saturation into consideration, then the low frequency oscillation of the system is simulated according to the model. next, from the view point of energy conversion of the inverter - induction system, a criterion for the low frequency oscillation is proposed to determine whether the system is in low frequency oscillation which is judged by whether the interval of the negative current component of the inverter input current is more than 1 / fc ( fc is the carrier wave frequency of the inverter ) or not
首先引入開關函數概念，建立了正弦脈寬調制（ spwm ）逆變器供電異步電動機，考慮主磁路飽和時的變頻調速系統整體數學模型，模擬系統的低頻振蕩；其次從逆變器-異步電動機系統能量轉換角度出發，提出通過檢測逆變器輸入電流中負電流的間隔時間是否大於1 / f _ c （ f _ c為逆變器載波頻率）來判定系統是否出現低頻振蕩；最後的實驗結果驗證了系統低頻振蕩建模和判據的實用性和正確性。 -
Ds signal is twice modulated with the rapid pseudorandom noise sequence and the carrier. so it appears cyclostationary. in the field of spectral correlation, ds signals appears its characteristic as fallows : for the amplitude of spectral correlation, the information of carrier frequency and pn code rate are contained on the spectrum frequency equal to zero sheet, and also the pn code rate is contained on the sheet of spectrum frequency equal to carrier frequency ; for the phase of spectral correlation, the information of carrier initial phase is contained on the sheet of cyclic frequency equal to double carrier frequency
Ds信號是經過高速偽隨機序列和正弦載波二次調制的寬帶信號，因此具有周期平穩特性，它在譜相關域表現為:幅頻特性在譜頻率等於零截面切片上包含了載頻和偽碼速率信息特徵，在譜頻率等於載頻截面切片上包含了偽碼速率信息特徵;相頻特性在循環頻率等於兩倍載頻截面切片上包含了載波初相信息特徵。
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