narrow band frequency 中文意思是什麼
narrow band frequency
解釋
窄帶頻率-
Another attribute is the flux or radiant power that can be delivered in that narrow frequency band.
另一個性質就是在這樣窄的頻帶內可以給出很高的光通量或輻射功率。 -
From the result we get the following conclusion : for narrow - band signal, the effect of the method based on fft is best. for wide - band signal, when snr is up to certain degree ( higher than - 7db or so ), the curves of square error of modified methods are more obvious and closer to crb. for an echo composed of more than one frequency or direction, space - frequency distribution could show more direct information of frequency and direction, which is more advantaged to make precise judge and estimation for doa of echo
從估計結果發現，對于窄帶回波信號，基於fft的方法估計性能大大優于其他方法；對于寬帶回波信號，在信噪比達到一定程度（高於約- 7db ）時，補償后的幾種估計法的性能改善均比較明顯，誤差曲線越來越接近crb曲線；對于回波中存在多頻率多方位的情況，空間?頻率分布圖能提供較為直觀的頻率及方位信息，因此應用空間?頻率估計法來進行方位估計，更有利於進一步對回波的具體方位進行準確判斷和估計。 -
At first some modification is made in conventional beam forming of frequency domain, namely to estimate doa by arrays outputs on compensated spacial frequency points of echoes. then the cwt is utilized to signal processing in space - frequency domain for estimation of doa, and the corresponding modification is also made. in the dissertation, the computer simulations of doa estimation for both narrow - band and wide - band echoes are given, so do the necessary comparison among several methods and crb
首先在傳統的頻域波束形成演算法的基礎上，提出對寬帶信號的頻率補償，也即對寬帶回波信號的各空間頻率根據時間頻率的差異進行相應補償，然後對各陣元輸出求和來得到方位估計；其次將連續小波變換引入到空間?頻率處理中，從而完成對目標方位的估計，並進行了相應地補償。 -
The merits of dds such as super fine frequency resdutlon 、 high frequency accuracy 、 easy programmed can be in combination with the excellent character of narrow - band tracing filter merits of pll
它可以將dds的超高頻率解析度、高頻率精確度、容易實現程式控制等優點與鎖相環良好的窄帶跟蹤濾波特性相結合。 -
By making full use of favourable narrow - band tracing filter character of pll and by combining the merits of dds such as super fine frequency resolution 、 high frequency accuracy 、 very fast frequency hoping with it, the pll / pll + dds frequency synthesizer presents wide band high quality source and super small frequency hoping step. while the electronically tuned filter abates the image interference and notably improves the selectivity. the theorem of frequency synthesizer and center - frequency - fixed filter is simply but adequately introduced first in this paper
課題中所採用的pll或dds pll鎖相頻率合成方法充分發揮鎖相環良好的窄帶跟蹤濾波特性，並結合dds的高頻率解析度、高頻率精確度和高速頻率捷變等優點，分別實現了系統所要求的高質量寬帶本振源和小步長頻率捷變；採用電調諧選頻技術，則大大改善了接收機的選擇性和抗干擾能力。 -
In this system two oscillator are used for mixing. pll for high local oscillator and dds + pll for low local oscillator. by making full use of favourable narrow - band tracing filter character of pll and by combining the merits of dds such as super fine frequency resolution, high frequency accuracy, very fast frequency hoping with it, the pll / pll + dds frequency synthesizer presents wide band high quality source and super small frequency hoping step
系統採用兩次混頻，其中高本振的設計採用pll鎖相環頻率合成來實現，充分發揮了鎖相環頻率合成器的優良特性，實現了系統所要求的高質量寬頻帶本振源；低本振採用pll + dds頻率合成來實現，結合pll優良的鎖相特性與dds的高頻率解析度、高頻率精確度等優點，實現了頻率的小步進高精度合成。 -
Experiments show that, when use msp430f149 audio sensor to identify vehicles that contain plane, tank, truck and so on by time domain features and two - level f - ratio, the recognition rate is 82. 1 % ; when use both msp430f149 audio sensor and arm9 sensor to identify vehicles, and the recognition rate is much better than the original system and msp430f149 audio sensor. line spectrum of power spectra and 3 / 2 spectrum is used as frequency features on arm9 sensor, and it is caught by narrow - band bandpass filter
實驗證明，在主頻為8mhz的msp430f149感知器上，採用基於時域特徵和二階f比的識別演算法，能夠實時地完成對飛機、坦克、卡車等交通工具的識別;將msp430f149感知器與基於arm9的高端感知器配合使用，且高端感知器採用功率譜線譜或3 / 2維譜線譜作為頻域識別特徵，能夠實時的對各類交通工具做更高性能的識別。 -
From some characteristics observed, such as the short lift time, narrow frequency band, fast frequency drift, quasi - periodic pulsation, spike event and complex magnetic structure, it is considered that the radiation mechanism of these events may be principally due to the electromagnetic waves magnified directly by the instable electronic cyclotron
從它們的觀測特徵：短壽命，窄頻帶，頻率快速漂移，及尖峰事件與磁結構復雜的大黑子活動區密切相關等，認為這些事件的輻射機制可能是電子迴旋脈澤不穩定直接放大電磁波所致。 -
Lastly, the paper designs an example and tests its amplitude frequency response. at last, this paper points out that this method can efficiently control the performance of narrow band fir digital filters. both test and application indicate that practical performance and ideal performance are almost identical
在此基礎上給出窄帶fir濾波器的詳細結構，分析了窄帶fir濾波器的多級實現原理，並且對窄帶fir濾波器的的基本特性進行了分析，這些特性包括：頻率特性、抗混疊特性、去鏡象特性。 -
Frequency response, quantization noise, reconstruction error and its sensitivity to mismatch among adcs are studied at length in prqmf banks adc system, and the theoretic results include : ( 1 ) the distortion / aliasing functions of hybrid filter banks adc system is similar with that of switch capacitor filter banks adc system ; ( 2 ) for wide or narrow band input signal, the effective resolution of the two adc systems is 0. 51og2m bits higher than their adc ; ( 3 ) reconstruction error ' s sensitivity to mismatch among adcs of the two adc systems is reduced effectively than time interleaved adc system
2對prqmf濾波器組adc系統的頻響、量化噪聲特性、重建誤差特性以及重建誤差對adc間的失配敏感性進行了理論分析研究，所得到的理論結果為： （ 1 ）混合濾波器組adc系統與開關電容濾波器組adc系統的失真/混迭函數一致； （ 2 ）無論輸入寬帶還是窄帶信號，這兩種adc系統的有效解析度均比其adc提高了0 . 5log _ 2m比特； （ 3 ）這兩種adc系統的重建誤差對其adc間的失配敏感性均明顯低於時間交織adc系統。 -
The receiver works on active mode and passive mode in different time. in active mode, the receiver is narrow - band and high sensitive, and if phase - lock technology is used to stabilize receiving frequency. and in passive mode, the receiver is an all - power millimeter wave radiometer with periodic calibration to improve measure precision
此接收機採用分時工作體制，在主動工作方式時為窄帶的高靈敏度毫米波接收機，接收機中採用中頻鎖相技術，簡化了毫米波鎖相帶來的困難；在被動工作方式時為全功率型的毫米波輻射計，這種輻射計在每次測量后都採用兩個標準源對輻射計定標，實現周期定標，消除因系統增益波動和有效本機噪聲波動帶來的測量誤差，提高測量測量精度。 -
One way to reduce timing jitter is the use of narrow - band frequency - guiding filters periodically distributed along the transmission line
控制孤子的時間抖動和相互作用的一個重要方法是在傳輸線中周期性地安放濾波器。 -
This dissertation is mainly concerned about the radiation of the tem - horn arrays which radiate uwb ( ultra wideband ) pulse, it mainly involves three parts : theory, numerical stimulation and experiment. the uwb antenna is a new research field in the world which has many differences from nb ( narrow band ) antenna. the most difference is that the uwb antenna such as tem - horn radiates nanosecond pulse which has wide frequency spectrum, but the nb antenna radiates single frequency signal
超寬帶天線是一項新興的研究領域，它與窄帶天線有很多不同之處，最根本的不同在於：超寬帶天線例如tem喇叭天線是輻射納秒級短脈沖信號，這種脈沖信號有很寬的頻譜；而窄帶天線大都是輻射單一頻率時諧信號的。 -
The design of low frequency narrow band - pass quartz crystal filter
低頻窄帶石英晶體濾波器的研製 -
On the basis of the former research works, we present the detecting method as follows : for the narrow band characteristic of the track signal we use under - sampling instead of nyquist sampling to reduce the sampling rate. as to the carrier frequency, the spectrum of the 18 - information frequency - shift track signal has two peaks, then the carrier frequency is the average of the two peak frequency, to um - 71 jointless track signal, it has only one peak, then the carrier frequency is the peak frequency
針對移頻軌道信號的窄帶特性提出了使用欠采樣技術代替奈奎斯特采樣的方法，以降低信號的采樣頻率;國產18信息移頻軌道信號頻譜具有雙峰，雙峰頻率平均值就是信號的載頻頻率，而um - 71無絕緣軌道信號頻譜單峰，峰值頻率即為信號的載頻頻率。 -
The above waveforms discussed are to synthesize the wb or uwb with narrow band pulses. assuming the transmitting uwb linear frequency modulation ( chirp ), dechirp processing is introduced, and the method involved to obtain high resolution by reducing the if bandwidth is presented. furthermore, dechirp processing used to sar imaging is discussed, and the processing steps are described
< wp = 4 >以上研究的兩種信號形式都是通過窄帶子脈沖串相參合成的方法來獲得超寬帶回波信號，本文還探討了去斜率（ dechirp或stretch ）方法，分析了去斜率降低接收機中頻帶寬、 fft獲得目標一維距離像的原理，並探討了線性調頻去斜率合成孔徑雷達成像，給出了具體實現步驟。 -
In the first place, start with theoretic model of distributed fbg strain - sensing network, sensing principle of fiber bragg grating is analyzed and sensing model created. on the basis of analyzing advantages and disadvantages of several familiar multiplexing and demodulation techniques, a mixture multiplexing method that combines optical frequency domain reflectometry ( ofdr ) and wavelength division multiplexing ( wdm ) is proposed to address fbg sensing array. at the same time, tunable narrow - band light source, which is composed of wide - band light source and tunable optical filter, is adopted to demodulate multiplex signals
首先，論文從分散式光纖光柵應變傳感網路的理論模型入手，分析了光纖布拉格光柵的傳感機理，建立光纖光柵應變傳感模型；在分析比較了常見幾種復用技術和信號解調技術的優缺點基礎上，提出應用光頻域反射復用技術和波分復用技術相結合的混合復用方法來解決光纖光柵應變傳感網路的尋址問題，採用由寬帶光源和可調諧光濾波器組成的可調諧窄帶光源來解調復用信號，通過理論分析和實驗研究證實了系統方案的可行性。 -
The technology of very low bit rate for hf ( high frequency ) communication means that, one technology of ecm ( electronic counter measures ) resistant communication is developed for low bit data message exchange in the time of battle which data communication is destroyed by electronic disturber. it is regarded by armies in the battle of information, because that it can overcome the very low snr ( signal noise ratio ), very high narrow - band interference and multipath with maxium delay of fifty millisecond
短波最低限度通信技術是在戰時強電磁干擾情況下能實現保證最低限度的數據報通信的一種抗干擾通信技術。由於其能有效的克服極低信噪比、較強的窄帶干擾和幾十毫秒的多徑，在信息戰中受到各軍高度重視。 -
The hardware design includes pl2101 power line node, realization of narrow - band interferences in direct sequence spread spectrum signal using frequency - domain algorithm
其中硬體設計包括pl2101電力線節點、窄帶干擾自適應抑制系統的實現。 -
Because of the good sensibility, ultrasonic narrow band signal analysis technique with 1mhz central frequency was chosen to differentiate the heat treatment samples above - mentioned. there are obvious differences among heat treatment products in principal frequency, spectral peak ' s quantity, amplitude and distribution. that is to say, the technique of ultrasonic narrow band power spectral can be applied to characterize the microstructures of multi - phased alloy steels
利用窄帶信號頻譜分析技術靈敏度高的突出優點，選取中心頻率為1mhz的窄帶超聲信號，對上述不同熱處理試樣進行超聲功率譜分析，發現不同熱處理產物在功率譜主頻率、譜峰特徵（幅度、數量、分佈）等方面，都存在不同程度的差異。
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