carrier n. 1.运送人,搬夫;负荷者;使役,〔美国〕信差,邮递员;送报人;〔英国〕运输行,运输业者。 2.传书鸽,信鸽。 3.(车后的)货架;吊架;托架。 4.水管,引水沟。 5.运载工具;搬运机;移动滑车。 6.【医学】带菌者,病媒。 7.航空母舰。 8.【电学】载波;载流子;【拓】承载子;【化学】载体,填料;导染剂。 a mail [letter] carrier邮递员。 a band carrier传送带。
variable adj. 1.易变的,变化无常的,无定的 (opp. constant, steady)。 2.可变的,能变的;变换的。 3.【数学】变量的;【天文学】变光的;【生物学】变异的。 Prices are variable according to the exchanges. 物价跟着汇率变动。 a man of variable character 反复无常的人。 a rod of variable length (伸缩)如意棒。 a word of variable construction 可以作种种解释的词。 variable capital 可变资本。 a variable budget 临时预算。 n. 1.易变的东西。 2.【数学】变量,变数,变项,变元 (opp. constant);【天文学】变星 (=variable star);【航海】(方向不定的)变风,不定风 (opp. trade wind); 〔pl.〕 (贸易风带中的)变风带。 adv. -ably ,-ness n.
Ddc ( digital down - conversion ) high - efficiency structure is studied to realize the variable carrier frequency band - pass signal acquisition on wideband condition 参考软件无线电设计的概念和国内外相关文献,提出了多项滤波下变频结构的fpga实现。
Parallel structure of poly - phase decomposition and parallel mixer is applied in the ddc circuit , it solves the bottleneck in mixing and increases the handle speed . the partition of the tuning channel according to the digital mixing sequence , and the ddc by means of decimating first , the low - pass filtering and mixing realize efficiently the down - conversion of the variable carrier frequency band - pass signal . according to the structure of the ddc and the requirement of the frequency 短数据快速测频算法的具体实现:使用并行流水线的设计方法,提高了系统的数据吞吐率,在100mhz的系统时钟下,能够实时处理400mhz ~ 600mhz速率a / d采样的数据,在64点采样, 100mhz系统时钟情况下,初次测频占用时间640ns ,以后每次测频占用时间缩短到160ns ,实时地提供多相滤波下变频所需的载频位置信息,缩短了接收机的调谐时间。
Filter poly - phase decomposition method is adopted in this dissertation . the partition of the tuning channel according to the digital mixing sequence , and the digital down - conversion by means of decimating first , the low - pass filtering and mixing realize efficiently the down - conversion of the variable carrier frequency band - pass signal 本文采用滤波器多相分解方法,按数字混频序列划分调谐信道,使用先抽取,后低通滤波,再混频的数字下变频结构,高效实现了变载频带通信号数字下变频。