fixed adj. 1.固定的;确定的,不变的,固执的。 2.【化学】凝固的,不易挥发的。 3.〔美口〕(在经济上)处境…的。 4.〔美俚〕(比赛等)通过作弊预先安排好结果的。 a fixed deposit 定期存款。 a fixed fact 〔美国〕确定事实。 a fixed gun 【军事】固定机枪。 a fixed income 固定收入。 a fixed point 警察常驻的地方。 fixed par of exchange 汇兑的法定平价。 a fixed oil 不挥发性油,固定油。 well fixed 〔美国〕生活宽裕。
Secondly, adopting a filter bank composed of 12 iir narrow-band notch filters to eliminate feedback . 9 fixed filters are used for feedbacks which are inherent in room and 3 dynamic filters are used for new feedbacks when all available filters are in use 其中,9个静态陷波器用来抑制声环境中的固有声反馈,3个动态陷波器用来抑制扩声系统使用过程中可能出现的声反馈。
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 课题中所采用的pll或ddspll锁相频率合成方法充分发挥锁相环良好的窄带跟踪滤波特性,并结合dds的高频率分辨率、高频率精确度和高速频率捷变等优点,分别实现了系统所要求的高质量宽带本振源和小步长频率捷变;采用电调谐选频技术,则大大改善了接收机的选择性和抗干扰能力。