MATLAB讲义第七章作业及答案

1、一、 用窗函数法设计线性相位fir低通滤波器，通带截止频率wp=0.5，ws=0.6,阻带衰减不小于40db，通带衰减不大于3db解：因为衰减不小于40db，可选择的窗口有哈明窗和汉宁窗。而汉宁窗有较小的过度带，因此具有较小的阶数，因此先用汉宁窗。方法一：clearwp=0.5*pi;ws=0.6*pi;deltaw=ws-wp;n0=ceil(6.2*pi/deltaw);%根据汉明窗设计计算所需的滤波器长度，课本211页查表n=n0+mod(n0+1,2);%为实现第一类偶对称滤波器，应确保长度n为奇数wdhm=hanning(n);%求窗函数wc=(ws+wp)/2;%求截止频率tao=

2、(n-1)/2;n=0:n-1;m=n-tao+eps;%求理想脉冲响应hd=sin(wc*m)./(pi*m);hn=hd.*wdhm;%设计的脉冲响应subplot(2,2,1),stem(n,hd);xlabel(n);ylabel(hd(n);title(理想脉冲响应)subplot(2,2,2),stem(n,wdhm);xlabel(n);ylabel(wdhm);title(汉宁窗)subplot(2,2,3),stem(n,hn);xlabel(n);ylabel(h(n);title(设计的滤波器频率特性)b=hd.*wdhm;h,w=freqz(b,1);subplot(2

3、,2,4),plot(w,20*log10(abs(h);grid;title(幅度响应);结果:方法二： wp=0.5*pi; ws=0.6*pi; wd=ws-wp; n=ceil(8*pi/wd); wc=(0.5+0.6)*pi/2; window=hanning(n+1); b=fir1(n,wc/pi,window); freqz(b,1,512)winger tuivasa-sheck, who scored two tries in the kiwis 20-18 semi-final win over england, has been passed fit after a

4、lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading into the encounter but australia have not conceded a try since josh charnleys effort in their first pool match against england on the ope

5、ning day.aussie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league international federation player of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi -

6、 with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the all blacks in 2011.id give every award back in a heartbeat just to get across the line this weekend, said williams.the (lack of) air u

7、p there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he

8、told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has al

9、so ordered an immediate investigation into the referees actions.待添加的隐藏文字内容2cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska. baumgartner the disappointing news: mission aborted.the supersonic desce

10、nt could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the lower level of

11、the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the bounda

12、ry layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.they blew it in 2008 when they got caught cold in the final and th

13、ey will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by englands josh charnley in the opening game of the tournament.that could be classed as a weakness,

14、a team under-cooked - but i have been impressed by the kangaroos focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. theyve been great at all t

15、he unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.it is as though their entire tournament has been preparation for the final.in johnathan thurston, cooper cronk, cameron smith and either billy slater or greg inglis at full-back they have a spine that is unmatched in rugby league. they have played in so many high-pressure games - a priceless asset going into saturday.the kiwis are a lot les