%?plotspec（xTs）?plots?the?spectrum?of?the?signal?x
%?Ts?=?time?（in?seconds）?between?adjacent?samples?in?x

function?plotspec（xTs）

N=length（x）;???????????????????????????????%?length?of?the?signal?x
t=Ts*（1:N）;????????????????????????????????%?define?a?time?vector?
ssf=（-N/2:N/2-1）/（Ts*N）;???????????????????%?frequency?vector
fx=fft（x（1:N））;????????????????????????????%?do?DFT/FFT
fxs=fftshift（fx）;??????????????????????????%?shift?it?for?plotting
subplot（211）?plot（tx）??????????????????%?plot?the?waveform
xlabel（‘seconds‘）;?ylabel（‘a(chǎn)mplitude‘）?????%?label?the?axes
subplot（212）?plot（ssfabs（fxs））?????????%?plot?magnitude?spectrum
xlabel（‘frequency‘）;?ylabel（‘magnitude‘）???%?label?the?axes

%verify?parseval?equalize?power?using
%sum（abs（fxs）.^2）/N
%sum（abs（x）.^2）
%?use?axis（[02-1.11.1]）?for?specsquare.eps


%?%%?Reading?Arbitrary?Format?Text?Files?with?TEXTSCAN
%?%?This?example?shows?how?to?read?an?arbitrary?format?text?file?with
%?%?%?|textscan|.?This?function?is?similar?to?|textread|?however?it?also
%?%?allows?you?to?read?the?file?one?block?at?a?time?and?each?block?can?have
%?%?a?different?format.?The?information?in?the?text?file?test80211.txt?is
%?%?the?result?from?a?wireless?network?communication?quality?test.?Each?block
%?%?is?a?different?environment?（e.g.?mobile?indoor?outdoor）.?The?numerical
%?%?results?show?the?data?error?rate?over?a?range?of?noise?levels?for?a
%?%?number?of?independent?tests.
%?
%?%?Copyright?1984-2006?The?MathWorks?Inc.
%?%?$Revision:?1.1.6.7?$??$Date:?2007/10/15?22:53:31?$
%?
%?%%?File?Format
%?%?After?4?lines?of?introduction?this?particular?file?is?made?up?of?a
%?%?number?blocks?of?data?each?with?the?following?format:
%?%
%?%?*?Two?headerlines?of?description
%?%?*?A?parameter?m
%?%?*?A?p?x?m?table?of?data
%?%
%?%?All?the?information?is?read?into?cell?arrays?allowing?the?storage?
%?%?of?different?size?blocks.
%?
%?%%?Open?the?Text?File?for?Reading
%?fid?=?fopen（‘tes