function y=iden1(signal)
fs = 2e+6;       						% sampling rate (samples/second) 
sr = 1e+5;  						% symbol rate (symbols/second) 
fc=2e+5;                                %ÔØ²¨ÆµÂÊ
Ts = 1/fs; 								% sampling period 
Td = 1/sr;						% symbol period 
m = fs/sr;				% samples per symbol 

l=length(signal);
n=0:l-1;
w=exp(-i*2*pi*fc*n*Ts);
ft=abs(fft(signal.^2));
type=0;
[x,idx]=max(ft);
p=angle(signal.*w);
dp=diff(p);
for k=1:length(n)-1
   if dp(k)>pi
       dp(k)=dp(k)-2*pi;
   elseif  dp(k)<-pi
       dp(k)=dp(k)+2*pi;   
   end
end    
dp=abs(dp);
dy=(pi/180)*10;
length1=length(find(pi/2-dy<dp&dp<pi/2+dy));
length2=length(find(pi-dy<dp&dp<pi+dy));
%hist(dp,100);
if (x>5*(mean(ft(idx+5:idx+30))))&&(x>5*(mean(ft(idx-30:idx-5))))%¿ªÊ¼ÅÐ¶¨
    type=3;
else
     if length1>10*length2
    type=2;
    else type=1;
    end
end
y=type;