function en_output = encoderm( x, g, alpha, puncture )% Copyright Nov. 1998 Yufei Wu% MPRG lab, Virginia Tech.% for academic use only% uses interleaver map 'alpha'% if puncture = 1, unpunctured, produces a rate 1/3 output of fixed length% if puncture = 0, punctured, produces a rate 1/2 output % multiplexer chooses odd check bits from RSC1 % and even check bits from RSC2% determine the constraint length (K), memory (m) % and number of information bits plus tail bits.[n,K] = size(g); m = K - 1;L_info = length(x); L_total = L_info + m;  % generate the codeword corresponding to the 1st RSC coder% end = 1, perfectly terminated;input = x;output1 = rsc_encode(g,input,1);% make a matrix with first row corresponing to info sequence% second row corresponsing to RSC #1's check bits.% third row corresponsing to RSC #2's check bits.y(1,:) = output1(1:2:2*L_total);y(2,:) = output1(2:2:2*L_total);% interleave input to second encoderfor i = 1:L_total   input1(1,i) = y(1,alpha(i)); endoutput2 = rsc_encode(g, input1(1,1:L_total), -1 );y(3,:) = output2(2:2:2*L_total);% paralell to serial multiplex to get output vector% puncture = 0: rate increase from 1/3 to 1/2;% puncture = 1; unpunctured, rate = 1/3;if puncture > 0		% unpunctured   for i = 1:L_total       for j = 1:3           en_output(1,3*(i-1)+j) = y(j,i);       end   endelse			% punctured into rate 1/2   for i=1:L_total       en_output(1,n*(i-1)+1) = y(1,i);       if rem(i,2)      % odd check bits from RSC1          en_output(1,n*i) = y(2,i);       else      % even check bits from RSC2          en_output(1,n*i) = y(3,i);       end     end  end% antipodal modulation: +1/-1, 在調制模塊中實現BPSK調整% en_output = 2 * en_output - ones(size(en_output));