convolutio​nal_encode​r_output

Hi,

Im trying to build a communication system with SIMULINK. I use a very simple topology and I would like some feedback on the resulting output. I use for a very simple 3 blocksarchitecture. 1) From workspace. In this block I load a column vector of 20 elements representing input bits. My vector is: [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0].'; 2) I use the convolutional encoder block with rate 1/3 .More specifically I use the command poly2trellis(7, [133 165 171]) in the trellisstructure field. 3) I use a 'to workspace'block to see the output. Since the rate is 1/3 I would expect an output vector to be a column vector [60x1]. Instaed I observe a vector that is 20x3.

Assuming I want to put this data to another block (i.e. a BPSK modulator, or an AWGN channel). When I do so again the same mattrix is maintained. Why I do not have the output of 60 bits and I still take this mattrix? In reality, you put 20 in , you get 60 out and thus the data rate falls by 1/3. Now that the output is in mattrix format , how I can observe that? I mean I wanna have a column vector in order to continue working with other blocks, and this thing really confuse me. Also, when I run some examples inherent in MATLAB, the output seems to be a column vector, and this is what I would like to take as well. (i.e in the MATLAB example 300 bits are input bits and 600 are output). Why I cannot do this in my case?Could you please help me out with it as its getting really frustrating?

Thanks, Angelos