Trellis diagrams in MATLAB?

Derek Kusiak

unread,

Sep 20, 2000, 3:00:00 AM9/20/00

to

Is there a way to generate a trellis diagram from the generator
polynomial(s) of a convolutional encoder in MATLAB? I have a block
diagram (generator polynomials) for a rate 1/2 (K = 7) convolutional
encoder and I'm hoping there is a relatively painless way to generate a
trellis diagram for it.

Thanks.

Brandon Hombs

unread,

Sep 21, 2000, 3:00:00 AM9/21/00

to

Hey there.
I had a similar problem a year or two ago in one of my undergrad
classes. I
wrote a matlab script and you can apply it to the constraint length 7
code.
I didn't optimize it to solve for the transfer function at that
constraint
length (only up to 6) but I think you could do this if you do
Gauss-Jordan
elimination on the transfer function matrix. If you get it in echelon
form
with the correct row at the bottom the transfer function pops out.
Anyway,
I'll send you the matlab file I used to solve it. There is a simulink
demo
for Viterbi decoding that will also produce it, I think. I don't know
what
your uses for this are, but if you do use it please do not plagiarize
it.
If you make any improvements please send me a copy.

A sample input for this is the following sequence:

» convcodes
what is the constraint length:5
what is the code rate:1/3
code connections (in octal): 23
code connections (in octal): 33
code connections (in octal): 45

ans =

I make now guarantees on the accuracy of dfree

Do you want to plot the trellis: y
Do you want to determine the transfer function: y
Do you want to use Matlab(m or M) solver or matrix (w or W) form: w
Do you want to plot the BER: y
Enter the channel BER model
Viterbi uses exp(-Eb/No)
i.e. for DPSK enter 1/2*exp(-Eb/No)
also note that 1/2*erfc(x/sqrt(2))=Q(x): 1/2*exp(-Eb/No)

It sounds like you only need trellis plots for constraint length 7 rate
1/2
with code words 171, 133 (I'm guessing).

Then it will make a few pretty plots and show you the transfer function
and
stuff. It will do trellis diagrams for any code rate 1/2 or 1/3 for
constraints up to at least 14.

If anyone else wants a copy of this let me know and I'll send it to you
but
I hesitate to post it.

Brandon Hombs

kirankumar palthi

unread,

Dec 30, 2012, 10:39:12 PM12/30/12

to

Hi,
Can you please send me the copy of trellis plot code.

Thanks,
Kirankumar

Brandon Hombs <ho...@ecn.purdue.edu> wrote in message <39CA2EC3...@ecn.purdue.edu>...

kiran joshi

unread,

Jan 24, 2014, 4:32:07 AM1/24/14

to

Derek Kusiak <sp...@grog.net> wrote in message <39C8ED17...@grog.net>...

> Is there a way to generate a trellis diagram from the generator
> polynomial(s) of a convolutional encoder in MATLAB? I have a block
> diagram (generator polynomials) for a rate 1/2 (K = 7) convolutional
> encoder and I'm hoping there is a relatively painless way to generate a
> trellis diagram for it.
>
> Thanks.

Dear,
i m M.E. (wireless communication) student i need trellis codes with generate generator matrix for my thesis. kindly mail me the matlab codes about trellis codes whatever all are neccessary at kira...@gmail.com plz....
sincerely,
kiran joshi

Resmi N C

unread,

May 5, 2015, 1:33:58 AM5/5/15

to

Hello,

Would you mind sending me the matlab script for plotting trellis diagram. Thank you in advance...

Regards,

Resmi

AYUSH SRIVASTAV

unread,

May 13, 2015, 5:10:15 AM5/13/15

to

I need some help with the codes urgently. Brandon can you please help ?

Amr

unread,

Sep 7, 2016, 10:01:11 AM9/7/16

to

Dear Brandon Hombs,
Can you please send me a copy of this code
Thanks in advance !

Regards,
Amr

Marta Ortiz

unread,

Nov 2, 2016, 5:52:10 AM11/2/16

to

Hi Brandon!

I know it´s been a long time, but could I kindly request you to send this matlab script?
My email address is mar...@gmail.com

Thank you very much!!