[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] line codes and FSM/Trellis

From: Achilleas Anastasopoulos
Subject: Re: [Discuss-gnuradio] line codes and FSM/Trellis
Date: Sat, 15 Jan 2011 17:34:23 -0500

> Can every common line code be represented by a FSM?

yes: recall that any algorithmic description is essentially an FSM.
line codes in particular can be represented with very "small" FSMs,
ie, only a few states are required.

> Can every common line code be decoded by a trellis decoder?

if it can be described by an FSM then yes (btw, by "trellis decoder" i
assume you mean
the Viterbi algorithm).

In some instances, if you only work with an error-free sequence (and a
linear FSM),
then you don't even
need the VA (you can always use it if your sequence is noisy!).
In that special case you can decode it with another FSM which implements the
"inverse" process.

Eg: differential encoding:
y_t = y_{t-1}  +  x_t
(the state is y_{t-1}, the input is x_t, the output is y_t)

and differential decoding:

x_t  = y_t-y_{t-1}
(the state is y_{t-1}, the input is y_t, the output is x_t)

> Can anyone give me a pointer for literature?

i don't know of anything specific to line codes...

> What would be the easiest way to implement a _encoder_ in GNU Radio.



reply via email to

[Prev in Thread] Current Thread [Next in Thread]