Hello All,
I have been looking into using gnuradio for packet processing. I am
having a hard time understanding exactly how to make this work.
What I would like to do is send out packets of around 200 symbols or
so. I think I understand how to do this at the transmit end.
What I am stuck on
On Wed, Feb 21, 2007 at 12:46:59PM -0500, Tim Meehan wrote:
Hello All,
I have been looking into using gnuradio for packet processing. I am
having a hard time understanding exactly how to make this work.
Yes, packet processing in the flow graph environment is a bit of a
challenge. Hence the
Tim,
I think there are two parts in your question:
1) how to detect an incoming packet and do something with it.
2) how to operate the viterbi algorithm block in a packet to packet
basis without generating the flow graph again.
I only know how to answer the latter question:
The viterbi
Hi Achilleas,
I was interested in various length packets. I am taking a fixed
length packet ( say 200 symbols ) and then bitstuffing it, resulting
in a packet = 200 symbols. I then receive this with the viterbi
algorithm and then finally unbitstuff. So in this, case K = 200 +
number of
Tim,
If the number of additional bits is not significantly
bigger than the fixed packet length (in your example 200),
then you can instantiate the VA with the MAXIMUM expected
length (eg, K=200+10). For this to work you have to
1) put a block before it that appends 0's (or something else)
in
Achilleas,
Could the Viterbi block be implemented in such a fashion that the
algorithm was a streaming implementation as opposed to a fixed block
size?
That way, you could just send in a vector of deinterleaved soft
decisions, and (with a little bit of overhead) the Viterbi block could
take in
Brian,
Yes it can!
You need to set a decision delay D and then it would operate in a
fixed-delay mode, ie, it would spit out a decision at every time instance
with a delay of D compared to the input sample.
The survivor matrix (of size DxS) will need to be updated at every
time instance in
Achilleas,
I agree, I do not think that anything in gr-trellis needs to be
modified to get my desired effect. I think the m-block stuff may
provide the hooks to make this a lot easier to code up. In the short
term, I will probably write up something quick and dirty just to get
my desired
