Re: gr_unpacked_to_packed_bb, modulation

GNU Radio
1

I think you are making wrong use of the unpacked_to_packed block:

Your source is a file with bytes.
These should be considered “packed”
(i.e., bits are packed into a byte).

Thus you need to unpack them using
packed_to_unpacked_bb(2,GR_MSB_FIRST)
The output of this block will be bytes, each having
only 2 bits worth of data in them, sop they can be used
as inputs to the lookup table…

Achilleas

2

I think you are making wrong use of the unpacked_to_packed block:

I think so to. I was creating the file in Matlab, writing zeros and ones
as chars to a file, used that file as input to the flow- graph…

So to get my original code to work, I had to write “27” in the data file
(27 = 00011011b). Hence producing the four symbols I was looking for.

Why did my block work? It is packing the LSB from k bytes into one
byte… Kind of a “unpacked_to_unpacked_bb”- block… I think there is
some cleaning, polishing and asserting to be done in that code to have
it in “gnuRadio- shape”, but if there is interest in such a block, I can
try to fix it up as good as I can, and post it.

Thank you very much for the clarifications, I’ve been guessing and
banging my head for a while with this.
//Mattias