Forum: GNU Radio Problems with Packet Encoder - Packed to unpacked - Unpack k bits - Packet Decoder

3600460d51024c4af49d686de15cbd31?d=identicon&s=25 Ramiro Utrilla (rutrilla)
on 2014-05-16 17:56
Attachment: dealing_with_packets.jpg (200 KB)
Hi everybody,

I'm currently working with some modulations (M-QAM, M-PSK) and my
results are almost the same for all of them. I'm sending a wav file
which is a 4 minutes song and in reception I get just few seconds of the
song and with cuts. It seems that I'm losing lots of packets in the
process.

After try lots of things, I reduce my graph to the minimum eliminating
all the mod/demod modules, as you can see in the attached picture. So at
this point I'm getting the same results that I explain before and
because of it I'm thinking that my problem is not in the mod/demod part
of the graph and I think that they are in the use of the blocks: Packet
Encoder - Packed to unpacked - Unpack k bits - Packet Decoder.

The graph is:

WAV FILE SOURCE -> PACKET ENCODER -> PACKED TO UNPACKED -> UNPACK K BITS
-> PACKET DECODER -> WAV FILE SINK

As far as I know, these blocks do the following operations:

PACKET ENCODER: Convert float samples into bytes, each byte with 4
symbols of 2 bits each.
PACKED TO UNPACKED: Put a symbol of 2 bits in a byte in the MSB
position.
UNPACK K BITS: The opposite of "Packed to unpacked" block.
PACKET DECODER: The opposite of "Packet enconder" block.

Please, I would appreciate any help with this. I don't know what I'm
doing wrong.

Thanks in advance!!

Ramiro Utrilla
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