Re: [Discuss-gnuradio] Problem with the string of blocks: Packet Encoder - Packed to unpacked - Unpack k bits - Packet Decoder

[Mike Jameson]

You must include a throttle block just after the file source otherwise you will max out the CPU and things get messy as you have seen.

Mike

--
Mike Jameson M0MIK BSc MIET
Ettus Research Technical Support
Email: address@hidden
Web: http://ettus.com

On Mon, May 19, 2014 at 3:38 PM, Ramiro Utrilla <address@hidden> wrote:

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-minute song and in reception I get just a few seconds of the song within cuts. It seems that I'm losing lots of packets in the process.

After trying lots of things, I've reduced my graph to the minimum, eliminating all the mod/demod modules, as you can see in the attached picture. However, I'm getting the same results than before, so I tend to believe that my problem is not in the mod/demod part of the graph but in the use of the following string of blocks: 

Packet encoder - Packed to unpacked - Unpack k bits - Packet decoder.

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

PACKET ENCODER: Converts float samples into bytes, each byte with 4 symbols of 2 bits each.

PACKED TO UNPACKED: Puts 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 know that it's a pretty basic graph but I don't know what I'm doing wrong.

Thanks in advance!!

Ramiro Utrilla

P.D: I'm running GNU Radio 3.7.4 on a 64-bit PC with Ubuntu 14.04.

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