Re: [Discuss-gnuradio] PSK File transfer

[Stephen Andrew]

I did some more searching on the google machine and found: http://lists.gnu.org/archive/html/discuss-gnuradio/2012-04/msg00500.html

It's like my setup, minus the throttle and the pack K bits, with the addition of packets on either side of the modulator/demodulator. Ran the new setup, and it gives me the correct file on the output, but when I turn off "repeat" in the file source, I get no output.

Why is repeat magical, and why did I have to packetize my file before sending? Shouldn't it have just sent as a stream of bits without packets?

Thanks,

Stephen Andrew

Undergraduate, Electrical Engineering

Missouri University of Science and Technology

On Wed, Mar 26, 2014 at 2:44 PM, Stephen Andrew <address@hidden> wrote:

Sorry that was unclear. If I put in a file sink before the modulator, and call that file tx, and the file on the output of the demodulator rx, tx looks fine, but rx still looks like gunk.

Also, if I set the original file source to not repeat, my file sinks produce no data. Obviously, if one is sending a message, it only needs to be sent once, not repeated.

Thanks,

Stephen Andrew

Undergraduate, Electrical Engineering

Missouri University of Science and Technology

On Wed, Mar 26, 2014 at 4:45 AM, Martin Braun <address@hidden> wrote:

On 03/26/2014 08:32 AM, Stephen Andrew wrote:
> Hello,
>
> I'm trying to do a simple file transfer over PSK, but the text file I
> get on the output is garbled. I've got:
>
> file source -> throttle -> psk(4) mod -> psk(4) demod -> pack K (8) bits
> -> file sink
>
> If I put in a file sink before the modulator, I see the message just fine.

Do you mean if you put a file sink before the modulator, you get the
correct message in the file sink after the packer?

PSK Demod is a complete demod chain, it estimates freq. offset, timing
etc. It's probably not converging immediately, and then your signal is
bit-shifted.

M


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