Re: [Discuss-gnuradio] PSK File transfer

[Martin Braun]

On 03/27/2014 01:42 AM, Stephen Andrew wrote:
> 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?

The packetizer adds a preamble, which helps the demod lock and, more
importantly, and as pointed out in my earlier response, it helps you
find the byte boundaries.

Repeat is not magical, but the demod is stateful, and therefore works
better if rx'ing more data.

TBH, I didn't try this out, but I'll call this a very educated guess :)
For packetized data, you always need some kind of preamble.

Martin