Re: [Discuss-gnuradio] appending preamble with different power

[Nick Foster]

On Fri, 2011-06-24 at 04:00 +0900, Songsong Gee wrote:
> Ok. First of all, I'd like to run a code like below (pseudo):
> for i = 1 to 200 // preamble duration
>   amp = 32767
> end for
> amp = 100

Like I said earlier, this is unlikely to be a good approach to
synchronizing with a preamble.

> 
> Next, how many baseband samples are generated by DPSK or Frequency mod
> block for a single symbol input

Did you read the email you just replied to?

> 
> Composed with Android (Galaxys)
> 
> 2011. 6. 24. 오전 3:31에 "Nick Foster" <address@hidden>님이 작성:
> > On Fri, 2011-06-24 at 01:17 +0900, Songsong Gee wrote:
> >> Continueing with http://www.ruby-forum.com/topic/1983866,
> >> 
> >> 
> >> I have planned to append a preamble before an actual signal and
> turn
> >> RX on earlier than TX.
> >> 
> >> 
> >> Then RX will receive a signal like below:
> >> |---RX turn on------|---TX turn
> >> on-----------------------------
> >> (---trash signal---)(---preamble---)(---actual signal---)
> >> 
> >> 
> >> And this signal is demodulated and stored into a sink file.
> >> After that, I run a program that extracts an actual data only and
> >> compare it to the original.
> >> 
> >> 
> >> My concern is that this preamble should be assumed to be perfect
> i.e.
> >> no errors
> >> Of course, there isn't no error. However if I set an amplitude to
> >> maximum value, it can be said to be no error.
> > 
> > I don't understand what you mean here. You can find an "imperfect"
> > preamble sequence using a correlator.
> > 
> >> I have a pre-defined preamble sequence with length n (n = around
> >> 100-200, can be changed)
> >> 
> >> 
> >> Thus, I am trying to change amplitude of modulated signal for
> preamble
> >> and actual signal
> >> But I have problem with some quadrature modulation. Flow graphs are
> in
> >> below:
> >>
> http://dl.dropbox.com/u/11382666/for_gnuradio_mailinglist/M-DPSK.png
> >> http://dl.dropbox.com/u/11382666/for_gnuradio_mailinglist/M-FSK.png
> >> 
> >> 
> >> My question is that, how many samples after DPSK mod or frequency
> mod
> >> block corresponds to each sample from file source?
> > 
> > It's right there in the block, where it says "samples/symbol".
> > 
> >> I have to solve this problem in order to figure out how many
> samples
> >> are generated from preamble with length n.
> >> If I know that information, I can set a duration for Multiply const
> >> block having large value for preamble and normal value for actual
> >> signal
> > 
> > Why would you set the amplitude of the preamble differently than the
> > actual data?
> > 
> > --n
> > 
> >> 
> >> 
> >> And second question is that, although I know that information, I
> don't
> >> know how I can control value.
> >> For example, preamble with length 200, then I want to set large
> value
> >> for duration 200 * x (number of samples generated after DPSK,
> >> Frequency mod), and after that I want to set normal value for
> >> remaining duration.
> >> 
> >> 
> >> Is it too complex for gnuradio-companion flow graph to make? And is
> >> python hard coding possible?
> >> 
> >> 
> >> -- 
> >> Seokseong Jeon (aka Songsong Gee)
> >> 
> >> 
> >> _______________________________________________
> >> Discuss-gnuradio mailing list
> >> address@hidden
> >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > 
> > 
>