On 21 Feb, 16:38, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> On Thu, 21 Feb 2008 02:35:33 -0800 (PST), Bob <sten...@yahoo.com>
> wrote:
>
>
>
>
>
> >On 21 Feb, 08:14, c...@claysturner.com wrote:
> >> On Feb 20, 4:38*pm, Bob <sten...@yahoo.com> wrote:
>
> >> > On 20 Feb, 20:41, Mark <makol...@yahoo.com> wrote:
>
> >> > > > So now I see something,,,notice the small peak to the left of the
> >> > > > cursor on the second and fourth traces. Should this not be the same as
> >> > > > the peaks beside it?
>
> >> > > remember you are looking at the RRC filter..which is only 1/2 the
> >> > > picture
>
> >> > > pass this output though another RRC filter so that you have the full
> >> > > RC filter and you will see what the receiver sees...
>
> >> > > the Rx and Tx have matched filters and the NYquist filter is both of
> >> > > them in cascade,
>
> >> > > you are looking 1/2 way through the cascade..
>
> >> > > Mark
>
> >> > Hi Mark,
>
> >> > The pulses you see on the first link is what happens when I pass the
> >> > data through the RRC on the TX link. On the demod side links 2 and 3
> >> > are when the data from the modulator is passed through idential RRCs.
> >> > So, in effect I already have the RC response at the receiver. But is
> >> > it correct...that's what I would like to know?
>
> >> > Bob- Hide quoted text -
>
> >> > - Show quoted text -
>
> >> Hello Bob,
>
> >> The feeding of pulses into the RRC filter (via convolution) assumes
> >> your pulses become Kronecker deltas. Don't feed rectangular pulses,
> >> instead feed spikes into the RRC filter. Then after going through two
> >> of these in sucession, you will see a nice looking signal. You are
> >> currenly getting a bunch of ringing resulting from the rectangular
> >> pulse's response comingled (convolved) with the RRC's response. For
> >> simplifying the testing, just try an RC filter and look at its output.
> >> Two RRCs convolved is an RC. Try it!
>
> >> IHTH,
>
> >> Clay- Hide quoted text -
>
> >> - Show quoted text -
>
> >Hi Clay,
>
> >I did already try it. I fed the output of one RRC into another and
> >you're correct...I did get a nice RC pulse output.
> >In the test case, this was done for spikes well seperated. However,
> >for real test data, I don't have much choice as I have strings of 1's
> >and in most cases very few 0's between them. In this case, what are my
> >options?
>
> >Regards
> >Bob
>
> I haven't looked at your latest plots, but I'm a little confused by
> your last statement. * How many samples per symbol are there going
> into the transmit RRC filter? * If the answer is one, then you don't
> have to worry about the rectangular symbol problem. * If the answer is
> more than one, then only one of those samples per symbol should be
> non-zero if you want to avoid an additional sinx/x response in the
> filtering.
>
> Eric Jacobsen
> Minister of Algorithms
> Abineau Communicationshttp://www.ericjacobsen.org- Hide quoted text -
>
> - Show quoted text -

Hi Eric,

Hi Eric,

One sample per symbol into each RRC filter.

Bob