MATLAB Central Newsreader - BOX CAR

BOX CAR

guj — Sun, 19 Jul 2009 04:08:01 -0400

can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...

and how to plot it with my funtion

I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.

I am new to DSP ..:) still learning the things

Re: BOX CAR

Sprinceana — Sun, 19 Jul 2009 08:57:01 -0400

"guj " <gulatiakshay@gmail.com> wrote in message <h3u671$n0p$1@fred.mathworks.com>...
> can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...
>
> and how to plot it with my funtion
>
> I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.
>
> I am new to DSP ..:) still learning the things

You store your 296 sample long on your signal in a variable isn't it?

So you multiply:

reactwin(64) *name_of_variable (which consist of your 296 point signal).

You gave little details a little code and message of errors can guide us to help you quicker!

Michael

Re: BOX CAR

ImageAnalyst — Sun, 19 Jul 2009 14:07:11 -0400

On Jul 19, 4:57 am, "Sprinceana " <mihai...@yahoo.com> wrote:
> "guj " <gulatiaks...@gmail.com> wrote in message <h3u671$n0...@fred.mathworks.com>...
> > can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...
>
> > and how to plot it with my funtion
>
> > I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.
>
> > I am new to DSP ..:) still learning the things
>
> You store your 296 sample long on your signal in a variable isn't it?
>
> So you multiply:
>
> reactwin(64) *name_of_variable (which consist of your 296 point signal).
>
> You gave little details a little code and message of errors can guide us to help you quicker!
>
> Michael

------------------------------------------------------------------
Yeah, you think that's going to work??? The only way to do the
multiplication is if the arrays are the same size, Or multiply just
part of the longer one like this:
a=1:64
b=1:296
c=a .* b(1:length(a))

Or possibly they're thinking about a sliding window sort of thing,
like convolution, conv().

But you're right in that they really haven't given enough information
to give a decent answer.
Regards,
ImageAnalyst

Re: BOX CAR

guj — Tue, 21 Jul 2009 18:06:06 -0400

ImageAnalyst <imageanalyst@mailinator.com> wrote in message <c0146ddf-ae3f-4264-946b-2b85e4ff4c43@s31g2000yqs.googlegroups.com>...
> On Jul 19, 4:57?am, "Sprinceana " <mihai...@yahoo.com> wrote:
> > "guj " <gulatiaks...@gmail.com> wrote in message <h3u671$n0...@fred.mathworks.com>...
> > > can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...
> >
> > > and how to plot it with my funtion
> >
> > > I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.
> >
> > > I am new to DSP ..:) still learning the things
> >
> > You store your 296 sample long on your signal in a variable isn't it?
> >
> > So you multiply:
> >
> > reactwin(64) *name_of_variable (which consist of your 296 point signal).
> >
> > You gave little details a little code and message of errors can guide us to help you quicker!
> >
> > Michael
>
> ------------------------------------------------------------------
> Yeah, you think that's going to work??? The only way to do the
> multiplication is if the arrays are the same size, Or multiply just
> part of the longer one like this:
> a=1:64
> b=1:296
> c=a .* b(1:length(a))
>
> Or possibly they're thinking about a sliding window sort of thing,
> like convolution, conv().

>
> But you're right in that they really haven't given enough information
> to give a decent answer.
> Regards,
> ImageAnalyst

Lets see it like that

I have s which is a spectra signal length a, w another signal spectra of length b when i convolve spectra of both of them i get y=s*w..Now y has length a+b-1.......So for getting s back i need to apply low pass filter...say a rectangular function.....RECTWIN (in matlab)....

If i apply some thing like
y.*RECTWIN(length(s)) it wont work as they r of not equal size...so how will i apply it..am i clear now ...this question seem to trivial but i dont understand

Re: BOX CAR

ImageAnalyst — Wed, 22 Jul 2009 03:17:33 -0400

On Jul 21, 2:06 pm, "guj " <gulatiaks...@gmail.com> wrote:
> ImageAnalyst <imageanal...@mailinator.com> wrote in message <c0146ddf-ae3f-4264-946b-2b85e4ff4...@s31g2000yqs.googlegroups.com>...
> > On Jul 19, 4:57?am, "Sprinceana " <mihai...@yahoo.com> wrote:
> > > "guj " <gulatiaks...@gmail.com> wrote in message <h3u671$n0...@fred.mathworks.com>...
> > > > can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...
>
> > > > and how to plot it with my funtion
>
> > > > I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.
>
> > > > I am new to DSP ..:) still learning the things
>
> > > You store your 296 sample long on your signal in a variable isn't it?
>
> > > So you multiply:
>
> > > reactwin(64) *name_of_variable (which consist of your 296 point signal).
>
> > > You gave little details a little code and message of errors can guide us to help you quicker!
>
> > > Michael
>
> > ------------------------------------------------------------------
> > Yeah, you think that's going to work??? The only way to do the
> > multiplication is if the arrays are the same size, Or multiply just
> > part of the longer one like this:
> > a=1:64
> > b=1:296
> > c=a .* b(1:length(a))
>
> > Or possibly they're thinking about a sliding window sort of thing,
> > like convolution, conv().
>
> > But you're right in that they really haven't given enough information
> > to give a decent answer.
> > Regards,
> > ImageAnalyst
>
> Lets see it like that
>
> I have s which is a spectra signal length a, w another signal spectra of length b when i convolve spectra of both of them i get y=s*w..Now y has length a+b-1.......So for getting s back i need to apply low pass filter...say a rectangular function.....RECTWIN (in matlab)....
>
> If i apply some thing like
> y.*RECTWIN(length(s)) it wont work as they r of not equal size...so how will i apply it..am i clear now ...this question seem to trivial but i dont understand- Hide quoted text -
>
-----------------------------------------------------------------------
Don't use rectwin, and you certainly don't use a low pass filter to
extract a part of a signal (that would just mess up your convolution -
change it's shape). You just use regular indexing.
For example if you signal is 100 long and your kernel is 11 long, the
convolution will be 111 long. If you want the central 100 out of it,
just say
sameSizeSignal = convolutionResult(6:105);
Good luck,
ImageAnalyst

Re: BOX CAR

guj — Wed, 22 Jul 2009 05:24:04 -0400

ImageAnalyst <imageanalyst@mailinator.com> wrote in message <2121bfee-538d-4585-8c87-6d14651e416c@o36g2000vbl.googlegroups.com>...
> On Jul 21, 2:06?pm, "guj " <gulatiaks...@gmail.com> wrote:
> > ImageAnalyst <imageanal...@mailinator.com> wrote in message <c0146ddf-ae3f-4264-946b-2b85e4ff4...@s31g2000yqs.googlegroups.com>...
> > > On Jul 19, 4:57?am, "Sprinceana " <mihai...@yahoo.com> wrote:
> > > > "guj " <gulatiaks...@gmail.com> wrote in message <h3u671$n0...@fred.mathworks.com>...
> > > > > can any one tell me how can i apply window on my signal which is 296 sample long, i want to see only 64 samples..how can i apply rectangular window...
> >
> > > > > and how to plot it with my funtion
> >
> > > > > I tired RECTWIN(64) but is giving me straight line, and how can i multiply with 296 point signal.
> >
> > > > > I am new to DSP ..:) still learning the things
> >
> > > > You store your 296 sample long on your signal in a variable isn't it?
> >
> > > > So you multiply:
> >
> > > > reactwin(64) *name_of_variable (which consist of your 296 point signal).
> >
> > > > You gave little details a little code and message of errors can guide us to help you quicker!
> >
> > > > Michael
> >
> > > ------------------------------------------------------------------
> > > Yeah, you think that's going to work??? ?The only way to do the
> > > multiplication is if the arrays are the same size, Or multiply just
> > > part of the longer one like this:
> > > a=1:64
> > > b=1:296
> > > c=a .* b(1:length(a))
> >
> > > Or possibly they're thinking about a sliding window sort of thing,
> > > like convolution, conv().
> >
> > > But you're right in that they really haven't given enough information
> > > to give a decent answer.
> > > Regards,
> > > ImageAnalyst
> >
> > Lets ?see it like that
> >
> > I have s which is a spectra signal length a, w another signal spectra of length b when i convolve spectra of both of them i get y=s*w..Now y has length a+b-1.......So for getting s back i need to apply low pass filter...say a rectangular function.....RECTWIN (in matlab)....
> >
> > If i apply some thing like
> > y.*RECTWIN(length(s)) it wont work as they r of not equal size...so how will i apply it..am i clear now ...this question seem to trivial but i dont understand- Hide quoted text -
> >
> -----------------------------------------------------------------------
> Don't use rectwin, and you certainly don't use a low pass filter to
> extract a part of a signal (that would just mess up your convolution -
> change it's shape). You just use regular indexing.
> For example if you signal is 100 long and your kernel is 11 long, the
> convolution will be 111 long. If you want the central 100 out of it,
> just say
> sameSizeSignal = convolutionResult(6:105);
> Good luck,
> ImageAnalyst

i think convolution will be 110 in length and genrally when we use funtion like box car to reconsruct a signal back in fourier domain (i am not sure though)