Quadrature signal conversion/modulation

Is it sensible to say that qudrature conversion can be applied to any
signal, and the product of the conversion is an I/Q pair that represent the
inputs signal? 

Thanks,
Ben

On Jul 30, 7:27&#4294967295;pm, "B.chay" <Ben....@unitedgroupltd.com> wrote:
> Is it sensible to say that qudrature conversion can be applied to any
> signal, and the product of the conversion is an I/Q pair that represent the
> inputs signal?
>
> Thanks,
> Ben

Please define "quadrature conversion".  As far as I understand,
quadrature modulation is a mapping that takes k bits at a time,
and outputs one of 2^k possible complex-valued number.

Some others may take quadrature modulation as one of the next
steps, which is taking a complex-valued signal, multiplying with
exp(j 2 pi fc t), and taking the real value.

Which do you mean?

>On Jul 30, 7:27=A0pm, "B.chay" <Ben....@unitedgroupltd.com> wrote:
>> Is it sensible to say that qudrature conversion can be applied to any
>> signal, and the product of the conversion is an I/Q pair that represent
t=
>he
>> inputs signal?
>>
>> Thanks,
>> Ben
>
>Please define "quadrature conversion".  As far as I understand,
>quadrature modulation is a mapping that takes k bits at a time,
>and outputs one of 2^k possible complex-valued number.
>
>Some others may take quadrature modulation as one of the next
>steps, which is taking a complex-valued signal, multiplying with
>exp(j 2 pi fc t), and taking the real value.
>
>Which do you mean?

I think , he's reffering to the latter part.

 In any case, to answer the question, qudrature conversion converts a low
pass signal to a band pass signal(complex).

 So your assumption is correct if you are aware of the fact that there is
  frequency translation invloved.

-Chivak
>

On Jul 30, 7:42&#4294967295;pm, "chivak" <cd_pra...@hotmail.com> wrote:
> >On Jul 30, 7:27 pm, "B.chay" <Ben....@unitedgroupltd.com> wrote:
> >> Is it sensible to say that qudrature conversion can be applied to any
> >> signal, and the product of the conversion is an I/Q pair that represent
> >> the inputs signal?
>
> >Please define "quadrature conversion". &#4294967295;As far as I understand,
> >quadrature modulation is a mapping that takes k bits at a time,
> >and outputs one of 2^k possible complex-valued number.
>
> >Some others may take quadrature modulation as one of the next
> >steps, which is taking a complex-valued signal, multiplying with
> >exp(j 2 pi fc t), and taking the real value.
>
> >Which do you mean?
>
> I think , he's reffering to the latter part.

i thought what was meant is taking a real signal, x(t) or x[n], and
creating the complex analytic signal, which is


   x(t) + j*Hilbert{ x(t) }    (continuous time)

or

   x[n] + j*Hilbert{ x[n] }    (discrete time).


the spectrum of this is one-sided (nothing at negative frequencies),
at positive frequencies it's the same spectrum as x(t) (or x[n]) but
doubled and multiplying by e^(j*w0*t) (or e^(j*w0*n)) bumps the
spectrum up by an amount of w0 in whatever frequency domain.

r b-j