Reply by robert bristow-johnson●July 31, 20082008-07-31
On Jul 30, 7:42�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". �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
Reply by chivak●July 30, 20082008-07-30
>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
>
Reply by julius●July 30, 20082008-07-30
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?
>
> 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?
Reply by B.chay●July 30, 20082008-07-30
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