>JohnnyM wrote:
>
>>>JohnnyM wrote:
>>>
>>>>If a band-limited white noise source is mixed with a non-delayed
>>>>version of itself in a down-conversion process, is the noise
>>>>cancelled? If the noise is mixed with a version of itself, which
>>>>is time delayed by greater than a 1/BW, is the noise power out of
>>>>the mixer 2x one of the noise sources? I
>>>
>>>>modelled this process in matalb and dont get the expected result.
>>>>Thanks.
>>>>
>>>>This message was sent using the Comp.DSP web interface on
>>>>www.DSPRelated.com
>>>
>>>Are you using the term "mix" like the audio guys as in ADD or like the
>>>RF guys as in MULTIPLY?
>>>
>>>Mark
>>>
>>
>> Multiply-like the RF guys. My signals are complex and I am modelling
the
>> mixer as the sum of the straight product and the product of the signal
>> times its complex conjugate.
>> John
>>
>No. Study up on random processes, on what happens when you square a
>zero-mean random process (i.e. your noise times itself) and what happens
>when you multiply two zero-mean random processes (i.e. your noise times
>its complex conjugate).
>
>--
>
>Tim Wescott
>Wescott Design Services
>http://www.wescottdesign.com
I'll have to think about it. I took the above products to get the sum and
difference frequencies produced by the mixing process - this works for
detrministic signals, e.g., sin cos. If I think about this stochasically,
the two products certainly dont give the same thing - you get x(n)=
e^j(s(n)-s(n))+e^j(s(n)+s(n)), but is it incorrect? I would guess the
autocorrelations of the two terms of x(n) should be the same if this is
correct. For zero lag, the first term will gives what I expect (=1 for
correlated signals), but the second term doesn't, so it seems something is
wrong. What I am trying to to must have been done a thousand times before.
Can anyone suggest a reference or approach?
Thanks,
John M.
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com
Reply by JohnnyM●March 12, 20052005-03-12
>JohnnyM wrote:
>
>>>JohnnyM wrote:
>>>
>>>>If a band-limited white noise source is mixed with a non-delayed
>>>>version of itself in a down-conversion process, is the noise
>>>>cancelled? If the noise is mixed with a version of itself, which
>>>>is time delayed by greater than a 1/BW, is the noise power out of
>>>>the mixer 2x one of the noise sources? I
>>>
>>>>modelled this process in matalb and dont get the expected result.
>>>>Thanks.
>>>>
>>>>This message was sent using the Comp.DSP web interface on
>>>>www.DSPRelated.com
>>>
>>>Are you using the term "mix" like the audio guys as in ADD or like the
>>>RF guys as in MULTIPLY?
>>>
>>>Mark
>>>
>>
>> Multiply-like the RF guys. My signals are complex and I am modelling
the
>> mixer as the sum of the straight product and the product of the signal
>> times its complex conjugate.
>> John
>>
>No. Study up on random processes, on what happens when you square a
>zero-mean random process (i.e. your noise times itself) and what happens
>when you multiply two zero-mean random processes (i.e. your noise times
>its complex conjugate).
>
>--
>
>Tim Wescott
>Wescott Design Services
>http://www.wescottdesign.com
>
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com
Reply by Tim Wescott●March 12, 20052005-03-12
JohnnyM wrote:
>>JohnnyM wrote:
>>
>>>If a band-limited white noise source is mixed with a non-delayed
>>>version of itself in a down-conversion process, is the noise
>>>cancelled? If the noise is mixed with a version of itself, which
>>>is time delayed by greater than a 1/BW, is the noise power out of
>>>the mixer 2x one of the noise sources? I
>>
>>>modelled this process in matalb and dont get the expected result.
>>>Thanks.
>>>
>>>This message was sent using the Comp.DSP web interface on
>>>www.DSPRelated.com
>>
>>Are you using the term "mix" like the audio guys as in ADD or like the
>>RF guys as in MULTIPLY?
>>
>>Mark
>>
>
> Multiply-like the RF guys. My signals are complex and I am modelling the
> mixer as the sum of the straight product and the product of the signal
> times its complex conjugate.
> John
>
No. Study up on random processes, on what happens when you square a
zero-mean random process (i.e. your noise times itself) and what happens
when you multiply two zero-mean random processes (i.e. your noise times
its complex conjugate).
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by JohnnyM●March 12, 20052005-03-12
>
>JohnnyM wrote:
>> If a band-limited white noise source is mixed with a non-delayed
>version of
>> itself in a down-conversion process, is the noise cancelled? If the
>noise
>> is mixed with a version of itself, which is time delayed by greater
>than a
>> 1/BW, is the noise power out of the mixer 2x one of the noise
>sources? I
>> modelled this process in matalb and dont get the expected result.
>> Thanks.
>>
>> This message was sent using the Comp.DSP web interface on
>> www.DSPRelated.com
>
>Are you using the term "mix" like the audio guys as in ADD or like the
>RF guys as in MULTIPLY?
>
>Mark
>
Multiply-like the RF guys. My signals are complex and I am modelling the
mixer as the sum of the straight product and the product of the signal
times its complex conjugate.
John
>
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com
Reply by JohnnyM●March 12, 20052005-03-12
>
>JohnnyM wrote:
>> If a band-limited white noise source is mixed with a non-delayed
>version of
>> itself in a down-conversion process, is the noise cancelled? If the
>noise
>> is mixed with a version of itself, which is time delayed by greater
>than a
>> 1/BW, is the noise power out of the mixer 2x one of the noise
>sources? I
>> modelled this process in matalb and dont get the expected result.
>> Thanks.
>>
>> This message was sent using the Comp.DSP web interface on
>> www.DSPRelated.com
>
>Are you using the term "mix" like the audio guys as in ADD or like the
>RF guys as in MULTIPLY?
>
>Mark
>
Multiply-like the RF guys. My signals are complex and I am modelling the
mixer as the sum of the straight product and the product of the signal
times its complex conjugate.
John
>
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com
Reply by Mark●March 12, 20052005-03-12
JohnnyM wrote:
> If a band-limited white noise source is mixed with a non-delayed
version of
> itself in a down-conversion process, is the noise cancelled? If the
noise
> is mixed with a version of itself, which is time delayed by greater
than a
> 1/BW, is the noise power out of the mixer 2x one of the noise
sources? I
> modelled this process in matalb and dont get the expected result.
> Thanks.
>
> This message was sent using the Comp.DSP web interface on
> www.DSPRelated.com
Are you using the term "mix" like the audio guys as in ADD or like the
RF guys as in MULTIPLY?
Mark
Reply by JohnnyM●March 11, 20052005-03-11
If a band-limited white noise source is mixed with a non-delayed version of
itself in a down-conversion process, is the noise cancelled? If the noise
is mixed with a version of itself, which is time delayed by greater than a
1/BW, is the noise power out of the mixer 2x one of the noise sources? I
modelled this process in matalb and dont get the expected result.
Thanks.
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com