wcdma bandwidth

if you were designing a decimation filter for a baseband wcdma signal
that was oversampled, what target (decimated) bandwidth would you 
choose?
-- 
Randy Yates                      % "Maybe one day I'll feel her cold embrace,
Digital Signal Labs              %                    and kiss her interface, 
mailto://yates@ieee.org          %            til then, I'll leave her alone."
http://www.digitalsignallabs.com %        'Yours Truly, 2095', *Time*, ELO   

>if you were designing a decimation filter for a baseband wcdma signal
>that was oversampled, what target (decimated) bandwidth would you 
>choose?

Somewhere between 2.5 MHz and 4 MHz at baseband?

Steve

spope33@speedymail.org (Steve Pope) writes:

>>if you were designing a decimation filter for a baseband wcdma signal
>>that was oversampled, what target (decimated) bandwidth would you 
>>choose?
>
> Somewhere between 2.5 MHz and 4 MHz at baseband?

How could it possibly be 2.5 MHz? The chip rate is 3.84 Mc/s.
-- 
Randy Yates                      % "Maybe one day I'll feel her cold embrace,
Digital Signal Labs              %                    and kiss her interface, 
mailto://yates@ieee.org          %            til then, I'll leave her alone."
http://www.digitalsignallabs.com %        'Yours Truly, 2095', *Time*, ELO   

In article <m3d3qajfy6.fsf@ieee.org>, Randy Yates  <yates@ieee.org> wrote:
>spope33@speedymail.org (Steve Pope) writes:
>
>>>if you were designing a decimation filter for a baseband wcdma signal
>>>that was oversampled, what target (decimated) bandwidth would you 
>>>choose?
>>
>> Somewhere between 2.5 MHz and 4 MHz at baseband?
>
>How could it possibly be 2.5 MHz? The chip rate is 3.84 Mc/s.

You said "at baseband".

We could get into a philosophical discussion as to what
"2.5 MHz bandwidth at baseband" means, but I meant each
of the I and Q channels has a bandwidth from 0 to 2.5 MHz.



Steve

spope33@speedymail.org (Steve Pope) writes:

> In article <m3d3qajfy6.fsf@ieee.org>, Randy Yates  <yates@ieee.org> wrote:
>>spope33@speedymail.org (Steve Pope) writes:
>>
>>>>if you were designing a decimation filter for a baseband wcdma signal
>>>>that was oversampled, what target (decimated) bandwidth would you 
>>>>choose?
>>>
>>> Somewhere between 2.5 MHz and 4 MHz at baseband?
>>
>>How could it possibly be 2.5 MHz? The chip rate is 3.84 Mc/s.
>
> You said "at baseband".
>
> We could get into a philosophical discussion as to what
> "2.5 MHz bandwidth at baseband" means, but I meant each
> of the I and Q channels has a bandwidth from 0 to 2.5 MHz.

Doh! Right. (I was thinking of complex bandwidth).

I agree with 2.5 (5 MHz complex) based on a chip rate of 3.84 Mc/s 
and (according to the 3GPP spec) a RRC rolloff factor of 0.22. Is
that where your numbers come from?
-- 
Randy Yates                      % "So now it's getting late,
Digital Signal Labs              %    and those who hesitate
mailto://yates@ieee.org          %    got no one..."
http://www.digitalsignallabs.com % 'Waterfall', *Face The Music*, ELO

Randy Yates <yates@ieee.org> writes:

> spope33@speedymail.org (Steve Pope) writes:
>
>> In article <m3d3qajfy6.fsf@ieee.org>, Randy Yates  <yates@ieee.org> wrote:
>>>spope33@speedymail.org (Steve Pope) writes:
>>>
>>>>>if you were designing a decimation filter for a baseband wcdma signal
>>>>>that was oversampled, what target (decimated) bandwidth would you 
>>>>>choose?
>>>>
>>>> Somewhere between 2.5 MHz and 4 MHz at baseband?
>>>
>>>How could it possibly be 2.5 MHz? The chip rate is 3.84 Mc/s.
>>
>> You said "at baseband".
>>
>> We could get into a philosophical discussion as to what
>> "2.5 MHz bandwidth at baseband" means, but I meant each
>> of the I and Q channels has a bandwidth from 0 to 2.5 MHz.
>
> Doh! Right. (I was thinking of complex bandwidth).
>
> I agree with 2.5 (5 MHz complex) based on a chip rate of 3.84 Mc/s 
> and (according to the 3GPP spec) a RRC rolloff factor of 0.22. Is
> that where your numbers come from?

PS: And just rounding from 4.685 to 5.
-- 
Randy Yates                      % "Rollin' and riding and slippin' and
Digital Signal Labs              %  sliding, it's magic."
mailto://yates@ieee.org          %  
http://www.digitalsignallabs.com % 'Living' Thing', *A New World Record*, ELO

Randy Yates  <yates@ieee.org> wrote:

>spope33@speedymail.org (Steve Pope) writes:

>> In article <m3d3qajfy6.fsf@ieee.org>, Randy Yates  <yates@ieee.org> wrote:
>>>spope33@speedymail.org (Steve Pope) writes:
>>>
>>>>>if you were designing a decimation filter for a baseband wcdma signal
>>>>>that was oversampled, what target (decimated) bandwidth would you 
>>>>>choose?
>>>>
>>>> Somewhere between 2.5 MHz and 4 MHz at baseband?
>>>
>>>How could it possibly be 2.5 MHz? The chip rate is 3.84 Mc/s.

>> You said "at baseband".

>> We could get into a philosophical discussion as to what
>> "2.5 MHz bandwidth at baseband" means, but I meant each
>> of the I and Q channels has a bandwidth from 0 to 2.5 MHz.
>
>Doh! Right. (I was thinking of complex bandwidth).
>
>I agree with 2.5 (5 MHz complex) based on a chip rate of 3.84 Mc/s 
>and (according to the 3GPP spec) a RRC rolloff factor of 0.22. Is
>that where your numbers come from?

That's approximately my thinking.

Steve