westocl wrote:
>> westocl wrote:
>>>> westocl wrote:
>>>>> Hello all.
>>>>>
>>>>> Is it feasable to do an fft in 'real time' on different 'blocks' of
>>> data?
>>>>> (i understand the nomenclature real time may be inappropriate).
>>>>>
>>>>>
>>>>> Im thinking, in general usage of an FFT, some x[n] comes in one
> sample
>>> at
>>>>> a time and fills up a buffer and when that buffer (lets call it 128
>>> time
>>>>> domain samples) is filled a FFT is taken and the 'output' is 128
> points
>>> of
>>>>> frequncy domain data.
>>>>>
>>>>> Now.. instad of somthing like a sliding DFT where a window evaluates
>>> the
>>>>> previous 127 samples along with one new one, i have a situation
> where
>>> i
>>>>> want to give the 'fft buffer' 128 NEW data points... so every single
>>> 'time
>>>>> instant'...128 new x[n] data are available.
>>>>>
>>>>> If this were done would I get a new FFT output at every time
> instant?
>>>> You confused me. 128 new instances of x[n] for every n? How?
>>>>
>>>> Jerry
>>>> --
>>>> Engineering is the art of making what you want from things you can
> get.
>>>
>>> You are right...My notation is somewhat confusing by using x[n]. But
>>> imagine we had a switch that will switch to an already full buffer at
>>> every 'sample interval'. Then at the next instant we go to the next
> 128
>>> buffer and we call that x[n] and so on..
>> What fills these nearly full buffers? When? You seem to want 128 new
>> samples per sampling instant. That can't be sustained.
>>
>> Jerry
>> --
>> Engineering is the art of making what you want from things you can get.
>
>
> It seems thats exactly the case i will have... What i want to do is
> analagous to having 128 antennas and a situation where i have to take the
> FFT for each antenna. So some kind of rotary switch gives me the new
> antenna input data at every sample... and will keep spinning.

There's nothing unusual about simultaneously processing multiple
streams. But each stream would have it's own FT. There could be 128
samples collected at each sample interval, but probably not via a
multiplexer (rotary switch). One of us is still confused.

Jerry
--
Engineering is the art of making what you want from things you can get.