Re: Help.....DSP on ARM9 or ARM7!!!!


"linnix" <me@xxxxxxxxxxxxxxxxxx> wrote in message
news:1138664199.493845.11670@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Wilco Dijkstra wrote:
>> "jagdish.dsp" <jagdish.dsp@xxxxxxxxx> wrote in message
>> news:uuSdnROkSq5X0UPeRVn-uQ@xxxxxxxxxxxxxxx

>> > I have to implement 8192 point FFT on real time sound data....
>>
>> An ARM7 takes 2Mhz to perform a 8192 complex Q15 FFT. ARM9E is twice as
>> fast.
>
> That's for doing one per second, which is unlikely for any reasonable
> algorithm.

Without more detailed information it is reasonable to assume only one FFT
would be needed for each set of 8192 samples, ie. only 3.9 needed per
second. ARM7 goes up to 120Mhz, so it can handle around 50 complex
8192-point FFTs per second.

In another post you wrote:
>You need over 1GHz ARM, preferrable with muti-media instructions.

The fastest ARM (Cortex-A8) is about as fast as the TMS320C64x (TI's fastest
DSP). Exactly which audio codec needs _that_ much DSP power?

Wilco



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