RTOS/AM5728: Dsplib FFT questions

Mukul

Part Number: AM5728

Tool/software: TI-RTOS

There are set of FFT functions available in DSPLIB but there is no clear description of which FFT function shall be used in which scenario.

In my case I have an array of 16 bit real valued samples. I want to have 32 bit packed (16bit real , 16bit imag) complex array as output but I am not sure which of the library function does this most efficiently. I am using c66x DSP but want to implement FFT in fixed point only.

I believe if I am utilizing the info that my input is real then there shall be considerable optimization achieved from the given benchmark in test reports shared with dsplib.

Also if there are any comparisons available for following fixed point FFT functions then that will help a lot.

	DSP_fft16x16
	DSP_fft16x16r
	DSP_fft16x16_imre
	DSP_fft16x32
	DSP_fft32x32
	DSP_fft32x32s
	DSP_ifft16x16
	DSP_ifft16x16_imre
	DSP_ifft16x32
	DSP_ifft32x32

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

The RTOS team have been notified. They will respond here.

0 Rahul Prabhu over 8 years ago

TI__Guru** 116780 points

The Description for the function is part of the DSPLIB_Users_Manual.html that is part of the library under the folder dsplib_c66x_3_4_0_0\docs
In the document the index will point you to "API reference guide"

for FFT computation using real inputs, you can also refer to the following wiki :
processors.wiki.ti.com/.../Efficient_FFT_Computation_of_Real_Input

Hope this answers your question.

Regards,
Rahul

0 Mukul over 8 years ago in reply to Rahul Prabhu

Prodigy 30 points

Hi,

Thanks for the wiki link but my question was more like if we can use one of the available dsp library function for real input signal directly.
Even if its not available ready made can you please suggest that which one of these functions listed above can be modified for Q15 real input samples and hint about changes required thereof.

Regarding functionality difference question, I had already referred to the API references but there were no description which explains exact difference and need of all these functions (doing almost similar work). That means which function shall be used in what kind of scenario?

0 Mukul over 7 years ago in reply to Mukul

Prodigy 30 points

Hello, Please see if you can provide any better help on this as explained in my reply.

0 Rahul Prabhu over 7 years ago in reply to Mukul

TI__Guru** 116780 points

Mukul,

The fixed point FFT functions in the DSP library have been part of this library since the C64x+ when DSP only support fixed point operations. You can find details of all these 8 function in the application note here:
www.ti.com/.../spra884a.pdf (Refer Section 3.4 on FFTs)

Please let us know if this still doesn`t suffice your understanding.

Regards,
Rahul

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RTOS/AM5728: Dsplib FFT questions