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benreynwar / htfft

A high throughput FFT implementation
MIT License
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Prefered way to pause calculation #5

Open FranzForstmayr opened 2 years ago

FranzForstmayr commented 2 years ago

Is there a prefered way to pause a calculation?

For inserting a cyclic prefix of an ofdm transmission I need to stop the fft for a certain time after a calculation finishes. For example I'm using a FFT64, with SPCC=4, so 16 cycles are needed. The cyclic prefix length is 16 too, so i delay the next frame by four clock cycles and send another i_start signal. However, the output does not look like, if the delayed i_start is accepted.

See this image, two data frames with an zero frame in between, for better visibility. image

The output stream, the zero frame in between is not visible anymore. image

Is the i_first signal intended to be used as a start signal for each frame, or is it used just once, and the algorithm picks always the next N samples, regardless of the ì_first` signal?

benreynwar commented 2 years ago

Didn't notice this issue go past my email. Sorry about that. It's intended to be used at the start of each frame. It may be that you've found at bug. I'll look into this.