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@ -1,9 +1,9 @@ |
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/*
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* analyze_fft4096_iqem_F32.h Assembled by Bob Larkin 18 Feb 2022 |
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* |
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* External Memory **** BETA TEST VERSION - NOT FULLY TESTED **** <<<<<<<<<< |
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* External Memory - INO supplied memory arrays. Windows are half width. |
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* |
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* Note: Teensy 4.x Only, 3.x not supported |
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* Note: Teensy 4.x ONLY, 3.x not supported |
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* |
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* Does Fast Fourier Transform of a 4096 point complex (I-Q) input. |
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* Output is one of three measures of the power in each of the 4096 |
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@ -73,7 +73,7 @@ |
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* required if power averaging is used and about 58 kBytes without power averaging. |
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* |
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* In addition, this requires 64 AudioMemory_F32 which work out to about an |
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* additional 33 kBytesof memory. |
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* additional 33 kBytes of memory. |
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* |
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* If several FFT sizes are used, one at a time, the memory can be shared. Probably |
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* the simplest way to do this with a Teensy is to set up C-language unions. |
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@ -96,11 +96,6 @@ |
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* If xAxis=2 f=fs/2 on left edge, f=0 in middle |
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* If xAxis=3 f=fs/2 on right edgr, f=0 in middle |
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* |
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* If there is 180 degree phase shift to I or Q these all get reversed. |
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* xAxis=1 is a mathemetically consistent method. It has positive frequencies |
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* on the right and negative ones on the left. The center is half the sample |
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* rate, both + and -. Uniormly sampled data lives in this circular world.rate. |
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* |
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* Timing, maximum microseconds per update() over the 16 updates, |
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* and the average percent processor use for 44.1 kHz sample rate and Nave=1: |
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* T4.0 Windowed, dBFS Out (FFT_DBFS), 710 uSec, Ave 4.64% |
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@ -119,7 +114,7 @@ |
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* |
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* To use an alternate window function, just fill it into the array, window, above. |
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* It is only half of the window (2048 floats). It looks like a full window |
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* function with the righ half missing. It should start with small |
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* function with the right half missing. It should start with small |
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* values on the left (near[0]) and go to 1.0 at the right ([2048]). |
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* |
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* As with all library FFT's this one provides overlapping time series. This |
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@ -140,7 +135,7 @@ |
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* |
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* 22 Feb 2022 Fixed xAxis error, twice! |
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*/ |
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/* Info
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/* Info:
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* __MK20DX128__ T_LC; __MKL26Z64__ T3.0; __MK20DX256__T3.1 and T3.2 |
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* __MK64FX512__) T3.5; __MK66FX1M0__ T3.6; __IMXRT1062__ T4.0 and T4.1 */ |
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@ -298,7 +293,7 @@ private: |
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int outputType = FFT_RMS; //Same type as I16 version init
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int count = 0; |
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int nAverage = 1; |
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uint8_t xAxis = 0x03; |
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uint8_t xAxis = 0x03; // See discussion above
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// The Hann window is a good all-around window
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// This can be used with zero-bias frequency interpolation.
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