135 lines
6.9 KiB
Markdown
135 lines
6.9 KiB
Markdown
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# FFT Window Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example demonstrates how to use Window and FFT functionality from esp-dsp library. Example does the following steps:
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1. Initialize the library
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2. Initialize input signals with 1024 samples
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3. Apply window to input signal.
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4. Calculate FFT for 1024 complex samples
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5. Apply bit reverse operation for output complex vector
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6. Split one complex FFT output spectrum to two real signal spectrums
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7. Show results on the plots
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## How to use example
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### Hardware required
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This example does not require any special hardware, and can be run on any common development board.
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### Configure the project
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Under Component Config ---> DSP Library ---> DSP Optimization, it's possible to choose either the optimized or ANSI implementation, to compare them.
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### Build and flash
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Build the project and flash it to the board, then run monitor tool to view serial output (replace PORT with serial port name):
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```
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example output
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Here is an typical example console output.
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```
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I (128) main: Start Example.
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W (128) main: Hann Window
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I (128) view: Data min[256] = -inf, Data max[1] = 24.086628
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (138) view: Plot: Length=512, min=-120.000000, max=40.000000
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W (138) main: Blackman Window
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I (148) view: Data min[355] = -165.295654, Data max[1] = 24.083012
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (158) view: Plot: Length=512, min=-120.000000, max=40.000000
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W (158) main: Blackman-Harris Window
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I (168) view: Data min[128] = -inf, Data max[1] = 23.874702
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (178) view: Plot: Length=512, min=-120.000000, max=40.000000
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W (178) main: Blackman-Nuttall Window
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I (188) view: Data min[128] = -inf, Data max[1] = 23.890663
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (198) view: Plot: Length=512, min=-120.000000, max=40.000000
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W (198) main: Nuttall Window
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I (208) view: Data min[203] = -175.147400, Data max[1] = 23.858671
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (218) view: Plot: Length=512, min=-120.000000, max=40.000000
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W (218) main: Flat-Top Window
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I (228) view: Data min[256] = -inf, Data max[1] = 22.490753
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (238) view: Plot: Length=512, min=-120.000000, max=40.000000
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I (238) main: End Example.
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```
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