(See the README.md file in the upper level 'examples' directory for more information about examples.)
This example demonstrates how to use Window and FFT functionality from esp-dsp library. Example does the following steps:
- Initialize the library
- Initialize input signals with 1024 samples
- Apply window to input signal.
- Calculate FFT for 1024 complex samples
- Apply bit reverse operation for output complex vector
- Split one complex FFT output spectrum to two real signal spectrums
- Show results on the plots
This example does not require any special hardware, and can be run on any common development board.
If using Make based build system, run make menuconfig and set serial port under Serial Flasher Options.
If using CMake based build system, no configuration is required.
Also, under Component Config/DSP Library/Optimization for ESP32, it's possible to select optimized or ansi implementation to compare.
Build the project and flash it to the board, then run monitor tool to view serial output:
make -j4 flash monitor
Or, for CMake based build system (replace PORT with serial port name):
idf.py -p PORT flash monitor
(To exit the serial monitor, type Ctrl-].)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
Here is an typical example console output.
I (128) main: Start Example.
W (128) main: Hann Window
I (128) view: Data min[256] = -inf, Data max[1] = 24.086628
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0123456789012345678901234567890123456789012345678901234567890123
I (138) view: Plot: Length=512, min=-120.000000, max=40.000000
W (138) main: Blackman Window
I (148) view: Data min[355] = -165.295654, Data max[1] = 24.083012
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0123456789012345678901234567890123456789012345678901234567890123
I (158) view: Plot: Length=512, min=-120.000000, max=40.000000
W (158) main: Blackman-Harris Window
I (168) view: Data min[128] = -inf, Data max[1] = 23.874702
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0123456789012345678901234567890123456789012345678901234567890123
I (178) view: Plot: Length=512, min=-120.000000, max=40.000000
W (178) main: Blackman-Nuttall Window
I (188) view: Data min[128] = -inf, Data max[1] = 23.890663
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0123456789012345678901234567890123456789012345678901234567890123
I (198) view: Plot: Length=512, min=-120.000000, max=40.000000
W (198) main: Nuttall Window
I (208) view: Data min[203] = -175.147400, Data max[1] = 23.858671
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0123456789012345678901234567890123456789012345678901234567890123
I (218) view: Plot: Length=512, min=-120.000000, max=40.000000
W (218) main: Flat-Top Window
I (228) view: Data min[256] = -inf, Data max[1] = 22.490753
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0123456789012345678901234567890123456789012345678901234567890123
I (238) view: Plot: Length=512, min=-120.000000, max=40.000000
I (238) main: End Example.