update of readme

README.md

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 # RadioDSP-DNR-Stm32f407
+
+ THE RADIO DSP - DNR - PROJECT - Giuseppe Callipo - IK8YFW
+
+This is an open source project that define a simple platform to make an
+Audio DSP Processor for shortwave radio receiver with Digital Noise Reduction capabilities based on Spectral Subtraction. 
+
+The system uses the good performances offered by the stm32f4 processor based on the CortexM4 specification, thanks to DSP extensions it is possible to process 256-element FFT real time (bin) ensuring a good response on the DNR functionalities, filtering and visualization of the audio signal.
+Four filter elements have been implemented, currently fixed and implemented with Fir, with the following characteristics:
+Filter 0: passes through (> 16kHz)
+Filter 1: low pass for AM (<6kHz)
+Filter 2: low pass for SSB (<3kHz)
+Filter 3: Switch bandwidth for CW (500 Hz)
+
+The display of the spectrum of the signal received in 8kHz and one is also implemented
+secondary display to Waterfall with 3kHz zoom.
+
+The project is work in progress and may be subject to change without notice.
+
+ The RadioDSP openSource software is released under the license:
+            Common Creative - Attribution 3.0
+            
+Vy 73 de Giuseppe Callipo - IK8YFW