diff --git a/firmware/baseband/spectrum_collector.cpp b/firmware/baseband/spectrum_collector.cpp
index 5d1687b6..4256b362 100644
--- a/firmware/baseband/spectrum_collector.cpp
+++ b/firmware/baseband/spectrum_collector.cpp
@@ -27,7 +27,7 @@
 #include "event_m4.hpp"
 #include "portapack_shared_memory.hpp"
 
-#include "event_m4.hpp"
+/*  #include "event_m4.hpp"    that  line  is duplicated,  we can delete it .*/
 
 #include <algorithm>
 
@@ -105,24 +105,38 @@ void SpectrumCollector::post_message(const buffer_c16_t& data) {
 	}
 }
 
-template<typename T>
+/* 3 types of Windowing time domain shapes declaration , but only used Hamming  ,  shapes for  FFT  
+    GCC10 compile sintax error c/m  (1/2), 
+          The primary diff. between const and constexpr variables is that 
+          the initialization of a const var can be deferred until run time. 
+	      A constexpr var. must be initialized at compile time. ... 
+	      A var. can be declared with constexpr , when it has a literal type and is initialized.
+	 GCC compile sintax error c/m (2/2)
+ 	      Static assert --> Tests a software assertion at compile time for debugging.
+		  we keep the same safety  compile protection , just changing slightly the sintax  checking that the size of the called array is power of 2.
+	      if the bool  "constant expression" is TRUE (normal case) , the declaration has no effect.
+		  if the bool  "constant expression" is FALSE (abnormal array size) , it is aborted the compile with a msg error. 
+		  	  */ 
+
+
+template<typename T> // Although currently we are not using that Windowing shape, we apply the same GCC10 compile error c/m 
 static typename T::value_type spectrum_window_none(const T& s, const size_t i) {
-	static_assert(power_of_two(s.size()), "Array size must be power of 2");
+ static_assert(power_of_two(sizeof(s)), "Array size must be power of 2");   // c/m compile error GCC10 , OK for all GCC versions. 
 	return s[i];
 };
 
-template<typename T>
+template<typename T>   // Currently we are calling and using that Window shape.
 static typename T::value_type spectrum_window_hamming_3(const T& s, const size_t i) {
-	static_assert(power_of_two(s.size()), "Array size must be power of 2");
-	constexpr size_t mask = s.size() - 1;
+    static_assert(power_of_two(sizeof(s)), "Array size must be power of 2");   // c/m compile error GCC10 , OK for all GCC versions. 
+	const size_t mask = s.size() - 1;          // c/m compile error GCC10 , constexpr->const
 	// Three point Hamming window.
 	return s[i] * 0.54f + (s[(i-1) & mask] + s[(i+1) & mask]) * -0.23f;
 };
 
-template<typename T>
+template<typename T>   // Although currently we are not using that Windowing shape, we apply the same GCC10 compile error c/m  
 static typename T::value_type spectrum_window_blackman_3(const T& s, const size_t i) {
-	static_assert(power_of_two(s.size()), "Array size must be power of 2");
-	constexpr size_t mask = s.size() - 1;
+	static_assert(power_of_two(sizeof(s)), "Array size must be power of 2");   // c/m compile error GCC10 , OK for all GCC versions. 
+    const size_t mask = s.size() - 1;          // c/m compile error GCC10 , constexpr->const
 	// Three term Blackman window.
 	constexpr float alpha = 0.42f;
 	constexpr float beta = 0.5f * 0.5f;