page_title: Channel sounding
section_title: Data post-processing
hierarchical_section_title: Channel sounding / Description of existing approaches / Real-Time Ultra-wideband MIMO Channel Sounding / Data post-processing
caption_attribution_description: English: RUSK SOUNDING
context_page_description: Channel sounding is a technique that evaluates the radio environment for wireless communication, especially MIMO systems. Because of the effect of terrain and obstacles, wireless signals propagate in multiple paths. To minimize or use the multipath effect, engineers use channel sounding to process the multidimensional spatial-temporal signal and estimate channel characteristics. This helps simulate and design wireless systems.
context_section_description: A DFT over K-1 (one waveform lost due to array switching) waveforms that measured in each channel is performed (K: waveforms per channel).
  The frequency domain samples at the multitone frequencies are picked at every  sample.
  An estimated channel transfer function  is obtained by:
  where  is the noise power,  is a reference signal and  is the samples.
  The scaling factor c is defined as
caption: RUSK SOUNDING. 
    
      
        
          
            α
            
              m
              a
              x
            
          
        
      
      {\displaystyle \alpha _{max}}
    
   is the maximum Doppler frequency.
    
      
        
          
            τ
            
              m
              a
              x
            
          
        
      
      {\displaystyle \tau _{max}}
    
   is the maximum duration of the impulse response and S is the channel's spread (the red rectangle in the figure).[4]