EXPERIMENTAL TRANSVERSAL EQUALIZER FOR TI)-2 



1433 



at'teristic and aii}^ delay characteristic limited 011I3' by the number of 

 harmonics that are provided and the range of each. 



Basically, the transversal eciualizer consists of a delay line with 

 eciually spaced taps, with a means for independentl}^ controlling the 

 amount of signal fed through each of the taps to a summing circuit, 

 as shown schematically on Fig. 3. The input signal is fed into one end 

 of the delay line which is terminated at the other end. The center tap 

 is fed to the output and forms the main transmission path. 



The operation of the equalizer can best be described using the "time 

 domain" analysis based on the theory of paired echos.^ Portions of the 

 signal tapped off the "leading" or first half of the delay line will not be 

 delayed as much as the main signal and will introduce leading "echos". 

 Similarly, lagging echos can be obtained from the taps on the lagging 

 or second half of the delay line. Combinations of both types of echos, 

 either positive or negative as required, can be added to cancel out, to a 

 first approximation, distortion present in the input signal. 



This analysis can also be carried out in the frequency domain. To 

 obtain a family of cosine loss versus freciuency characteristics without 

 any appreciable delay characteristic, equal leading and lagging echos 

 of the same polarity are added to the main signal in the summing circuit. 

 To obtain a corresponding family of cosine delay versus frequency 

 characteristics without loss distortion, leading and lagging echos equal 



INPUT P 



L_^J 



OUTPUT 



Fig. 3 — Block schematic of transversal equalizer. 



