THEORETICAL FITNDAMEXTALS OF I'lLSK T1{AXSMIRST().\ 



i;-! 



5. IDEALIZED C'lIAUACTERISTICS WITH NATURAL LINEAR I'JLV.SE Sill FT 



With the type of amplitude characteristics discussed above it is 

 necessary to employ phase equaUzation to obtain a linear phase charac- 

 teristic. Furthermore, oscillations of appreciable amplitude remain in 

 the impulse characteristic. A virtually linear phase characteristic to- 

 gether with a reduction of these oscillations can be attained by a further 

 extension of the gradual cut-off in Fig. 10, such that co^ = coi . An ampli- 

 tude characteristic of this type, together with the corresponding impulse 



(a) 



FREQUENCY 

 CHARACTERISTIC 



0.2 0.4 



0.6 



0.8 



1.0 



1.2 



1.6 



Fig. 11 — Low-i);iss characteri.stio with gradual cut-ofl' and as.sociatcd impulise 

 characteristic. Linear phase characteri.stic as.sinnod. 



