236 



BELL SYSTEM TECHNICAL JOURNAL 



12 10 



UJ 



a. 



10-1 



10' 



^ \0' 



0.1 02 0.3 04 05 06 0.7 08 0.9 1.0 



FREQUENCY 



Fig. 11 — Approximate and exact envelopes of phase departure for low pass filters 



with a = 1/12. 



CD 80 



Z 40 



0.75 t.OO 1.25 1.50 175 2 00 2.25 2.50 2.75 3.00 3.25 



FREQUENCY 



Fig. 12 — Approximate and e.xact attenuation characteristics for low pass filters 



with a = 1/12. 



