346 



BELL SYSTEM TECHNICAL JOURNAL 



Z 12 



o 



t 28 



24 





12 16 20 24 28 32 36 



BEAT FREQUENCY IN CYCLES PER SECOND 



Fig. 8 — Carrier ratio for perceptible flutter with a square law detector. Noise 

 equivalent to 3 per cent modulation, for the upper curve, and to 0.95 per cent for the 

 lower curve. 



The Square Law Rectifier with Automatic Volume Control 



It has been predicted that the use of automatic volume control in 

 the receiving set should greatly increase the flutter effects observable 

 with a linear rectifier, while with a square law device these effects 

 should be the same for both automatic and manual control except, 

 perhaps, at the frequencies of reduced efficiency of the gain control. 

 An experimental check was made on the latter statement, the results 

 of which are shown in Fig. 9. It will be noticed that this curve is very 

 similar to the curves of Figs. 7 and 8. 



,20 



30 40 50 60 70 80 



BEAT FREQUENCY IN CYCLES PER SECOND 



Fig. 9 — Carrier ratio for perceptible flutter with automatic volume control. Noise 

 equivalent to 9.5 per cent modulation. 



