Band Width and Transmission Performance 



By C. B. FELDMAN and W. R. BENNETT 



In modern communication theory band width plays an important role as a 

 transmission parameter. The authors discuss the significance of signal band 

 width and frequency occupancy in relation to other transmission factors such as 

 power, noise, interference, and overall performance for certain specific multiplex 

 systems under assumed operating conditions. The intent of the paper is to 

 show how such problems may be attacked rather than to find an unequivocallj' 

 best system. 



The scope of the paper is described by the following table of Headings and 

 Captions. 



I. INTRODUCTION 



Fig. 1. Outline of multiplex transmission methods 



1. Non-simultaneous Load Advantage in FDM 

 Table I. Non-Simultaneous Multiplex Load Advantage 



2. Instantaneous Companding Advantage in Time Division 

 Fig. 2. Performance of an experimental instantaneous compandor 



3. Non-simultaneous Load Advantage in Pulse Transmission 



Fig. 3. Quantizing noise in each channel when PCM is applied to an FDM group 



4. Signal Band Width and Frequency Occupancy 



5. Regeneration and Re-Shaping 



6. The Radio Repeater 



Fig. 4. Arrangement of two-way two-frequency repeater of television type 



showing spacing of bands and antenna discrimination 

 Fig. 5. Discrimination of I.F. and R.F. circuits in television type repeater 



II. BAND WIDTH CHARACTERISTICS 



Fig. 6. Basic pulse shape and its spectrum 



Fig. 7. Marginal condition in reception of AM pulses and an FM wave in presence 



of noise. 

 Fig. 8. Time allotments in Pulse Position Modulation 

 Fig. 9. PPM-AM; fluctuation noise. Relations between band width, power, and 



signal-to-noise ratio. 

 Fig. 10. PPM-AM; CW and similar system interference. Relations between 



band width and signal-to-interference ratio. 

 Fig. 11. PPM-FM; fluctuation noise 

 Fig. 12. PPM-FM; CW and similar system interference 

 Fig. 13. PAM-FM; fluctuation noise 

 Fig. 14. PAM-FM; CW and similar system interference 

 Fig. 15. PCM-AM; peak interference 

 Fig. 16. PCM-FM; fluctualion noise 

 Fig. 17. PCM-FM; CW and similar system interference 

 Quantized PPM 



Fig. 18. Comparison of quantize 1 PAM with quantized PPM 

 Fig. 19. FD.M-F.\1; fluctuation noise 

 Fig. 20. FDM-FM; CW interference 



III. BAND WIDTH AND POWER TABLES 



Table II. Optimum Band Widths for Minimum Power for Message Tvpe Circuits 

 Table III. Optimum Band Widths for Minimum Power for Program Type Cir- 

 cuits 



490 



