INSTANTANEOUS COMPANDING OF QUANTIZED SIGNALS 



705 



(c) Saturated Improvement of Weak Signals 



For signal.s whose largest samples are confined to the region (e/V) « 

 m^ , compression is linear, with a saturation improvement noted in 

 Table I and plotted in Fig. 24 for comparison with Fig. 9. 



in 



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6 8 10 



20 



40 60 100 



200 400 600 1000 



m 



Fig. 24 — Saturated companding improvement for the weakest signals as a 

 function of the degree of "m-type" compression. Given a value of m, the corre- 

 sponding ordinate represents the reduction of quantizing error power (in db) 

 which results from companding of signals so weak that signal peaks satisfy the 

 relation (e/F) <K 7U~^ Thus, weaker and weaker signals are required to exploit 

 the added improvement which follows from an increase in m. This curve may be 

 compared with that for the ^-ensemble in Fig. 9. 



