PORTER: SOFAR PROPAGATION OF WIDE-BAND SIGNALS TO LONG RANGES 



wider bandwidth and you would see rays. You could, in principle, 

 even arrange your resolution window to be parallel to the mode dis- 

 persion curves and see only modes. 



So that it is in a sense gratuitous, and I think a very happy 

 fortune, that you happened to pick proportions that showed both at 

 once. 



Dr. Porter: To my mind the fundamental result is that 

 the energy in a wideband signal is the sum of the energy in each 

 mode at each eigenray arrival. That's another way of saying it 

 is the sum of the energy in each frequency, each eigenray arrival, 

 if the signal bandwidth times the dispersion of the channel is 

 large . 



That is quite a different statement than for narrowband signals 

 where you have to add the pressure in each mode. 



Dr. H. Weinberg (New London Laboratory, Naval Underwater Systems 

 Center): I'd like to make a statement that is really directed toward 

 the entire group, and I hope it is taken more as constructive 

 criticism. Now seems like a good time to bring it up. 



Very often somebody will discuss a method, a program, or a 

 technique and then almost the very next speaker will get up and say 

 that that method does not exist. In particular, a statement was 

 made a couple of times, for example, that there aren't any computer 

 programs taking account of shots, the broadband; in fact, a 

 couple of programs can do precisely just that. 



It is unfortunate that so little information flows between the 

 various labs with respect to the different models actually available. 

 I hope that something can be done to increase the speed of flow 

 between people who have use for such programs. 



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