set orogram (2) 
program (1) 
  
  
Signal-to-noise ratio Os / 
0,10 
  
average increase 
of rate of multiple 
  
————_ Drogram X 
nrogram (1) 
  
  
  
2,/0, 
signal-to-noise ratio do; /g, 
average vercentage (%) 
of compensation 
From above conclusions can be drawn as follows: 
(1) While signal-to-noise ratio >1, through a posteriori 
compensation, a significant accuracy increase can be obtained 
able, while signal-to-noise ratio <1, under many circumstances, 
4 certain amount of increase in accuracy can also be gained. 
(2) After a posteriori compensation, accuracy increase of 
rate of multiple tends to be larger when signal-to-noise ratio 
is larger, that is to say, if one wants to gain better results, 
it is necessary to reduce the noise and raise signal-to-noise 
ratio. | 
(3) The efficiency on elemination of systematic errors by 
using a posteriori compensation also tends to be higher along 
with the increase of signal-to-noise ratio, but such efficiency 
could not be increased proportionally. From Fige.5 it can be 
seen that when signal-to-noise ratio is about 3, systematic 
error can be eleminated by 80% or so, if the increase of 
signal-to-noise ratio can be done once more, efficiency for 
elemination of systematic errors increases only a little higher. 
(4) Under normal conditions, 60-70% systematic errors can be 
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