INTERMODULATION INTERFERENCE IN RADIO SYSTEMS 73 



which are subject to interference 10 per cent of the time when fully- 

 loaded with traffic. 



Careful channel selection is therefore a step toward better frequency- 

 usage. It is, however, only a small step, and a more effective solution 

 must be found if efficient frequency usage is to be achieved in areas 

 where sizeable numbers of operating channels are required. Such a solu- 

 tion for the mobile radio service is a "coordinated system," proposed in 

 a companion paper previously referred to, wherein additional measures 

 are described for reducing the probability of interference by proper 

 geographical system layout and the use of certain practicable operational 

 features. 



