02 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1953 



ity and the peak area can be allocated a large fraction of the total avail- 

 able. 



8. FM- is preferable to AM for land mobile service because its instan- 

 taneous gain control feature minimizes the flutter caused by the motion 

 of the mobile unit through standing wave patterns. This advantage in- 

 creases in importance as the carrier frequency increases. In addition, 

 FM with an adequate frequency swing provides an increased signal-to- 

 noise advantage over most of the coverage area. The somewhat greater 

 channel width required by FM is more than offset on an area coverage 

 basis by the closer co-channel spacing. 



