462 



Table 548 

 SKIP-DISTANCE AND RANGE TABLE 



For frequencies between 1500 and 30000 kc 



(This table was prepared by the Naval Research Laboratory.) 



Skip-distance — Shortest distance beyond the ground wave at which communication is 

 possible, or the point where the sky wave first comes to earth. On certain frequences and at 

 certain seasons communication is possible within the skip-distance due to echoes and around 

 the world signals. Skip-distance variations are not so very large in the day time but they 

 may be quite variable at night. It should be noted that the ground wave variations ranges 

 are based upon overland data; the ranges over sea are considerably greater. Useful working 

 ranges are, however, based entirely upon the sky wave. 



The above table was obtained from the general average of a large number of observations. 

 For the night ranges given it is assumed that the greater part of the path between the trans- 

 mitting and receiving stations is in darkness. 



As the distances given in this table are general averages many discrepancies may be 

 found in practice due to seasonal changes, sun spot activities, geographical location, local 

 weather conditions, etc. 



(a) For approximate wave lengths use Table 547. (b) Mobile, ships and coastal stations, aircraft, railroad 

 stock, etc. (c) Fixed, permanent stations handling point to point traffic, (d) Amateur, (e) Broadcast, (f) Not 

 reserved, (g) 1601 experimental, 1600-1652-1664-1680-1704-1712, portable, (h) U. S. entirely amateur, 

 (i) U. S. 2002-2300 experimental visual broadcasting, (j) 2398 experimental, (k) 2750-2950 experimental visual 

 broadcasting. (1) 3088 experimental, (m) 4795 experimental. 



Smithsonian Tables 



