Sunday, May 13, 2012


50 Kilowatts Daytime - U.S.

50 Kilowatts Daytime - U.S.

Something new here on the blog - RADIO-TIMETRAVELLER Maps. On occasion I will present a map of interest to the mediumwave DXer. Maps and charts are generated by the Radio Data MW program. Here is the first one. Data is from the 4-24-12 FCC database.

The map depicts all 50 kilowatt stations broadcasting during daytime hours in the United States. 248 stations are represented. Yellow flags indicate allocations in the daytime service class, pink flags the unlimited service class (24-7). The FCC defines service classes as DAYTIME, NIGHTTIME, UNLIMITED, and CRITICAL HOURS (the first two hours of daylight after sunrise and the last two hours of daylight before sunset).

Representative antenna pattern plots are also shown. As you can see, not all are omni-directional as might be expected for 50KW stations. Obviously due to map size constraints, a number of station flags overlap, as do their patterns. Thus, for example, you see KXEN-1010, St. Louis, MO, highly directional, sits under KMOX-1120's omni-directional pattern.

Now, some statistics.

60 stations are Class A. 157 are Class B. 0 are Class C. 31 are Class D.

134 are located east of St. Louis, 114 are west of St. Louis.

137 are "W" callsigns. 111 are "K" callsigns.

The 248 stations broadcast using 628 towers.

103 stations broadcast an omni-directional pattern (single tower). 145 broadcast a directional pattern (multi-tower).

4 stations are on the FCC "Silent" list: WSJC-810, KYWN-890, WQOM-1060, WDCD-1540.

If we divide the western hemisphere MW broadcast band in half (the center is at 1115 KHz), we have an equal number of MW channels below 1115 KHz and above 1115 KHz. There are 85 daytime 50KW stations broadcasting above 1115 KHz. 163 broadcast below 1115 KHz.

The last graphic is a plot centered on the geographic center of the contiguous U.S., near Lebanon, Kansas. It shows the distribution of 50KW daytime stations radiating out from this location, using a scale of 2000 miles. A vague outline of the continental US can be detected, with 4 satellite 50KW stations towards the northwest (Alaskan stations), and a solitary 50KW station to the southeast in Puerto Rico (WKVM-810).

50 Kilowatts Daytime - U.S.

Hope you enjoy the map and chart. Look for more interesting maps and statistics to come.


gkinsman said...

Interesting stuff, Bill. Is this Radio Data program something you wrote or a commercial product?


Hi Gary,

Nice to hear from you again.

Radio Data MW is a program I have been developing for about three years. I have a couple of thousand hours in it (about 35,000 lines of code). Basically, it takes the FCC database and lists stations by distance and signal strength according to your home location. It does many other things, like plotting antenna patterns, mapping, graphing, etc. Using a filter, you can filter stations any way you want. Not quite ready for prime time unfortunately. Some day I may release it. I plan on featuring it more in this blog to show what it does.

Take care and good DXing.