Wednesday, September 16, 2009

Three Helpful Web Sites For The MW DXer

Mediumwave DXers can be a pretty technical bunch. I know I am one in that crowd. I like to know "Why", "When", and "How". And mostly just "When, and is it Possible"? That is, in terms of receivable stations and the various possibilities thereof. Three web sites exist that can tell us some interesting technical things about the stations we want to receive.

Radio-Locator is probably the one I use the most. My favorite chunk of information available on this site are the antenna pattern/coverage maps. Type the call sign of the station you are interested in and up comes a page with a lot of information about the station. Click the coverage link on that page and see the predicted coverage drawn on a map. Stations with different day and night (and critical hours) antenna patterns have separate maps showing each coverage pattern. You can even click a latitude/longitude link which generates a Google map of the transmitter site.

Radio-Locator has three other great features for general station searching. A US state search allows you to search for stations by state. A format search allows you to search stations by format. A city/zipcode search allows you to locate stations by city or zipcode. There is also a Canadian station search page similar to the US state search. Radio-Locator also includes many Mexican stations in its database, searchable by call sign.

Next, V-Soft Communications owned by Doug Vernier, supplies software products for the communications world. Its important contribution to MW DXers is its Zip Code Signal pages. Type your zip code in the box and click the Find Stations button, and back comes a page listing all stations in your area with a signal strength of 50dBu or greater (display is in millivolts per meter - mV/m - for AM). Each station is linked so that a click on the station call sign takes you to the FCC page describing its facility - another wealth of information. Zip Code Signal also has a reverse look-up feature. Type the station call sign into another box, click the Find Zip Codes button, and a page is returned that shows all nearby zip codes where that station puts in a signal strength of 50dBu or greater (again, in mV/m for AM). Neat stuff.

Last, the FCC to the rescue. One of the most, if not THE most, comprehensive US station lists on the 'net comes from the US Federal Communications Commission. The FCC maintains a database of all US AM, FM, Travelers Information Stations (TIS), and many Canadian and Mexican stations. Information includes geographic coordinates of all transmitter sites, station power, owner, antenna type, and more. The FCC's AM Query web page will extract the information you desire from its official database records and present it in a readable format.

Give these three sites a look when you have a chance. I think you will find them as useful as I do.


gkinsman said...

What's a "good" level for mV/m? All of the "locals" that I listen to are below 20 mV/m (and most are below 10 mV/m).


That's a tough call Gary. Not sure what you mean by "a good level". A strong level?

Local WXXI here in Rochester, NY, at 5000 watts, 13.5 miles distant, puts in 5.59 mV/m here according to this site. That equates to about 75 dBu. I would consider it an average strength local.

WDNY-1400, Dansville, NY, I would consider kind of weak here, and it shows a mV/m figure of only 0.55. The station is only 1000 watts, at 26 miles distant, and through some heavy terrain.

In any event, these computed levels can't be taken as gospel, though they are useful as a relative "tool" for determining how one station compares to another. I would suggest that the V-Soft figures are kind of high for real-world strengths. I wish I had access to a meter to measure real-world values.