About the Canada/US AM Station Info Search Page


This page is basically a front end for searching an AM radio station database. The original database used in this search engine came from Lee Freshwater's excellent AM Logbook, which unfortunately is now defunct. In early 2004, I began doing my own updates to the database rather than swiping the info from Lee's site, mainly because it permitted more frequent updates to be done. The station transmitter coordinates used for the distance/bearing calculations were originally obtained from Werner Funkenhauser's WHAMLOG files (also now defunct). This info has now been merged into the main station database.


The entry forms for the Search Page are organized into two separate sections. On the left is the Station Lookup & Distance/Bearing Calculator. You use this form to retrieve data on a known station. If you want the information on distance and bearing from your location to this station, start by entering your own latitude and longitude. You then can save these values by clicking the Save button. The next time you visit the page, clicking in the lat/long entry boxes should bring back the values you entered before (note: this function uses JavaScript and cookies, so you must have these functions enabled in your browser for it to work). After entering your coordinates, all you have to do is enter the callsign of a station and click the Search button. If info is found for that station, it is shown in the display area below the entry forms. Since the input and output are on the same page, you don't have to have to hit your browser's Back button before doing another lookup - just enter another callsign and click Search again (in most browsers, simply clicking in the entry box itself will do the trick). If you wish, you can skip entering your lat/long info - then you will get just the basic station info without the distance/bearing/elevation angle calculations.

Included in the output display are the sunrise/sunset times, both for the current month and the following month, that apply to that station for power and pattern changes. These times are shown for the timezone that you choose, not the local timezone of the station. Also shown are today's actual sunrise/sunset times for the station, and if you entered your lat/long, for your location as well.

The UNID Station Search form on the righthand side has a different function: to help you identify a station heard on a given frequency. After selecting the frequency, you have two choices. If you have a tentative callsign, enter it and then click the Callsign Search button. When the output is returned, you should see listings of stations that have similar-sounding callsigns (if there are any). This is done with a very simplistic algorithm, so don't expect miracles! Normally you will enter letters between A and Z (in either upper or lower case). However, you can broaden the search by entering a "?" character as a wildcard instead of a particular letter - then it will match any letter in that position. For example, entering WE?K as the callsign with frequency set to 1230 will match WBLJ, WTCJ, WBOK, WCMA, WECK, and WCWA - but not WBHP, WTSV, etc, since the last letters of those calls don't sound much like "A". And, in case you're wondering... yes, the search routine does take into account that Canadians say "zed" instead of "zee". :-)

The foregoing applies to the default search technique, which I call a "fuzzy" search. However, you can also select an "exact" search, and it will show you only those callsigns that have an exact match for the non-wildcard characters. So, in the 1230 example given above, only WECK would match a search on WE?K. More recently, I added a "fuzzier" search option which broadens the "sound alike" parameters even further.

There is also a Show All Stations button for getting a listing of all stations on the frequency (equivalent to doing a Callsign Search with the callsign set to ????).

If you don't have a tentative callsign but you have an idea of the programming format, use the pulldown menu to select an appropriate format and click the Format Search button. This search is completely independent of any callsign you may have entered for a Callsign Search. Do keep in mind that station formats can change quite frequently, and this information will never be 100% correct (but it's much better than it used to be, now that I'm updating it fairly frequently).

Lastly, you can get a listing of all AM stations in a particular state or province by making a selection from the pulldown list and clicking the List button.


Q: Why do some of the day powers have an asterisk beside them?

A: This indicates that the station has a Pre-Sunrise Authority (PSRA), which allows the stations with little or no night authorization to begin operating at 6 AM instead of waiting until local sunrise (assuming that the latter is later than 6 AM to begin with). Most PSRA's allow a power of 500W to be used during this interval, though some are less. Some daytime stations also have a Post-Sunset Authority (PSSA) that permits them to operate at low power for up to two hours past their local sunset. This information is not included in the database, nor can you look it up on the FCC website. The best source of PSRA/PSSA data is the NRC AM Radio Log.

Q: What's the deal about "critical hours"?

A: Critical hours refer to the two hours of daylight after sunrise, and the two hours before sunset. Some stations are required to reduce power (possibly accompanied by an antenna pattern change) from their normal daytime facilities during these intervals in order to provide additional protection to co-channel stations. The database I'm using has no provision for storing critical hours info, but I often make a note of the power reductions in the Notes field (prefaced by CH:).

Q: What do those antenna symbols such as DA-1 mean?

A: They indicate the antenna configuration that the station is required to use.  Here's a summary:

Antenna Type Description
NDA Non-Directional Antenna
DA-1 Directional Antenna, same pattern day and night
DA-2 Directional Antenna, different patterns day and night
DA-3 Directional Antenna, different patterns day, night and critical hours (rare)
DA-N Directional Antenna at night, non-directional during day
DA-D Directional Antenna during day only, non-directional (or no operation at all) at night

Unfortunately, for reasons best known to the FCC, stations that have identical directional patterns day and night are often designated as DA-2 instead of DA-1. Apparently it happens when changes to the facility are made at some point; in any case, when in doubt, check the actual pattern(s) - my favorite source for pattern data is the FCCInfo Search site.

Q: Do you solicit donations? Do you plan to start charging for this service at some point?

A: Yes, and no. I'm a firm believer in communities of volunteers compiling and freely sharing information. I believe in the philosophy that "information wants to be free". All I ask from the users of this site is that they provide me with corrections when they find inaccurate information. However, if you really find the site useful in your DX activities, you may feel compelled to make a small donation to help keep it going. In that case, just follow the "donate" link at the bottom of the page, and you'll provide a little extra incentive!

Technical Stuff

In case you're wondering, the software behind this engine is written in Perl, a nice programming language that is particularly good for extracting information from text files and creating CGI programs for web applications. My original distance and bearing calculations were based on algorithms that I found in the ARRL Antenna Book, but I have now replaced them with some public domain code by Darrell Kindred. This is the same code as used by the Indo.com How Far Is It site. The elevation angle calculation is my own derivation, and it assumes propagation via the E layer - this is usually, but not always, the case in the AM band, so don't take it too seriously. The sunrise/sunset calculations are done with the Perl Astro::Sunrise module.

The server that hosts this application runs the Apache web server and the Linux OS, of course!

Shortcomings and Bugs

This is not what you would call a polished piece of software. The error handling is fairly minimal at the moment, so it's certainly possible to generate bogus results by entering strange data. I trust that you won't do that. :-) One longstanding bug, that the station lookup form only accepted North latitudes and West longitudes, has finally been fixed.


Feel free to send me mail to provide updates, report bugs or suggest improvements. Due to intolerable local noise levels, I am no longer an active AM DXer myself, so it is unlikely that I will put significant effort into improving the capabilities of this site, but I will continue to keep it updated, at least for the time being.

Barry McLarnon, VE3JF
Ottawa, ON

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