| About
the Canada/US AM Station Info Search Page |
Introduction
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.
Instructions
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.
FAQ
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.
Feedback
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