Radio DX'ing ____________ UNDER CONSTRUCTION .. day & night

To those who wonder what is a DX'er..........
someone who is curious about distant (thus "DX") radio stations, and find pleasure in
receiving the unusual, impossibly far, difficult, stations, or increasing number of stations they have received.
This includes "Hams": Amateur Radio (Short Wave) Operators and listeners (SWL's).

Many DX'ers will stay up thru the night wee hours just to catch some far distance AM.

My DX'ing is primarily in AM, FM & TV broadcast, with a high interest in technical aspects:
propagation (atmosphere and earth conditions that make variations in reception),
AM directional patterns and antenna sites, station coverage & signal strength at a given distance.
I write programs to calculate "possible" stations to receive, patterns,
and to decoding of the public FCC site data.

In my family, Sandy holds the DX record, an FM from Vicksburg, MS, 1200 miles from the
Mass Turnpike in Blandford, MA, on a car radio! It was alternating with a NYC FM on
same frequency and another unidentified station. She caught enuf info on tape (ads, slogans)
so the station did verify reception. That day had very unusual FM conditions: "ducting",
where storm clouds can act as a mirror at FM frequencies (simplified) .

AM day / night conditions are extremely different.
At day, AM signals travel only by "ground wave", short distances, depending on
transmitter power and directional pattern. A 1kw non-directional can reach 20 mi.
(several NYC 50kw stations can be caught weakly around Boston daily, ~180 mi).
The AM dial is highly alive with small stations daytime.

But when the Sun sets, the ionosphere ( a layer of the Earth's atmosphere) acts
like a variable radio mirror for AM frequencies, causing signals to bounce and reach much
greater distances. Since most stations are required to protect (not interfere with) others,
at night there are fewer AM stations on the air, usually with lower power, and more stringent
directional pattern.

For example, see my "animated" day / night plot of Springfield-Worcester, MA & Hartford, CT area
d/n Spgfld-Worc-Hartf
I wrote the plotting program, including gathering state / country outlines & town locations from Precision Mapping 2.0,
and more recently from Topozone (USGS) site. Station data is from the FCC public data site.
Please note these are theoretical patterns, not considering ground constants and other factors.

AM stations affect others over a wide area; night protection must be considered over all of the
US, Canada, Mexico, and even the West Indies, Central America, & South America.
Here is an "animated" day / night plot of 1510. Most of the smaller stations go off the air at night.
KGA Spokane WA, and WLAC Nashville TN, are the night dominate stations on 1510, with
WWZN Boston(Waltham) MA also powerful, but must protect KGA and WLAC.
Also CJRS, Sherbrooke, Quebec, though no longer on the air, must be protected per international treaty.
WNLC New London CT used to be also a powerful station (left the air in 1998), and is included
for reference sake.
North America 1510 d/n
Yup, from another of my programs, station data is from the FCC public data site, and
state / country outlines etc are from Precision Mapping 2.0, and Topozone.


4-03-08... Save the towers!
WBZ's original site, in East Springfield, was at the 1921 Westinghouse manufacturing complex.
The Westinghouse complex, including the towers,
is planned to be demolished & become a shopping center!
Location: Page Blvd, near I-291 crossing Roosevelt Ave.

I am promoting the site's radio historical uniqueness to be honored,
for Packard Development to include preserving the original WBZ towers in their plans.
Email me for possible actions, or more information.

For an article on WBZ, which includes the link to Donna Halper's "Early History of WBZ",
Please visit bostonradio.org

Here is an image, from Microsoft Visual Earth ("Live search"), recently,
in which the 2 towers are visible, with very keen eyes, on Westinghouse buildings.
I drew arrows to the towers centers.

Towers are in the west end of the complex. This gif, from USGS, shows the whole complex.

A towers picture from Garrett Wollman's former Boston Radio Archives ~1999,
viewed from Page Blvd at estimated 225 degrees off north.
they appear taller then reality, I estimate 100' tall above the buildings.



With my radio DX interest, over various years, I enjoyed talking with Boston area
Broadcasting Engineers: especially Ed Perry & Grady Moates.

Here's a polar graph of what I consider an unusually complex night pattern (ground pattern)
WDER, Derry NH, AM 1320 (only 1kw at night, but....). It takes 4 towers, with complex phasing
and power ratios in insure protection to other stations on its frequency, as the FCC requires.
It has many signal lobes into the sky, someday I'll create a 3D version of graph.
(wooo, interesting math!)
WDER night pattern
This is from another of my programs, and station data is from the FCC public data site.
Of course when developing the program, I compared results to other sources, before I accepted
my results. Hey, I'm a TEST Engineer, I -must- verify things!

Here's a preliminary 3D plot (no hidden lines removal)
WDER night pattern 3D

WMEX, AM 1510, in the 60's & 70's, was a major force in Boston rock & roll (this was before
FM stations were developed enuf to give better sound then AM, and recognized by listeners).
I even caught it from home (New Lebanon NY).
WMEX was easy to receive, but WNLC New London CT, was on the same frequency, thus WMEX
often faded (typical DX'ing occurrence) and WNLC took over ...later WMEX would fade back in...
WMEX's site was in the swamp of the Neponset River, in North Quincy (south of Boston about 8 miles)

In the late 70's, some &^%#$% developer decided to build tall apartment buildings barely south of
the WMEX site, which grossly affected the directional antenna pattern , and caused reduced reception
for much of the former listening area. In 1980, with FM stations taking over the music airwaves,
WMEX's popularity died, & was sold. In 1981, the site was abandoned, and the station moved to a
new site in Waltham (currently WWZN), which did allow new directional patterns, since aiming to
Boston meant it could cause less interference to KGA Spokane WA, and WLAC Nashville TN, which are
the night dominate stations on 1510. [see my day/night 1510 map]
Also, in 1998, WNLC "surrendered" AM, replacing with FM, which made it easier yet for WWZN.

I am presently researching the old site, only 3 cut-off stubs are remaining.
I want to learn the old antenna parameters, to generate a directional plot and compare to WWZN.
It is possible, but very difficult, to estimate parameters from desired coverage area, required protection to
other 1510 stations pre 1980's.... but doubt I could ever exactly match the past FCC data.
...Wish I had a working GPS unit!!!!

I have the distinct honor of causing a change to the FCC database (well, I called attention
to the error and provided preliminary correction, Ed Perry interfaced with the station, and submitted
the change to the FCC):
WBRS, Brandeis College, Waltham, MA: coordinates were wrong, on a USGS map,
plotted as on the round stone tower on the Castle, when actually the transmitting ring antenna
is on the Rabb building. I interpolated coordinates on the USGS, & called Ed.
He checked my data (with a GPS unit?), and a few months later, the FCC files had the change!



update: 4/03/08 11:30pm