Cohasset / Hippisley
Sat May 6 23:38:26 EDT 2006
Bill O'Neill wrote:
> Cohasset / Hippisley wrote:
>> With a decent receiver and minimal line noise it's often audible in
>> Central NY during the day. It's 9:30 a.m. as I type this, and I'm
>> listening to WBZ here in Old Forge, in the western Adirondack
>> Mountains, maybe 30 miles east of Watertown NY and the eastern end of
>> Lake Ontario.
> For some reason, WBZ doesn't do well at all here, day or night, in
> this area (Shoreham and north to Burlington along the lake).
> Particularly the last two years. A lot of hash, noise. The NYC AMs do
> much better. Good that WGY (810 Schdty) and WROW (590 Schtdy) make it
> D/N). My radio listening still seems to be a good dose of AM dial on
> typical days.
Many possible factors could be at work:
1. Automobile ignition (and fuel pump) hash seems to have gotten worse
over the years, and I've noticed on my GM cars that each individual car
seems to get worse as it gets older and metal-to-metal body and frame
joints become highly resistive with increasing corrosion. At home and in
the neighborhood all of us now are subject to far more "radiators" of
junk on the broadcast band frequencies. Uninterruptible power supplies
(UPSs) are particularly troublesome in the 1-3 MHz range, especially if
they're Type A FCC rated (office & industry environment) rather than FCC
Type B (residential). But almost everything in your house these days
that uses electricity has a deservedly bad reputation -- microwave
ovens; any device that uses a wall-wart; PC monitors and power supplies;
plasma TVs; etc.
2. Power line "leaks" from defective transmission system hardware are a
major source of hash on the broadcast band. Similarly, high intensity
"garbage" from defective furnaces and industrial equipment can travel
for miles before being attenuated enough to be below the normal noise
floor in your car radio or table radio. Because so few people listen to
weak signals on the AM broadcast band these days, there is very little
pressure exerted on the power utilities to fix either of these
problems. Typically, it takes continual, repetitive complaining, backed
up with semi-quantitative data some rough localization information, to
3, Although fairly rare, it's worth keeping in mind that when the
maximum usable frequency (MUF) is low enough, there can be a "skip zone"
on the AM broadcast band -- especially the upper end -- at the
transition from ground wave to sky wave reception. Also, depending on
the lengths and phasing of the vertical elements in a broadcast
station's directional array, there may be deliberately placed nulls in
the vertical pattern that result in minimal strength at certain
distances and directions from the station.
4. Lack of diversity reception is another factor. We have a sprawling
one-story house, and I find that many of the AM broadcast stations that
are big at my desk in my office / radio room are not so great on the
clock radio in the master bedroom at the other end of the house, and
vice versa. The clock radio receives AM with the good old ferrite
loopstick, whereas the equipment in my office has the advantage of
listening on a variety of outdoor antennas that I can switch between.
The distance between the ferrite loopstick and the nearest of the
outdoor antennas is about 100 feet. If I were serious about this stuff,
I'd switch to single-sideband reception and bring all the antennas to a
single electronic "voting" circuit that could pick the "right" antenna
at any given instant.
Nevertheless, at both ends of the house, the consistently big nighttime
signals include 1130 (Bloomberg NYC), 1090 (WBAL), 880 (NYC), 1020
(KDKA), 770 (NYC), 1060 (KYW), 1080 (WTIC), 1520 (WKBW -- or is it WBKW
these days?), and 1530 (?). Of these, the selective fade can be
extremely irritating on all except 1130 and 880. For whatever the
reason, those two stations just don't seem to suffer as much in this
part of the state from selective fade -- whether at one end of my house
or the other, or in my car between here and Utica, 60 miles to the south.
5. Finally, local terrain characteristics may cause localized "dead
spots" in the coverage areas of stations. Moving to a new home may
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