Many HPR listeners send complaints
about trouble with reception, particularly on KIPO, which is currently
being rebuilt and is still broadcasting at low strength. However,
high rises and mountains also cause FM reception problems (see
below for former HPR Director of Operation Mark Wagner's HPR Reception
Handbook, link below) that are unavoidable.
THE HAWAII PUBLIC RADIO RECEPTION HANDBOOK
by
Mark Wagner
We often hear from listeners having difficulty receiving one or
more of our stations. We'd like to give you some tips for maximizing
your reception.
Let's begin by discussing some terminology. Reception problems
are often caused by:
Multipath: The direct FM signal (which is what you want to receive)
may be reflecting off surrounding objects such as tall buildings,
cranes - even aircraft. You hear both the direct signal and the
reflected signal, which arrives at your receiver a split second
later. This can cause interference and make your radio hard-to-tune
to the precise frequency that you want. Multipath is most noticeable
while driving in your car. Your radio is constantly on-the-move
and subject to changing conditions of reflected signal, especially
in downtown areas. In the days before cable television became the
norm, television viewers could see multipath in the form of "ghosts"
in the image.
Terrain Shielding: This occurs when Hawaii's beautiful mountains
block the direct path between our transmitter and your receiver.
FM and TV signals require "line-of-sight" for perfect
reception. In a literal sense, one must be able to "see"
the transmitter to receive it without interference. In reality,
there are only few places where one actually has true line-of-site
to a particular station. The receiver may be blocked from a clear
"view" of the transmitter by buildings, terrain, highway
overpasses, or, for high rise dwellers, many layers of steel-reinforced
concrete. As long as some signal is being received by your radio,
reception may still be quite good. But, when the signal strength
drops below a certain level, the program may begin to sound noisy.
In a moving vehicle, the signal may cut in and out very quickly
and sound similar to multipath. This is the case for 88.1 listeners
on the H-1 between Punchbowl and the University area. You are "terrain
shielded" from the transmitter by several ridge lines running
up and down the Koolaus. As you drive away from this area, going
Ewa, Diamond Head or Makai, you'll hear a better signal.
Front End Overloading: Here's a nasty one. This is mostly a problem
in urban Honolulu. There are several powerful FM and TV transmitters
located on tall buildings in town. Ever driven down Ala Moana Blvd.
between Kalakaua and Atkinson and had 89.3 or 88.1 FM suddenly replaced
by a commercial station? The relatively higher-power commercial
transmitter (within a few hundred yards of you) has overloaded the
tuning section of your radio, blocking out the "weaker"
HPR station. If you are close enough, it might be possible to pick-up
the offending station all across the dial. Better quality FM receivers
are less-susceptable to this problem.
If you're a shortwave listener (like me) and live in the city
(as I do), you'll know that it is impossible to listen to a shortwave
radio due to front end overloading. Here's where terrain shielding
becomes a friend. Go out to Sandy Beach, parts of Windward Oahu
or, if you're really serious - past Dillingham Field toward Kaena
Point. At the latter location, you are terrain-shielded from almost
every station on the island and away from most electrical lines.
The shortwave band comes alive - putting the whole world at your
fingertips. It's nothing to pick-up the big powerhouses like NHK
Tokyo, Radio Australia, the BBC and Deutsche Welle; a good receiver
should pick up many smaller stations you've never heard before.
Antennae & Receivers
Volumes could be written about radio receivers and how best to
pick up signals in problem areas. It's sad that most receivers are
"not made the way they used to be." This is particularly
frustrating when it occurs in so-called "high end" (expensive)
receivers. It's not unusual to find a kitchen radio that picks up
signals better than a very expensive home stereo system.
By far the best receivers are in our cars. Generally, car radios
are designed to be very sensitive and capable of tuning to desired
frequencies while filtering-out as much interference from other
stations as possible. As explained above, the reception environment
is constantly changing as we drive, and car radios need to be up
to the task. It's not unusual to pick up your favorite station in
your car parked in the driveway, only to enter your house to find
that you can't pick it up as well with your stereo. Without getting
too deep into techno-babble, the detector and tuning section (known
to engineers as the "front end") of your car radio is
better designed than a lot of home radios. Circuit designers have
taken a lot of shortcuts in recent years, and radios just don't
seem as sensitive as they once were. I have a 40-year-old Telefunken
9 tube receiver that receives AM, FM and the complete shortwave
band - all with no external antenna.
There are things you can do to improve reception. If your radio
has provisions for an external antenna, you can install an antenna
or antenna-amplifier combination. Some notes about amplifiers: to
amplify a signal, you must first be able to receive it, even a little,
in the first place. You can't amplify something that isn't there.
In the case of interference, an amplifier will make matters worse,
although a tunable FM antenna-amp might help optimize reception
of the frequency that you do want.
If your receiver/tuner has an external antenna connection, it
will usually be in the form of 3 screws. One of these screws will
be a "ground" connection. The other two will be labled
75 ohm or 300 ohm. One of the two antenna wires will connect to
either the 75 ohm or 300 ohm connector (see antenna manual to determine
which value to use). The other antenna wire will go to the ground
connection. Newer receivers may have a single threaded connector
like the one on the rear of your TV or VCR. This is an "F type"
connector, and is always a 75 ohm connection. Do not attach your
incoming TV cable to your stereo's F connector (if so equipped)
unless you know that an FM service is available from your cable
company (see "Cable FM Services" below).
Types of FM Antennae
The least expensive antenna is known as a "wire dipole."
This consists of a 4-6 foot flat wire that connects to the rear
of your receiver. A 58-inch cross section is attached to the end
of this. It looks like a large "T." Radio Shack offers
these for $3.29 (cat. number 42-2385). Dipoles can solve most reception
problems. You may hang it from a wall (maybe hiding it behind a
curtain or a large framed print), or simply drop it on the floor
behind your radio. There is no "right way" to use this
antenna; simply move it around until the station you want comes
in.
An amplified antenna, in addition to slightly increasing the incoming
signal, usually allows fine-tuning of the desired frequency. Radio
Shack offers these in the $30-$40 price range. As explained above,
certain types of interference may be amplified along with the desired
signal. If you are receiving interference from another station,
use the antenna on the "low" (low amplification) setting
and try tuning the radio and antenna for optimum performance.
Cable FM services
A few years ago, one could connect an FM receiver to the incoming
TV cable. A "splitter" adapter would allow both the VCR/TV
and the FM receiver to use the same incoming cable service. Cable
companies would pick up FM stations right off- -the-air using conventional
receivers and rebroadcast the stations over the cable system on
slightly shifted frequencies. The signals going through the cable
were still FM signals, and your receiver was quite happy to tune
to them just as it would have had they been picked-up through a
conventional antenna. This meant that people living deep in valleys,
on the North Shore and other hard-to-reach areas could listen to
any FM station on the island...if they had cable.
Most island cable companies have converted or are in the process
of converting to digital cable signals and have dropped the old FM
service. Digital distribution allows more cable channels to be carried
on their system, and provides better TV signal quality. Additionally,
most cable systems offer digital music services with CD quality audio,
as well as high speed Internet access through services like Road Runner.
If local FM stations are carried as part of this service, their signals
are also digitized and sound equally good. Contact your cable company
regarding fees and availability of this service. Here on Oahu, Oceanic
offers local FM stations on its digital service. KHPR is on Ch. 841.
KIPO is Ch. 842. A digital cable box is required.
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