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.
