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Most
of us enjoy the benefits of boating with a cellphone. We can stay in touch
with home and work, if desired, or dial ahead for a slip or a restaurant
table. That is, until that annoying moment when we cruise beyond the range
of the cell towers or our service fails for more mysterious reasons. My
challenge this month is to explain how the mess of gadgets and wires pictured
above is actually one sensible system for getting the most out of marine
cellular.
For more than a year
now, I’ve been testing the Digital Antenna PowerMax cellular amplifier
and four-foot, 9-dB boat antenna shown in the left portion of the photo
above. One of the first things I learned was just how badly cellphones
lie! I hunted down the code that unlocks the “field test” menu
on my Nokia 5165, a hidden feature on most cells. After doing this I was
able to see the same detailed signal-strength readings that technicians
use to diagnose problems, as opposed to the “optimistic” graphic
meter shown to us civilians. In the photo at right, the -75 figure is
true signal strength measured in dBm (milliwatt decibels). The dBm readings
work similarly to school grading in reverse; -55 calls are about as good
as cell gets, while -100 calls flat out flunk. Though I found that -75
conversations were in the choppy, “Can you hear me now?” style,
you can see that my phone awards itself a four-bar “A” for such
signal strength.
My Nokia’s regular
signal meter doesn’t just exaggerate; it’s also slow to respond
to rapid fluctuations in signal quality, a condition I see frequently
on the field-test screen and hear as noise and busted words. Are you reminded
of your own cell’s temperamental nature? Joanne Johnson, head of
marketing at Digital Antenna, says that my phone’s deceptiveness
is typical and a source of much frustration. Cell users have a hard time
knowing what their phone is really up to, let alone how much an added
amp or antenna is actually helping. (By the way, if you want to get geeky,
the codes to unlock field testing are available from some cell dealers
and on Web sites like www.antennaguy.com.)
I can tell you that
Digital’s gear really works. I often saw 5- to 10-dBm improvements
just by attaching my phone to the antenna, another 10 to 15 by adding
the amplifier, which also seemed to flatten signal fluctuations. I was
the strange guy repeatedly calling my own office answering machine from
the boat (and pickup truck, as I also had a 3-dB car antenna) last season.
I’d find a marginal reception area and then place separate calls
with the cell alone and with the bidirectional booster attached. I could
hear the difference both ways, first in my machine’s outgoing message
and then when I got home on the messages I left.
Cell signal boosting
helps mostly with range. I can’t report solid numbers because of
Maine’s irregular coastline and islands, but I’ve read reports
of better than 50-mile cell calls off Florida’s well-defined network
using Digital equipment, and I believe them. Mind you that cell-saturated
South Florida is subject to the phenomenon of decreasing range as it’s
populated with more, but smaller-area, cell antennas (see “Saltwater
Cellular,” September 2001). My equipment also helped when the signal
was partially blocked by a high island or hill. While I still found some
dead spots produced by such obstacles, a couple of times I saw my phone
go from “no service” (worse than -100) to a reasonable signal,
a pleasure that Digital Antenna doesn’t even advertise as possible.
Digital’s gear
is also quite flexible. I use the older version of AT&T cellular—which
includes 800/1900 MHz TDMA and analog—but the $416 DA4000 amplifier
is FCC-approved for all wireless services except Nextel, for which there’s
an alternate model. The 561 antenna costs $205 and works with everything,
and there are other models in different lengths and/or combined with VHF
or AM/FM. Shakespeare Marine has been talking for some time about offering
an amplifier similar to Digital’s and recently distributed specs
for the $459 CA-819. Reportedly, it will, like the DA4000, wring the maximum
allowed power out of any cellphone (again, except Nextel’s) when
paired with the right antenna—3 watts in the low band, 2 in the high.
In fact, I’ve been testing the Digital gear this long because I was
hoping to compare it to Shakespeare’s; a shipping delay due to needed
modifications led me to put that project off for now.
Next page >
Part
2: While you really can improve cell performance on your boat, one unfortunate side effect is that your wireless phone gets wired. > Page 1, 2,
3, 4, 5,
6, 7
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