Lowrance lms-350a 操作ガイド
54
ACCURACY
You may have heard tales of extraordinary accuracy from GPS receivers.
The DOD requires accuracy of 10 to 15 meters from the satellite system.
However, only the military gets this precision. The way the military keeps
us and other unauthorized people from using the more precise system is
coding. In other words, the data coming from the satellites is encrypted.
Civilian GPS receivers use “C/A Code.” It’s accuracy is intentionally worse
than the military’s “P Code.” In this manner, civilian users worldwide can
benefit from excellent position fixes. Meanwhile, the military keeps the
most accurate system away from potential enemies. Theoretically, C/A
code can give accurate position fixes up to 15 meters. This is more than
adequate for most people.
You may have heard tales of extraordinary accuracy from GPS receivers.
The DOD requires accuracy of 10 to 15 meters from the satellite system.
However, only the military gets this precision. The way the military keeps
us and other unauthorized people from using the more precise system is
coding. In other words, the data coming from the satellites is encrypted.
Civilian GPS receivers use “C/A Code.” It’s accuracy is intentionally worse
than the military’s “P Code.” In this manner, civilian users worldwide can
benefit from excellent position fixes. Meanwhile, the military keeps the
most accurate system away from potential enemies. Theoretically, C/A
code can give accurate position fixes up to 15 meters. This is more than
adequate for most people.
However (as of this writing), the military isn’t satisfied with C/A’s potential
accuracy in the hands of the world. So, it’s degrading it further with
“Selective Availability” or SA. This is small, random errors intentionally
added to the system so your accuracy will typically be within 100 meters.
Of course, accuracy also depends on the angle of the satellite above the
horizon, signal-to-noise ratio, the number of satellites tracked at one time
(the more the better), and other factors. The smallest ranges on the plotter
may not be usable if the SA is high. The present position symbol can move
off the screen even while you’re sitting still.
accuracy in the hands of the world. So, it’s degrading it further with
“Selective Availability” or SA. This is small, random errors intentionally
added to the system so your accuracy will typically be within 100 meters.
Of course, accuracy also depends on the angle of the satellite above the
horizon, signal-to-noise ratio, the number of satellites tracked at one time
(the more the better), and other factors. The smallest ranges on the plotter
may not be usable if the SA is high. The present position symbol can move
off the screen even while you’re sitting still.
Don’t let this discourage you, however. GPS by nature has much faster
updates than other systems (such as Loran), and typically is much easier
to use. Accuracy, even with SA on is still better than most other navigation
systems. You’ve purchased one of the finest navigation instruments on
the market today. We hope you’ll enjoy it for many years to come.
updates than other systems (such as Loran), and typically is much easier
to use. Accuracy, even with SA on is still better than most other navigation
systems. You’ve purchased one of the finest navigation instruments on
the market today. We hope you’ll enjoy it for many years to come.
The Lowrance LGC-1 GPS Module
This GPS receiver is currently used in all Lowrance GPS receivers. It’s
small, rugged, and fast. The five channel design lets it track all satellites
in view and acquire up to five satellites at one time. It sends position
information to the LMS-350A once every second. By incorporating
Rockwell’s GPS receiver technology with Lowrance’s state-of-the-art
design and manufacturing capabilities, Lowrance brings to the consumer
the most advanced line of GPS marine navigation systems available in the
world.
This GPS receiver is currently used in all Lowrance GPS receivers. It’s
small, rugged, and fast. The five channel design lets it track all satellites
in view and acquire up to five satellites at one time. It sends position
information to the LMS-350A once every second. By incorporating
Rockwell’s GPS receiver technology with Lowrance’s state-of-the-art
design and manufacturing capabilities, Lowrance brings to the consumer
the most advanced line of GPS marine navigation systems available in the
world.