Memorex RX 1 Smart Manual de Instalação descarregar pdf (Página 69)

Keypad & Display Description | 67

You can deselect a particular PRN# by doing the procedure below:

Press the EDIT key.1

Scroll to the PRN number desired.2

Highlight “force unhealthy” softkey, press ENT to change the value to “-”.3

Press the EDIT key to exit.4

GPS3 - Visible Satellites

This screen provides some basic information about the GPS receiver performance just like

GPS1 and GPS2 screens. It shows the PRN satellite ID, the signal to noise ratio is indicated

under the S/N column, while the EL is the elevation angle and the AZ is the azimuth

direction. Typically, S/N numbers between 40-50 are good SNR numbers. Anything below

32 is considered very low and will not be tracked.

GPS4 - GPS Position Uncertainty

This screen presents a bar graph representing the Horizontal Dilution of Position (HDOP)

for the past 24 hours. This feature keeps track of how good (or bad) the GPS system was

and based on this you can figure out how it will be like the next day if you are navigating

within the same general area as the day before. This is a good tool for Hydro surveying

work. The HDOP limit designated by the dash line is typically set to 4. If the limit is

exceeded, an HDOP alarm will be sounded.

GPS5 - RAIM Status Screen

RAIM (Receiver Autonomous Integrity Monitoring) is a fault-detection feature required

by the IMO for commercial vessels. It is another layer of safety that alerts the operator

that a condition may exists in the GPS positioning solution that reduces the desired

accuracy of the ship’s position. This feature requires at least five or more GPS satellites

to operate properly, four satellites or less are considered to be a caution or unsafe RAIM

condition. If the statistical RAIM error exceeds a selected limit (100 meters default) a

“RAIM Unsafe (R-)” or “RAIM Caution (R?)” alarm will be indicated in the MX CDU.

This means that the RAIM estimated position error is equal or greater than the preset

limit. The operator is advised to take extra precautionary measures when using the

navigation solution until the RAIM indicator switches to “RAIM safe R+” condition. When

less than 5 satellites are receivable a “RAIM Caution” will be indicated.

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Memorex RX 1 Smart Manual de Instalação Página 69