DLP-MT-LPCOM1-NAVTEX receiver – How to do a test

May 3, 2023 Mikel Arrieta

NAVTEX (Navigational Telex) is a world wide coastal telex broadcasting system.

Motivation phase

Look at the picture

NAVTEX receiver
Is it working properly?
Do you struggle to sort out Navtex warnings?

How NAVTEX Works
NAVTEX is an acronym meaning Navigational Telex, and as its name shows, it is a kind of narrow band radio teletype system for sending (by frequency shift keying) text messages expressed in a 7-unit code. The difference is that a NAVTEX transmitter transmits nine control characters (header code) ahead of the main message, so that the receiver can identify the station, message type and serial number automatically.

NAVTEX System Operation
For navigation purposes, the world is divided into 21 areas (called Navareas).
Each Navtex station has an identification code, from “A” to “Z”. The frequency assigned to Navtex are 518 kHz and another (490 or 4209.5 kHz), and many stations exist in the same service coverage.
If the stations were to transmit without any rule, the system would collapse due to mutual interference. To avoid this problem, the following rules apply.
• The transmission schedule is determined so that two or more stations having a common service area may not overlap in time.
• Each station transmits with minimum required power to cover its service area (200 to 400 nautical miles nominal).

Motivation phase

SYSTEM CONFIGURATION

The system configuration should be understand before start the task

Motivation phase

Navtex is a part of the IMO (International Maritime Organization) and has been included in the Global Maritime Distress and Safety System (GMDSS).

Information phase

How to do a weekly test

A weekly test is explained step by step

The memory test checks ROM, RAM, data port, battery, keyboard and LCD for proper operation and displays program version numbers.
1. Press the MENU/ESC key to open the main menu.
2. Press ▼ to choose Service, and then press the ENT key.
3. Press ▲ or ▼ to choose Test, and then press the ENT key. The message “Start test?” appears.
4. Press ◄ to choose “Yes”, and then press the ENT key.
5. When the message “[ENT] Continue” appears at the bottom of screen, press ENT key to show the key test screen.
6. Press each key (except key) one by one. A key is functioning properly if its on-screen location fills in black when the key is pressed.
7. After all keys have been tested or no key is pressed after 10 seconds, the equipment starts the LCD test by showing the white and black display (level 0 to 9).
8. When the message “Hit any key” appears on the screen, press any key (except key) to show the Rx test screen. The alarm for receiving monitor sounds while the Rx test is being conducted.
9. When the message “[ENT] Finish” appears on the screen, press the ENT key or wait for one minute with no operation to finish. Also the test message is printed by pressing PRINT key when the item other than “None” at Printer on System menu.
10. Press the MENU/ESC key several times to close the menu.