This is the common list of questions asked in the support department here at ICS. If the question you wish to ask is not in this list please feel free to contact our support team. Details are on the contact pages of this site.
There are 3 allocated NAVTEX frequencies:
518 kHz is the main frequency, this is used World-wide printing English language information.
490kHz is allocated for local language use.
4209.5 MHz is allocated for 'Tropical or long range use'.
I have been having problems receiving weather forecasts from particular stations, even though I seem to receive navigation warnings from the same station. What could be the cause of this?
The reason could be a weak signal. Weather forecasts tend to be longer than navigation warnings and as such can be more susceptible to 'drop up' of radio reception than the shorter navigation warnings. A count of 16 consecutive error characters will result in the rejection of a message by the NAV4.
Raw NMEA data sent from the GPS can be printed by entering NMEA test mode. This causes the NAV4 to output all received NMEA data. To place the NAV4 in NMEA test mode push the 'Y' button 3 times in quick succession (NAV4 starts to tick). The NAV4 will print a list of all the NMEA data that it can use. Cancel the test mode by again pushing the 'Y' button 3 times in quick succession.
- The GPS must supply a valid position fix with time (UTC) of fix. Without this the NAV4 automatic log book function can not work.
- The instrument system connected to the NAV4 must provide information in NMEA 0183 version 2 or later format.
Raise the aerial.
Run a ground wire from the NAV4 to a seawater ground point.
A direct receive ground connection to the NAV4 can help if the vessel suffers from the effects of high levels of electrical noise. To do this, a ground wire should be run from the antenna screen connection (2) of the NAV4 to a seawater grounding point nearby. A keel bolt or metal skin fitting could provide a suitable ground point. Care should be taken not to compromise the vessels galvanic protection systems. If this could be a problem a .1uf capacitor should be inserted in the ground cable. This will isolate the ground cable from any DC current flow.
Correct installation of the antenna is very important, the ANT4a must be mounted 'in the clear' and well away from metal objects or rigging wires and away from other antennas by at least 50cm. Any compromise in the positioning of the antenna could result in reduced reception performance. There is normally very little advantage in placing a NAVTEX antenna at mast head, however raising the antenna up to about 6m above sea level can sometimes improve reception if problems are experienced. This could certainly be the case if the vessel suffers from high levels of electrical noise. Battery chargers, inverters and other electrical systems can cause such noise problems and effect the quality of long range NAVTEX reception. Elevating the antenna can move it out of the noise zone that can sometimes be associated with electrical equipment. Lifting it above the main effect of such electrical noise.
A simple resistance check across the disconnected antenna cable should indicate if a problem exists.
- The resistance reading across the antenna cable should be about 3-4 ohms, when testing using a low ohms setting on a test meter.
- An open circuit reading or a short circuit reading would indicate a problem with the antenna or associated wiring.
The ICS Leisure passive antenna should measure between 4 and 5 Ohm.
The antenna should measure 0.2 to 0.3 of an Ohm.
The latest of firmware for the NAV 4 is v2.67.
The main changes in this version is to allow you to cancel all stations and all categories if required.
Also it has a larger over night buffer, each message is underlined, and there is a none volatile message log to save unit reprinting old messages if the unit is turned off and on again.
The paper feed roller has been damaged by pulling on the paper or caused by a paper jam. The NAV 4 will need a replacement printer assembly.
Please contact support, the contact details are on the support page.
If you have just changed the paper, you may have replaced it the wrong way round.
Make sure the paper leaves the roll from the back at the top and takes a very sort turn into the printer.
The NAV4 buffer fault report is a standard report produced by the NAV4 if the print buffer overflows. This is not a fatal error report and you have no need to worry. The buffer fault report indicates that your NAV4 has noticed a printing error when recalling a NAVTEX message from memory.
This type of report is however rather unusual, if a GPS or instrument system is connected it could also be related to the amount of NMEA data sent to the NAV4.
NAV 6 & NAV 6+
In Navtex Mode select the Sort View, change to Date Criteria and then select Descending Order. The latest and all new message will then appear at the top of the display.
The NAV6 or NAV6plus should give good Navtex reception within the published service area. Over a sea path, this can extend to as much as 200 – 300 nautical miles from the transmitting station during daylight hours. If the direct signal path crosses land to any significant extent however, attenuation may occur which could reduce the reception range to as little as 50 miles.
Navtex range increases significantly at night and can extend to as much as 1000 miles – sometimes more.
Background electrical noise in a marina, the presence of high cliffs and the masts of surrounding vessels can all contribute to poorer reception when in harbour, rather than at sea.
If you want to increase the sensitivity of your system and hence the range of reception, there are two things that can be done to optimise the installation. Either one of them can lead to a big improvement.
- Connect the screen of the interconnecting cable from the connecting block direct to a good electrical ground. This can either be a specially installed ground plate, or the keel bolts on a non-encapsulated keel.
- On a yacht, have the back stay insulated and connect it directly to the top of the NAV6 sensor, in place of the whip antenna.
For the ultimate in results, try both.
We would emphasise that in normal circumstances, none of these measures should be necessary. However, if you wish to frequently receive Navtex at extreme range, either may be worth trying.
If I toggle through all the available screens using the 'Mode soft key' only the Navigate and the Set-up screen show, why no NAVTEX screen?
The 'Antenna Frequency' setting is currently set to 'NONE'.
Go to the NAVTEX options set-up page and select a receive 'Frequency'.
- If you have a NAV6 select either 490 kHz or 518 kHz
- If you have a NAV6plus you can select either of the above or 'BOTH' for both frequencies at the same time.
The text font size currently selected is Medium or Large, station names are only displayed when the 'small' font is selected.
An isolated 24V to 12V converter, ICS Pt No. 500.13, is available.
An isolated 12V to 12V converter, ICS Pt No. 500.02, is available.
One possible cause is you may have set the unit to be a slave where it should be set to Master if you have only one LCD display.
If your unit indicates that the antenna type is none then the LCD display has lost communication with the antenna sensor.
This will also flag the ERR tabs next to the two channel at the top of the display for 490 and 518KHz.
There can be many reasons for this, for example a poor connection or a break down in the antenna. For more assistance with this problem please contact support via the support page.
NAV6plus customers attempting to interface to Raymarine SeaTalk systems using a Raymarine Z290 SeaTalk to NMEA bridge may experience problems with the data contained within the RMB (recommended minimum navigation) sentence. Please ensure that you have the latest software from Raymarine in your Z290. Z290 Versions 6 and earlier (any Z290 unit purchased before May 2002) do not transmit the RMB sentence correctly which may result in one or more of the following symptoms on the NAV6plus:
- No cross track error (XTE).
- Incorrect closing speed.
- Incorrect range.
- Incorrect bearing.
Please contact your Raymarine dealer to obtain an update for your Z290.
Please note that the SeaTalk bridge does not convert all SeaTalk data elements to the NMEA equivalent. Please consult the user manual from your SeaTalk bridge which will indicate which data items you will be able to view on your NAV6plus.
Buy a Raymarine 'Seatalk to NMEA bridge' from your local dealer. This will convert the instrument data present on the Seatalk bus into the NMEA format that the NAV6plus can understand.
Certain Raymarine (previously Raytheon) equipment offers the facility to bridge instrument data transmitted on SeaTalk to an NMEA output. Unfortunately this bridging facility is not comprehensive in all cases, for instance a RC520 will display wind information if it is available on the SeaTalk interface, but does not bridge the wind data to its NMEA output interface.
We recommend that you carefully read the user manual for any Raymarine products that you own before connecting an NMEA output to the Nav6's NMEA input. You may find that the data that you wish to display on the NAV6 is not output by the Raymarine equipment (as in the example above).
In these cases we recommend that you purchase a Raymarine Seatalk to NMEA bridge product and use this to bridge Seatalk instrument data to the NAV6's NMEA input.