Technical Support
mailto:
soporte@marimsys.com
FAX:
+ 56 32 814253
Tel:
+ 56 32 815005
Autocalibrate
Marimsys BRIDGE
NMEA 0183 Protocol
NMEA Signal Messages
NMEA Troubleshooting
Satellite Reception Systems
Marimsys BRIDGE (TCAMS)
Multiplexer - Troubleshooting
In general, most users will find the installation and operation of the multiplexer to be
trouble-free. However, if faults should arise, the following procedures are recommended to
diagnose the problem.
The majority of faults with electronic equipment are due to worn or incorrect wiring. In case of trouble, the following should be checked first:
Power Supply Connections
Instrument Connections
RS-232 Interface
Failure of the multiplexer to transmit data is generally caused by conflicting computer messages and requires that the unit be reset by cutting its electrical power for a few seconds. Direct determination of the presence of an NMEA 0183 signal is obtained by attaching a digital multimeter, set to DC Voltage to the two wires: if the reading jumps up and down with a repeating and regular rhythm (it may be a rapid or slow rhythm) you almost certainly have NMEA signals present. Check the signals at the emission point on the system in question, at the entrance to the multiplexer, at the exit from the multiplexer, and finally as the signal enters the COM port of the computer.
If all connections seem to be correct and a suitable ammeter is available, the power supply current should be checked. The power supply current should be approximately 0.075 A. Any reading significantly above or below this figure indicate a defective unit which must be replaced. Please contact Marine Imaging Systems, Inc. for further assistance.
Image Quality - Noise
This is the static which visually appears as a blurred portion of the
image. It can also appear as a jagged horizontal line, one pixel high in which the
color appears abnormal - as that line of the would be filled-in, it is blocked by static.
Noise is heard on the speaker as static. It is caused by RF interference or
the progressive acquisition and loss of the satellite signal by the antenna. Beware
of unexpected temperatures which occur in a horizontal line only a pixel or perhaps a few
pixels high.
In order to properly georeference the images, it is recommended that the system be stopped when the noise of satellite acquisition ends. This will generally be several minutes after the first reception. Then restart image reception. This will provide a clear and uninterrupted bottom of the image for the georeferenciation algorithms - and result in accurate placement of the Latitude and Longitude grid.
It is perfectly normal to have this noise appear at the top and the bottom of an image. This is the satellite coming up into the receiving arc of the antenna, and then dropping down out of that arc. During this transition from no reception to good reception, there will always be noise. This static area will be wider in rough sea conditions due to vessel motion widening the band of transition when the antenna is acquiring and losing the signal.
Noise appearing throughout an image, especially if the image is a short one on the screen, indicates that it is a low angle pass, and never gets up into the clear reception angle. This can be verified by checking with Track 2 to determine the pass angle. Noise sporadically appearing in an image can be caused by radio transmitters (or other RF emitters) in close proximity to the SIRS receiving antenna. Of special concern are RF emitters which either broadcast near the 137 MHz frequency of satellite reception, or on a harmonic frequency. Marine VHF, aircraft VHF and amateur 2 meter radio are generally suspect. The static pattern will continue on the image during the time that the RF emission is being broadcast, and will abruptly stop when the emission ceases. Trial an error will isolate the culprit. At system installation elimination or minimization of possible transient sources will have been performed by the Marimsys technician. Should later interference appear - focus on transmitters added to the immediate area following installation. Antenna movement, or in extreme cases the addition of further GAsFET filters will remedy the problem.
Small Images
See above under "Image Quality - Noise"
Image will not show infrared
"Not an infrared section" error message. The bands at the sides
of the infrared portion of the download contain the calibration information for the
infrared temperature mapping. If static occurs at a critical portion of these bands,
no infrared information will be available for the portion of the image beside the
"noisy" bands. Other portions of the image will generally provide
infrared data.
Rarely the image will laterally displace or lose synchronization during reception due to interference, and the image will continue coming in with the bands laterally shifted. If the problem is caught during the beginnings of the download, and the image on the screen is small, Esc(ape) out and then begin reception again with RECIBE, and RECIBE IMAGEN. If there is a considerable amount of good image on the screen, GRABAR the image before restarting reception. Generally synchronization will be regained with the second try.
Sometimes infrared information can be obtained by using a different portion of the image, one with less static and the synchronization bands clearer and in the correct position. Alternatively, trying to select ESCALA DE TEMPERATURA in the first screen, when the two bands are available sometimes will produce a thermal image. Should these methods not work to display temperature, discard the image and wait for the next image to be received.
Image and Program Act Strangely
Most probably there has been another program loaded into the computer which is
conflicting with SIRS. Esc(ape) out of SIRS and shut down any TSR's
(Terminate and Stay Resident) utilities which may have been recently loaded. Then
restart SIRS.
With some images, the static on the sidebars can throw the program off. Esc(ape) out of the program, and start the program up again. If the program seizes up, Ctrl + Alt + Del will shut the system down in a warm reboot; as will turning off the power supply, and then restarting the computer. This is not a normal way to exit the program, but will bring the system under control.
As a last resort, reinstall the programs with the installation disks provided.
Poor Image Quality
Check all connections from the satellite antenna down to the receiver module.
If problems are revealed repair them and reseal the system.
If no obvious problems are encountered, try taking out the pre-amplifier and replacing it with a barrel connector. If image quality is equal to or better than before the pre-amp replacement, the pre-amp is at fault - generally as a result of water intrusion. Replace it.
If reception quality deteriorates with the barrel connector substitution referred to in the previous paragraph, other components or connections are suspect. Check the feed to the pre-amp at the scanner module, it should be approximately according to the specs in the manual section "Pre-Amplifier".
Check the coaxial cable for continuity from the pre-amp down to the receiver. If the cable and its connections checks out OK, there are no other user serviceable components; contact the nearest Marimsys service technician.