DigiBOAT Website NASA AIS Engine

Introduction

The NASA AIS Engine is a simple, cheap device for receiving AIS enabled ships and then displaying them in the Software-On-Board (SOB) charting and navigation program.

You obviously attempt these modifications at your own risk, we take NO RESPONSIBILITY for what you're about to do to your NASA AIS Receiver. And we make no guarantees that it will work even if you follow these instructions exactly. We've done this to a couple of NASA's now, and they both work still (and have survived extensive full-time testing since).

More about the NASA AIS Receiver ?
What is AIS ?
What is DigiBOAT ?
What is "Software-On-Board" (SOB) ?

Brief

The main drawback with the NASA Engine is that without active targets available, it is impossible to determine whether (1) the NASA device is working; and (2) whether the NASA device and the PC are correctly communicating.

Of course, if you are installing the NASA in an area with active AIS transponding ships, then you wont get as much benefit out of fitting the LEDs (Light-Emitting-Diodes), however there's still an element of "peace of mind" involved with being able to tell, at a glance, that the NASA is at least receiving power.

In an effort to resolve these shortcomings, for less than a dollar, anyone semi-skilled with a soldering-iron can add the components that NASA forgot...

It is assumed that you are competent soldering circuit-board (PCB) sized components. If not practice on someone else's circuit board before destroying your NASA device.

The NASA unit is stated to draw a negligible current of 45 mA. Each standard sized LED will draw a max of 20 mA. The red LED will be permanently on, the others on periodically, so the total power consumption will be about a max of 70 mA, which is still negligible.

Apologies

You may notice that the job I did on my NASA is not very slick! 

If I knew at the time that I wasn't going to destroy my $300+ device, I would have taken a small amount of extra time and care and would have, no doubt, achieved a more professional result.

The bottom line is - it works! and rather than destroying it, I believe that I have significantly improved it.

Parts List

• Fine-point soldering-iron

• Hot glue gun

• Very small flat-head screwdriver

• Medium size philips (star) screwdriver

• Very sharp knife

• 4x LEDs (different colours recommended)

• 1x 560Ω ¼-watt resistor

• 3x 180Ω ¼-watt resistors

• A few inches of heat-shrink tubing

• A few inches of hook-up wire

LED Functions

Example when a GPS is connected:

• The red LED will be permanently ON while the NASA is receiving power.

• The yellow LED will flash almost continuously (when the GPS is ON and set for Data-Output).

• The green LED will flash every two seconds (as it relays the GPS command to the PC). Additional GREEN flashes will occur if/when AIS data is ready to send to the PC.

• The orange LED will flash once when SOB starts, or when the COM port is opened via the [Open COM] button on SOB's "Raw NMEA Form".

Example with no GPS:

• The red LED will be permanently ON while the NASA is receiving power.

• The yellow LED will never light up.

• The green LED will flash if/when AIS data is being sent to the PC.

• The orange LED will flash once when SOB starts, or when the COM port is opened via the [Open COM] button on SOB's "Raw NMEA Form".

Build Instructions:

1. Unplug all cables (aerial, power, serial) and turn the unit upside down.
   Remove the four philips screws in the four corners.
   Open the unit and remove the bottom half to expose the circuit board:

2. Use the soldering-iron to butcher both sides of the NASA box to make space for the LEDs to protrude. Trim away the excess with the sharp knife and rebuild the step where the two sides of the box meet. Make sure you leave enough space for the screw hole strut to fit to the other side.
   
   NOTES:
   Don't do this in a room with a smoke alarm! You might consider doing this in a well ventilated area.
   You will need to re-tin your soldering-iron after burning the plastic with it. After decades of soldering I'm still not very good at this, so I suggest you get instructions from another source on tinning the iron.
   There is probably a simple and neat way to do this without using the soldering-iron (a drill perhaps?), but the soldering-iron is already warmed-up and the right shape, and I need practice tinning, and who's going to pass-up an opportunity to burn and melt something? - so I used the iron.
   

3. Cut the short leg of the RED LED to a length of about 5mm, lightly twist and solder the 560 ohm resistor to it.
   Solder a 25mm (1 inch) length of hook-up wire to the free side of the 560 ohm resistor. Cover the resistor and bare wire with with heat-shrink (right up to the LED housing) and shrink it (cigarette lighter works well).
   
   Cut the short legs of the other 3 LEDs the same and solder the 180 ohm resistors in the same way.
   Solder a 25mm (1 inch) length of hook-up wire to the other side of each resistor.
   Slide a length of heat-shrink over each resistor to completely cover all bare wires as for the red LED.
   
   Solder the other ends of the four wires from the 4 resistors together, with a further single short length of wire also soldered to it (black, in the photo below). Shrink some more tubing over this to hide the bare join.
   

   NOTE: Seven more pieces of heat-shrink still must be applied to the bare sections in this photo - they have been left out for clarity.

   
   

4. Using the small flat-head screwdriver, gently clear away about 4mm of the protective coating on the three tracks in the places marked A, B & C in the photo. Scratch the protective coating off until shiny metal is revealed. If for any reason you cut the tracks - don't be too worried, you'll be able to repair the cut while soldering on the hook-up wire.

    

5. Using more pieces of hook-up wire, connect the long legs of the LEDs to the circuit board at the locations marked in the photo (using heat-shrink to cover all bare wires and joins first):
   GREEN to A
   YELLOW to B
   ORANGE to C
   RED to D
   NOTE: When soldering the wires to the circuit board tracks, first get a Layer of solder to stick to the bare track, then solder the wire on.
   

   
   

6. Solder the free end of the wire connecting all the resistors (black, in the photo above) to the existing solder spot marked E in the photo.
   
   

7. Finally, glue the LED arrangement to the circuit board to line up with your pre-prepared holes in the side of the casing - don't glue the LEDs to the box, if you put your holes in the centre where the two halves of the box join, then the LEDs should sit nicely on the circuit board. NOTE: don't forget to leave space around the mounting hole for the screw support in the bottom half of the box. Also put a dab of glue over the solder joints A, B and C (this is more for corrosion and vibration protection not for adhering the wire to the track - the solder does this). (In this example, a different location for the "E" connect point has been used)