AngusMcDoon
Well-Known Member
I've been thinking about a crew watching MOB alert device. This would consist of a small box (74mm x 56mm x 24mm) that each crew carries in their pocket that would every 4 seconds send a radio message to a central receiver. The central receiver would monitor for these incoming messages, and if nothing was received from one would sound an alarm. By connecting the central box to a GPS via NMEA it would know the boat's position the last time an incoming message was received from the non-transmitting transmitter and could guide the boat back to that position. Doing some tests I have found that the range of the radio transceivers I tried is about 25m.
The central receiver would cope with up to 4 transmitters. On the central box there would be a small backlit 2 line lcd display showing how long ago in seconds it was since a message was received from each transmitter. When any transmitter's value reached a configurable time (30-90 seconds) an alarm message would show and an alarm tone sound from an in-built beeper, and also a switched 12V output to connect whatever loud alarm device you wanted. There would be a simple user interface on the central box with a couple of buttons to enable/disable the channels being monitored, silence or cancel an alarm and do any other configurations (like backlight level). Here is the LCD showing that channel 4 is enabled and last received a message from transmitter 4 one second ago, channels 1-3 not being monitored...
The crew box would just be a plain box. Stick a couple of AAA batteries in it and it will last a year. No need for any switches, buttons or displays.
I could make the crew boxes for £10 each and the central box for £25. It would all be open source as usual, so anyone could make up one themselves if they wanted. My idea for the case for the central bit would be to use an off the shelf box back and get a top 3D printed so it looks reasonable. Postage would be on top of these prices as it would depend on how much I was sending and combining, but would only be what it costs me, which is around £3-4.
The hardware and software is pretty much done, but looks like this at the moment...
Would there be any takers to progress this project?
The central receiver would cope with up to 4 transmitters. On the central box there would be a small backlit 2 line lcd display showing how long ago in seconds it was since a message was received from each transmitter. When any transmitter's value reached a configurable time (30-90 seconds) an alarm message would show and an alarm tone sound from an in-built beeper, and also a switched 12V output to connect whatever loud alarm device you wanted. There would be a simple user interface on the central box with a couple of buttons to enable/disable the channels being monitored, silence or cancel an alarm and do any other configurations (like backlight level). Here is the LCD showing that channel 4 is enabled and last received a message from transmitter 4 one second ago, channels 1-3 not being monitored...
The crew box would just be a plain box. Stick a couple of AAA batteries in it and it will last a year. No need for any switches, buttons or displays.
I could make the crew boxes for £10 each and the central box for £25. It would all be open source as usual, so anyone could make up one themselves if they wanted. My idea for the case for the central bit would be to use an off the shelf box back and get a top 3D printed so it looks reasonable. Postage would be on top of these prices as it would depend on how much I was sending and combining, but would only be what it costs me, which is around £3-4.
The hardware and software is pretty much done, but looks like this at the moment...
Would there be any takers to progress this project?
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