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Marine VHF Channel 83 – Interesting Chatter

Came across this today while scanning through frequencies. Not sure of their exact QTH, but there’s references to the Oldham area in Manchester, about as far away as you can get from any marine or commercial shipping area in the county. I didn’t hear any marine callsigns or vessel names either so I’m guessing that they’re using the frequency illegally.

UPDATE!
I’ve been reliably informed that there is a frequency overlap between the marine band Channel 83 & a local comms repeater here in Stockport.I find the fact that Ofcom have allowed a frequency overlap here a little odd, since the marine band is used on the inland waterways, although not as much as coastal marine locations.

 

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Marine Potable Water Management System

LCD Panel
LCD Panel

Having two separate water tanks on nb Tanya Louise, with individual pumps, meant that monitoring water levels in tanks & keeping them topped up without emptying & having to reprime pumps every time was a hassle.
To this end I have designed & built this device, to monitor water usage from the individual tanks & automatically switch over when the tank in use nears empty, alerting the user in the process so the empty tanks can be refilled.

Based around an ATMega328, the unit reads a pair of sensors, fitted into the suction line of each pump from the tanks. The calculated flow is displayed on the 20×4 LCD, & logged to EEPROM, in case of power failure.

Water Flow Sensor
Water Flow Sensor

When the tank in use reaches a preset number of litres flowed, (currently hardcoded, but user input will be implemented soon), the pump is disabled & the other tank pump is enabled. This is also indicated on the display by the arrow to the left of the flow register. Tank switching is alerted by the built in beeper.
It is also possible to manually select a tank to use, & disable automatic operation.
Resetting the individual tank registers is done by a pair of pushbuttons, the total flow register is non-resettable, unless a hard reset is performed to clear the onboard EEPROM.

Main PCB
Main PCB

View of the main PCB is above, with the central Arduino Pro Mini module hosting the backend code. 12-24v power input, sensor input & 5v sensor power output is on the connectors on the left, while the pair of pump outputs is on the bottom right, switched by a pair of IRFZ44N logic-level MOSFETS. Onboard 5v power for the logic is provided by the LM7805 top right.

Code & PCB design is still under development, but I will most likely post the design files & Arduino sketch once some more polishing has been done.