WetRuler--Measuring Ocean Height
Introduction: WetRuler--Measuring Ocean Height
The announcement came early this summer that the area in Alaska called Prince William Sound would be unexpectedly hit by a global warming initiated Tsunami. The scientists who made the discovery pointed to an area of rapidly retreating ice that had left behind a mountain of debris that would slip into a fjord and initiate a 30 foot wave that would eventually hit the town of Whittier. This has happened before, during the 1964 earthquake where shaking initiated multiple tsunamis in the surrounding fjords and devastated the coast including Whittier and Valdez with multiple deaths. Cruise boats already wary from the virus decided not to go near the area and the USFS offered refunds on any cabins that had been rented. A week later a Tsunami warning hit all of our cell phones! An underwater beacon had detected a wave associated with a small earthquake off the coast. All regional towns were told to evacuate if near water. It came to nothing. How do you measure these events? This Instructable details the building of small sensors that are able to measure ocean height and send the data to either a LORA receiver or straight to GSM. The units are compact and seem resilient to their environment and are solar operated. I have tested them here for achieving reproducible tide heights but they could be also used for wave height and Tsunami predictions.
Step 1: Gather Your Materials
There are two sending units that I built--one involves GSM(cell phone) upload and the other LORA upload. You may also consider interfacing with a Sat beacon since many of these areas do not have cell phone coverage. The sensor at the heart of these instruments is the MS5803-14BA and its use and assembly in different scenarios can be found in these web sites: https://thecavepearlproject.org/2016/09/21/field-...and http://owhl.org. The second of these shows a brilliantly designed remote logger with its own custom designed PCB for long term measurement of wave height. The sensors seemed to be tolerant of water for months to a year depending on setup.
1. MS5803-14BA--you can get these from DigiKey for $13 but you need to do some surface soldering work or get a pre-made breakout board from SparkFun but it will set you back $60. If you DIY it you will need a small Adafruit board to solder it to and some low temp solder gel(140F) that I found helpful. The cavepearlproject has a great tutorial on how to hand solder these--I suggest getting a cheap rework station from Amazon for $30.
2. 152
LILYGO 2pcs TTGO LORA32 868/915Mhz ESP32 LoRa--$27 these are for the LORA box.
3. ARDUINO MKR GSM 1400 $55--this is a great board. It works perfectly with the Hologram sim. Unfortunately I could not get their Arduino Sim to work with their new service in spite of multiple tries. If you still have access to 2GM service you can go with something cheaper but that totally failed up in Alaska.
4. Solar Cells Uxcell 2Pcs 6V 180mA Poly Mini Solar Cell Panel Module DIY for Light Toys Charger 133mm x 73mm $8
5. 18650 Battery $4
6. TP4056--charger $1
7. Switch Rugged Metal On/Off Switch with Green LED Ring - 16mm Green On/Off $5
8. Icstation 1S 3.7V Lithium Ion Battery Voltage Tester Indicator 4 Sections Blue LED Display $2
9. Adafruit TPL5111 Low Power Timer Breakout--brilliant little timing device $6.00
10. N-channel power MOSFET - 30V / 60A $1.75
11. Differential I2C Long Cable Extender PCA9600 Module from SandboxElectronics X2 ($18 each) -- there is some mentioned success with long cables for I2C in the literature but with daily 25 foot tides in Alaska you need long cables...oh yea some cable..I used big box 23 g 4 twisted pair cable suitable for outside.
12. Adafruit BMP388 - Precision Barometric Pressure and Altimeter $10
Step 2: Build the Sensors
The sensors have to be surface soldered to small PCBs. The two prior works give you some hints about how to do it. I bought both the sensors and the tiny boards from Digikey. Use the low temp solder from Adafruit and dab just the tiniest amount adjacent to the feet of the sensor as you place it on the board. Use a rework blower to melt it into place. 832