The system now consists of 3 elements:
1. A tide sensor on the dock.
2. An internet interface.
3. A remote tide level monitor with an LCD screen.
The interconnect is based on Freewave 900 Mhz spread spectrum serial radios. They are running in multipoint mode.
The tide sensor is powered by a 12 volt battery charged by a solar panel. The sensor is based on a Parallax Ping (parallax.com) ultrasonic transducer, connected to a Arduino microcontroller (www.arduino.cc) with a custom program (sketch) developed by the author. The program measures the distance from the Ping acoustic transducer to the water. In oder to calculate depth, vs. a reference, the user enters an offset (distance from the transducer to the bottom) in inches through the serial interface on the Arduino through a simple user interface.
The Arduino can be set to take continuous samples or samples every 15 minutes. Continuous sampling mode is used during initial installation to make sure everything is working. Each sample consists of 10 acoustic pings taken at 1 second intervals and averaged. The averaging is an attempt to remove wave action from the tide calculation. Samples are transmitted on the serial interface to the Freewave Radio (freewave.com).
The internet interface is based on an IObridge IO-204 with a Serial Smart Board SB-5 (see IObridge.com). Another Freewave radio receives the serial data stream from the TIDE SENSOR forwards it to the internet. IObridge has excellent internet logging services, and the ability to tweet and/or email this information. I'm tweeting tide levels now on twitter account Capecodda.
TIDE LEVEL MONITOR:
The tide level monitor is an Arduino micro-controller with an LCD interface connected to a 3rd Freewave Radio. The serial data stream is parsed by the Arduino and a tide level is displayed. A short custom program (sketch) that parses the serial data stream and displays tide height was developed by the author.
Next step is packaging.