My 2nd-year project is to build a submersible probe, which is basically a remote control submarine equipped with a ready-made wireless camera. this probe will be used to find something under the water. after the receiver receiver the signal, it will activate the motor.
1. since the signal must travels across 2 mediums (air and water), what type of signal can be used (ultrasonic, VHF, or UHF)?
2. if there is no way to transmit signal across 2 different medium, i am going to raise an antenna to the surface of water to receive the signal. Any comment?
3. what range of frequency and modulation is suitable in this project? most RC (remote controlled) toy operate on 27 MHz or 49 MHz.(http://entertainment.howstuffworks.com/rc-toy2.htm)
4. most of the transmitter and receiver circuit i have studied online doesn't mention if it is multi-channel or not. As long as i know, each command signal is comprised of a series of pulse signal.(http://entertainment.howstuffworks.com/rc-toy3.htm). if i need 8 channels to control the movement of the submarine (1-up, 2-down, 3-left, 4-right, 5-forward, 6-backward, 7 & 8 reserved for extension). how to make this?
5. how does the receiver distinguish the 8 different command signals? do i need a special IC at the receiver?
6. i wish someone can show me the complete schematic diagram for the 8-channels transmitter-receiver circuit. Any comments and suggestion is very welcomed :) thank you!