System Sensors
Hydrophone
Building off our design for Græy, we strove to make the system as independent as possible. We offloaded as much filtering as possible to custom designed hardware, freeing up resources within the microprocessor. Each hydrophone has its own daughter-board containing noise-isolated circuitry. This includes the pre-amp, a custom amp, a custom variable frequency filter, adjustable between 10khz to 40khz, a digital potentiometer for variable gain, and a custom active high-pass filter to ensure the signal is as clean as possible.
Imaging Scanning Sonar
We switched to Ping360 sonars from Blue Robotics for their increased image scanning capability. Previously we used the one dimensional ping sonar which only allowed us to receive distance values in the direction the sonar was pointing. The new 360 degree sonar allows us to get a snapshot view of our whole environment so we can analyze where the mission objects are and which direction we should head in.
Modem
To safely and effectively operate two subs simultaneously in the water, it is paramount to have a consistent and efficient communication system. This season, we emphasize the importance of being able to have two submarines effectively communicate with each other in the water, in addition to providing useful information to the ground station such as images, updates on current tasks, and other odometry status messages. Our original design was modeled around the compact m64 modems by WaterLinked. To test these modems, we developed a bench test utilizing a raspberry pi and a hobbyist power divider/regulator for power and serial communication. The results of these modem tests demonstrated that they were unreliable and their 64 bits per second were insufficient if we desired to send any images. This led us to begin implementing new modems that were more reliable and offered a higher bandwidth.