Surfsonar shows the depth of water while surfing

Surf Sensor Adds Depth To Finding The Ultimate Wave

To say that the ocean is a dynamic environment would be a gross understatement, especially when coastlines are involved. Waves crash, tides go in and out, and countless variables make even the usual conditions a guessing game. When [foobarbecue] goes surfing, he tries to take into account all of these things. The best waves at his local beach are directly over an ever-moving sand bar, and their dynamics are affected by depth, another constant variable. [foobarbecue]’s brilliant solution to understanding current conditions? Build a depth finder directly into his surf board!

At the heart of the “surfsonar” is the Ping Sonar Echosounder, a sonar transducer designed for AUV’s and ROV’s. [foobarbecue] embedded the transducer directly into the board. Data is fed to a Raspberry Pi 4b, which displays depth and confidence (a percentage of how sure it is of the measurement) on a 2.13 inch e-Paper Display Hat.

Power is provided by a PiSugar. Charging is done wirelessly, which we’d say is pretty important considering that the whole device is sealed inside a modified surfboard.

While it’s not a low budget build, and there’s yet room for improvement, early reports are positive. Once away from the breaking waves, the device confidently shows the depth. More testing will show if the surfsonar will help [foobarbecue] find that ever-moving sandbar!

Surf hacks are always welcome, we’ve featured the LED Strip Lit Surfboard as well as the Surf Window, which tells its owner if the surf is up. Be sure to let us know about any cool hacks you find when you’re out surfing the ‘net via our Tips Line!

Homebrew Sounder Maps The Depths In Depth

For those who like to muck around in boats, there’s enough to worry about without wondering if you’re going to run aground. And there’s really no way to know that other than to work from charts that show you exactly what lies beneath. But what does one do for places where no such charts exist? Easy — make your own homebrew water depth logger.

Thankfully, gone are the days when an able seaman would manually deploy the sounding line and call out the depth to the bottom. [Neumi]’s sounding rig uses an off-the-shelf sonar depth sounder, one with NMEA, or National Marine Electronic Association, output. Combined with a GPS module and an Arduino with an SD card, the rig can keep track not only of how much water is below it, but exactly where the measurement point is. The whole thing is rigged up to an inflatable dinghy which lets it slowly ply the confines of a small marina, working in and out of the nooks and crannies. A bit of Python and matplotlib stitches that data together into a bathymetric map of the harbor, with pretty fine detail. The chart also takes the tides into account, as the water level varies quite a bit over the four hours it takes to gather all the data. See it in action in the video after the hop.

There’s something cool about revealing the mysteries of the deep, even if they’re not that deep. Want to go a little deeper? We’ve seen that before too.

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Robot Pet Is A Chip Off The Old Logic Block

When [Ezra Thomas] needed inspiration for his senior design project, he only needed to look as far as his own robot. Built during his high school years from the classic 1979 Frank DaCosta book “How to Build Your Own Working Robot Pet”, [Ezra] had learned the hard way the many limitations and complexities of the wire wrapped 74xx series logic chips surrounding its 8085 processor.

[Ezra] embarked on a quest to recreate the monstrosity in miniature, calling it Pet on a Chip. Using a modern FPGA chip allows the electronics to shrink by an order of magnitude and provides flexibility for future expansion. Implementing an 8 bit CPU on the amply sized FPGA left plenty of room for a VGA GPU, motor controller, serial UART, and more. Programming the CPU is handled by a custom assembler written in Python.

The results? Twelve times less weight, thirteen times less power draw, better performance, and a lot of room for growth. [Ezra] hints at an I2C bus expansion as well as a higher level programming language to make software development less of a hurdle.

The Pet On A Chip is a wonderfully engineered project and we hope that we’ll be seeing more such from [Ezra] as time goes by. Watch his Pet On A Chip in action in the video below the break.

If [Ezra]’s FPGA escapades have you wondering how to get started, you can check out this introduction to FPGA from the 2019 Hackaday Superconference. And if you have your own FPGA creation to share, please let us know via the Tip Line!

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Hide Silent, Hide Deep: Submarine Tracking Technologies Of The Cold War

All through the cold war, there was a high-stakes game of cat and mouse in play. Nuclear powers like the United States and the Soviet Union would hide submarines armed with nuclear missiles underwater. The other side would try to know where they were so they could be targeted in the event of war. The common wisdom was that the United States had many high tech gadgets to help track enemy submarines, but that the Soviet Union was way behind in this area. This was proven false when a Soviet Victor-class boat followed a US missile submarine for six days. Now, a recently declassified CIA report shows how the Soviets didn’t use sonar at all but developed their own technology.

There is something fascinating about submarines. Like an old sailing ship, submarines are often out of touch with their command bases and the captain is the final authority. Like a space ship, the submarine has to survive in an inimical environment. I guess in all three cases, the crew doesn’t just use technology, they depend on it.

Although the submarine has some non-military uses, there are probably more military subs than any other type. After all, a sub is as close to a cloaking device as any real-life military vehicle has ever had. Before modern technology offered ways to find submarines using sonar or magnetic anomalies, a completely submerged submarine was effectively invisible.

There was a lot of speculation that the Soviet Union lacked sufficient technology to use sonar  the way the US did. However, in some cases, they had simply developed different types of detection — many of which the West had discarded as impractical.

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Submarine To Plane: Can You Hear Me Now? The Hydrophone Radar Connection

How does a submarine talk to an airplane? It sounds like a bad joke but it’s actually a difficult engineering challenge.

Traditionally the submarine must surface or get shallow enough to deploy a communication buoy. That communication buoy uses the same type of radio technology as planes. But submarines often rely on acoustic transmissions via hydrophones which is fancy-talk for putting speakers and microphones in the water as transmitters and receivers. This is because water is no friend to radio signals, especially high frequencies. MIT is developing a system which bridges this watery gap and it relies on acoustic transmissions pointed at the water’s surface (PDF warning) and an airplane with high-precision radar which detects the oscillations of the water.

The complexity of the described setup is mind-boggling. Right now the proof of concept is over short distances and was tested in a water tank and a swimming pool but not in open water. The first thing that comes to mind is the interference caused by waves and by aerosols from wind/wave interactions. Those challenges are already in the minds of the research team. The system has been tested to work with waves of 8 cm (16 cm measured peak to trough) caused by swimmers in the pool. That may not sound like much, but it’s about 100,000 times the surface variations being measured by the millimeter wave radar in order to detect the hydrophone transmissions. Add to that the effects of Doppler shift from the movement of the plane and the sub and you have a signal processing challenge just waiting to be solved.

This setup is very interesting when pitched as a tool for researching aquatic life. The video below envisions that transmitters on the backs of sea turtles could send communications to aircraft overhead. We love seeing these kinds of forward-thinking ocean research projects, like our 2017 Hackaday prize winner which is an open source underwater glider. Oceanic studies over long distances have been very difficult but we’re beginning to see a lot of projects chipping away at that inaccessibility.

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Sonar In Your Hand

Sonar measures distance by emitting a sound and clocking how long it takes the sound to travel. This works in any medium capable of transmitting sound such as water, air, or in the case of FingerPing, flesh and bone. FingerPing is a project at Georgia Tech headed by [Cheng Zhang] which measures hand position by sending soundwaves through the thumb and measuring the time on four different receivers. These readings tell which bones the sound travels through and allow the device to figure out where the thumb is touching. Hand positions like this include American Sign Language one through ten.

From the perspective of discreetly one through ten on a mobile device, this opens up a lot of possibilities for computer input while remaining pretty unobtrusive. We see prototypes which are more capable of reading gestures but also draw attention if you wear them on a bus. It is a classic trade-off between convenience and function but this type of reading is unique and could combine with other bio signals for finer results.

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Ultrasonic Array Gets Range Data Fast And Cheap

How’s your parallel parking? It’s a scenario that many drivers dread to the point of avoidance. But this 360° ultrasonic sensor will put even the most skilled driver to shame, at least those who pilot tiny remote-controlled cars.

Watch the video below a few times and you’ll see that within the limits of the test system, [Dimitris Platis]’ “SonicDisc” sensor does a pretty good job of nailing the parallel parking problem, a driving skill so rare that car companies have spent millions developing vehicles that do it for you. The essential task is good spatial relations, and that’s where SonicDisc comes in. A circular array of eight HC-SR04 ultrasonic sensors hitched to an ATmega328P, the SonicDisc takes advantage of interrupts to make reading the eight sensors as fast as possible. The array can take a complete set of readings every 10 milliseconds, which is fast enough to allow for averaging successive readings to filter out some of the noise that gets returned. Talking to the car’s microcontroller over I2C, the sensor provides a wealth of ranging data that lets the car quickly complete a parallel parking maneuver. And as a bonus, SonicDisc is both open source and cheap to build — about $10 a copy.

Rather use light to get your range data? There are some pretty cheap LIDAR units on the market these days.

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