An LRAD (Long Range Aucustic Device) is a device that can transmit audio in the audible range over a large distance. The technology involves a directional loudspeaker, a lot of amplification and a tone generator that typically transmits audio in the high audible frequency range close to ultrasounds (over ). Initially the technology has been used to transmit audio between vessels at sea, especially as a deterrent for military vessels, but the police has adopted the system and have been using it for crowd suppression. The official LRAD seems to just be an extremely loud and obnoxious tone generator with various setting, just like a boombox, that is capable of transmitting a car-alarm-like tone and some other preset settings that are meant to be annoying.

However, one of LRAD's setting is a close-to-ultrasound cca. setting that is somewhat "better" given that humans are capable of perceiving ultrasounds, above the theoretical biological upper audible limit of . The ultrasound setting on very high frequencies is barely perceivable and thereby quite able to be a great device that can be used to annoy people. Another benefit for using ultrasounds is that high frequencies in the upper domain of human audible hearing are tough to localize by humans such that anyone hearing the ultrasounds will be confused on the location of the source.

You are stuck in a former Soviet gas-station-state, with the police, army and state blended together like manbearpig, with corruption all around you, such that if you are a foreigner, know how to add up two numbers, are gorgeous; then you might have attracted the attention of the shitdwellers and, unfortunately, as slavish nations go, nobody will stop until some corpses are lined up.

The symptoms include:

• cars parked in your driveway with headlights on,
• honks too loud and above the admissible sound level in front of your house,
• police tailgating or doing one-too-many run-bys to not seem gay,
• hearing small burst of close-to-ultrasound sounds in your ears,
• the dog-owners in your area mishandle their dogs such that they bark with no end in sight,
• car alarms go off and last for ages,
• loud motorcycles whose owners bribe the police so they can continue making noise

then it is clear that it is about time you start doing damage.

One solution is to irradiate a wide area with some ultrasounds every time the legal noise pollution limit is overstepped, acting as a deterrent, and with the hopes that holistically over time the behavioral patterns of the people in the area will change given the LRAD deterrent.

The Dazer dog deterrent is a handheld device that uses a battery to emit ultra-sounds with the hopes of making dogs run away.

In order to find out what frequency it uses, the Dazer is hooked up to an oscilloscope and the frequency is measured directly on the speaker contact (the metal-like dish at the bulky end of the device).

By holding down the button in the centre of the PCB, the oscilloscope is observed and it seems that the Dazer generates a tone.

The amplitude is fixed to the voltage input, a few millivolts off the battery that powers the device. That being said, the Dazer can be reverse-engineered in order to construct a more powerful device out of it that will be able to irradiate a large area.

The modifications are very easy to accomplish: the tone generator can be either a Dazer, some other commercial dog-repellent device or an Arduino that can generate tones such as the Arduino Uno, the amplifier has to be able to amplify ultrasounds, that means, it will have to have its frequency response range reaching above and definitely up to at the minimum as the Dazer, whilst the speakers also have to have a frequency range matching the amplifier and the ultrasounds generated by the tone generator.

The tone generator and the amplifier have to more than likely be powered separately, the output from the tone generator is fed into an amplifier that then discharges into an array of speakers or a single speakers depending on the desired setup. Typically, amplifiers are mono, not stereo, but it is possible to find stereo amplifiers, which is great if there are two speakers available. In principle, having two speakers increases the radiation area and achieves a sound gain of , which is not twice as loud, but still good to cover a larger area given the positioning of the speakers.

• the speakers found are a pair of XTC PT-1 Piezo Tweeters, rated at each with a frequency response range of to which is more than sufficient to carry close-to-audible ultrasound,

• an amplifier that advertises at least the full range of the speakers, such as an Arduino amplifier based on TPA3116; the amplifier that was found has a frequency range between and making it great for the project

• either an Arduino with a tone output pin, or reversing the Dazer ultrasound emitter,

• an Arduino decibel-meter as a sensor for sound pollution and with the possibility of automation, perhaps the Gravity Analog Sound Meter released by DFRobot would be suitable

Using a decibel-meter could help in case the ultrasound emitter should be activated automatically when the noise levels go above legal levels. This could be part of an experiment where the noise levels of an area are measured and compared to the noise levels after the usage of this device, with the hopes that through automation and letting the device do its job, the noise levels in the area will decrease automatically.

Given the LRAD results it seems plausible that this should work and also has the extra benefit of leaving the system unattended. Whenever the audio levels go above legal levels, the ultrasound cannon is activated and everyone and everything in the area is irradiated indiscriminately with ultrasounds acting hopefully as a deterrent.

Otherwise, some form of manual control should be added in order to be able to use the LRAD at will when necessary. In any case, the data from the decibelmeter has to be accumulated before-and-after using the device in order to be able to judge the outcomes.

TBA

Mount this puppy on a satellite and place it around Earth's orbit.