What is the range of the device?

It can detect an approaching person or animal from approximately 25 meters away.


Do I have to use headphones?

No. The device works with or without headphones.


Can I pair it with my wireless headphones?

Yes! The device is compatible with Bluetooth™ or wired headphones.


Will the device work if it is in my backpack?

Yes! The device is strong enough to detect through walls and doors, so will have no trouble detecting movement through fabric.


Does the device provide 360-degree detection?

No. Place the device facing the direction you want it to monitor.


I don't run. Is the DefendSix device still for me?

Yes! Though designed for runners, the device can improve personal safety for everyone. Place it in a front pocket of your backpack when walking to and from school. Take it with you when you go hiking or even when it's time to walk the dog. DefendSix can be used in almost any situation in which you need to know if you are being approached.


How is radar used in this device?
 

There are many ways RF waves are used to perform Radar functionality from continuous wave transmissions to pulsed tone bursts. Each has different pros and cons with respect to performance, analytical features, cost of hardware, etc. For now, we are gaurding the specifics of some of those aspects as we are evaluating multiple approaches for different hardware revisions, however, if you watch the sneak peak video you will see some hints by the sensor readout graphs showing doppler shifts as Breanna walks toward it and away.


Wont it see everything I move past?


Yes it will, but it will not trip the alarm if those objects are moving away. Since our application utilizes doppler shifts, we can see a difference between an approaching object and a departing object. You may find it easier to consider the common doppler example of a fire truck driving with its siren on. As the truck drives toward you, the alarm has a high pitch. Once it passes, the frequency drops and sounds lower. This phenomenon is called the doppler shift. In addition our device uses a directional antenna so that waves are only sent out in the direction it is facing. This keeps it from seeing objects you are approaching.


What if there are a lot of people moving behind me?

This device is designed to help alert you if someone is approaching you. If you have a lot of people moving around behind you and approaching then it will go off.  Ideally this is more useful for getting your attention at a time that you may not be expecting someone to be behind you.


What kind of false positives will it detect?

That is hard to say at this time due to amount of testing done so far. Radar measurements are usually preffered in many applications because of the physics of the sensing mechanism. With doppler shift, you wont see a departing object give a positive shift that an approaching object would. However, if the device is not properly positioned it may be seeing objects you wouldnt want. For example, if you put the device in your side pocket and walk forward, it will seethe objects in front of you moving towards you. Similarly if you wear it correctly and move backwards, it will see anything behind you as relatively approaching you. A more plausible detection challenge is consistently monitoring an approaching object long enough to say with confidence there is an approaching object. We've had tests where if the user is moving the device irradically, it will cut down on the range of the device.


Will it see dogs chasing me, bikes, cars, birds?
 

Yes, but the range will vary for each of those. Our numbers are based on an average sized person. The sensor isnt measuring "people", but rather its picking up reflections from everything it emits to. Every object will have some respective Radar Cross Section, RCS, that determines how much energy it will reflect back. Cars have bigger radar cross sections than people so they can typically be sensed from farther away. Dogs are smaller than people and will be picked up at shorter ranges. 


Is it safe to have on your body?


Yes, we are very aware of safety precautions for RF devices and we are having our product certified for FCC compliance to ensure our hardware is below the FCC guidelines of 1.6W/kg. Our antenna transmit power is less than your typical cell phone. This is one of the tradeoffs that limit our sensing range.


Will it connect to my bluetooth mp3 player?
 

The Defend Six rev 1 is being made to minimize hardware complexity and power requirements. It can work on its own, as a standalone device using an internal speaker. It can have wired headphones plugged into it for the alert to play on and similarly have a wired input from any mp3 device to route music to be played over the wired headphones. Finally, it can be paired with a smartphone using bluetooth and use an app to recieve alert messages and interupt your phone that is streaming music to wired or wireless headphones. However if your mp3 player cant support apps, it will likely not pair in this first rev. As we optimize the design and verify the basic features, we will introduce more capabilities and other features.


What other applications can this work on?
 

As you might imagine, there are a lot of ways to use this technology in your life. It could be used as a proximity warning device for your home and monitor through walls for traffic. It can be used to let you know when to get out of other peoples way if your walking a hyper dog or are prone to zoning out. It can be used in your car, tent, hotel, etc. to alarm if someone is approaching. And many other activities.


Will this keep me from being a target?

This device was conceived after repeated stories of people being caught off guard. When we started researching and talking with law enforcement we found that awareness is your best defense. Second to that is some basic training on how to protect yourself. Our talks with law enforcement informed us that many assaults can be stopped by removing the element of surprise. This device is a tool to help users do just that. By giving the user a heads up, they are given a chance to proactively assess the situation with time to react.