Bicycle detector

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Niku
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Bicycle detector

Post by Niku » Tue May 08, 2007 8:56 am

I'm looking for a device that I can mount on the back of my bicycle for the purpose of alerting me of bicycles approaching from the rear. The device would have to be battery operated, and I would want it to be able to detect bicycles from 20 to 30 feet behind me. What else? Well, I wouldn't want to spend more than one hundred dollars. Also, it would be nice to be able to focus the beam more narrowly than the ninety degrees I have been reading about. That's about it. Is there anything like this available?

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Chris Smith
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Post by Chris Smith » Tue May 08, 2007 9:23 am

They have kits and whole Radar units using ultra sonics.

Start there.

Niku
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Post by Niku » Tue May 08, 2007 11:06 am

Chris Smith wrote:They have kits and whole Radar units using ultra sonics.

Start there.
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Thanks, but where? Where do I look for such things? I might add that this is not my first posting on the subject. I have tried electronics firms, and bicycle accessory websites, etc. I have tried stores, manufacturers, and clubs. I have sent at least 30 messages on this subject asking for information on ultrasonic, ultrasound, radar, infra red, and I have asked about motion detectors, proximity devices, and any other logical sounding descriptions. Some people have said that they have heard of such a device, but they can't remember where. Others have suggested a mirror, which I have.

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Chris Smith
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Post by Chris Smith » Tue May 08, 2007 12:15 pm


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haklesup
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Post by haklesup » Tue May 08, 2007 12:51 pm

There are many ways to detect movement when the detector is stationary but for a moving target and detector you would need to discriminate between objects that are receeding, advancing and stationary.

That takes some decent processing power for a reliable warning beep regardless of if it is radar or ultrasonic. Only in the last few years have such systems even become available for cars and only on premium models for high option prices.

There was something here but I didn't read the whole page
http://www.halfbakery.com/idea/Bicycle_ ... 0detection

One idea on that page was for a theremin like device, funny noises when an object gets close. Could be maddening to use.

If I were to try this, I might try a Microwave proximity detector. If you didn't ride too close to bushes or parked cars it might provide adequate sensitivity to alert when a moving object enters your bubble. The detectors are dirt cheap and easy to find. You can make blinders out of metal sheets.

Given the size of cameras and video displays, a rear view cam is a practical reality. With some DSP processing of the video image, one could lock onto something like the reflectors on the pedals or front and estimate the other bikes path WRT your own.

I can think of several ways to start developing such a device but to my knowledge nothing turnkey exists yet. A mirror and not using headphones are really the best options for awareness AFAIK.

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Chris Smith
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Post by Chris Smith » Tue May 08, 2007 1:30 pm

I saw a show the other day about these locating systems.

They made two different types of recognizing hardware, while both made the beep change into a higher pitch as they got nearer to the object.

When the object was far, the beeps were quite slow and unusual.

As things got nearer the pitch and the clicks sped up.

Add in some directional cones to skirt out unwanted objects and Im sure you should be able to hear the beep change as riders come near the angle that your trying to discriminate with.

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jwax
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Post by jwax » Tue May 08, 2007 5:28 pm

Haklesup suggested a good one- video. Rear view systems are cheap- they're made for RV's but could easily be modified. Plus. theres video software that contains motion detection- you select the camera area you want it to "beep" at.

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