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Homemade Radar

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spook051484

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Hi I was wondering if someone could tell me of a way to (using your computer) make a "radar" that could be used to monitor ground level activity. The reason why I don't want a sensor is that I would be using this device on a very large open area, also I would want to monitor the area so an alarm(or a little blinking light ect.) going off when someone moves into that area wouldn't be exactly what I want, I thought of using my web camera but the usb cord isn't long enough for me to have it connected to my computer and still be able to put it on my desk. :roll: So using that is sorta out of the question. well I appreciat you help :D
 

tansis

New Member
Mil spec radar systems can detect an object as small as a person at a distance of 5km in open terrian from the background signal clutter, but you would not want to be wearing contact lenses within 10 meters!

How big an area are you trying to guard?

Ultrasonics (in Air) are good up to around 10 meters (30 feet)
Infra Red (pyrolectric) sensors are better, but good optics are an essential part of any design.
Microwave - Doppler Shift , not stictly radar ( no range information ) but uses the difference in phase between the transmitted and recieved signal to determine direction of movement . Here in the uk contractors working on the roads use temporary traffic lights as do some pedestrian crossings these use a simple system ( little more than a couple of flip-flops and an amplifier ) based upon doppler shift using the Plessy GDSMII microwave block. Detection range is governed by return signal strength, a 40 ton truck gives a better echo than a motorbike, exellent results at 150 feet with good shaped horn antenna ( at distances of less than 20 feet with the doppler detection set right the movement of a targets rib-cage is detectable)
 

spook051484

New Member
I would say that I would be watching over an area of about 40 feet(I would only need to cover 180 degrees though) I would need it to be able to at the very least guest-a-mate the distance of the object (just to give me a general idea)

The millitary design sounds interesting, how would it work? Just out of curiosity what happens if you are wearing contacts and you are close to one of those?

The reason behind my question is becuase a while ago I was at Walmart with my brother (looking for wedding gifts) and we found these "toy" spy cameras and listening devices and such (one of these were tracking devices!)

These probably don't work very well, but it got me thinking if some company can make a product that only cost $15 that can track a radio signal than what is to stop me from doing something similar? Of course I would rather work on a radar system isntead.
 

tansis

New Member
To be honest you could probably get by with pyrolectric infra red sensors near the perimeter of the detection threshold using an rf module link to overcome the distance problem. There is a product on the gadget shop website that works in this manner. If the length of the perimeter is not to great a capacitive proximity senosr(s) could be used to detect a person crossing or near the "fence" line.

Scanning I/R sensors are one solution to obtaining a range to target but this involves building hardware similiar to that used in heat seeking missiles and the like.
( Oscillating or Rotating Mirror in front of PIR sensor ) similair to the sort of thing used in simple laser displays

Full blown radar requires very high speed counters to implement, the gear is out there but VERY expensive and none of the commercial maufacturers are interested in talking to private individuals on a hobby electronics basis

A heat seeking "robot" based on an an off road R/C model car carrying a paint grenade might be interesting though, you could not outrun it, you will not see it coming, you might hear it, but by then it would be to late!


DO NOT DO THIS
IT WILL BE FATAL
NOT EVEN AS A JOKE FOR A "JACKASS" VIDEO
I (bleep)THEE NOT
IF YOU THINK I AM KIDDING , PUT A HENS EGG IN A MICROWAVE FOR FIVE MINUTES AT FULL POWER!

(CLEAN MICROWAVE OVEN AFTERWARDS OR MOTHER WILL KILL YOU)

If I bypassed the door switch on a microwave oven and invited some poor sap to put his head in while I switched it on...

THE CORONERS / C.S.I. REPORT WOULD GO SOMETHING LIKE THIS:

The the water in the cranium vapourised and forced the the brain tissue out of the skull via the optic nerve, ear canal and the base of the skull where the spinal cord enters. :shock:

Would rather go feet first into a bark chipper!

And your contact lenses would be be stuck to the cornea of the eye, in normal life they "float" in place using the surface tension.This fluid qiuckly boils away under certain conditions , not just microwave RF but ArcWelding as well.
 
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