Hi all!
I'm a newbie to this site and am looking for some help.
i am about to start my third year in electronics and i have to submit a project brief when i get back.
My project must incorporate at least the following :
a member of the 8051 family μC and an LCD display. it must also have a military theme.
My initial plan is to submit a project on: small scale radar using ultrasonic TX/RX to detect movement within a 20 meter range, display the position on a matrix display and maybe a distance to the target on the LCD display.
The size of the target would be that of an average man and the environment would be a woodland clearing.
Would this be possible? any help or even other project ideas would be greatly appreciated!
thank you!!

 

First thing, if you are using ultrasound, it is SONAR, not RADAR.
Most hobby ultrasound projects don't have that range, but if you used a higher power transmitter it might be possible. You would need 2 spaced out recievers to get direction and distance in a horizontal plane, and probably a good deal of experementation.

 

Since it will be used in a woodland area, I do not know if Ultrasound would be the best thing to use since you will get a lot of echo feedback from the surroundings and may not get an accurate reading of a person in the same area....

Using something like a Laser radar (or Lidar) would probably be better.

LIDAR (Light Detection And Ranging) is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The prevalent method to determine distance to an object or surface is to use laser pulses. Like the similar radar technology, which uses radio waves, the range to an object is determined by measuring the time delay between transmission of a pulse and detection of the reflected signal. LIDAR technology has application in Geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, remote sensing and atmospheric physics.[1] Applications of LIDAR include ALSM (Airborne Laser Swath Mapping), laser altimetry or LIDAR Contour Mapping. The acronym LADAR (Laser Detection and Ranging) is often used in military contexts. The term "laser radar" is also in use even though LIDAR does not employ microwaves or radio waves, which is definitional to radar.

B. Morse

 

thanks for the help guys,
i think the LADAR could be the way to go alright, although i was thinking that a good way of reducing unwanted feedback noise would be to include a time delay into received signals meaning that it will only give info on moving objects.
anyway you've definently given me something to work with.
cheers!!

 

If you want to use ultrasonics (which is something I played with a few years ago) and you want to increase the range try making a directional tube to mount the sensors in. We created some aluminium cones out of solid blocks. They were about 30mm wide and about 20mm long with a hole at the back large enough for the sensor and then tapering out forming a conical collector. Worked a treat.

 

PS. Always think outside the square. The strangest ideas are sometimes the best.

 

thanks thats a great idea! also i was wondering does anyone know the general cost of suitable sensors. i've been looking around and can only find fairly expensive sensors. i hope that i'm just looking in the wrong places!!

 

You could try Maplins. We have a similar store here in Australia and they sell TX and RX pair for about $10.

 

thanks, found some there. just a quick question tho, does the distance a set of ultrasonic sensors work depend on the sensors or the circuitry they are connected to. could i use a basic set and increase the power input to them to increase their range?

 

Hi all, just an update for anyone who may be interested.
found this site which explains more about ultrasonic sensors and their traits:http://www.sensorsmag.com/sensors/a...-sensor-proximity-or-distance-measurement-825
in a nut shell for larger distance measurement you need to work in lower frequencies, i.e 40Khz sensor could work up to 30.2 feet or roughly 10 meters.
still unsure weather or not it can be improved upon with circuitry tho..
anyway thanks for the help! keep on truckin!!

 

Of course, the LIDAR pinging may be a dead giveaway of your position. How about a passive IR sensor -- such as used in burglar alarms -- to do the scanning, then once you've found the motion, ping the limited area to get the distance, DOT, etc. This may also have the advantage of using less energy, although this is just a wild-eyed guess.

--Rich

 

Of course, the LIDAR pinging may be a dead giveaway of your position. How about a passive IR sensor -- such as used in burglar alarms -- to do the scanning, then once you've found the motion, ping the limited area to get the distance, DOT, etc. This may also have the advantage of using less energy, although this is just a wild-eyed guess.

--Rich

There are IR based Laser that can be used for a LIDAR/LADAR....

and PIR sensors used in burglar alarms are not very directional, and if used in a woodland area, outdoors in the winter, a PIR sensor will not detect movement since these sensors are designed to be triggered by heat given off by humans.....

WiKi:

A Passive InfraRed sensor (PIR sensor) is an electronic device that measures infrared (IR) light radiating from objects in its field of view. PIR sensors are often used in the construction of PIR-based motion detectors (see below). Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall.[1]

B. Morse

 

You might think about cutting the tube to lengths that are resonant to the frequencies you're using. Basic physics.

 

There are IR based Laser that can be used for a LIDAR/LADAR....

and PIR sensors used in burglar alarms are not very directional, and if used in a woodland area, outdoors in the winter, a PIR sensor will not detect movement since these sensors are designed to be triggered by heat given off by humans.....
B. Morse

If you break open a PIR -- at least the ones we make -- you'll see a series of reflectors bouncing the IR into the sensor. The sensor is "de-directionalized" by the reflectors. In fact, the installer is supplied with black tape so he can customize the area of detection of the PIR.

The sensors can be quite sensitive: I worked in a place where cats walking around would trip the sensor. They operate on temperature change, not on how big the "blob" is.

Many years ago (the early 80's?) Steve Ciarcia used a Radio Shack "Solar Cigarette Lighter" and an IR detector to scan the woods around his home, looking for burglars.

--Rich

 

What you are trying to do with your movement sensor is actually going to be looking for doppler shift in the frequency of your sound, the same way that some bats, whales, dolphons and insects can.

A target approaching is going to increase frequency or blue shift if you were using light. A target that is retreating from you will decrease frequency or redshift.
So basically you want to create an FM type detection circuit. FM has a useful feature that it tends to lock onto the strongest signal so if two targets are at the same distance and the same size you should read which one is moving faster. If one of the targets is bigger like a man versus a mouse you will get a signal from the man. If one target is closer it will be the one detected.

You will also want to look at phased array technology. That will be a good use for the micro controller and should not overwhelm it at sound frequencies with no more than maybe 6 elements in your array. If you worked with interferometry using 2 to 6 actual sensors in each sensing element, you could improve your resolution by several magnitudes and really get some useful information from your device.

This would probalby put you way over budget and stretch your development schedule - just like a real Military Tech Project.

 

ok so here is what i have so far. i have uploaded a simple block diagram of how i visualize it is going...
i have a sensor array (maybe five sensor pairs) being feed from a demultiplexer so as only one pair operate at a time.
the signal being feed in is from a simple FM super het circuit.
the μC monitors the output from the demodulator and compares it to values in a lookup table.
the values found from the look up table give good approximations for location and distances. these get feed to the LCD and LED matrix.
the LCD outputs a distance in meters and the matrix displays a visual representation of the target location...
think i'm on the right track!

 

I suggest you pulse freq modulate the indicator in your LCD. For example flash the top half of the target indicator to indicate retreat with speed of flashing indicating speed. Flash the bottom part half if target is approaching and again flash faster if they are moving fast.

Yes definitely indicate which way the target is moving and how fast.

 

do you mean include an indication to the direction target is moving?

 

I also suggest you set different target levels for your project, with the first being a motion monitoring system that might be able to just detect moving targets and sound a silent alarm. Picket sensors - aim for disposable/reusable - that a spec force recon team might use to secure their perimeter.

Once you have that basic project done you can keep going and build your full scanner.

I am not sure how you will implement the PIC but you could add a logging function that allows the team to leave the picket sensor behind and check it later.

It could also trigger other devices like vid cameras for audio video recording and a power down hide mode in case of too close an approach - possibly enemies using RF detection gear.

It could also be used as a robot sensor or to trigger claymores.

 

ya that is some good advice. i must sit down and structure it properly. set targets and goals, and if i meet them to then move the bar a bit more to achieve a better project.
at the moment i am gathering facts to see if would be an acceptable project to submit to the lecturer in-charge of project selection.
we each get to put in a report for one project and if refused the lecturer selects a project for us.
he has previously refused proposals including 1. G.P.S because of the U.S ability to alter readings we recieve for tacticle reasons, 2. LASER. i'm not sure why he doesn't like LASER projects.