Long Distance range finder
Chris Drzewiecki
Posts: 26
Is there a range finder like the Devantech or PING ultrasonic sensor that has a range of 30 meters or more?
Thanks,
Chris
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-Chris
Thanks,
Chris
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-Chris
Comments
it may be limited application, but it's a nice long or shortrange diy sensor project.
http://www.philohome.com/sensors/lasersensor.htm
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-Chris
-M
http://www.acuityresearch.com/products/index.shtml
I have used these guys before in my old job they were great to deal with ...
and yea nice toy's I mean equipment
Thanks,
Chris
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-Chris
Basically mapping the area and looking for changes.
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
this might help or atleast give you so good reading material.
Rich
That being said, there are ultrasonic sensors out there that do better than the ping. Senscomp has an electrostatic ducer that they claim ranges to ~15m when used with their drive electronics (although the PDF specs say both 35' and 15.2m in different places). This is about the best that I have seen in an ultrasonic device.
You'll pretty much be limited to their 600 series "smart sensor" which are the only devices they sell in qtys less than 10 units. They do have some eval kits for their electrostatic products but I didn't look at them... They also offer piezoceramic ducers but I doubt you can drive those hard enough... You could do the math - they generate 125dB at 30cm max and they have a 30 deg beam angle. I'm sure there is an eq to calculate 2 way loss due to spreading and absorption so you could get an idea of what range SPL will drop below the sensitivity of the rcv transducer.
Anyways.
I just ordered a 600 series smart sensor ($65) and their piezo eval kit ($60). They were professional and shipped the units quickly. Still in transit so I can't tell you more.
http://www.senscomp.com/index.html
Thanks,
Chris
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-Chris
Rich
Unlike the "laser" measuring tools you will find at the local home center, these use the laser for rangefinding not just to point where the ultrasonic transducer is pointing.
Yes for only about $400 you can get a laser tape measure http://www.leica.loyola.com/products/disto/disto_lite5.html. I had a chance to use one last week at the setup for one of the FIRST regionals. They are very nice. I believe it has a 200m range with a 3mm resolution! That is about 1 part in 2 to the 16th resolution. The Disto Plus version has a Bluetooth output and +-1.5mm acuracy (for $700 I think).
If money is just pouring from you pockets then perhaps http://www.leica-geosystems.com/metrology/en/ndef/lgs_35316.htm would be of interest to measure a 3D space.
Rick B
...Low power Radar...
Good points
.....Radar tuning circuits are available on the inet, you need to pick a very low "tuning" freq, and cheap to make...
.....Effect range on 300mw is about 60m or so, AND, it's distrubution drops very quickly at the edge of the effective range...
.....Scanning would return... speed, vector (direction relitive to sending unit), distance object.
.....Easy calabration... turn it on, it completes x scans and it "knows" whats stationary within it's effective range.
Pad Points
....Need a Operators lic to operate (if you use too much power, local law inforcemet may get ticked at you)...
....Somewhat easly to be fooled... (ground clutter is an issue unless your scanner is designed to look more down then out)...
....Power hungry device... it's gonna take power to run everything... and it will add up quickly...
I played with a radar calabration unit, and got several police offers rather upset with me. THe unit was tuned to 55 mph single, and I was testing it for dopler shift when police came to visit me. I was told that everyone on the local road down from me was being clocked at 55, in a 35 zone. The senior officer noticed that the stationary cars were also doing 55 mph, which lead them to me. All was cool about 2 hours later, my hardware was shut down. I surrendered the unit to the chief in exchange for not being ticked for "interferance with a Officer"... And my brother kicked my butt for taking is Popular Electronics project out... and getting it taken... Oh well...
But the idea is still there... just don't use the G, K or J bands...
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Just tossing my two bits worth into the bit bucket
KK
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It's either that or Man do I know how to kill a subject... [noparse]:)[/noparse]
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Just tossing my two bits worth into the bit bucket
KK
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What's the resolution they're after (didn't read the whole thread)?
You might find that to get very fine resolution, you need a very small pulse width and a fast Pulse Repitition Frequency.
Also, what's the smallest measurement to be made?· When you're "mini-radar" is transmitting, it can't receive (unless you use a bistatic radar...similar to the pings' transmitter and receiver).....say you have a 2uS pulse.· Radio waves have a speed close to that of light...so 3x10^8 (300,000,000 m/s)....so lets say you have a single antenna that transmits and receives....you have to be able to protect your receiver so that your transmitter doesn't "fire" directly in to it and kill it (we use something called a T/R cell -- when it sees a high powered signal it ionizes some radioactive gas that blocks the signal from going in to the receiver....you could also use a circulator).· So depending on the protection you use, you could have a delay time that results in you being "blind" for a lot longer there by reducing how close in you can see.
For easy math, your receiver is blind for 2uS.· At the speed of light this is distance = velocity * time = 300,000,000 x 2uS = 600meters (someone check my math please).· So, by the time you're pulse has left the transmitter, 2uS has passed.
If you go bistatic (a separate antenna for transmit and receive) then you have to do a really good job of isolating your receiver in order to "see" any reflections while your pulse is firing.· You certainly don't want the transmitter to spuriously affect your receiver....nevertheless, I think you'd still be blind during the "firing" period.
Drop your pulse width to 0.8uS (one mode we run), and your distance decreases to 240meters.· At 1nS you get a distance of 0.3meters (12inches).
I'd love to see someone make this work on the cheap....but me thinks its a lotta work and probably·$$ to get it there.
Another method would be to use a continuous·wave transmitter on·top of a servo·spinning.· Have the receiver facing the opposite direction on the same servo and spin the·[url=mailto:cr@p]cr@p[/url] outta the thing.· Problem there is the sidelobes from your transmitter might cause false echo's...also,·2nd trip echo's would be a problem.
A side note:·NOAA in the·US·runs in the S-band (~2.8Ghz) and we up in Canada use C-band (5.6Ghz).· Currently we're·concerned with foreign wireless router manufacturers as their routers will operate in the C-band and will likely blank out our radar if they're in close....on the flipside, if they get too close, we'll probably obliterate their receivers!·
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Thanks for the info. I was posting from memory of something that happened, and I really hadn't thought of the "complexities" of it.
Now I know why ground radar has a blind spot around it... it's because it's blind during the transmit... duhhhh, I should have thought of that.
Thanks again..
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Just tossing my two bits worth into the bit bucket
KK
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