Ground Phase ..Child Repossession tool/unit/watch/thing/ . . . .
Bits
Posts: 414
I am going to make this for my nephew who lives near water and busy cities. Often walking in crowds he gets lost.
I have an idea. Its a watch or bracelet that comes in three versions men, women and child. The idea would consist of an electronic circuit used to set up ring like parameters like a "wrestling rink". The circuits would be networked to all 3 watches. Each watch will send a signal that contains child's location, heat, cold, speed, sound, time.
I want to use the propeller as the face on the watch.
Wristband would be square segments. Each segment contains a circuit or 2
What issues do you think will stop my design? Any other ideas to build in to the design?
Feedback welcome
I have an idea. Its a watch or bracelet that comes in three versions men, women and child. The idea would consist of an electronic circuit used to set up ring like parameters like a "wrestling rink". The circuits would be networked to all 3 watches. Each watch will send a signal that contains child's location, heat, cold, speed, sound, time.
I want to use the propeller as the face on the watch.
Wristband would be square segments. Each segment contains a circuit or 2
What issues do you think will stop my design? Any other ideas to build in to the design?
Feedback welcome
Comments
What are the smallest battery out there? At least the size of a AAA case but with more power.
Nice to see your back.
If your thinking of using beacon signal amplitude to estimate distance between bracelets, I don't think this will work well. The absolute signal transmit and reception losses vary greatly.
GPS location communication would work much better and not be subject to signal losses until full dropout.
How about the equivalent of the dog shock collar perimeter fencing. A buried wire with a 100KHz signal which the collar senses when it gets to close.
Duane J
http://www.amberalertgps.com/
Thanks for the advice but I want to be mobile with this too.
ElectricAye
That device sounds impressive - ill be searching for it here in a few minutes
I was thinking that the watches would be linked to each other so that no other equipment is needed.
Dad has his watch on and kid has one too, when kids watch is to far away dads will alarm. In this scenario the watch would be transmitting a signal that can only transmit say 100 yards. Once the signal degrades due to the distance increasing, dads watch will sound an alarm. Other features could be added as well but this would consume more power and since I want this device to be small I need to be power wise.
Has to be mobile, small and long lasting.
Maybe something like an Xbee? Those signals are line-of-sight and are reduced by obstacles like walls and human bodies. A prototype would be looking somewhat bulky, but perhaps you could get it down to size. But I bet they hog power.
Although it sounds like you are wanting to build your own device/s here's a link to the Loc8tor website that might give you ideas
http://www.loc8tor.com/uk/store?gclid=CIXD2pqYl7ICFeTLtAodQU4AXA
Attachment not found.
As I understand it so far:
R1 and C3 bias the transistor. R1 is a pull up and C3 blocks DC only allowing AC to pass to the base of the transistor.
C1 and L1 make the tank circuit, I assume varying the frequency by varying C1, hence Frequency modulation.
C2 I cant wrap my head around, is it used for propagating the energy towards the antenna?
Please help me out and be prepared to argue
>baluns provide impedance transformation in addition to conversion between balanced and unbalanced signal modes.
There are a lot of places kids go where GPS wouldn't work, the beacon would be pretty cool!
It's a great idea but I am not sure something like this is practical or even possible without some infrastructure along the lines of the cellular network, however here are my ideas.
Battery/watchband: For the battery I recall reading (possibly a post here) about a lithium battery made from thin flexible layers that could be made into a band.
Locating: GPS is the obvious one, but it could be backed up by using cellular towers to triangulate location based on signal strength.
Communications: Wristband to wristband (hereafter "band")could be a form of Bluetooth on steroids used to send a data squirt containing position and status info once per time period.
User interface: A simple on off for the child band. On when the band is clasped around the wrist, off otherwise. Something a bit larger for the monitoring band, perhaps a small lcd screen with touch panel for displaying relative location and status information.
Radio is going to create a lot of problems for reasons others have mentioned; probably much easier to go with Zigbee modules rather than roll your own. But you might also want to think about 49KHz ultrasonic sound. Sound gets blocked but then blockage for X seconds is an alarm condition. You can get reasonable range but much better you can use turnaround time to estimate distance. That won't work with radio because the distances are so short that you would need some fairly serious tech to measure turnaround times.
For RF VHF and lower frequencies are more practical if you want to use signal strength to estimate distance because they're less affected by say a crowd of water-bearing human bodies. But those need longer antennas than microwaves (maybe a good reason for that pendant with an antenna in the neck piece). 2 GHz is especially bad because that band is license-free because it was reserved for microwave ovens, and it was picked for that use because researchers determined that 2 GHz was the frequency most efficiently absorbed by water.
Welcome home Bits, nice to see you back and stirring again.
Consider a pulse coded CW transmit function in a wristwatch or bracelet format for the caregiver/hab worker. maybe a simple tap to set range and led interface to confirm w/ output power. On the child side a receiver set up to react in the absence of this coded signal. If the receiver looses contact for x seconds/minutes, have it contact via blueooth a cellphone in a secure pocket on the child to dial up and start transmitting GPS location code so that the caregiver or if need be the authorities can track the person. The number called can open an app such as google maps to translate the GPS into realtime positioning on a map.
Just a thought with a bit of personal interest in this type of application.
Frank
I should have said AC component, since realising my mistake and looking again at the circuit diagram I realised that the circuit may not work as intended as the small cappy would ground any AC signal that should be heading for the aerial, am I correct in thinking so?
Good to see you around!
The early days of bio-telemetry saw a lot of clever circuits come into being. A different approach was necessary due to the need to make them very small, and to run a long time on a small battery, and to transmit not only presence but also parameters such as body temperature. A classic reference is Bio-Medical Telemetry: Sensing and Transmitting Biological Information from Animals and Man by Stuart MacKay. It came out in the days before integrated circuits, so it has a lot of explanation of simple circuits such as the one in your post #10. I was shocked to see how much $$ that book is bringing on ebay, but any college engineering or biology library should have a copy.
http://www.google.com/imgres?imgurl=http://espimages.biz/2149/I/450/lrgsuresteps1.gif&imgrefurl=http://www.generalforum.com/parenting/have-kids-leash-67077-page8.html&h=500&w=600&sz=54&tbnid=yMggPw81TPGqMM:&tbnh=90&tbnw=108&prev=/search%3Fq%3Dchild's%2Bharness%2Bimage%26tbm%3Disch%26tbo%3Du&zoom=1&q=child's+harness+image&usg=__10kNx1ZPHCPxU2Oh1OGMMd-4TIQ=&sa=X&ei=k05GUNX2B4rriwLQv4CQBg&ved=0CEIQ9QEwCg&dur=9172
Immediate tactile feedback of child presence, no batteries, no poor transmission/reception.
A lot of dirty looks though!!!
Dirty looks are generally born of ignorance and caluosness on the part of many who will not realize that that may be the only way a child with special needs may ever be able to be out in public for any number of reasons. Some are runners, others have zero awareness of the hazards of the environment outside the home. Others may have a parent with a disability that will not permit them to safely keep up with a child who is still learning that sometimes limits are needed. I used to think poorly of these devices too. I know better now.........
/RANT
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