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Is GPS data signed and timestamped by the satellite?
No, GPS is not signed. I think there may be in future some signed signals. Maybe it is used on military part of GPS.
GPS spoofing is a well know problem, and problems are usually "solved" in hardware. If signal strength on some satellites changes quickly: do no trust it. Multiple antenna (on extreme of lorry/ship) and comparing strength of signal helps. Some directional antenna helps to know that signal expected from a satellite come from where it is expected. And often some gyroscope, compass, or and tracking, to check plausibility of data.
Note: fishing boat uses it to decoy own position (in protected area/economic exclusive zones). They causes a lot of troubles to other ships and boats (and sometime to ground equipment).
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Inspired by a recent Kickstarter campaign: http://www.kickstarter.com/projects/dominikmazur/camfind-a-mobile-visual-search-app?ref=category
The app uses the mobile camera to take a picture and identify virtually any object. Snapping a photo of a movie poster will recognize the movie and pull up results on the web for you about it, taking a picture of a product will show you websites that product is available for sale on.
My question is, is this realistic? I find it very intriguing, but it object detection really that simple? I'm interested in some feedback regarding resources to help someone get started in learning about this topic.
Computer vision and Pattern Recognition is not easy at all. It's an entire field related to Artificial Intelligence. It is, however, relatively straightforward to understand at a high level though. There is NO WAY they are doing this all on the client. The phones just aren't fast enough, and do not have even close to enough storage space.
What they are most likely doing is sending the image to their servers, then use some kind of nearest neighbour approximation on the image, and run the result through a decision tree look-up in a massive database on images which all have some hash. This will give a close match to an image they have (assuming they have A LOT of images in there database), even if only part of the image matches. Then, using the hash, they look up some other information about that image to send to the device.
Hope that Helps!
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I know this may not be the correct place to post this, but how do I know if a certain chip is dead? My friend has this Atmega32 and he seems to have connected it to 9V battery for a minute maybe.. He's unsure about it, but I think the chip is damaged, So, is there any way to check if that is the case?
You have read the datasheet right! - the Electrical Characteristics section.
Even if it appears to work, parts of it may have failed, or stressed to the point that they will fail soon. Any necessary over-voltage protection should ideally be designed into your circuit's power-supply design.
Does it program? Do the I/O ports work? Did it emit magic smoke?
Likely, its dead.
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I'm new with zigbee i need you to help me learn about it and know how to implement an embedded system using it
thanks in advance
One good place to look is on the Digi site. They have several products to help you, including embedded development kits.
If you want to go Open Source, look at Source Forge. They have some open source stacks. I have not used any of them, so I cannot comment beyond knowing that they exist.
Depending on your needs, you might want to just look at XBee, which is a subset of zigbee. There are some nice development tools for XBee. I have used an XBee expansion shield with the .net micro framework and boards provided by TinyCLR to do a wireless prototype.
Creating a zigbee stack on your own would be a fairly large task, so only you can determine if there is ROI in doing so. I would be more inclined to buy it in.
Get a ZigBee Starter Kit. Lots of vendors provide one; gust Google that exact phrase.
For example: AVR 8-Bit RISC - IEEE 802.15.4/ZigBee - Tools
Or you can ZigBee on a PIC/Microchip at very low cost. http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2112
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My teenage step-daughter is autistic, and tends to want to run away from school, leisure-club and sometimes even from home. This is very bad for her safety, and a great concern for us.
I am looking for a way to track her, so we can find her again when she runs away.
Here is my ideal (possibly unrealistic) scenario:
Tiny GPS device with GSM/GPRS
Can be woken up via sms when needed (so battery will last longer)
When activated, spins up GPS + Data connection and starts hitting a predefined URL with device ID and long+lat every 15 seconds
Battery life 7 days on standby (ie. when never activated)
Can be disabled put back to sleep via sms
I have googled and researched this for a while, but have yet to find a device that fits these requirements.
The solution could also be a mobile phone of some sort, that I can lock down.
You could do most of that with any Android handset using prey
http://preyproject.com/blog/2010/01/prey-arrives-on-mobiles-android-version-available
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How do you connect these to your computer? Which one would be easier to burn?
The information you seek can be found by comparing the data sheets: AT89C51, AT89S51, however you will see in this first link that it states:
Not recommended for new designs. Use AT89S51.
So that probably makes your last question irrelevant, you should use the AT89S51 regardless.
With regard to your second question (which I interpret as "connecting to a development host"), I suggest that you use an off-the-shelf development board unless you have the means and skill to produce your own. In-system programming can be achieved through the UART (there's an app. note in the link above), so you'll need a PC with an RS-232 serial interface and a NULL-Modem cable (the latter may come with the board). If you do not have a serial port on your PC, get a USB serial port adapter.
Obviously you need the development tools; at leas a compiler, and for debugging you'd benefit from an emulator; again the link above has references to tools.
Overall; read the manufacturer's documentation is the answer to all your questions! ;-)