jtd wrote:
U have mis understood. The Central server is not connected in any way to the rails - atleast initially. After the user hears the info, particularly the url "prabhedevi c" (alongwith instructions abt local landmarks) he will enter this url, http://www.mylocation.org/mumbai/prabhadevi/c/ MYDESTINATION in HIS preferred device, ideally a gprs enabld phone (possibly midp compliant).
A VI user cannot be expected to type out a long url. However, that can be resolved with speech commands. The above system is fine but will be service provider (SP) dependent and will not be available to subscribers of other SPs. For simple location information we can altogether do away with electronic railings and power requirements and go for braille embossed ones with a flat plate welded on, to handle 5 to 10 lines of a page. The entire electronics is now mobile network based. What about fringe areas where network is still a problem? How will the SPs interact with each other and share resources?
Why are we looking at solar panels and batteries? Like street lights, these could be powered by the municipal electricity or traffic signal posts. Maybe a battery backup for power breakdowns.
Because it will cost Rs.10000/- per meter of digging and aquaint you serfs with all the Royalnesses in the fiefdom of BMC. As it is they might cast a spell on you and make your project into a frog.
Anyway its not going to be an individual local digging. When it is implemented across an entire city, many Govt. agencies will be involved. It will need blessings of the top ministers anyway.
What about a cheap laser diode pumping high density packets into a receiver. The rail has a hollow docking port to simply place the receiver's probe into it for a few seconds, so no shake problem. A beep will tell the user that data is transferred. This will make it cheap and will also function as the user position aligner.
Forget about finding a hole in a high footfall area. The laser diode will cost more than the entire fm and bluetooth setup put together. even if u used el cheapo infrared u are still mandating an esoteric device for the end user.
It need not be hollow. It can be convex, like a bump on the inner side of the rail and the reading device concave. The devices need not be curved or have to meet, like the bar code readers in malls. The laser diode Tx. and Rx. unit is used in optical scroll mice for minute traction information and the entire mouse costs less than Rs. 400/-. We are making a device to help a particular group of people with special needs. Let the regular ones log into mumbainfo.com on their mobiles using gprs. The advantage of optical format is that we are simply breaking the wire and converting direct digital signals into light and back to digital. No modulation or demodulation. No RF interference. No license. Simply push a tar.bz package into the user's device and the user issues voice commands to ask questions or clicks a Yes button when a question on his destination comes up in the sequence of voice prompts and gets voice replies from the machine on how to get there. As simple as that.
For power, if we can get a low power laser diode Tx. circuit, then we can experiment on the use of a split transformer where the primary and its core is in the hand held unit and the secondary and its core is in the fixed Tx. unit. When the two cores meet, a high frequency oscillation in the primary ferrite core, passes the electromagnetic field into the secondary core to generate just the power required to transfer the zipped package. I recollect, the EHT transformer of the B/W television runs on the 15625 Hz. horizontal frequency and 4 to 5 turns of ordinary wire around its ferrite core can generate voltage for the CRT's filament.
Regards,
Rony.
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