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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