On Tuesday 05 September 2006 07:05 pm, Rony wrote:
krishnakant Mane wrote:
hi, yes, central server is the way to go this is what I was advicing from quite some time.
Central server makes use of a computer and needs underground wiring or expensive wireless network. Plus a power consumption of over 300 watts. Local tiny broadcaster circuits are cost effective and maintainence free. Install and forget. The choice is now FM or WLAN or Bluetooth as per Dinesh's suggestion.
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). This will hit the server hosting mylocation.org and serve an ogg (mp3??) file which will play on his phone. No wiring, no cable. Wlan / bluetooth is out because of price associated with a relatively big processor and protocol stack.
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.
We also need to check out power consumptions of all the 3 devices mentioned above for a TX. range of 5 feet only, not 100 feet.
less than a watt for fm+mp3 player. 7 to 8 watts for Wlan. 3+ watts for bluetooth - u cant just stick in a blutooth with two wires u have to process events from the bluetooth device and write out a digital stream to it's input, so while the bluetooth device itself will be less tahn 500mw the rest of the electronics to drive it will suck power.
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.