Milp
From Www.india-gii.org
A 2$ phone, no running costs
You heard it here first :-)
The 2$ device consists of a mike, an integrated circuit “chip”, a laser pointer, a battery, a button. Let us, for now, call it a milp. To use it, you must carry a FM radio receiver, which you probably already own, so that doesn’t count towards our budget. You are a farmer, and you have just broken your leg in the woods. It is late at night, and there is nobody within shouting distance. What do you do?
Your FM radio is tuned to your local chat station, no problem there. It is playing hit music, interspersed with kids chatting, asking for help with their homework. You just hold the mike of your milp to the radio, point the laser towards the canopy under the water tower and hit the button. The operator is thankfully not asleep. She sees your laser flashing, points a flashlight at you, so you know and everyone else around, that you have been spotted. The operator now redirects her tripod, points her camera at you, and zooms in, with your laser pointer in the cross-hairs. She then tightens the tripod in position and presses the trigger of the camera. Suddenly, you have that irritating high-pitched “feedback” sound on the radio. This tells you, that you are on the air, and everyone in the village has been woken up, and can hear you.
You turn down your radio, point your mike at your face, and start speaking. Before you pass out, you hear reassuring words from your wife on the radio, who has used her milp, to tell you that help is on the way.
The milp does a very simple thing. It modulates the optical output of a laser pointer in some way, using the mike output as a modulating signal.
At some high point in the village, one which has line of sight with its customer base, we have the operator with her receiver. It consists of a camera with a zoom lens, with a photo-diode or equivalent at its focus. The electronic signal this produces is demodulated by a chip, and fed to a FM transmitter. This transmitter plays music, unless someone attracts the attention of the operator, who then points her camera at his flashing milp, thus bringing its proud owner on the air.
This combination of devices is nothing but a cordless microphone, which uses optics to bridge distance, instead of radio frequency waves. Why? Because you can focus light much better than you can radio waves, so your “antenna” is smaller and cheaper, your power requirements lower. This region of the spectrum is unregulated around the world, so your device can be legally used anywhere without a license.
Why isn’t anyone using this already? Well, lots of wireless optical communication systems are in use, but not in numbers. Why not? In the West, because this device needs very sophisticated aiming hardware, for slight motion or breeze can throw the light beam off the receiver. Such hardware is expensive.
In developing countries, as I have pointed out, you can get a stereoscopic robot with fine mechanical control abilities quite cheap: we call it a human being.
What this system provides us, is a free audio chat channel, in which the entire village can participate. Your only running expenses are very little electricity, and operator salary, if you can’t find volunteers to do it.
Your capital cost is two dollars per villager for the milp, a common small FM transmitter and some optical and electronic hardware at the receiver, say $50 once for the entire village.
Communications today surely doesn’t come cheaper than that!
Arun
