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GPS chips! ₹ 2000 currency notes !Can it be done at all? Brijesh Kumar, Assistant Professor, IIT Roorkee

GPS chips! ₹ 2000 currency notes !Can it be done at all? Brijesh Kumar, Assistant Professor, IIT Roorkee

GPS chips! ₹ 2000 currency notes !Can it be done at all? Brijesh Kumar, Assistant Professor, IIT Roorkee

It is not possible to do it this way. The “news” that was floating around was that this chip would be based on reflection of power from a satellite. I could not stop laughing when I heard that people are saying that a small “nano” chip will reflect this much power that a satellite will receive and decode it. Not possible.

If this technology were possible, Tata Sky and other DTH companies would be making a killing of selling our viewing data to advertisers. A lot of power is required to send a signal from the satellite to this earth. Similar amount of power is required to send a signal from the earth to the satellite. Let us say a satellite transmits at 50 Watts over the area of India, then the power density on earth would be 15 nanowatts/sq. meter. So, even if the whole Rs. 2,000 note were a “nano-chip”, the power incident on it (if it were perpendicular to the satellite) would be 0.15 nanowatts. If we assume that the nano-chip is 100% reflective, the power transmitted by the chip would be 0.15 nanowatts. Now, this signal has to reach back to the sattellite which is 36,000 km above the earth. Let us assume that the size of the satellite receiver is 10 sq. meter and the nanochip transmits all of its power only in 2*pi solid angle, we get the receiver receiving 1.84 * 10^-25 wattsof power. That is equivalent to one photon (light particle) hitting the receiver every 12 days.

Is it true that ₹ 2000 currency notes in India are embedded with GPS chips? Can it be done at all?

Do you think that there is a detector in this world that can detect a photon every 12 days? But, even if we assume that such a detector can be built. How will you take care of interference of signal from millions of such notes?

If you did not understand, all the above technicalities, the simple version is that it is not possible to do it because the reflected power from such a chip will be very small and it will be very difficult to distinguish the signal from millions of notes. If such a technology was feasible, we would have had satellite phones, not cell phones. Moreover, DTH communication would not have been one way, but a two way communication. Right now, the DTH communication is one way. Your set top box can only receive information from the satellite, but it cannot send any signal back to the satellite. That is why, the customer care people ask you to keep your set top box on when changing the package. They have no knowledge of your set top box being on or off. If they send a signal and your set top box is not on at that time, the set top box will not receive the information and if you turn on your set top box later, the set top box does not know about the change in package, so it will keep on showing you the previous package.

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Brijesh Kumar, Assistant Professor, IIT Roorkee
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