During my latest exploration trip to D.C. one of the experiences that stuck with me was their smart card and how it works. I had a great time touring the city; click here for more about the trip itself. I stayed in a hotel in Maryland and drove to the Metro parking garage to park my car and took the train into the city. As with any city where I'm taking public transit around to explore the area, I always get their transit card and purchase their equivalent of a day pass.
The smartrip card is a transit pass that instead of swiping to get through the turn-style, you have to place it on the RFID/NFC reader in order to open the gates. Since it's a tap-to-pay system, I'll be using this example to illustrate how it works.
I was always fascinated and interested in exactly how this system works because no matter how long I've been in the tech field, I still get excited over being able to place a card, badge, phone app onto a device and watching something happen. I'll briefly go into how this particular technology works and how it contributes to the ease and convenience of every day activities.
 |
Transit card for D.C. Metro |
RFID- Stands for Radio Frequency Identification. This involves two devices that "communicate" with each other using coils (serves as antennae), the magnetic field of those two devices, that conducts the transfer of information wirelessly once within range of that magnetic field; and a small data-filled chip, whose information is transferred as a result of the first two components interacting with each other.
NFC- Stands for Near Field Communication. While this is a type of RFID, the benefit to this is since it only uses HF (high frequency) to transfer data you have to be closer to the magnetic reader to trigger that wireless data transfer.
RFID uses a range of both LF (low frequency) and HF (high frequency) during it's wireless energy transfer any data that is present is also transmitted and carried over. NFC only uses HF to transfer data, and tends to be more secure as there is a limit to the amount of data that's transmitted, (it only has room for a small string of characters). While RFID tends to spit out all of it's data more "carelessly", when within range of the readers' magnetic field.
Here's how this all comes together; the smartrip card has a chip in it that has the monetary balance that was paid to purchase the card, as the data on it. That card is then placed directly on the RFID reader, and similar to how an RFID tag and RFID reader interact once both components enter each other's magnetic field; the data on the card is transmitted wirelessly and the turnstyle gates open up, allowing entry.
This same process works for phones, digital business cards, apps etc. that also use NFC beaming and even bluetooth technology to transmit data.
It's really a cool sight to see, how technology has advanced to the point where you're able to send a document from your phone to one of your friends, by simply tapping the back of your phone to theirs.
Or even better yet, use bluetooth to connect to their phone and transfer documents to them from across the room. Prime example of this is Apple's "Airdrop" feature.
 |
Transit Card for L.A. Metro |
The Smartrip card data is managed by the software used on the machines that you purchase the cards from. That software has a transaction ledger of the balances on the card and "writes" that data to the chip on the card. When the card is used, that data is transmitted to another device which utilized the same software to record the remaining balance of how much is used.This process repeats when the card is refilled.
While you can find a brief explanation of how RFID and NFC works here, let me know your thoughts below on whether this technology has helped to improve your life or if you feel that's it's not secure enough. Comment below.
