A recent article on Forbes alleges that New York is using EZ Pass tags to monitor and track citizens, proven by way of a hacked moo-cow experiment. Is there more to this story than the cute little cow can tell us?
Government Monitoring Via EZ-Pass: Big Brother or Traffic Control?
It’s true; you are being monitored as you drive the streets of New York City. But how else can is it possible to move 8 million people and 55 million visitors through the city without traffic jams and gridlock?
This not-so-insidious vehicle tracking results in a more efficient system to get you from point A to B, or give emergency vehicles priority and keeping the heaviest traffic to a minimum.
Your personal data isn’t being processed – you are a marker in a vast grid, as is every other car on the road. If you are driving around Times Square and mid-town, of course, that little “moo cow” will go off like a Pachinko style slot machine.
According to Transcore, “This system helps diagnose traffic conditions and reports information on bottlenecks to the city’s traffic management center. Engineers there use the system’s near-real-time data to make adjustments, changing signal patterns to improve flow and/or transmitting traffic advisories to motorists.”
At one time there was an initiative to keep track of motorists and charge them higher fees during peak times to discourage travel on the busiest roads. That turned into a political conflict and the idea was scrapped.
Moo-Cow Alert: Potential Problems With the Antenna
The little cow a hacker modified to go off whenever it was scanned is cute, but there are a few potential problems.
Depending on where in the circuit the attached modifications were, they could have extended the reception. A passive EZ tag’s reach is only approximately 3meters or less. Active tags (battery powered) can have a reach up to 100m, according to Microsoft EMEA Manufacturing Industry Solutions Architect, Simon Holloway.
The design of a loop antenna – ones most often used in EZ tags – is a touchy balance. We most easily describe loop antennas as a balanced LC circuit. When the inductive impedance is equal to the capacitive impedance, we say that the circuit is at resonance.
And then there’s the Q (Quality) factor – too high of a Q and you’ll get ringing in the antenna (like feedback in a podium microphone) The Q has to be calculated so as to pass the single frequency band and yet not to be so pointed a peak you miss most of the curve.
Other things to consider when making modifications are made to a passive loop antenna are diameter of the wire, length of the wire as well as its impedance. What is the wire made of? Is it stranded or solid core? Anyone of these factors can send your receive circuit into default.
EZ Pass Sensor Hacking: More Complex Than You’d Think
I have great respect for microwave and RF engineers who design one of the most unsung circuits of our day. Finely tuned; vehemently cursed when not properly constructed correctly: Microwave antenna are the most used and least understood components of our wireless world.
Hill, K. E-ZPasses Get Read All Over New York (Not Just At Toll Booths). (2013). Accessed September 27, 2013.
TransCore. Literature. (2013). Accessed September 27, 2013.
Holloway, Simon. Microsoft Developer: RFID an Introduction. (2006). Accessed September 27, 2013.
Texas Instruments. HF Antenna Design Notes. (2003). Accessed September 27, 2013.