Monitoring an EZ-Pass (RFID) card

Wolfbyte

I live in NJ where we use EZ-Pass for automated toll payment and traffic monitoring.· I would like to construct a device that flashes a led and / or makes a noise when the tag is read.·

I have done some research online and have determined that the EZ-Pass system operates at 900MHZ - I do not need to get any information off of the chip - just the fact that it responded to a query.

My thoughts were for a RFID reader / RF receiver, a STAMP module and an LED/Speaker.

Any suggestions would be greatly appreciated.

Eric.

Franklin

Your first job will be to buy or construct a 900MHZ receiver/transmitter that works with ez-pass. Do some Googling to see if such a thing exists within your budget.

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- Stephen

Wolfbyte

Let me start by saying I am not an EE and don't play one on TV, having said that it eseems to me that the signal is electronic so it can be received and amplified to the point that the BS2 can sense it and then it could perform it's function - I don't need to get any info from the signal and transmitting isn't required either - this is to provide visual/audible alert that the box had responded (checking up on big brother) - I was hoping that an antenna located right next to the transponder would pick up a signal without a real RF receiver.
Eric.

Mike Green

It doesn't work that way. You need some kind of real RF receiver. Otherwise, any noise from the engine or other electronics in the car or in adjacent cars or nearby radio transmitters could falsely trigger it.

Wolfbyte

Thanks Mike, I suspected as much, was hoping that a very directional antenna (shielded in all directions except towards the transponder) would allow the unit to sense the signal (and only the signal) - I guess it isn't going to be that easy... I've done a bit of hunting and haven't been able to find a cheap receive only RF module using 900MHZ, could you suggest a source?