What Is A Transponder Key For A Car?
A transponder is essentially an electronic chip, which has a fine wire coil around it to transmit and receive electromagnetic signals. The chip itself is similar to the memory storage in your computer or smartphone in that it doesn’t require a constant source of power to retain memory. This is known as non-volatile memory. The kind of transponder used in a car key is known as a Magnetic Coupled Transponder system. These systems don’t require constant electricity, and therefore don’t have their own power source. A car key transponder operates in a radio frequency range (around 125kHz), meaning that it can penetrate plastic or rubber, which is why we’re able to place it within the bow of the key. Because they don’t have their own power source, car key transponders only have a range of between 1-15cm.
How Does A Car Key Transponder Work?
As well as a transponder chip in the key, modern cars also have an induction coil that is fitted around the ignition barrel. When the key is inserted into the barrel and turned to the ‘on’ position, the induction coil sends out a pulse of electromagnetic energy. The wire coil around the transponder chip absorbs this energy, which powers the chip and causes it to emit a signal, which is the key’s identification code. This signal is sent back to the induction coil, which reads the code. If the code is recognised by the vehicle’s on-board computer, it will commence the car’s start procedure and allow it to run. In recent years transponder systems have been developed to use cryptographic or rolling codes so that the code cannot be copied from the vehicle’s computer.
hyea: 
And yes, the issue with the 'improved' DESS was that there was too much power swamping the read.... :thumbup:
