Reducing false wake-up in a low frequency transponder

Abstract

A bidirectional remote keyless entry (RKE) transponder comprises an analog front-end (AFE) having a programmable wake-up filter that predefines the waveform timing of the desired input signal, minimum modulation depth requirement of input signal, and independently controllable channel gain reduction of each of its three channels, X, Y, and Z. The wake-up filter parameters are the length of high and low durations of wake-up pulses that may be programmed in a configuration register. The wake-up filter allows the AFE to output demodulated data if the input signal meets its wake-up filter requirement, but does not output the demodulated data otherwise. The AFE output pin is typically connected to an external device for control, such as a microcontroller (MCU). The external device typically stays in low current sleep (or standby) mode when the AFE has no output and switches to high current wake-up (or active) mode when the AFE has output. Therefore, in order to keep the external control device in the low current sleep mode when there is no desired input signal, it is necessary to keep no output at the AFE output pin. This can be achieved by controlling the wake-up filter parameters, minimum modulation depth requirement of input signal, and channel gains of the AFE device. These features can reduce false-wake up of the bidirectional RKE transponder due to undesired input signals such as noise signals.

Description

[0001] The parent application number of this application is 200580016443.9, the filing date is April 14, 2005, and the title of the invention is "Reduction of False Awakening in Low Frequency Transponder". Technical field [0002] The present invention generally relates to inductively coupled magnetic field transmission and detection systems, such as remote keyless entry (RKE) and passive keyless entry (PKE) systems, and more specifically to a method for reducing false wakeups in such systems Equipment and methods. Background technique [0003] In recent years, the use of remote keyless entry (RKE) systems in automotive and security applications has increased significantly. The traditional remote keyless entry (RKE) system consists of an RKE transmitter and a base station. The RKE transmitter has an activation button. When an activation button is pressed, the RKE transmitter transmits the corresponding radio frequency data to the base station. The base station receives the data an...

AI Technical Summary

Problems solved by technology

However, there is a problem that when the transponder receiver is affected by noise sources such as electromagnetic radiation (EMR) emanating from eg television and computer monitors having substantially the same frequency as the interrogation signal, the RKE device will be woken up unnecessarily

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