Programmable selective wake-up for radio frequency transponder

Abstract

A remote keyless entry (RKE) transponder has a programmable selective wake-up filter for determining whether the RKE transponder should wake-up to process a received signal. The wake-up filter correlates the timing of an input signal's carrier amplitude on and off time periods to a predefined programmable time period profile for a desired signal which has a certain carrier on time (time period on) and a certain carrier off time (time period off) arranged into a coded “header.” When a received signal matches the predefined time period profile, then the RKE transponder will wake-up to process the incoming signal data. The predefined time period profile may be programmable and may be stored in a header configuration register. Each RKE transponder has unique predefined time period on and time period off profiles.

1 . A method for waking up a remote keyless entry (RKE) transponder for further processing of incoming data on a signal, said method comprising the steps of: 
 receiving a signal with an analog front-end (AFE) of a remote keyless entry (RKE) transponder;    determining after a settling time period whether the received signal is off for a short gap time and if the short gap time occurs within a fixed time period;    if not, do not wake up the RKE transponder, and    if so, then 
 determining whether the received signal is on for a predefined high time period (T WAK H); and  
 determining after the predefined high time period (T WAK H) whether the received signal is off for a predefined low time period (T WAK L); 
 if not, do not wake up the RKE transponder, and  
 if so, then 
 waking up the RKE transponder for further processing of data from the received signal.  
 
 
   
   
   
       2 . The method according to  claim 1 , wherein the steps of determining whether the received signal on and off times substantially match the predefined high time period (T WAK H) and the predefined low time period (T WAK L), respectively, are done with a wake-up filter that compares the received signal on time to the predefined high time period (T WAK H) and the received signal off time to the predefined low time period (T WAK L).  
   
   
       3 . The method according to  claim 2 , wherein the wake-up filter uses timing of an internal oscillator in determining whether the received signal on and off times substantially match the predefined high time period (T WAK H) and the predefined low time period (T WAK L), respectively.  
   
   
       4 . The method according to  claim 2 , wherein the predefined high time period (T WAK H) is programmable.  
   
   
       5 . The method according to  claim 2 , wherein the predefined low time period (T WAK L) is programmable.  
   
   
       6 . The method according to  claim 1 , wherein the step of waking up the RKE transponder further comprises the step of waking-up an external control device for accepting data from the received signal.  
   
   
       7 . The method according to  claim 6 , wherein the external control device is selected from the group consisting of digital processor, microcontroller, microprocessor, digital signal processor, application specific integrated circuit (ASIC) and programmable logic array (PLA).  
   
   
       8 . The method according to  claim 2 , further comprising the steps of storing the predefined high time period (T WAK H) and the predefined low time period (T WAK L) in a configuration register.  
   
   
       9 . The method according to  claim 8 , when the steps of storing the predefined high time period (T WAK H) and the predefined low time period (T WAK L) in the configuration register are done with an external control device.  
   
   
       10 . The method according to  claim 2 , wherein the step of receiving the signal further comprises the steps of receiving the signal with a plurality of remote keyless entry (RKE) transponders, each of the plurality of RKE transponders having an analog front-end (AFE) and a wake-up filter, wherein each of the wake-up filters uses a different predefined high time period (T WAK H) so that only one of the plurality of RKE transponders will wake-up during reception of the signal.  
   
   
       11 . The method according to  claim 2 , wherein the step of receiving the signal further comprises the steps of receiving the signal with a plurality of remote keyless entry (RKE) transponders, each of the plurality of RKE transponders having an analog front-end (AFE) and a wake-up filter, wherein each of the wake-up filters uses a different predefined low time period (T WAK L) so that only one of the plurality of RKE transponders will wake-up during reception of the signal.  
   
   
       12 . The method according to  claim 1 , wherein the RKE transponder has at least one AFE for receiving the signal.  
   
   
       13 . The method according to  claim 12 , wherein the at least one AFE comprises three signal input channels.  
   
   
       14 . The method according to  claim 1 , wherein the received signal is at a frequency from about 100 kHz to about 400 kHz.  
   
   
       15 . The method according to  claim 1 , wherein the received signal is at a frequency of about 125 kHz.  
   
   
       16 . A remote keyless entry (RKE) transponder having selective wake-up, comprising: 
 a remote keyless entry (RKE) transponder having an analog front-end (AFE) for receiving a signal; and    a wake-up filter that determines, after a settling time period of the received signal and a short gap time that the signal is off, whether on and off times of the received signal substantially match a predefined high time period (T WAK H) and a predefined low time period (T WAK L), respectively, and if so waking up the RKE transponder for further processing of data from the received signal.    
   
   
       17 . The RKE transponder according to  claim 16 , wherein the AFE comprises an amplifier and a modulated signal detector.  
   
   
       18 . The RKE transponder according to  claim 16 , wherein the predefined high time period (T WAK H) and the predefined low time period (T WAK L) are programmable.  
   
   
       19 . The RKE transponder according to  claim 16 , wherein the RKE transponder further comprises a configuration register for storing the predefined high time period (T WAK H) and the predefined low time period (T WAK L).  
   
   
       20 . The RKE transponder according to  claim 19 , wherein the RKE transponder further comprises an external control device for programming the predefined high time period (T WAK H) and the predefined low time period (T WAK L) into the configuration register.  
   
   
       21 . The RKE transponder according to  claim 19 , wherein the external control device is selected from the group consisting of digital processor, microcontroller, microprocessor, digital signal processor, application specific integrated circuit (ASIC) and programmable logic array (PLA).  
   
   
       22 . The RKE transponder according to  claim 16 , wherein the RKE transponder has at least one AFE for receiving the signal.  
   
   
       23 . The RKE transponder according to  claim 22 , wherein the at least one AFE comprises three signal input channels.  
   
   
       24 . The RKE transponder according to  claim 22 , wherein the AFE receives signals at about 125 kHz.  
   
   
       25 . The RKE transponder according to  claim 22 , wherein the AFE is adapted to receive signals from about 100 kHz to about 400 kHz.