Apparatus with receiver having selectable threshold time constant

• US 20040036589A1
• Filed: 08/20/2002
• Published: 02/26/2004
• Est. Priority Date: 08/20/2002
• Status: Active Grant

• Current Assignee: TRW Inc. (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Lin, Xing Ping
• Granted Patent: US 6,809,638 B2
• Time in Patent Office: Days
• US Class Current: 340/445
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: B60C 23/0479 Communicating with external units being not part of the vehicle, e.g. tools for diagnostic, mobile phones, electronic keys or service stations

Abstract

An apparatus (10) comprises a controller (82) for receiving a control parameter. At least one tire condition sensor (26-32) senses a tire condition and transmits a tire condition signal (34) indicative of the sensed tire condition. A receiver (78) receives the tire condition signal (34) and compares the received tire condition signal (34) to a changeable threshold to output a digital signal indicative of the received tire condition signal (34). The changeable threshold changes at time intervals determined by a time constant of the receiver (78). The time constant of the receiver (78) is variable. The controller (82) is operatively connected to the receiver (78) and varies the time constant of the receiver (78) in response to the received control parameter.

Claims

1. An apparatus comprising:

a controller for receiving a control parameter;

at least one tire condition sensor for sensing a tire condition and for transmitting a tire condition signal indicative of the sensed tire condition; and

a receiver for receiving the tire condition signal and for comparing the received tire condition signal to a changeable threshold to output a digital signal indicative of the received tire condition signal, the changeable threshold changing at time intervals determined by a time constant of the receiver, the time constant of the receiver being variable,

the controller being operatively connected to the receiver and varying the time constant of the receiver in response to the received control parameter.

2. The apparatus of claim 1 wherein the receiver includes a detector, the detector having a comparator for comparing the received tire condition signal to the changeable threshold.

3. The apparatus of claim 2 wherein the detector includes an RC integrator for determining a value of the changeable threshold, the RC integrator including the variable time constant.

4. The apparatus of claim 2 wherein the detector includes a charging time constant and a discharging time constant, the variable time constant being one of the charging and discharging time constants.

5. The apparatus of claim 1 further including a transmitter device for transmitting a convenience function signal requesting performance of a convenience function, and wherein the receiver is adapted to receive the convenience function signal and to compare the received convenience function signal to the changeable threshold to output a digital signal indicative of the received convenience function signal.

6. The apparatus of claim 5 wherein the receiver includes a detector, the detector having a comparator for comparing the received convenience function signal to the changeable threshold.

7. The apparatus of claim 5 wherein the control parameter received by the controller is indicative of which one of the tire condition signal and the convenience function signal is being received by the receiver, the control parameter being determined by monitoring at least one of a data rate and data format of a signal being received.

8. The apparatus of claim 5 further including a condition switch, the condition switch being actuatable to provide the control parameter in response to sensing a condition indicative of one of operation of the vehicle and occupation of the vehicle.

9. The apparatus of claim 5 wherein the variable time constant includes first and second time constants, the receiver having a greater ability for receiving the tire condition signal when the first time constant is selected and having a greater ability for receiving the convenience function signal when the second time constant is selected.

10. The apparatus of claim 9 further including first and second switches, closure of only the first switch resulting in selection of the first time constant and closure of only the second switch resulting in selection of the second time constant.

11. The apparatus of claim 10 further including first and second capacitors, the first capacitor having a first capacitance and the second capacitor having a second capacitance, the first and second capacitances being different, closure of the first switch operatively connecting the first capacitor to the receiver and closure of the second switch operatively connecting the second capacitor to the receiver.

12. An apparatus comprising:

at least one tire condition sensor for sensing a tire condition and for transmitting a tire condition signal indicative of the sensed tire condition;

a convenience function transmitter for transmitting a convenience function signal requesting performance of a convenience function;

a display device being operable for displaying the sensed tire condition;

a function device being actuatable for performing the convenience function;

a vehicle-based receiver for receiving signals including the tire condition signal and the convenience function signal, the receiver having a variable time constant and outputting digital signals indicative of the received signals; and

a controller being operatively connected to the display device and the function device and receiving the digital signals from the receiver, the controller, in response to the digital signals, controlling the display device and the function device.

13. The apparatus of claim 12 wherein the receiver includes a detector, the detector having a comparator for comparing the received signals to a threshold value, the threshold value changing at time intervals determined by the variable time constant.

14. The apparatus of claim 13 wherein the detector includes an RC integrator for determining the threshold value, the RC integrator including the variable time constant.

15. The apparatus of claim 13 wherein the detector includes a charging time constant and a discharging time constant, the variable time constant being one of the charging and discharging time constants.

16. The apparatus of claim 12 wherein the controller determines which one of the tire condition signal and the convenience function signal is being received and varies the variable time constant in response to determining which one of the tire condition signal and the convenience function signal is being received.

17. The apparatus of claim 16 wherein the controller determines which one of the tire condition signal and the convenience function signal is being received by monitoring at least one of a data rate and data format of a signal being received.

18. The apparatus of claim 16 further including a condition switch actuatable to provide a condition signal in response to sensing a condition indicative of one of operation of the vehicle and occupation of the vehicle, the controller receiving the condition signal and, in response to the received condition signal, determining which one of the tire condition signal and the convenience function signal is being received.

19. The apparatus of claim 12 further including first and second time constants, the receiver having a greater ability for receiving the tire condition signal when the first time constant is selected and having a greater ability for receiving the convenience function signal when the second time constant is selected.

20. The apparatus of claim 19 further including first and second switches, closure of only the first switch resulting in selection of the first time constant and closure of only the second switch resulting in selection of the second time constant.

21. The apparatus of claim 20 further including first and second capacitors, the first capacitor having a first capacitance and the second capacitor having a second capacitance, the first and second capacitances being different, closure of the first switch operatively connecting the first capacitor to the receiver and closure of the second switch operatively connecting the second capacitor to the receiver.