TRANSMITTER MODULATION SWITCHING

• US 20080136590A1
• Filed: 02/13/2008
• Published: 06/12/2008
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Kachouh, Patricia, Baumgartner, Josef, Ostrander, Gerald
• Granted Patent: US 7,859,389 B2
• Time in Patent Office: Days
• US Class Current: 340/5.72
• CPC Class Codes: B60R 25/2072 with means for preventing jamming or interference of a remote switch control signal
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user

Abstract

An example receiver/transmitter for a passive start and entry system switches between amplitude shift keyed modulation and frequency shift keyed modulation to maintain clear uninterrupted and dependable communication with a remote transmitter in the presence of interfering signals. The receiver/transmitter is switched to receive incoming FSK signals in response to the RSSI becoming saturated by undesired signals. The switch to FSK signal modulation occurs by signaling the remote transmitter to change over and begin sending FSK modulated signals. The FSK modulated signals are then received without significant interference.

Claims

1. A method of receiving a signal with a receiver of a remote keyless entry system comprising the steps of:

a) determining that a received signal strength indicator (RSSI) is saturated such that undesired radio frequency signals prevent clear reception of a desired Amplitude Shift Keyed signal;

b) switching a receiver to Frequency Shift Keyed Modulation responsive to determining that the RSSI is saturated; and

c) sending a signal to a remote transmitter instructing the remote transmitter to send an FSK modulated signal.

2. The method as recited in claim 1, including the step of decoding an incoming ASK signal with the RSSI.

3. The method as recited in claim 1, wherein the incoming FSK signal is not decoded with the RSSI.

5. The method as recited in claim 1, including resuming communication between the receiver and the remote transmitter in ASK modulation responsive to the RSSI not being saturated by undesired RF signals.

6. The method as recited in claim 1, wherein the remote transmitter comprises a Key Fob.

4. The method as recited in claim 4, wherein the a remote transmitter transmits an ASK signal responsive to a signal from the receiver when the RSSI is saturated.

7. A remote keyless entry system comprising:

a receiver/transmitter including a received signal strength indicator (RSSI);

a remote transmitter communicating with the receiver/transmitter, the remote transmitter capable of sending an Amplitude Shift Keyed (ASK) signal and a Frequency shift keyed (FSK) signal, wherein the receiver/transmitter is switched over to receive FSK signals and the remote transmitter is switched from an ASK signal to an FSK signal in response to the RSSI becoming saturated such that a desired ASK signal cannot be clearly received.

8. The system as recited in claim 7, wherein the receiver/transmitter is initially set to receive ASK modulated signals and the RSSI is utilized to measure and decode the ASK signals.

9. The system as recited in claim 7, wherein the RSSI is not utilized to measure and decode an incoming FSK modulated signal.

10. The system as recited in claim 7, wherein the remote transmitter comprises a key fob.

11. The system as recited in claim 7, wherein the remote transmitter comprises a passive device.

12. The system as recited in claim 7, wherein the receiver/transmitter is supported within a vehicle and is in communication with at least one vehicle system.