RF receiver ASK/FSK duty cycle optimization algorithm

• US 20070064838A1
• Filed: 09/07/2006
• Published: 03/22/2007
• Est. Priority Date: 09/16/2005
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Wang, Wayne, Anderson, John
• Granted Patent: US 7,702,038 B2
• Time in Patent Office: Days
• US Class Current: 375/329
• 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 23/0462 Structure of transmission protocol
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2209/61 Signal comprising different frequencies, e.g. frequency hopping
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: H04B 1/00 Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence

Abstract

An RF receiver for receiving transmissions of different modulations includes cycling between a first mode for receiving transmissions of a first modulation that occurs frequently and a second mode for receiving transmission of a second modulation that occurs infrequently. The example RF receiver is cycled between a first modulation for receiving the FSK transmission from the TPM system and a second modulation for receiving the ASK transmission from the RKE system. The RF receiver cycles between different modulations to detect the most frequent FSK modulated transmissions while also detecting and receiving the relatively infrequent ASK modulated RKE transmissions without an undesirable delay.

Claims

1. A method of operating an RF receiver for an automobile comprising the steps of:

a) operating the RF receiver in a first mode for receiving Frequency Shift Keyed (FSK) modulated transmissions for a first period;

b) switching the RF receiver to a second mode for receiving an Amplitude Shift Keyed (ASK) modulated transmission for a second period, shorter than the first period;

c) switching the RF receiver back to the first mode responsive to the RF receiver determining that no ASK modulated transmissions is present; and

d) maintaining the RF receiver in the second mode responsive to a first ASK modulated transmission being detected.

2. The method as recited in claim 1, wherein the second period is of a duration determined to detect the presence of the first ASK modulated transmission and shorter than a period required to receive the entire first ASK modulated transmission, such that receipt of the first ASK modulated transmission in the second period provides a prompt for the RF receiver to operate in the second mode to receive a second ASK modulated transmission.

3. The method as recited in claim 2, wherein a first time interval between the first ASK modulated transmission and the second ASK modulated transmission is fixed.

4. The method as recited in claim 3, wherein the RF receiver switches back to operate in the first mode responsive to receiving the first ASK modulated signal until the first time interval expires where the RF receiver switches back to the second mode to receives the second ASK Modulated signal.

5. The method as recited in claim 3, wherein the first period is of a duration shorter than the first time interval between the first ASK modulated transmission and the second ASK modulated transmission.

6. The method as recited in claim 1, wherein a second time interval between receiving a first FSK modulated transmission and a second FSK modulated transmission is variable.

7. The method as recited in claim 1, wherein the ASK modulated transmission is transmitted for a remote keyless entry (RKE) system and includes several identical packets of data transmitted at fixed intervals.

8. The method as recited in claim 1, wherein the FSK modulated transmission is transmitted for a tire pressure monitoring (TPM) system and includes several identical packets of data transmitted at variable intervals.

9. The method as recited in claim 8, wherein the variable intervals between the several data packets varies responsive to detected operating condition of the automobile.

10. A method of receiving transmissions from a tire pressure monitoring (TPM) system and a remote keyless entry (RKE) system with one RF receiver comprising the steps of:

a) operating the RF receiver in a first mode for receiving a Frequency Shift Keyed (FSK) modulated transmission from the TPM system for a first period;

b) switching the RF receiver to a second mode for receiving an Amplitude Shift Keyed (ASK) modulated transmission from the RKE system for a second period shorter than the first period and shorter than the ASK modulated transmission;

c) searching for an ASK modulated transmission; and

d) switching the RF receiver back to the first mode responsive to no ASK modulated transmission being detected, and prompting the RF receiver to be in the second mode for receiving a second ASK modulated signal responsive to receiving a first ASK modulated transmission during the second period.

11. The method as recited in claim 10, including the step of determining the time at which the second ASK transmission is expected responsive to receiving the first ASK transmission.

12. The method as recited in claim 11, wherein a first interval between the first ASK transmission and the second ASK transmission is fixed.

13. The method as recited in claim 10, wherein a second interval between a first FSK modulated transmission and a second FSK modulated transmission is variable.

14. The method as recited in claim 10, wherein the second period is shorter than the first period and shorter than a duration of the first and second ASK modulated transmissions.