LOW POWER RF CONTROL SYSTEM

• US 20100279639A1
• Filed: 07/09/2010
• Published: 11/04/2010
• Est. Priority Date: 03/24/2004
• Status: Active Grant

• Current Assignee: Somfy Activites SA (Somfy SA)
• Original Assignee: Somfy Sas (Somfy SA)
• Inventors: WALKER, Winston Glenn, SAAR, David A.
• Granted Patent: US 7,860,481 B2
• Time in Patent Office: Days
• US Class Current: 455/226.2
• CPC Class Codes: E06B 9/68 Operating devices or mechanisms, e.g. with electric drive
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: H04W 52/029 reducing the clock frequency of the controller
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A low power rf control system includes a controller that operates at a low clock speed when an associated rf receiver is deenergized and a high clock speed when the controller energizes the receiver. The receiver can be on for a short period, off for a short period when no preamble pulses from a remote control device are received, on for a short period, and then off for a longer period until the next cycle. The receiver remains on to process a command signal when a preamble signal is detected. A DC-DC down converter can be used as a power supply for the receiver, and a SAW resonant circuit can be used as an IF oscillator for the receiver. An LC filter can be associated with the receiver for filtering the IF signal.

Claims

1. A radio-frequency (rf) control system for operating a component at least in part in response to an rf signal from a remote control device manipulable by a user, comprising:

at least one rf receiver associated with the component and configured for processing an rf signal; and

at least one controller associated with the component and controlling the receiver, wherein the controller adaptively adjusts a noise threshold above which a carrier must be detected to indicate the presence of a control signal,

wherein a slow receiver signal strength indicator (RSSI) filter and a fast RSSI filter are connected between a RSSI output of the rf receiver and inputs of the controller, a time constant of the fast RSSI filter being less than a time constant of the slow RSSI filter,

wherein the output of the fast RSSI filter is used by the controller to determine whether a carrier signal has been detected,

wherein the output of the slow RSSI filter is connected to a comparator to provide a digital signal to the controller, and

wherein the controller raises the noise threshold when the controller determines that a false carrier has been detected.

2. The system of claim 1, wherein the slow RSSI filter is used by the controller to detect a continued presence of a signal to reduce the effect of noise.

3. The system of claim 1, wherein the modulation of the signal is of the amplitude shift keying type.

4. The system of claim 1, wherein the frequency of the signal is 433 MHz.

5. The system of claim 1, wherein the time constant of the slow RSSI filter is 200 microseconds.

6. The system of claim 1, wherein the time constant of the fast RS SI filter is 10 microseconds.

7. The system of claim 1, wherein the controller causes the receiver to be energized for first wake-up time periods according to a wake-up paradigm of wake-up events, energization being resumed when a carrier signal is present.

8. The system of claim 7, wherein the first wake-up time period is 80 microseconds.

9. The system of claim 1, wherein the controller operates at a high frequency when the receiver is energized and at a low frequency during a receiver sleep period, the high frequency being greater than the low frequency.

10. The system of claim 1, wherein the controller operates at an intermediate frequency between low and high frequencies prior to energizing the receiver after a receiver sleep period.

11. The system of claim 1, wherein the false carrier has been detected when attempting to process a signal without successfully decoding the signal.

12. The system of claim 1, wherein the component is powered by at least one battery.

13. The system of claim 1, wherein the component is selected from the group of components consisting of window coverings, awnings, skylight covers, and screens.

14. The system of claim 1, wherein the rf signal includes a preamble including plural pulses, each having a duty cycle in excess of fifty percent (50%).

15. The system of claim 14, wherein the preamble includes at least six pulses.

16. The system of claim 1, comprising at least one bypass capacitor electrically connected between the receiver and ground, the bypass capacitor having a capacitance of below five hundred picoFarads (500 pF).

17. The system of claim 16, comprising plural bypass capacitors, at least one having a capacitance not substantially more than one hundred picoFarads (100 pF).

18. The system of claim 1, comprising at least one surface acoustic wave (SAW) resonator circuit to establish an intermediate frequency (IF) oscillator for the receiver.

19. The system of claim 18, comprising an LC filter associated with the receiver for filtering an IF signal.

20. The system of claim 1, wherein the component is powered by at least one battery, and the system further comprises a DC-DC down converter electrically interposed between the battery and receiver to provide a voltage to the receiver.