Low-power radio-frequency receiver

Patent metadata

Field	Value
Publication number	US-10041292-B2
Application number	US-201213415537-A
Country	US
Kind code	B2
Filing date	Mar 8, 2012
Priority date	Mar 11, 2011
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A low-power RF receiver has a decreased current consumption. The receiver may be used in control devices, such as battery-powered motorized window treatments and two-wire dimmer switches. The receiver uses an RF sub-sampling technique to check for RF signals and then puts the receiver to sleep for a sleep time that is longer than a packet length of a transmitted packet to conserve battery power. The receiver compares detected RF energy to a threshold that may be increased to decrease the sensitivity of the receiver and increase the battery lifetime. After detecting an RF signal, the receiver is put to sleep for a snooze time that is longer than the sleep time and just slightly shorter than the time between two consecutive transmitted packets.

First claim

What is claimed is:

1. A load control device for controlling an electrical load receiving power from a power source in response to RF signals transmitted by an RF transmitter, the RF transmitter adapted to transmit a predetermined number of consecutive packets at a predetermined transmission rate during a given transmission event, each of the packets including a same command and characterized by a packet length, the load control device comprising:
an RF receiver adapted to receive packets from the RF transmitter, the RF receiver operable to be periodically enabled for a sample time period to determine if the RF transmitter is transmitting one of the consecutive packets, the RF receiver operable to enter a sleep mode for a sleep time period between consecutive sample time periods if the RF receiver determines that the RF transmitter is not transmitting one of the consecutive packets during the sample time period; and
a controller operatively coupled to the RF receiver, the controller operable to determine that the RF transmitter is transmitting one of the consecutive packets during the sample time period and to subsequently receive an entire packet of the consecutive packets, the controller operable to control the electrical load in response to the entire packet received from the RF transmitter;
wherein the sleep time period of the RF receiver is longer than the packet length of each of the packets, the sample time period of the RF receiver is less than the packet length, and the sample time period and the sleep time period between sample time periods are sized to ensure that the sample time period coincides with at least one packet of the predetermined number of consecutive packets in the transmission event.

2. The load control device of claim 1 , wherein:
the controller and the RF receiver are operable to be powered by a battery.

3. The load control device of claim 2 , wherein the controller can be controlled into a sleep mode in which the controller consumes less power than in a normal mode.

4. The load control device of claim 3 , wherein the RF receiver is operable to determine if detected RF energy exceeds a detect threshold, the RF receiver operable to wake up the controller from the sleep mode to enter the normal mode in response to determining that the detected RF energy exceeds the detect threshold.

5. The load control device of claim 4 , wherein the controller is operable to put the RF receiver and the controller to sleep for a snooze time in response to determining that the detected RF energy exceeds the detect threshold, the RF receiver and the controller operable to wake up after the snooze time such that the controller is operable to receive one of the consecutive packets.

6. The load control device of claim 5 , wherein the snooze time is slightly less than a break time between two subsequent ones of the consecutive packets.

7. The load control device of claim 4 , wherein the controller is operable to adjust the detect threshold of the RF receiver, wherein the detect threshold can be increased to prevent noise signals from causing the RF receiver to wake up the controller thereby conserving battery power.

8. The load control device of claim 7 , wherein the controller is operable to adjust the detect threshold from an extended range threshold close to a noise floor to an extended battery mode threshold greater than the extended range threshold.

9. The load control device of claim 2 , wherein the electrical load comprises a motor for adjusting a covering material of a motorized window treatment, the load control device comprising:
a motor drive circuit coupled to the motor for driving the motor to thus open and close the covering material.

10. The load control device of claim 9 , further comprising:
a drive shaft; and
at least one lift cord rotatably received around the drive shaft and extending to a bottom of the covering material for raising and lowering the covering material;
wherein the motor is operatively coupled to the drive shaft such that the motor is operable to raise and lower the covering material by rotating the drive shaft.

11. The load control device of claim 2 , further comprising:
at least one visual indicator operable to display an indication of a state of the load.

12. The load control device of claim 11 , wherein the load control device comprises a battery-powered remote control.

13. The load control device of claim 2 , wherein the load control device comprises a temperature control device operable to control a heating and/or cooling system in response to the entire packet received from the RF transmitter.

14. The load control device of claim 1 , further comprising:
a controllably conductive device adapted to be coupled in series electrical connection between the power source and the electrical load for controlling the power delivered to the electrical load;
wherein the controller is operatively coupled to a control input of the controllably conductive device for controlling the power delivered to the electrical load in response to the entire packet received from the RF transmitter.

15. The load control device of claim 14 , further comprising:
a power supply coupled in parallel electrical connection with the controllably conductive device, the power supply operable to conduct a charging current through the electrical load in order to generate a DC supply voltage for powering the controller.

16. The load control device of claim 14 , further comprising:
a ground terminal adapted to be coupled to earth ground; and
a power supply adapted to conduct a charging current through the ground terminal in order to generate a DC supply voltage for powering the controller.

17. The load control device of claim 14 , wherein the electrical load comprises a lighting load and the load control device comprises a dimmer switch for controlling an amount of power delivered to the lighting load to adjust an intensity of the lighting load.

18. The load control device of claim 1 , wherein a packet break time period exists between any two consecutive packets.

19. An RF communication system comprising:
an RF transmitter adapted to transmit a predetermined number of consecutive packets at a predetermined transmission rate during a given transmission event, each of the packets including a same command and characterized by a packet length; and
an RF receiver adapted to receive packets from the RF transmitter, the RF receiver operable to be periodically enabled for a sampling time to determine if the RF transmitter is transmitting one of the consecutive packets, the RF receiver operable to enter a sleep mode for a sleep time period between consecutive sample time periods if the RF receiver determines that the RF transmitter is not transmitting one of the consecutive packets during the sample time period;
wherein, if the RF transmitter is transmitting one of the consecutive packets during the sample time period, the RF transmitter is operable to be enabled to subsequently receive an entire packet of the consecutive packets; and
wherein the sleep time period of the RF receiver is longer than the packet length of each of the packets, the sampling time of the RF receiver is less than the packet length, and the sampling time and the sleep time period between sampling times are sized to ensure that the sampling time coincides with at least one packet of the predetermined number of consecutive packets in the transmission event.

20. The RF communication system of claim 19 , further comprising:
a plurality of

Assignees

• Cooney Andrew Karl
• Crafts Jordan H
• Dejonge Stuart W
• Knode Galen E
• Lenz Jonathan T
• Mierta Justin J
• Mosebrook Donald R
• Lutron Electronics Co

Inventors

• Cooney Andrew Karl
• Crafts Jordan H
• Dejonge Stuart W
• Knode Galen E
• Lenz Jonathan T
• Mierta Justin J
• Mosebrook Donald R

Classifications

• H04W52/028

  switching on or off only a part of the equipment circuit blocks · CPC title

• H04W52/0235

  where the received signal is a power saving command · CPC title

• H04W52/0229

  where the received signal is a wanted signal · CPC title

• H04W52/0225

  using monitoring of external events, e.g. the presence of a signal · CPC title

• H04W52/0219

  where the power saving management affects multiple terminals · CPC title