Method and apparatus for mitigating radio frequency interference (RFI) in a portable electronic device while conserving battery power

Patent metadata

Field	Value
Publication number	US-9614561-B2
Application number	US-201314068225-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Oct 31, 2013
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A method and circuit for mitigating RFI in an electronic device that occurs while the device is in a low power mode utilizes one or more antenna elements in the device to receive RF energy. When the RF energy is sufficiently high that it could affect signal states in the device while in the low power mode, the device transitions from the low power mode to an active mode and begins an RFI mitigation process to ensure signal states and other circuit operations in the device are not changed by the RFI.

First claim

We claim:

1. A circuit for a portable electronic device, comprising:
an antenna element disposed inside the electronic device;
a radio frequency energy detector coupled to the antenna element that provides an output which corresponds to a level of radio frequency coupled energy received by the antenna element;
a threshold detector coupled to the radio frequency energy detector that asserts an output while the level of radio frequency coupled energy received by the antenna element, as indicated by the output of the radio frequency energy detector, is above a first pre-selected threshold indicating exposure of the portable electronic device to radio frequency interference (RFI), and wherein the RFI is known to corrupt or alter data signal states of a component of the portable electronic device; and
a controller that is responsive to the output of the threshold detector, and transitions from an inactive state to an active state to perform RFI mitigation wherein the output of the threshold detector is asserted to refresh the component of the electronic device while the output of the threshold detector is asserted, and the controller transitions back to the inactive state upon completion of the RFI mitigation, thereby ensuring that the component is protected from the exposure of the portable electronic device to the RFI, while also conserving battery power to the portable electronic device.

2. The circuit of claim 1 , wherein the controller continuously refreshes the component while the output of the threshold detector is asserted.

3. The circuit of claim 1 , wherein the threshold detector de-asserts the output of the threshold detector upon the level of radio frequency coupled energy received by the antenna element falling below a second pre-selected threshold, and wherein the controller transitions from the active state to the inactive state upon the output of the threshold detector being de-asserted.

4. The circuit of claim 1 , wherein the first pre-selected threshold is adjustable.

5. The circuit of claim 1 , wherein the controller refreshes the component by reading from the component.

6. The circuit of claim 1 , wherein the controller refreshes the component by writing to the component.

7. The circuit of claim 1 , further comprising a user-perceptible alert responsive to the output of the threshold detector being asserted.

8. The circuit of claim 7 , wherein the user-perceptible alert indicates that the user to move or re-position the device with respect to a potential source of the RFI.

9. The circuit of claim 1 , wherein the output of the threshold detector is provided to an interrupt line of the controller.

10. The circuit of claim 1 , wherein the controller refreshes the component by issuing a refresh command to the component.

11. The circuit of claim 1 , wherein the electronic device transitions from the active state to the low power state in response to energy being detected which is indicative of the RFI falling below a second pre-selected threshold.

12. The circuit of claim 1 , wherein the component comprises a user interface component, and the electronic device comprises a portable radio.

13. The circuit of claim 1 , wherein the component being refreshed as part of the RFI mitigation is a user interface component comprising at least one: a display, a keypad, and an accessory connector and respective display signals, keypad signals and accessory connector signals associated therewith.

14. The circuit of claim 1 , wherein refresh of the component as part of RF mitigation is not periodic.

15. The circuit of claim 1 , wherein pins connected to signal lines of the component are terminated at each end of the controller and the component in a high impedance termination, thereby making the signal lines susceptible to RFI.

16. A method of mitigating radio frequency interference (RFI) in a portable battery powered device, comprising:
detecting, while the portable battery powered device is in a low power state, incidence of RFI at a user interface component of the battery powered device, and wherein the RFI is known to corrupt or alter data signal states of a user interface component of the portable battery powered device;
responsive to detecting the incidence of the RFI, transitioning the portable battery powered device from the low power state to an active state;
responsive to transitioning from the low power state to the active state, performing RFI mitigation by the device on the user interface component; and
responsive to completing the RFI mitigation, transitioning the portable battery powered device from the active state back to the low power state, thereby ensuring the user interface component is protected from the exposure of the portable electronic device to the incidence of RFI, while also conserving battery power to the portable battery powered device.

17. The method of claim 16 , wherein the device performs the RFI mitigation until the incidence of the RFI is no longer detected, whereupon the device transitions back to the low power state.

18. The method of claim 16 , wherein detecting incidence of RFI comprises:
receiving RF energy at an antenna in the device that is in close proximity to at least one signal line of the device;
producing an output by an RF energy detector that is coupled to the antenna, wherein the output has a level that corresponds to a level of the RF energy;
comparing the output of the RF energy detector to a first pre-selected threshold at a threshold detector of the device; and
asserting an RFI interrupt by the threshold detector when the output of the RF energy detector exceeds the first pre-selected output, wherein asserting the RFI interrupt causes a controller of the device to perform the RFI mitigation.

19. The method of claim 16 , wherein performing the RFI mitigation comprises refreshing a signal state on at least one signal line in the device.

20. The method of claim 19 , wherein refreshing the signal state is performed continuously while the incidence of RFI is detected, and ceased upon the incidence of RFI ceasing to be detected.

21. The method of claim 16 , further comprising:
determining that the incidence of RFI has ceased; and
transitioning the device from the active state to the low power state.

22. The method of claim 16 , wherein the battery powered device comprises a portable radio.

23. The method of claim 16 , wherein the user interface component of the portable battery powered device comprises at least one of: a display, a keypad, and an accessory connector and respective display signals, keypad signals and accessory connector signals associated therewith.

24. The method of claim 16 , wherein the refresh of the user interface component is not periodic.

25. The method of claim 16 , wherein pins connected to signal lines of the user interface component are terminated at each end of the controller and the user interface component in a high impedance termination, thereby making the signal lines susceptible to RFI.

26. A portable two-way radio device, comprising:
a controller that has a low power mode and an active mode;
at least one component that is coupled to the controller, wherein each component is coupled to the controller by at least one signal line;
at least one antenna element disposed inside the portable two-way radio device;
a radio frequency energy detector coupled to the at least one antenna element that provides an outpu

Assignees

• Motorola Solutions Inc
• Motorola Solutions Inc

Inventors

• Bartels Peter J
• Alfaro Javier
• Jelavic Stanko
• Johnson Graeme Peter

Classifications

• H04W52/0238 Primary

  where the received signal is an unwanted signal, e.g. interference or idle signal · CPC title

• H04W52/0209

  in terminal devices · CPC title

• H04B15/00

  Suppression or limitation of noise or interference (by means associated with receiver H04B1/10) · CPC title

• H04B1/10 Primary

  Means associated with receiver for limiting or suppressing noise or interference · CPC title

• H04B1/12 Primary

  Neutralising, balancing, or compensation arrangements · CPC title