Recursive digital filter using fixed point arithmetic

• US 5,757,362 A
• Filed: 06/07/1995
• Issued: 05/26/1998
• Est. Priority Date: 01/05/1995
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Levine, James Lewis
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LAO, LUNYI
• Application Number:
  US08/487,528
• Time in Patent Office: 1,084 Days
• Field of Search: 345/156, 345/157, 345/158, 345/166, 345/163, 348/734, 248/148 B, 463/37, 382/265, 382/260, 364/724.01, 364/724.03, 364/724.17, 364/736, 364/761, 364/723
• US Class Current: 345/166
• CPC Class Codes: G06F 3/0308 comprising a plurality of distinctive and separately oriented light emitters or reflectors associated to the pointing device, e.g. remote cursor controller with distinct and separately oriented LEDs at the tip whose radiations are captured by a photo-detector associated to the screen
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/04892 Arrangements for controlling cursor position based on codes indicative of cursor displacements from one discrete location to another, e.g. using cursor control keys associated to different directions or using the tab key arrangements for controlling cursor position based on coordinate signals G06F3/038
• CPC Class Codes: H04N 5/44 Receiver circuitry for the reception of television signals according to analogue transmission standards H04N5/14 takes precedence

Abstract

There is provided a digital processor that includes a recursive filter having means for using fixed point arithmetic for performing division. The recursive filter includes means for saving a remainder after each division and multiplication operation and for adding the remainder to a dividend in the subsequent division operation.

Claims

1. A remote pointing system for controlling a cursor location on a display device comprising:

a pointing device for controlling said cursor location on said display device by transmitting a plurality of signals, each of said signals being aimed off a pointing axis of the pointing device in different directions;

a receiver for receiving said signals from said pointing device;

a digital processor for processing said signals as data representing a of aim on said display device by said pointing device, said digital processor controlling said cursor location on the display device, said digital processor comprising a recursive filter including means for using fixed point arithmetic, said recursive filter including means for saving a remainder after each division and for adding said remainder to a dividend in a subsequent division operation.

2. A remote pointing system as in claim 1, wherein said plurality of signals includes at least three signals.

3. A remote pointing system as in claim 1, wherein said pointing device includes a plurality of infrared light emitting diodes for generating said plurality of signals.

4. A remote pointing system as in claim 1, wherein said pointing device includes a plurality of signal generating means, each of said signal generating means including a circuit for sequentially pulsing said signals with pulse trains for causing said signal generating means to individually and sequentially emit modulated signals.

5. A remote pointing system as in claim 1, wherein said receiver comprises an infrared detector and amplifier tuned to a predetermined pulse frequency.

6. A remote pointing system as in claim 1, wherein said receiver includes a demodulator for converting said signals to analog base-band pulses.

7. A remote pointing system as in claim 6, wherein said receiver includes an analog-to-digital converter for digitizing said analog base-band pulses.

8. A remote pointing system as in claim 1, further comprising a cursor controller responsive to said digital processor for controlling said cursor location on said display device.

9. A remote pointing system for controlling a cursor location on a display device comprising:

a pointing device for remotely controlling the cursor on the display device, said pointing device comprising;

at least three infrared light emitting diodes (IRLEDs), each of said IRLEDs aimed off a main or pointing axis of the pointing device in different directions; and

a circuit connected to each of said IRLEDs responsive to a user input for sequentially pulsing said IRLEDs with pulse trains so as to cause the IRLEDs to individually and sequentially emit modulated infrared light signals;

a receiver and controller located proximate to said display device, said receiver and controller comprising;

an infrared detector and amplifier tuned to a predetermined pulse frequency;

a demodulator to convert received signals to analog base-band pulses;

an analog-to-digital convertor to digitize the analog base-band pulses;

a digital processor to process the digitized analog base-band pulses as data representing a point of aim on the display device by the pointing device, said digital processor controlling the position of a cursor on the display device; and

a cursor controller responsive to said digital processor for controlling a cursor position on the display device,

wherein said digital processor includes a recursive filter using fixed point arithmetic for performing division, said recursive filter saving the remainder after each division operation and adding said remainder to the dividend in the following division operation.

10. A method of controlling a cursor location on a display device using a pointing device comprising steps of:

transmitting a plurality of signals from said pointing device to a receiver, said signals being aimed in different directions;

receiving said signals with said receiver;

processing said signals with a filter as data representing a point of aim on said display device by the pointing device; and

ensuring output values follow changes in input values for said filter comprising steps of using fixed point arithmetic for performing division of said input values and saving the remainder after each said division and adding said remainder to the dividend in the subsequent division.

11. A method as in claim 10, wherein said transmitting step includes a step of transmitting at least three signals in different directions.

12. A method as in claim 10, wherein said transmitting step includes a step of transmitting infrared light signals.

13. A method as in claim 10, wherein said transmitting step includes a step of sequentially pulsing said signals with pulse trains so as to cause said signals to individually and sequentially emit modulated signals.

14. A method as in claim 10, wherein said receiving step includes a step of amplifying said signals to a predetermined pulse frequency.

15. A method as in claim 10, wherein said receiving step includes a step of converting said signals to analog base-band pulses.

16. A method as in claim 15, wherein said receiving step includes a step of digitizing said analog base-band pulses.

17. A method as in claim 10, further comprising a step of controlling said cursor location based on said processing step.