Average power control of wireless transmission having a variable duty cycle

• US 20080232436A1
• Filed: 03/21/2007
• Published: 09/25/2008
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: Novanta Inc.
• Original Assignee: TZero Technologies Incorporated (Novanta Inc.)
• Inventors: Schwartz, Adam L., Arnott, James Christopher
• Granted Patent: US 7,733,979 B2
• Time in Patent Office: Days
• US Class Current: 375/146
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 2200/105 A non-specified detector of the power of a signal being used in an amplifying circuit
• CPC Class Codes: H03F 2200/393 A measuring circuit being coupled to the output of an amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/287 when the channel is in stand-by

Abstract

A method an apparatus for controlling a transmission signal power level of a transmitter is disclosed. The method includes receiving a root-mean-squared target power level. A duty cycle of a transmission signal is determined that indicates power on and power off periods over a predetermined sensing interval. A transmission signal power level is sensed. The transmission signal power level is adjusted to be approximately equal to the target power level divided by the duty cycle.

Claims

1. A method of controlling a transmission signal power level of a transmitter, comprising:

receiving a target power level;

determining duty cycle of a transmission signal that indicates power on and power off periods over a predetermined sensing interval;

sensing a transmission signal power level;

adjusting the transmission signal power level to be approximately equal to the target power level divided by the duty cycle.

2. The method of claim 1, further comprising:

receiving a transmission indicator that is active during transmission of signals;

sensing the transmission signal power level while the transmission indicator is active.

3. The method of claim 1, wherein the target power level is a root-mean-squared target power level of −

41.3 dBm/MHz over a 1 mS period.

4. The method of claim 1, wherein the predetermined sensing interval is 1 mS.

5. The method of claim 1, wherein the transmission signal power level is adjusted by an adjustable gain amplifier of a transmitter chain of the transmitter.

6. The method of claim 1, wherein the transmission signal power level is adjusted after the predetermined sensing interval.

7. The method of claim 1, wherein the transmission signal power level is adjusted while the transmission indicator is inactive.

8. The method of claim 2, wherein sensing a transmission signal power level of the transmission signal comprises:

taking M measurements of a power level of a transmission packet;

computing a first instantaneous power level by averaging the M measurements.

9. The method of claim 8, further comprising computing a second instantaneous power level of the transmission signal, comprising:

sensing the first instantaneous power level of N transmission packets; and

computing the second instantaneous power level by detecting the maximum of the first instantaneous power levels of the N transmission packets.

10. The method of claim 8, further comprising computing a second instantaneous power level of the transmission signal, comprising:

sensing the first instantaneous power level of N transmission packets; and

computing the second instantaneous power level by averaging the first instantaneous power levels of the N transmission packets.

11. The method of claim 1, wherein the duty cycle of the transmission signal is computed based on the power on-time divided by the sum of the power on-time and the power off-time.

12. The method of claim 1, wherein the duty cycle of the transmission signal is provided by a transmission scheduler.

13. The method of claim 5, wherein the adjustable gain amplifier comprises course gain adjustment settings and a fine gain adjustment.

14. The method of claim 13, wherein the course adjustment settings are controlled by a scheduler, and the fine gain adjustment is controlled to maintain the transmission signal power level.

15. A UWB transmitter comprising:

a power detector for detecting an instantaneous power level of a transmission signal of the transmitter;

an adjustable gain amplifier for adjusting the instantaneous power level of the transmission signal;

a controller for receiving a target power level, and setting the adjustable gain amplifier, wherein the instantaneous power level is made substantially equal to the target power level divided by a duty cycle of the transmission signal.

16. The transmitter of claim 15, wherein detecting an instantaneous power level of a transmission signal of the transmitter comprises:

taking M measurements of a power level of a transmission packet;

computing a first instantaneous power level by averaging the M measurements.

17. The transmitter of claim 16, wherein detecting the instantaneous power level of the transmission signal, comprises:

sensing the first instantaneous power level of N transmission packets; and

computing the instantaneous power level by detecting the maximum first instantaneous power level of the N transmission packets.

18. The transmitter of claim 16, wherein sensing the instantaneous power level of the transmission signal, comprises:

sensing the first instantaneous power level of N transmission packets; and

computing the instantaneous power level averaging the first instantaneous power level of the N transmission packets.

19. The transmitter of claim 15, wherein the duty cycle of the transmission signal is computed based on the power on-time divided by the sum of the power on-time and the power off-time.

20. The transmitter of claim 19, wherein the duty cycle of the transmission signal is provided by a transmission scheduler.

21. The transmitter of claim 15, wherein the target power level is a root-mean-squared target power level of −

41.3 dBm/MHz over a 1 mS period.