Channel Reception Characteristics Through Clock Rate Adjustment

• US 20120218017A1
• Filed: 02/28/2011
• Published: 08/30/2012
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Psion Inc (Zebra Technologies Corporation)
• Original Assignee: Psion Inc (Zebra Technologies Corporation)
• Inventors: ROY, Iain
• Granted Patent: US 8,406,722 B2
• Time in Patent Office: Days
• US Class Current: 327/172
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/12 Neutralising, balancing, or compensation arrangements
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus

Abstract

A method, apparatus and system are described for adjusting the frequency of one or more clock signals used by a device. The one or more clock signals are adjusted by a determined amount when a channel quality metric of an RF channel in use by the device indicates a degradation in the reception quality.

Claims

1. A method for improving reception channel quality comprising:

monitoring a radio frequency channel quality metric (RF metric) of a radio frequency channel in use by a device;

determining as a target clock signal a clock signal used by a clocked component of the device to adjust when the RF metric violates a threshold;

determining a clock adjustment to apply to the target clock signal;

adjusting a rate of the target clock signal according to the clock adjustment; and

returning to monitor the RF metric of the radio frequency channel or an RF metric of another radio frequency channel in use by the device.

2. The method of claim 1, further comprising:

determining a center frequency of the RF channel,

wherein determining the target clock signal to adjust comprises;

determining as the target clock signal a clock signal used by one or more clocked components of the device having a harmonic of the clock signal'"'"'s rate closest to the center frequency of the RF channel.

3. The method of claim 1, further comprising:

determining a center frequency of the RF channel,

wherein determining the target clock signal to adjust comprises;

determining one or more possible clock signals used by one or more clocked components of the device, each of the possible clock signals having a respective rate that has a harmonic within a given range of the center frequency;

determining, for each clock signal of the one or more possible clock signals, an interference value based on a weighted value of a distance between the closest harmonic of the respective clock signal and the center frequency;

selecting, as the target clock signal, the clock signal having the interference value indicative of a clock signal most likely to interfere with the RF channel.

4. The method of claim 3, wherein the weighting value for each clock signal of the one or more possible clock signals is determined based on one or more of:

the power of the clock signal;

a distance between a clock signal path in the device and an antenna for the RF channel; and

a predetermined radiated power from the clock signal path of the device at the antenna for the RF channel.

5. The method of claim 1, further comprising:

determining a center frequency of the RF channel,

wherein determining the target clock signal to adjust comprises;

determining one or more possible clock signals, each of the possible clock signals having a rate that has a harmonic within a given range of the center frequency; and

randomly selecting, as the target clock signal, a clock signal of the one or more possible clock signals.

6. The method of claim 1, further comprising:

determining a frequency band of the RF channel,

wherein determining the target clock signal to adjust comprises;

determining one or more possible clock signals, each of the possible clock signals having a rate that has a harmonic within a given range of the center frequency; and

selecting, as the target clock signal, the clock signal having a greatest overlap between a frequency band of the clock signal and the frequency band of the RF channel.

7. The method of claim 1, further comprising:

determining a plurality of target clock signals to adjust when the RF metric violates the threshold;

determining a plurality of clock adjustments to apply to respective clock signals of the plurality of target clock signals; and

adjusting the plurality of target clock signals according to the respective clock adjustment of the plurality of clock adjustments.

8. The method of claim 1, wherein the RF metric comprises one or more of:

a determined bit error rate of the RF channel;

a determined packet error rate of the RF channel; and

a determined signal to noise ratio of the RF channel.

9. The method of claim 1, further comprising:

determining a received signal strength indicator (RSSI) of the RF channel; and

determining the target clock signal when the RSSI value is above a minimum value threshold.

10. The method of claim 1, further comprising:

receiving the RF metric from the device over a wired or wireless communication path; and

communicating the clock adjustment over the wired or wireless communication path.

11. An apparatus for improving reception channel quality comprising:

a channel monitor component for monitoring a radio frequency channel quality metric (RF metric) of an RF channel used by an RF receiver of a device; and

a clock control component for determining as a target clock signal a clock signal used by a clocked component of the device to adjust when the RF metric is above or below a threshold and for determining a clock adjustment to apply to the target clock signal, the clock control component further for returning to monitor the RF metric of the radio frequency channel or an RF metric of another radio frequency channel in use by the device.

12. The apparatus of claim 11, further comprising a clock source component generating the target clock signal adjusted according to the clock adjustment.

13. The apparatus of claim 11, wherein the clock control component determines the target clock signal as the clock signal of the device components having a harmonic of the clock signal'"'"'s operating rate closest to a center frequency of the RF channel.

14. The apparatus of claim 11, wherein the clock control component determines one or more possible clock signals, each of the possible clock signals operating at a rate that has a harmonic within a given range of a center frequency of the RF channel, determines for each clock signal of the one or more possible clock signals, an interference value based on a weighted value of a distance between the closest harmonic of the respective clock signal and the center frequency of the RF channel, and selects as the target clock, the clock signal having the interference value indicative of a clock signal most likely to interfere with the RF channel.

15. The apparatus of claim 11, wherein the weighting value for each clock signal of the one or more possible clock signals is determined based on one or more of:

the power of the clock signal;

a distance between a clock signal path in the device and an antenna for the RF channel; and

a predetermined radiated power from the clock signal path at the antenna for the RF channel.

16. The apparatus of claim 11, wherein the clock control component determines one or more possible clock signals, each of the possible clock signals operating at a rate that has a harmonic within a given range of the center frequency and randomly selecting, as the target clock signal, a clock signal of the one or more possible clock signals.

17. The apparatus of claim 12, wherein the clock control component determines a plurality of target clock signals to adjust when the RF metric is above or below the threshold, determines a plurality of clock adjustments to apply to respective clock signals of the plurality of target clock signals and controls generation of the plurality of target clock signals by the clock source component according to the respective clock adjustment of the plurality of clock adjustments.

18. The apparatus of claim 11, wherein the RF metric comprises one or more of:

a determined bit error rate of the RF channel;

a determined packet error rate of the RF channel; and

a determined signal to noise ration of the RF channel.

19. The apparatus of claim 11, further comprising:

the radio frequency (RF) receiver receiving an RF signal on at least the RF channel;

the component operating at a rate of the clock signal; and

a clock source providing a base frequency for generating the clock signal for the component of the device.

20. The apparatus of claim 11, further comprising:

a plurality of RF receivers,

wherein the channel monitor monitors a respective RF metric associated with a respective RF channel used by each of the RF receivers.

21. The apparatus of claim 11, wherein a base frequency of the clock signal generated by the at least one clock source varies based on one or more environmental conditions.

22. A system comprising:

an electronic device for improving reception channel quality comprising;

a channel monitor component for monitoring a radio frequency channel quality metric (RF metric) of a radio frequency channel used by an RF receiver; and

a clock control component for determining as a target clock signal a clock signal used by a clocked component to adjust when the RF metric is above or below a threshold and for determining a clock adjustment to apply to the target clock signal, the clock control component further for returning to monitor the RF metric of the radio frequency channel or an RF metric of another radio frequency channel in use by the device; and

a peripheral device comprising;

the clocked component operating at a frequency of the clock signal;

the RF receiver;

a clock source generating the clock signal;

a RF metric component for determining the RF metric associated with the RF receiver and communicating the RF metric to the channel monitor of the electronic device; and

a local clock generator for controlling the clock source to generate the clock signal according to the clock adjustment of the target clock determined by the clock control component of the electronic device.