Clock system and method for reducing the measured level of unintentional electromagnetic emissions from an electronic device
First Claim
1. A clock system for reducing the measured level of electromagnetic emissions, measured by a measuring device employing a C.I.S.P.R. quasi-peak detector tuned to a narrow band frequency range, from an electronic device having unintentional electromagnetic emissions at frequencies derived from the system clock frequency, comprising:
- a variable frequency system clock; and
means for varying the frequency of said variable frequency system clock in a range between first and second predetermined frequencies such that the system clock is operating outside the narrow band frequency range for a time period substantially greater than the time period the system clock is operating in the narrow band frequency range to spread the emission energy over the frequency range and reduce the measured electromagnetic emission levels at the narrow band frequency range to which the measuring device is tuned.
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Abstract
A clock system and method for reducing the measured level of electromagnetic emissions, measured by a measuring device employing a C.I.S.P.R. quasi-peak detector from an electronic device having unintentional electromagnetic emissions at frequencies derived from a system clock is achieved by varying the frequency of the system clock in a range between first and second predetermined frequencies to spread the emission energy over the frequency range and reduce measured emission levels.
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Citations
8 Claims
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1. A clock system for reducing the measured level of electromagnetic emissions, measured by a measuring device employing a C.I.S.P.R. quasi-peak detector tuned to a narrow band frequency range, from an electronic device having unintentional electromagnetic emissions at frequencies derived from the system clock frequency, comprising:
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a variable frequency system clock; and means for varying the frequency of said variable frequency system clock in a range between first and second predetermined frequencies such that the system clock is operating outside the narrow band frequency range for a time period substantially greater than the time period the system clock is operating in the narrow band frequency range to spread the emission energy over the frequency range and reduce the measured electromagnetic emission levels at the narrow band frequency range to which the measuring device is tuned. - View Dependent Claims (2, 3, 4)
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5. A clock system for reducing the measured level of electromagnetic emissions, measured by a measuring device employing a C.I.S.P.R. quasi-peak detector tuned to a narrow band frequency range, from an electronic device having unintentional electromagnetic emissions at frequencies derived from the system clock frequency, comprising:
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a variable frequency system clock; and means for varying the frequency of said variable frequency system clock in a range between first and second pre-determined frequencies such that a time period that the system clock is operating in the narrow band frequency range is of short enough duration to spread the emission energy over the frequency range and reduce the measured electromagnetic emission levels at the narrow band frequency range to which the measuring device is tuned. - View Dependent Claims (6, 7, 8)
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Specification