Circuit and method for detecting AC voltage pulses
AssigneeInfineon Technologies AG
InventorsThomas Hauser, Frank Hurtgen, Christian Kranz
Life of this patent
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Abstract
A detection circuit and method for detecting AC voltage pulses at a defined frequency relate to first transforming an input signal to a low-frequency signal by multiplying the input signal by a mixing frequency. This down-mixed signal can then be filtered and evaluated. The circuit is particularly suitable for identifying charge unit signals in the telephone network.
Claims20
A circuit for detecting AC voltage pulses at a defined frequency, comprising:
- an analog/digital converter unit for converting an input signal to a sequence of sample values;
- at least one mixing stage for multiplying the sequence of sample values by a mixing frequency signal;
- at least one filter stage for defining a permissible intermediate frequency band and for obtaining converted sample values by filtering the sequence of sample values having been multiplied by the mixing signal;
- and
- an evaluation unit for determining whether an AC voltage pulse is present by using the converted sample values.
A telephone portion including a circuit for detecting charge unit signals at a defined frequency, the circuit comprising:
- an analog/digital converter unit for converting an input signal to a sequence of sample values;
- at least one mixing stage for multiplying the sequence of sample values by a mixing frequency signal;
- at least one filter stage for defining a permissible intermediate frequency band and for obtaining converted sample values by filtering the sequence of sample values having been multiplied by the mixing signal;
- and
- an evaluation unit for determining whether a charge unit signal is present by using the converted sample values.
A method for identifying different types of AC voltage pulses each having a defined frequency, the method which comprises:
- digitizing an input signal to form a sequence of digitized sample values;
- obtaining a sequence of converted sample values by converting the sequence of sample values using any desired sequence of steps including multiplying the sequence of sample values by predetermined mixing frequency signals and filtering the sequence of sample values to define a permissible intermediate frequency band;
- and
- using the sequence of converted sample values to determine whether a specific type of AC voltage pulse is present.
Dependencies are inferred from the claim text.