Reverse Nyquist slope filter
AssigneeNorth American Philips Corporation
InventorAllen H. Boardman
Life of this patent
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Abstract
A circuit for providing a mirrored version of a preselected transfer function includes a circuit having the preselected transfer function coupled to receive a signal modulated by a signal that is to experience the mirrored transfer function. The modulated signal at the output terminal of this circuit is mixed with a signal at a frequency that is greater than the carrier frequency of the modulated signal. The signal resulting from this mixing operation then is low pass filtered to provide the desired mirrored response.
Claims14
An apparatus for providing a transfer function that is inverse to a preselected transfer function comprising:
- means for providing a carrier signal at a predetermined frequency;
- means for providing an input signal;
- means coupled to said carrier signal means and said input signal means for modulating said carrier signal by said input signal to provide a modulated signal;
- circuit means having said preselected transfer function coupled to receive said modulated signal for providing a first signal in accordance with said modulated signal and said preselected transfer function;
- frequency means for providing a second signal having a second frequency integrally related to which said predetermined frequency;
- and combining means coupled to said circuit means and said frequency means for combining said first and second signals to provide an output signal such that said output signal to said input signal ratio defines a transfer function that is inverse to said preselected transfer function.
A method for providing a transfer function that is inverse to a preselected transfer function comprising the steps of:
- providing a carrier signal at a predetermined frequency;
- providing an input signal;
- modulated said carrier signal by said input signal to provide a modulated signal;
- coupling said modulated signal to a circuit having said preselected transfer function to provide a first signal in accordance with said preselected transfer function and said modulated signal;
- coupling said carrier signal to a frequency circuit that is responsive to said carrier signal for providing a second signal at a frequency corresponding to said predetermined frequency;
- and
- combining said first and second signal to provide an output signal such that said output signal to said input signal ratio defines a transfer function that is inverse to said preselected transfer function.
An apparatus for providing a transfer function that is inverse to a preselected transfer function comprising:
- means for providing a carrier signal at a predetermined frequency;
- means for providing an input signal;
- means coupled to said carrier signal means and said input signal means for modulating said carrier signal by said input signal to provide a modulated signal;
- circuit means having said preselected transfer function coupled to receive said modulated signal for providing a first signal in accordance with said modulated signal and said preselected transfer function;
- frequency means coupled to said carrier signal means for providing a second signal having a second frequency corresponding to said predetermined frequency;
- and
- combining means coupled to said circuit means and said frequency means for combining said first and second signals to provide an output signal such that said output signal to said input signal ratio defines a transfer function that is inverse to said preselected transfer function.
Dependencies are inferred from the claim text.