US 6,665,021 B2 · System and process for filtering single tone signals

Abstract

A signal processing system and process for digitally filtering a single tone digital signal is disclosed. The system includes a single tone signal generator, which may or may not perform frequency modulation. The single tone signal generator receives an input signal and generates a frequency indicator which is used internally by the single tone signal generator and is also communicated to a direct realization filter. The direct realization filter uses the frequency indicator to generate a phase offset indicator, which is communicated back to the single tone signal generator. The single tone signal generator uses the frequency indicator and the phase offset indicator to generate a phase-adjusted single tone signal. The direct realization filter generates a filter gain and multiplies the single tone signal with the filter gain to produce a filtered single tone signal.

Claims73

Dependent claims

A direct realization filter comprising:

a phase approximator that receives a frequency indicator and generates a phase offset indicator according to a known desired phase response of the direct realization filter;
a gain approximator that receives the frequency indicator and generates a filter gain according to a known desired gain response of the direct realization filter;
and
a multiplier that receives the filter gain and a single tone signal and multiplies the filter gain by the single tone signal to generate a digitally filtered single tone signal.

1 more element

In a system for generating a digitally filtered single tone signal, the system comprising a single tone signal generator that receives an input signal and a phase offset indicator and generates a frequency indicator and a single tone signal, a direct realization filter coupled to the single tone signal generator for generating the phase offset indicator and the digitally filtered single tone signal, the direct realization filter comprising:

a phase approximator that receives the frequency indicator and generates the phase offset indicator according to a known desired phase response of the direct realization filter;
a gain approximator that receives the frequency indicator and generates a filter gain according to a known desired gain response of the direct realization filter;
and
a multiplier that receives the filter gain and the single tone signal and multiplies the filter gain by the single tone signal to generate the digitally filtered single tone signal.

1 more element

A system for generating a digitally filtered single tone frequency modulated (FM) signal, the system comprising:

a frequency indicator generator that receives an input signal and generates a frequency indicator from which a frequency of an unfiltered FM signal can be derived;
a frequency modulator that receives the frequency indicator and a phase offset indicator and generates the unfiltered FM signal;
and
a post-modulation filter that receives the frequency indicator and the unfiltered FM signal and generates the phase offset indicator and the digitally filtered single tone FM signal, the post-modulation filter comprising
a phase approximator that receives the frequency indicator and generates the phase offset indicator according to a known desired phase response of the post-modulation filter,
a gain approximator that receives the frequency indicator and generates a filter gain according to a known desired gain response of the post-modulation filter, and
a first multiplier that receives the filter gain and the unfiltered FM signal and multiplies the filter gain by the unfiltered FM signal to generate the digitally filtered single tone signal.

4 more elements

A method for generating a digitally filtered single tone frequency modulated (FM) signal, comprising:

receiving an input signal and generating a frequency indicator from which a frequency of an unfiltered FM signal can be derived;
receiving the frequency indicator and a phase offset indicator and generating the unfiltered FM signal;
and
receiving the frequency indicator and the unfiltered FM signal and generating the phase offset indicator and the digitally filtered single tone FM signal by
generating the phase offset indicator according to a known desired post-modulation filter phase response,
generating a filter gain according to a known desired post-modulation filter gain response, and
multiplying the filter gain by the unfiltered FM signal to generate the digitally filtered single tone FM signal.

4 more elements

means for receiving the frequency indicator and generating the phase offset indicator according to a known desired phase response of the direct realization filter;
means for receiving the frequency indicator and generating a filter gain according to a known desired gain response of the direct realization filter;
and
means for receiving the filter gain and the single tone signal and multiplying the filter gain by the single tone signal to generate the digitally filtered single tone signal.

1 more element

A system for generating a digitally filtered single tone frequency modulated (FM) signal, the system comprising:

means for receiving an input signal and generating a frequency indicator from which a frequency of an unfiltered FM signal can be derived;
means for receiving the frequency indicator and a phase offset indicator and generating the unfiltered FM signal;
and
means for receiving the frequency indicator and the unfiltered FM signal and generating the phase offset indicator and the digitally filtered single tone FM signal, comprising
means for receiving the frequency indicator and generating the phase offset indicator according to a known desired phase response of a post-modulation filter,
means for receiving the frequency indicator and generating a filter gain according to a known desired gain response of a post-modulation filter, and
means for receiving the filter gain and the unfiltered FM signal and multiplying the filter gain by the unfiltered FM signal to generate the digitally filtered single tone signal.

4 more elements

A method for generating a digitally filtered single tone frequency modulated (FM) signal, comprising the steps for:

receiving an input signal and generating a frequency indicator from which a frequency of an unfiltered FM signal can be derived;
receiving the frequency indicator and a phase offset indicator and generating the unfiltered FM signal;
and
receiving the frequency indicator and the unfiltered FM signal and generating the phase offset indicator and the digitally filtered single tone FM signal by
generating the phase offset indicator according to a known desired post-modulation filter phase response,
generating a filter gain according to a known desired post-modulation filter gain response, and
multiplying the filter gain by the unfiltered FM signal to generate the digitally filtered single tone FM signal.

4 more elements

Dependencies are inferred from the claim text.

System and process for filtering single tone signals

Life of this patent

System and process for filtering single tone signals

Life of this patent

Abstract

Claims73