Patent Document ID: 20020147556
Application ID: 09994814
Patent Status: 0

Claim One:
1. Circuitry for detecting a plurality of tonal signals each having a particular nature in either one of a frequency domain and a time domain while distinguishing the plurality of tonal signals from each other, comprising: a rough frequency analyzing circuit for roughly analyzing an input signal in a frequency band with first accuracy in the frequency or time domain to thereby roughly distinguish the plurality of tonal signals to produce a first result, the frequency band consisting of a plurality of subbands; a plurality of fine frequency analyzing circuits each assigned to particular one of the plurality of subbands which is associated with a particular target tonal signal of the plurality of tonal signals for detecting, in the particular subband, an attribute of a power variation of the target tonal signal with respect to time with second accuracy in a direction of the frequency or time domain to thereby finely identify the target tonal signal to produce a second result, the second accuracy being higher than the first accuracy; and a control circuit for selectively enabling and disabling said plurality of fine frequency analyzing circuits in accordance with the second result; whereby one of said plurality of fine frequency analyzing circuits is enabled which is selected under the control of said control circuit.