Method and apparatus for reducing or removing click noise
The invention relates to an apparatus and a method for detecting and correcting input signals regarding click noise, using a first detector unit and a second correction unit, the detector unit differentiates the input signal and extracts the noise signal and compares the sum of two noise samples with a threshold value and in case this sum exceeds the threshold value a click is observed, while the correction unit corrects the input signal in the phase domain and differentiates it prior to outputting the corrected signal.
1. A method for detecting and correcting click noise in input signals processed by an FM radio receiver, the method comprising:
differentiating, with a detector unit, first and second input phase signals;
extracting, with the detector unit, first and second noise signals;
comparing, with the detector unit, a sum of the first and second noise signals with a threshold value;
detecting, with the detector unit, the click noise when the sum exceeds the threshold value;
correcting, with the correction unit, the first input phase signal; and
outputting a differentiated version of the corrected phase signal.
2. A method according to claim 1 , wherein the differentiation creates an MPX signal.
3. A method according to claim 1 , wherein the extraction takes place in a block an subtracts a low pass filtered signal from a delayed signal.
4. A method according to claim 1 , further comprising:
adding two consecutive noise signals to create a further signal;
comparing an absolute value of the further signal with a predetermined threshold value; and
detecting the clock noise when the absolute value exceeds the predetermined threshold value.
5. A method according to claim 1 , further comprising:
correcting a predetermined number of phase signals after detecting the click noise.
6. A method according to claim 5 , further comprising:
correcting three phase signals.
7. A method according to claim 1 , wherein the method has been implemented within a digital signal processor.
8. An apparatus configured to reduce click noise in input phase signals processed by an FM radio receiver, the apparatus comprising:
a detector unit that is configured to differentiate the first and second input phase signals, extract first and second noise signals, compare a sum of the first and second noise signals with a threshold value, and detect the click noise when this sum exceeds the threshold value; and
a correction unit that is configured to correct the first input phase signal and output a differentiated version of the corrected phase signal.
9. An apparatus according to claim 8 , wherein the click noise is removed.