Embodiments provide a device for removing noise of a power source and an apparatus for converting an audio signal, which remove a noise component which comes from a power source terminal of an audio signal converting apparatus stepwise and transfer power to a converting unit and an amplification unit included in the audio signal converting apparatus from a power source terminal to remove power noise.

Aspects of this disclosure relate to a VLIF receiver with automatic phase noise adjustment. The presence of an interfering signal is sensed within a bandwidth around a desired channel frequency. Then the local oscillator phase noise is automatically adjusted to optimize blocking. The phase noise adjustment includes increasing the bandwidth of a phase-locked loop.

The present invention is a modular signal converting apparatus and method, and particularly, discloses a signal converting apparatus, which is modularized for playback of digital contents and is usable while being combined with another electric device.

The embodiments provide an apparatus for converting an audio signal, in which a left channel line and a right channel line connected to an amplification unit of an audio signal converting apparatus are covered with the ground and connected to a chassis of the audio signal converting apparatus, and a digital signal line and an analog signal line are disposed to be spaced apart from a substrate to improve crosstalk and remove noise.

Embodiments provide a device for removing noise of a power source and an apparatus for converting an audio signal, which remove a noise component which comes from a power source terminal of an audio signal converting apparatus stepwise and transfer power to a converting unit and an amplification unit included in the audio signal converting apparatus from a power source terminal to remove power noise.

Various embodiments relate to a method for calibration of a center frequency of a BPF in an FSK transceiver, the method including the steps of filtering a carrier frequency signal by the BPF to produce a filtered signal, detecting, by a phase-frequency detector (PFD), a difference in phase between the carrier frequency signal and the filtered signal from the BPF, sweeping a calibration code of the BPF, detecting a transition in the sign of the phase difference and capturing a calibration code associated with the transition in the sign of the phase difference for calibration of the BPF.

Aspects of this disclosure relate to a VLIF receiver with automatic phase noise adjustment. The presence of an interfering signal is sensed within a bandwidth around a desired channel frequency. Then the local oscillator phase noise is automatically adjusted to optimize blocking. The phase noise adjustment includes increasing the bandwidth of a phase-locked loop.

The present invention proposes an audio signal muting apparatus setting and adjusting a time for removing pop noise and muting an audio signal based on the set and adjusted timing. Further, the present invention proposes a digital signal converting apparatus for muting an analog audio signal based on a timing for removing pop noise when converting a digital audio signal into an analog audio signal in connection with an audio signal reproducing apparatus.

An audio system having a variable reset volume, and a method of conditionally resetting a volume parameter, are described. The audio system can include a processor to generate an audio signal for a speaker to convert into a sound. A volume parameter of the audio signal can be set before a user pauses playback of the audio signal. The processor can determine that the volume parameter is outside of a resting volume range, and that the user resumes playback of the audio signal at least a selected interval after pausing playback. The processor can responsively reset the volume parameter when playback is resumed to a different level based on one or more acoustic factors, such as an audio decay time of a surrounding environment. The different level can be within the resting volume range. Other aspects are also described and claimed.

Provided is a sound pickup loudspeaker apparatus that has a mechanism for detecting situations in which sound amplification should not be performed and stopping sound amplification from a speaker. The sound pickup loudspeaker apparatus is installed in a vehicle. At least a sound pickup position and a sound amplification position are assumed to be present in the vehicle. The sound pickup loudspeaker apparatus includes a noise level estimation unit that determines a noise level that is an estimated value of the magnitude of a noise component included in a sound pickup signal obtained from a microphone that collects sound emitted from the sound pickup position, and a control unit that performs control such that (i) when the noise level is not greater than a predetermined threshold value or is less than the threshold value, an acoustic signal based on the sound pickup signal is played back from a speaker at the sound amplification position, and (ii) when the noise level is greater than the threshold value or is at least the threshold value, the acoustic signal is not played back from the speaker.