Abstract: An audio converting device including a digital high-pass filter, an expander, a digital low-pass filter, a delta-sigma modulator, a digital-to-analog converter, an analog low-pass filter and a gain control unit is provided. The digital high-pass filter in this invention can filter out a direct-current component of digital audio data such that the production of noise is avoided when the volume is adjusted by users.

Abstract: A sample rate converting device includes a noise shaper and a sample rate converter. The noise shaper is for receiving a digital input signal, noise-shaping the digital input signal, and then outputting an n-bit digital stream. The sample rate converter, which is coupled to the noise shaper, receives the n-bit digital stream and outputs a digital output signal. Since the n-bit digital stream is a digital signal with a smaller number of bits in each sample, the computation efforts of interpolation are reduced. Hence, less resource is needed to complete the conversion.

Abstract: The present invention offers an over-sampling digital-to-analog converter with variable sampling frequencies to process input signals of variable sampling frequencies. The over-sampling digital-to-analog converter comprises an expander, which expands said input signals with a fixed rate of M to produce over-sampling signals; a digital low-pass filter, which filters out high-frequency ingredients of over-sampling signals and then outputs data with a first rate; a data buffer, which receives the outputted data by said digital low-pass filter with the first rate and outputs the data with a second rate; a modulator, which reads data in said data buffer with the second rate and modulates the data; a digital-to-analog converter, which converts the modulated data to analog signals; and an analog low-pass filter, which filters out high-frequency ingredients of said analog signals for producing output signals.

Abstract: A sample rate converting device includes a noise shaper and a sample rate converter. The noise shaper is for receiving a digital input signal, noise-shaping the digital input signal, and then outputting an n-bit digital stream. The sample rate converter, which is coupled to the noise shaper, receives the n-bit digital stream and outputs a digital output signal. Since the n-bit digital stream is a digital signal with a smaller number of bits in each sample, the computation efforts of interpolation are reduced. Hence, less resource is needed to complete the conversion.

Abstract: The present invention offers an over-sampling digital-to-analog converter with variable sampling frequencies to process input signals of variable sampling frequencies. The over-sampling digital-to-analog converter comprises an expander, which expands said input signals with a fixed rate of M to produce over-sampling signals; a digital low-pass filter, which filters out high-frequency ingredients of over-sampling signals and then outputs data with a first rate; a data buffer, which receives the outputted data by said digital low-pass filter with the first rate and outputs the data with a second rate; a modulator, which reads data in said data buffer with the second rate and modulates the data; a digital-to-analog converter, which converts the modulated data to analog signals; and an analog low-pass filter, which filters out high-frequency ingredients of said analog signals for producing output signals.

Abstract: The present invention is to provide a device and a method of sample rate conversion for digital image. With the present invention, the alias effect caused by shrinking the image and the blurred effect caused by enlarging the image will be eliminated. The device of the present invention comprises a ratio-adjustable expander used to receive image signal, increase the sample rate of the image M times based on the adjusting ratio for the image to generate a expanding signal; a low pass filter (LPF) used to receive the expanding signal from the expander, filter out the high rate and output the filtered signal; and a fix ratio decimator used to receive the filtered signal, low down the sample rate by N times and generate the output signal. The value of M will be changed with the adjusting ratio while the value of the N is fixed. The LPF includes the factor 1+z−1+ . . . +z−(N−1) and the factor 1+z−1+ . . . +z−(M−1).

Abstract: The present invention discloses an FSK/GFSK demodulator with digital frequency offset compensation, comprising: an FSK/GFSK signal demodulator, for receiving a transmission signal from an antenna and generating an inter-medium frequency (base-frequency) signal after amplification and filtering; an analog-to-digital converter (ADC), for receiving the inter-medium frequency (base-frequency) signal from the FSK/GFSK signal demodulator and converting the signal into a digital signal; a digital frequency discriminator, for receiving the digital signal from the analog-to-digital converter and generating a discriminated signal; a digital band-pass filter, for filtering off a high-frequency component and a DC component of the discriminated signal and generating a demodulated signal; and a data slicer, for receiving the demodulated signal and generating a received signal. The digital band-pass filter is composed of a digital low-pass filter and a digital high-pass filter connected in series.

Abstract: An audio converting device including a digital high-pass filter, an expander, a digital low-pass filter, a delta-sigma modulator, a digital-to-analog converter, an analog low-pass filter and a gain control unit is provided. The digital high-pass filter in this invention can filter out a direct-current component of digital audio data such that the production of noise is avoided when the volume is adjusted by users.