Digital signal

About: Digital signal is a research topic. Over the lifetime, 44213 publications have been published within this topic receiving 345279 citations.

Device and method for data compression/decompression using a discrete wavelet transform

Abstract: An apparatus produces an encoded and compressed digital data stream from an original input digital data stream using a forward discrete wavelet transform and a tree encoding method. The input digital data stream may be a stream of video image data values in digital form. The apparatus is also capable of producing a decoded and decompressed digital data stream closely resembling the originally input digital data stream from an encoded and compressed digital data stream using a corresponding tree decoding method and a corresponding inverse discrete wavelet transform. A dual convolver is disclosed which performs both boundary and nonboundary filtering for forward transform discrete wavelet processing and which also performs filtering of corresponding inverse transform discrete wavelet processes. A portion of the dual convolver is also usable to filter an incoming stream of digital video image data values before forward discrete wavelet processing. Methods and structures for generating the addresses to read/write data values from/to memory as well as for reducing the total amount of memory necessary to store data values are also disclosed.

Method and apparatus for generating a pulse width modulated signal

Abstract: A method and apparatus for a pulse width modulated (PWM) signal (30, 130) is provided. The input is a digital signal which is a modulated signal (24, 124). In the illustrated form, the modulated input signal is either a PDM signal or a PCM signal. In one embodiment of the present invention a PCM to PWM converter (16, 116) includes correction of duty ratio circuitry (48). The methodology used may include recursion on the values obtained after prediction, interpolation, and correction. The digital to analog conversion system (10) uses a PDM to PWM converter (20) which operates in an all digital domain and includes no analog circuitry.

Digital radio transmission system

Abstract: A digital radio transmission system for compensating for co-channel or adjacent channel interference or signal level variations and distortions is provided. The system includes apparatus for transmitting a digital signal having a first signal level from a first location to a second remote location, apparatus for monitoring at the second remote location the bit error rate of the received digital signal and apparatus for changing the level of the transmitted digital signal when the received bit error rate is different from a predetermined value.

Apparatus and method for deriving a digital image correction factor in a receiver

Abstract: An apparatus and method for deriving a digital image correction factor in a receiver. In one embodiment, a receiver circuit may include an error detection circuit configured to receive a digital signal comprising in-phase (I) and quadrature (Q) components and to detect an error in a complex image correction factor, and an error correction circuit coupled to the error detection circuit and configured to modify the complex image correction factor dependent upon the detected error. In one specific implementation of the receiver circuit, the error detection circuit and the error correction circuit may be coupled in a feedback loop, where the error detection circuit may be configured to iteratively detect the error in the complex image correction factor, and where the error correction circuit may be configured to iteratively correct the error.

Subtraction of electrocardiographic signal from respiratory electromyogram

Abstract: Presented is a method to selectively suppress interfering electrocardiographic artifacts from the surface-recorded respiratory muscle electromyographic (EMG) signal. This method has application in the frequency analysis of respiratory muscle EMG.