Digital signal

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

A digital filterbank hearing aid-design, implementation and evaluation

Abstract: A digital filterbank that can be used in a hearing aid is proposed. Complementary interpolated linear phase impulse-response filters are used to minimize the number of multiplications per sample. The filterbank has eight bands, each with sidelobes of about 40 dB. It can be realized with a total of 27 multiplications. If a multiplication with 0.5 is implemented as a shift, then the total will be 19. The hearing aid was implemented on a general-purpose digital signal processor for real-time evaluations. A portable processor system based on Texas TMS320E25 was constructed for testing under real-world conditions. >

Bar code scanner and method

Abstract: A scanner for scanning bar code labels and for providing data related thereto to a host computer includes a scanning apparatus for optically scanning bar code labels and for providing an electrical signal in response thereto, and a decoding circuit, responsive to the scanning apparatus for translating the electrical signal into a digital signal. A microprocessor, responsive to the decoding circuit, controls operation of the scanner and translates the digital signal into data to be provided to the associated host computer under control of control characters. The scanner further includes a non-volatile random access control memory in which control characters are stored, and an interface, connected to the host computer and to the microprocessor, for transferring data from the microprocessor to the host computer and for transferring control characters from the host computer to non-volatile random access control memory via the microprocessor.

X-ray detectors with digitized preamplifiers

Abstract: With direct digitization of detector pulses, software algorithms are used to calculate the energy of incident photons. Fast high resolution sampling adc's and digital signal processors replace shaping amplifiers and spectroscopy adc's. The difference between the classical analog approach for pulse processing and direct digitization can be summerized as follows. In analog systems, a preamplifier output is filtered by analog means and then digitized to be acquired in a multichannel analyzer, whereas the full digital system will digitize first and then filter by application of algorithms. According to the sampling theorem, both approaches are equivalent. However, using digital signal processing for filtering allows the use of filter functions that cannot be practically realized with analog means. Those digital filter functions promise resolution and throughput close to the theoretical limit. The first commercially available ADSP (Analog to Digital Signal Processor) uses a moving window deconvolution to deconvolve the preamplifier characteristic. All algorithms are calculated in real time, thus there is no dead time added through the computation of an event. A filter function with a trapezoidal impulse response calculates the energy in real time. An adaptive digital trigger allows excellent low energy detection. Another benefit for X-ray applications are very long shaping constants, resulting in 125 eV resolution at 5.9 keV with SiLi detectors. The ADSP consists of an analog linear amplification stage, a 20 MHz sampling adc, circuits for digital signal preprocessing, and four floating point DSPs, performing 240 MFLOP/s. It has been built into a 2-wide NIM module to replace virtually any adc/shaping amplifier combination.

Digital transmisson including add/drop module

Abstract: In a transmission system, adding and/or dropping any one or more of a plurality of digital signals of one or more digital transmission bit rates is facilitated by employing a un- lque transmission signal in which data words associated with Individual digital signals are arranged in prescribed groups. The transmission signal data word groups are obtained by formatting the individual digital signals to be combined into a unique channel frame format common to all of the digital signals and by employing a unique one-step multiplexing process to insert digital words from the channel frames into the group of data word positions in the transmission signal associated with the particular signal being combined. Consequently, digital signals may be added to the transmission signal by formatting them into the common channel frame format and, then, inserting the digital words therefrom in the one-step multiplexing process into an associated group of data words positions in the transmission signal. Digital signals are dropped from the transmission signal by extracting associated groups of data words from the transmission signal, identifying the corresponding channel frames and deformatting the data bits from channel frames of corresponding digital signals being reconstructed.

Cooperative feedback system and method for a compensation system associated with a transmitter or codec

Abstract: A cooperative feedback system (210) is provided for a compensation system associated with a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network (113). The cooperative feedback system is particularly suited for providing feedback to a compensation system (130) for correction distortion resulting from rob bits signaling (RBS), digital loss, or other types of digital signal degradation. The cooperative feedback system includes a compensation selector (204) in a transmitter (181) that combines compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. A receiver (214) is configured to receive the modified digital data frames (118b) from the digital network (113), to determine if accuracy of each of the modified digital data frames has increased based upon a corresponding compensation, and to communicate one or more quality feedback signals (118a) to the transmitter (181) via the digital network (113). The transmitter (181) receives the quality feedback signal(s) and selects and implements the compensation that yields a highest accuracy based upon the quality feedback signal(s).