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702 results about "Gain factor" patented technology

The amplification factor, also called gain , is the extent to which an analog amplifier boosts the strength of a signal . Amplification factors are usually expressed in terms of power .

Using gain-adaptive quantization and non-uniform symbol lengths for improved audio coding

Techniques like Huffman coding can be used to represent digital audio signal components more efficiently using non-uniform length symbols than can be represented by other coding techniques using uniform length symbols Unfortunately, the coding efficiency that can be achieved by Huffman coding depends on the probability density function of the information to be coded and the Huffman coding process itself requires considerable processing and memory resources. A coding process that uses gain-adaptive quantization according to the present invention can realize the advantage of using non-uniform length symbols while overcoming the shortcomings of Huffman coding. In gain-adaptive quantization, the magnitudes of signal components to be encoded are compared to one or more thresholds and placed into classes according to the results of the comparison. The magnitudes of the components placed into one of the classes are modified according to a gain factor that is related to the threshold used to classify the components. Preferably, the gain factor may be expressed as a function of only the threshold value. Gain-adaptive quantization may be used to encode frequency subband signals in split-band audio coding systems. Additional features including cascaded gain-adaptive quantization, intra-frame coding, split-interval and non-overloading quantizers are disclosed.
Owner:DOLBY LAB LICENSING CORP

Class-D amplifier having high order loop filtering

An amplifier having an active and passive gain stage connect to a load for driving a load according to a system analog input. A first embodiment of the amplifier in accordance with the present invention includes a logic network connected between a comparator network and a switching system, wherein the comparator network connects to the passive gain stage. Specifically, the active gain stage may include an active filter connected to receive an analog or digital input and provide a difference between the analog or digital input and the feedback signal relative to the gain factor of a gain unit connected to the active filter. The passive gain stage includes a passive filter. The logic network generates at least one switching signal which controls the switching system that includes at least one switching device to selectively provide power to the load. An output signal from the switching system provides output for the amplifier and is fed back to the active gain stage. In another embodiment, the output is a two-level signal and the passive and active filters are second order low pass filters, where the gain factor is about 25 or more. In yet another embodiment, the gain factor is approximately 250. Moreover, the amplifier may include a digital delta-sigma modulator connected to supply a two level input.
Owner:TEXAS INSTR INC

Feedforward prediction of scalefactors based on allowable distortion for noise shaping in psychoacoustic-based compression

A method of encoding a digital signal, particularly an audio signal, which predicts favorable scalefactors for different frequency subbands of the signal. Distortion thresholds which are associated with each of the frequency subbands of the signal are used, along with transform coefficients, to calculate total scaling values, one for each of the frequency subbands, such that the product of a transform coefficient for a given subband with its respective total scaling value is less than a corresponding one of the distortion thresholds. In an audio encoding application, the distortion thresholds are based on psychoacoustic masking. The invention may use a novel approximation for calculating the total scaling values, which obtains a first term based on a corresponding distortion threshold, and obtains a second term based on a sum of the transform coefficients. Both of these terms may be obtained using lookup tables. The total scaling values can be normalized to yield scalefactors by identifying one of the total scaling values as a minimum nonzero value, and using that minimum nonzero value to carry out normalization. Encoding of the signal further includes the steps of setting a global gain factor to this minimum nonzero value, and quantizing the transform coefficients using the global gain factor and the scalefactors.
Owner:CIRRUS LOGIC INC

Device-to-device (D2D) cluster data sharing method under cellular environment

The invention discloses a device-to-device (D2D) cluster data sharing method under a cellular environment. The method comprises the following steps that: step1. before D2D cluster retransmission begins, each mobile equipment in the D2D cluster firstly acquires a packet error matrix (PEM) which belongs to the mobile equipment itself; step 2. a retransmission gain factor of the each mobile equipment in the D2D cluster is calculated; step 3. the mobile equipment with the highest retransmission gain factor is taken as a transmitter in the D2D cluster retransmission; step 4. the transmitter retransmits a data packet needed to be retransmitted in the cluster and updates the PEM of the each mobile equipment; step 5. if the updated PEM still contains a ''0'' element, the step 1 to the step 4 are repeated till the PEMs of all the mobile equipment in the D2D cluster are ''1'' matrixes. In the method of the invention, through effectively reducing retransmission times in the D2D cluster, related signaling costs of D2D communication under the cellular environment can be substantially saved and simultaneously system time delay can be shortened. The method is beneficial to realization of a real time multimedia service.
Owner:SHANGHAI RES CENT FOR WIRELESS COMM
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