44 results about "Polyphase filter bank" patented technology

Disclosed is an amplitude-scaling resilient audio watermarking apparatus and method. An encoding apparatus includes: a polyphase filterbank for dividing an audio signal into a plurality of subbands; a psychoacoustic module for applying a psychoacoustic model to the audio signal to provide a signal-to-mask ratio; a watermark encoder for evaluating an encoding parameter from the subbands according to the signal-to-mask ratio and embedding the encoding parameter and a watermark into subbands corresponding to the middle frequency; and a synthesis filterbank for synthesizing the subband signals to output a watermarked audio signal. A decoding apparatus includes: a polyphase filterbank for dividing a received audio signal into the predetermined number of subbands; an EM estimator for estimating an scale factor from an encoding parameter contained in the audio signal and a watermarked subband according to an EM algorithm, and generating the quantizer step size Δ_d of a decoder according to the amplitude-scaling; a watermark decoder for extracting a watermark from a subband corresponding to the middle frequency considering the quantizer step size; and an integrated determiner for integrating outputs of the watermark decoder to determine a watermark.

A polyphase channelizer converts an intermediate frequency wideband signal into a complex signal that is sampled by parallel analog-to-digital converters having a bank of samplers respectively clocked by staggered clocking signals for respective converters for feeding I and Q quadrature samples to a polyphase filter bank of finite impulse response filters driving a fast Fourier transform processor for providing channelized digital signal outputs. The parallel analog-to-digital converters can operate at lower speeds but are parallel connected for effectively operating at required higher speeds. The channelizer channelizes the wideband signal using a polyphase clock for enabling high speed sampling and converting through low speed parallel analog to digital converters.

The invention discloses a digital channelizing method and circuit, relating to the technical field of broadband reception. The method comprises the following steps of: S1, determining a channel number 2M of a part to be analyzed and an FFT (Fast Fourier Transform Algorithm) point number of a corresponding integrated part during signal reconstruction; S2, determining a multi-phase filter order L after extraction according to a prototype filter order N and the channel number 2M of the part to be analyzed; S3, determining a coefficient of a multi-phase filter group; S4, performing multi-phase filtering on the part to be analyzed; S5, performing Fourier transformation on filtered signals to obtain yA; S6, judging whether the signals distribute in a cross-channel manner or not, if not, executing a step S7, and if so, executing a step S8; S7, performing baseband processing on the obtained signal yA and then outputting a signal yA'; S8, performing Fourier transformation on the signal yA to obtain yS; S9, leading the signal ys to a multi-phase filter group CS in the integrated part for filtering to obtain yf; and S10, interpolating 0 into the obtained signal yf and performing delayed addition to obtain a system output yout. According to the invention, the adaptability to signal reception can be enhanced, and the computation amount is reduced at the same time.

The invention discloses an orthogonal frequency division multiplexing (OFDM) channel estimation method based on a filter bank, which comprises the following steps: generating the complex exponential pilot data having the same center frequency with the OFDM sampling sub-carrier, multiplexing with the information source data, filtering the pilot data corresponding to the pilot on the receiving terminal by a multiphase filter bank which is realized by the N point FFT, then performing the least squares estimation to the output data of each corresponding channel to obtain the initial channel frequency domain estimation data, and obtaining the initial channel frequency domain data of all the sub-carriers through the processing of linear interpolation, then performing the IFFT process, performing the zero fill and the FFT process to the L point major tap coefficients in the time domain, and finally obtaining the channel parameters corresponding to all the positions of the sub-carriers through the interpolation in the frequency domain. The method of the invention solves the defects of poor channel estimation under the condition of low signal to noise ratio in the existing schemes, and have the advantages of stable performance, low cost, low error code floor and the like.

The invention provides a digital channelized receiver system for broadcast signal monitoring. The digital channelized receiver system for broadcast signal monitoring is suitable for synchronous and in-time monitoring on multichannel time-domain overlapped broadcast signals by a broadcast signal monitoring organization, and is suitable for the recording and evidence obtaining of abnormal broadcast signals. The digital channelized receiver system comprises a front signal receiving module, an analog-digital conversion module, a digital channelized module, a component channel detection and demodulation module and a component channel signal recording module. Extraction with a maximum extraction ratio is conducted at the input end of each channel of multichannel time-domain overlapped broadcast sampled signals based on poly-phase filter banks technology by the digital channelized module, and the broadcast sampled signals are deposited into the corresponding RAM addresses according to the channel numbers. When one channel signal is completely deposited, channelization smoothing is conducted according to the corresponding channel number filter parameter deposited in ROM, and time division multiplexing of the filter is realized. According to the digital channelized receiver system for broadcast signal monitoring, synchronous and in-time monitoring on multichannel time-domain overlapped broadcast signals is achieved, the work efficiency is improved, the calculated amount of the system is lowered, and the noise of the receiver is limited to minus 58 d B.

A time scale modification method employs separate bands obtained through an analysis polyphase filter bank with separate time-scale modification processing for the bands. The outputs are combined using a synthesis filter bank. Some constraints are imposed on the time-scale modification processing, such a limitation of the range of overlap adjustment values for bands other than the greatest energy band, to eliminate noise due to aliasing and inter-channel phase mismatch. This invention produces output quality considerably higher than conventional time-domain time-scale modification methods for general music signals with computational requirements comparable to those of conventional time-domain time-scale modification methods.

The invention discloses an integral demodulation method of MF-TDMA non-uniform multi-carriers, and relates to related technologies such as filtering, extraction, digital reconstruction, and modulation and demodulation of digital signal processing in a communication field. Different from an integral demodulation method of uniform channel branches based on a multi-phase filter group, the non-uniform channelization technology based on a total reconstruction modulation filter group is adopted, and flexible reconstruction and integral demodulation of non-uniform TDMA signals with multi-path different symbol rates at any frequency point can be realized in a certain bandwidth by means of processing of an analysis filter, a comprehensive filter and the like. According to the invention, the integral demodulation of the non-uniform multi-path TDMA signals in an FPGA is realized, the number of processing paths is larger, the realization complexity is low, and the cost of a central station demodulator is lowered; in addition, when the method is applied to a central station of a large-capacity TDMA satellite communication system, the system is more flexible in networking processing mode, is higher in processing capability and is compatible with a uniform multi-carrier integral demodulation function.

Provided is a broadband multichannel digital correlation receiver. The broadband multichannel digital correlation receiver comprises a digital acquisition module used for inputting an intermediate-frequency analog broadband signal, performing poly-phase filtering channelization processing and quantification processing on the intermediate-frequency analog broadband signal, and obtaining a quantified orthogonal signal; a correlation processing module connected with the digital acquisition module and used for receiving the quantified orthogonal signal, performing multiple correlation operation on the quantified orthogonal signal, and obtaining a multiple correlation result; and a synchronous control module connected with the digital acquisition module and the correlation processing module to perform control and used for receiving a state signal and the multiple correlation result of the digital acquisition module and the correlation processing module and packing the received state signal and the multiple correlation result for output. According to the receiver, poly-phase filtering channelization processing of the intermediate-frequency analog broadband signal is performed by employing a poly-phase filter bank and a cascaded half-band filter bank so that the bandwidth and the central frequency point of a baseband signal required to be observed can be flexibly selected, and the influence brought by radio interference of an external environment is reduced.

The invention discloses an improved generation method of a multiphase filter, and belongs to the field of radio techniques. The method comprises the following steps of according to operation requirement parameters, generating an FIR filter based on a window function method of the FIR filter; dividing the FIR filter into n first sub-filters, to form n multiphase filter banks, wherein n is more than and equal to 2; further dividing the FIR filter into n second sub-filters, using second sub-filters of which the passband is adjusted as baseband filters, and adding the baseband filter between each two adjacent first sub-filters, wherein the passband of the added baseband filter is within the stop band of the two first sub-filters connected therewith. The method is applied to the multiphase filter, and can effectively eliminate spectral interference between the filter banks.

A full spectrum modulator processes a plurality of CATV channels from separate paths. Each path has (i) a first filter for pulse shaping an input channel signal and upsampling a channel frequency thereof, (ii) an interpolator for interpolating the output of the first filter to a common sample rate, and (iii) a decimator for centering the output of the interpolator on a predetermined channel bandwidth. An IDFT processor receives channel signal outputs from the decimators. A polyphase filter bank receives IDFT processed parallel channel signals from the IDFT processor. A commutator converts the processed parallel channel signals from the polyphase filter bank to a single stream of data. A second filter upsamples the single stream of data to a fixed output sampling rate and low pass filters alias signals therefrom. Both standard and harmonically related carrier CATV channel frequency plans are accommodated.

Methods to improve the data carrying capacity of CATV DOCSIS systems and other communications systems are disclosed. Communications channels may be more efficiently spaced with reduced or absent guard bands by using receivers with adaptive signal cancellation methods, equalizing circuits, or polyphase filter banks and Fast Fourier Transform signal processing methods to correct for higher levels of cross-talk. QAM type communications channels may also be utilized on a synchronized two-transmitter at a time basis by adjusting the transmitters to predefined signal levels, such as +1, −1, +½, −½ to enable the combined signals to be distinguished at the receiver. These two methods may be combined to create a still higher data throughput system.

This invention discloses a compensation method for time delay in a mobile communication system including: A, determining numbers of multiphase filters in a multiphase filter set according to the accuracy stage of sample period and time delay compensation and getting a set of multiphase filter coefficients by extracting a set of the filters from high stage filters, B, selecting one coefficient from the set of coefficients as the coefficient of a molded filter in radio link, which adjusts time delay of a RF link by the group time delay difference character of the multiphase filter to realize accurate compensation to time delay.

The invention discloses a signal demodulation processing plate for a satellite communication gateway station, including an intermediate frequency signal receiver. The intermediate frequency signal receiver is connected with at least two A/D converters, one A/D converter is directly connected with an FPGA unit, and the rest A/D converters are all connected with a DDC. The DDC is connected with the FPGA unit. The FPGA unit is connected with a DSP unit and a communication interface. The FPGA unit comprises a numerical control oscillation module. The numerical control oscillation module is connected with a cascaded integrator comb filter module. The cascaded integrator comb filter module is connected with a halfband filter module. The halfband filter module is connected with a channelization poly-phase filterbank module. The signal demodulation processing plate for the satellite communication gateway station utilizes the FPGA to achieve the DDC function, and the FPGA unit is internally provided with a channelization poly-phase filterbank, thereby achieving multi-channel signal simultaneous processing on the basis of not increasing the processing plate structure.

A method and apparatus for analyzing an input signal. A nonlinear filter system comprises a plurality of polyphase filter banks corresponding to a plurality of orders of nonlinearity. Each of the plurality of polyphase filter banks is configured to process an input signal with respect to a plurality of selected frequency subbands to generate an output signal that corresponds to a corresponding order of the each of the plurality of polyphase filter banks.

The invention provides an FPGA (field programmable gate array) circuit board and a telescope digital operational board; the FPGA circuit board includes a multi-phase filter module, a Fourier transformmodule, a power detection module and a cache module; the multi-phase filter module is used for performing multi-channel signal parallel filtering on signals from an analog-digital conversion module;the Fourier transform module is used for performing fast Fourier transform on the signals subjected to parallel filtering; the power detection module is used for performing signal power detection on the signals subjected to fast Fourier transform; the cache module is sued for caching the signals subjected to signal power detection. The FPGA (field programmable gate array) circuit board and the telescope digital operational board have the advantages that by providing the Fourier transform module and the multi-phase filter module and combining multistage DDC (direct digital control), PFB (polyphase filter bank), FFT (fast Fourier transform) and FIR (finite impulse response), a best frequency resolution on FPGAs of the same level is achieved; a great bandwidth is provided.