6 results about "Raised-cosine filter" patented technology

The application discloses a kind of communication signal parameter blind estimation methods, devices and program products for intelligent instrument, involve signal identification field, to with low complexity calculation cost, accurately estimate the carrier frequency offset value of electromagnetic signal, symbol rate and pulse shaping filter type.The application carries out normalization to received signal, carrier frequency offset rough correction, estimates carrier frequency offset and meets rate, carries out the pre-estimation of pulse shaping filter type from the spectrum diagram of rough correction signal, and, for square root raised cosine filter / Raised cosine filter, first sequentially carrier frequency offset correction is carried out to first signal, based on square root raised cosine filter Matching filter, and based on symbol rate construction constellation diagram, finally according to constellation diagram, distinguish whether square root raised cosine filter or Raised cosine filter.The application realizes comprehensive, accurate, reliable estimation to electromagnetic signal parameter with low calculation complexity, realizes the automation and wisdom of electromagnetic signal measurement.

The application relates to the technical field of optical communication, in particular to a method for suppressing low-frequency noise, which comprises the following steps: at a sending end, converting an input original service signal into a digital signal to obtain a digital signal sequence; performing a shaping filter operation on the up-sampled digital signal sequence by using a root-raised cosine filter, then performing a frequency spectrum inversion operation on the filtered digital signal sequence to obtain an inverted digital signal sequence; in a channel, transmitting the inverted digital signal sequence, and simultaneously introducing a low-frequency noise signal; at a receiving end, performing a frequency spectrum inversion operation on the digital signal sequence with the introduced low-frequency noise signal, then performing a root-raised cosine matching filter operation and a down-sampling operation to obtain and output a final digital signal. The application does not need to introduce additional devices, thereby reducing the cost of a communication system; the algorithm has low complexity, and the flexibility of suppressing the low-frequency noise is high; even if the low-frequency noise is randomly changed, the application still has a good suppression effect.

The invention provides a timing estimation method and device, electronic equipment, a storage medium and a product. The method comprises the steps of obtaining a raised cosine filtering peak value, a peak value left-side correlation value and a peak value right-side correlation value; based on the peak value, the peak value left-side correlation value and the peak value right-side correlation value, determining a target loss function and a gradient value corresponding to the target loss function; iteratively decreasing and updating the gradient value based on a preset adjustment step length; and when the updated gradient value meets a target threshold value, determining a timing estimation result. Therefore, compared with an existing estimation method based on quadratic function approximate fitting, the method has the advantages that the target loss function is constructed by directly utilizing the peak value and related value information of the raised cosine filter, continuous optimization is carried out in a gradient descent iteration mode, and estimation can be carried out by fitting the actual characteristics of the impulse response function of the raised cosine filter better.

The invention discloses a modulation and demodulation method for unmanned aerial vehicle communication, which is realized based on a Xilinx Zynq-7000 series FPGA (Field Programmable Gate Array) hardware platform and is suitable for a 50km-level long-distance and high-speed moving scene. A modulation end adopts a 3pi / 8 dynamic phase rotation algorithm to eliminate phase ambiguity, an I / Q signal is generated through an assembly line CORDIC algorithm, a raised cosine filter with a roll-off coefficient of 0.35 is configured, and out-of-band rejection is greater than 45dB. A demodulation end combines an improved Costas ring and a Gardner timing synchronization technology, can realize + / -25kHz frequency offset capture and 0.5-degree RMS phase tracking precision, adopts a normalized LMS equalizer to suppress multipath distortion, and integrates a diversity antenna dynamic switching mechanism. A layered clock architecture and a resource reuse strategy are adopted in the system, logic resource occupation and power consumption are reduced, and 20 / 5MBaud symbol rate dynamic switching is supported. According to actual measurement, the throughput reaches 48.6 Mbps under the transmission distance of 52 km, the end-to-end time delay is smaller than 12.7 ms, the system can adapt to the temperature environment of-40 DEG C to + 85 DEG C and the high-speed moving condition of 200 km / h, frequency hopping anti-interference and error correction capacity is achieved, and the high-reliability communication requirement of the unmanned aerial vehicle in the complex environment is met.

The application discloses a kind of root raised cosine filter-based optical fiber identification method, first utilize optical fiber imaging system to obtain optical fiber image, then adjust to certain width with fiber core width, utilize root raised cosine filter to the optical fiber brightness curve filtering, calculate the height difference, height ratio or width ratio of peak and valley in the filtered optical fiber brightness curve and other characteristic parameters to distinguish four common optical fibers.The application first applies root raised cosine filter in signal processing to optical fiber identification, realizes the wave formation shaping process of optical fiber brightness curve by filter, makes optical fiber brightness curve more standard, more easily extracts the characteristics of optical fiber brightness curve, so as to realize the rapid identification of optical fiber type, and improve the accuracy of optical fiber identification.

A system may include an analog front-end circuit configured to receive signals from an antenna array and a digital circuit coupled to the analog front end. The digital circuit may include a digital beamforming circuit configured to include a Nyquist fractional delay filter that is piecewise continuous in the frequency domain. The Nyquist fractional delay filter may be implemented as a Gaussian Nyquist filter, a generalized raised cosine Nyquist filter, or another Nyquist filter. The fractional delay filter may be critically sampled and evaluated numerically or with a closed-form time-domain expression. The fractional delay filter may be part of a digital beamforming phased array antenna system.