41 results about "Binary frequency shift keying" patented technology

A cost-effective continuous phase logic-based modulator and demodulator are provided to allow communications using binary frequency shift keying (BFSK) as well as M-ary FSK techniques. The modulator of the 1-bit precision modem architecture is based on a 1-bit precision numerically controlled oscillator (NCO), which provides complete programmability with respect to a frequency of the 1-bit precision logic-based modulator and/or demodulator. The 1-bit precision NCO includes an adder and a phase accumulator register which is clocked by a master clock signal. A two-input multiplexer has a single bit symbol value to generate BFSK, or larger input multiplexers can be implemented to provide M-ary FSK. The output of the 1-bit precision NCO is upconverted to an intermediate frequency using a simple logic function, i.e., XNOR logic. Alternatively, the intermediate frequency may be arrived at without the need for upconversion by directly utilizing a harmonic alias at a desired IF frequency. The undesirable portion of the upconverted signal may be suppressed using I/Q image rejection, and/or an appropriate bandpass filter may be used. A band limited, hard limited signal at the high IF is presented to the 1-bit precision demodulator as a receive IF signal, which is treated as a 1-bit quantization of the signal. The receive IF signal is digitally down-converted to a low IF signal to produce an alias signal at the low IF frequency.

The invention provides a carrier communication method and system for a BFSK (Binary Frequency Shift Keying) spread-spectrum power line. The method comprises the following steps of: (1) replacing an information bit of a transmitted data message with a special spread-spectrum PN (Pseudo-random Number) code sequence by a communication sending terminal to generate spread-spectrum data, modulating thespread-spectrum data to a carrier wave sending frequency range according to a BFSK modulation mode, and coupling to the power line through a coupling circuit; (2) detecting an interference state of the power line, automatically selecting a carrier communication frequency range and a communication working mode and simultaneously initiating a message including the working mode and carrier wave information by the communication sending terminal; and (3) sampling modulated BFSK signals by a communication receiving terminal after carrier wave signals received by the power line are modulated by the communication receiving terminal, despreading the signals according to a PN code of the communication receiving terminal to restore out the original information bit, and restoring out a communication message transmitted by the sending terminal according to a stipulated frame format. According to the method provided by the invention, the interference on the power line is automatically monitored, and the best communication frequency range and communication mode are automatically switched, thereby the reliability and the stability of power line carrier communication are improved.

A cost-effective continuous phase logic-based modulator and demodulator are provided to allow communications using binary frequency shift keying (BFSK) as well as M-ary FSK techniques. The modulator of the 1-bit precision modem architecture is based on a 1-bit precision numerically controlled oscillator (NCO), which provides complete programmability with respect to a frequency of the 1-bit precision logic-based modulator and/or demodulator. The output of the 1-bit precision NCO is upconverted to an intermediate frequency using a simple logic function, i.e., XNOR logic. The undesirable portion of the upconverted signal may be suppressed using I/Q image rejection, and/or an appropriate bandpass filter may be used. A band limited, hard limited signal at the high IF is presented to the 1-bit precision demodulator as a receive IF signal, which is treated as a 1-bit quantization of the signal. The receive IF signal is digitally down-converted to a low IF signal to produce an alias signal at the low IF frequency. The received symbols are correlated with expected local frequencies representing a mark and a space. The correlation is integrated in an oversampled manner relative to the symbol interval. A decision is made as to which symbol was received using, e.g., a magnitude comparator.

A BFSK demodulator comprises a three-channel frequency-to-voltage converter, an information signal inputting the first-channel frequency-to-voltage converter, a converted information signal inputting the second-channel frequency-to-voltage converter, wherein outputs of first and second channel frequency-to-voltage converter are connected with a capacitor, a output voltage signal produced by the first and second frequency-to-voltage converters and the capacitor, inputting into a positive terminal of the comparator after high frequency noise filtering through a first low-pass filter, a carrier signal inputs into the third-channel frequency-to-voltage converter; and an output from the third-channel frequency-to-voltage converter connected to a capacitor; and a reference voltage signal is produced after high frequency noise filtering through a second low-pass filter, producing a demodulated signal after comparing the information voltage signal with the reference voltage.

The invention discloses an underwater sound MODEM (modulator-demodulator) for an underwater interphone, which can realize the underwater transmission of coded digital voice data. A single chip microcomputer (MSP430F149) is used as a data processing core, 2FSK (binary frequency shift keying) modulation-demodulation way is adopted, a small-sized receiving-transmitting integrated ultrasonic transducer under mass production and a conventional modulation-demodulation chip are used, a 12V lithium battery is used for supplying power, and an RS-232 (reference standard-232) standard serial interface is equipped. The maximal power consumption of the entire machine is 210mW, the maximal data transmission speed is 2.4kbps, the maximal valid communication distance is 300m, error rate is low, and the real-time performance is good. Since the underwater sound MODEM has characteristics of low cost, low power consumption and small size, the underwater sound MODEM is applicable to the underwater interphone. The underwater sound MODEM can be connected with a voice processor and is used for transparently transmitting the coded voice data, so that the reliable voice communication among diving working personnel can be guaranteed.

A method and a device for transmitting and receiving a signal on the basis of multiple antennas are provided.

A transmitting device may include a radio frequency (RF) module transmitting a quadrature amplitude modulation (QAM) signal of a first symbol corresponding to a hybrid frequency shift keying and quadrature amplitude modulation (FQAM) mode and transmitting a QAM signal of a second symbol corresponding to a QAM mode through a second antenna; and a modulation module mapping the QAM signal of the first symbol to one frequency tone among the preset number of frequency tones according to a frequency shift keying (FSK) signal of the first symbol and mapping the second symbol to the frequency tone to which the first symbol is mapped.

The invention provides an electric energy and signal synchronous wireless transmission method based on soft switching harmonic characteristics. According to the method, a stroboscopic mapping model isadopted to solve all soft switch working points existing in the system, the current resonance characteristics and harmonic content of a primary side current coil of the system under the soft switch working points are calculated and analyzed, fundamental waves of an inverter of the wireless power transmission system at the soft switch working points are taken as energy carriers, and third harmonics are taken as signal carriers. Based on the frequency deviation amplification effect, a binary frequency shift keying (2FSK) modulation method is adopted to achieve signal modulation, a demodulationcircuit is designed to achieve signal demodulation, and finally synchronous wireless transmission of electric energy and signals is achieved. The method can meet the requirements of high-speed and high-accuracy wireless transmission of signals while ensuring high-quality and high-stability electric energy transmission of the system.

The invention discloses a hybrid machine learning signal classification method based on PCA dimension reduction, includes the following steps: 1 according to instantaneous autocorrelation classification method, setting zero-crossing threshold and standard deviation threshold for LFM signal, BPSK signal, binary frequency shift keying 2FSK signal and quadrature phase shift keying QPSK signal, separating LFM signal and QPSK signal from other signals; 2, adopting normalized amplitude duty cycle, normalized central instantaneous phase absolute value variance and normalized central instantaneous frequency absolute value variance for residual signal BPSK signal and 2FSK signal in two-stage classification, and adopting principal component analysis PCA algorithm to realize feature dimension reduction;3, the SVM classifier being used to obtain the optimal classification objective function, and the BPSK and 2FSK signals are distinguished. The invention adopts machine learning technology to realize classification, which has high automation degree and good classification effect.

Disclosed are a method and a system for implementing near field communication (NFC). The method includes: modulating a digital signal to generate an audio signal with a transmitting device by utilizing a binary frequency shift keying modulation scheme; playing the generated audio signal with the transmitting device; receiving the audio signal by a receiving device; sampling the audio signal by the receiving device; and demodulating the sampled audio signal for obtaining the digital signal by the receiving device. The present disclosure is capable of implementing NFC between mobile communication devices not having NFC chips equipped, thereby solving the problems that hardware requirements which utilize schemes of the NFC standard are higher, and current application ranges are narrow.

In described examples, binary frequency shift keying modulation is implemented by choosing appropriate phases of a high frequency clock (40) to generate a modulated intermediate clock frequency. The high frequency clock is chosen to be (M+0.5)*fc, where fc is the carrier frequency, and M is an integer. Depending on the binary data "1" or "0" to be transmitted (45), "M" or "M+l" clock phases from the high frequency clock are converted (43) to an intermediate clock (44) that is 2*N times faster than the carrier frequency, where N is an integer. This intermediate clock (44), generated entirely in the digital domain, has the required data modulation in it, and is used for generating (46) N pulse width modulated (PWM) phases (47) of waveforms operating at the carrier frequency. The N phases (47) are then weighed appropriately (48) to synthesize a sine waveform (49) whose lower harmonics are substantially suppressed.

The invention discloses a method for realizing voice call. A sender draws a pattern in a preset area, encodes the scanned information of all the pixels or pixel change lines in the area into binary data, modulates the binary data into audio signals of two frequencies through binary frequency shift keying, and finally, transmits the audio signals to an opposite terminal through an ordinary voice call channel; and the opposite terminal performs decoding, and redisplays the pattern drawn by the sender in the preset area. In addition, the invention discloses a device for realizing voice call. Through the technical scheme of the invention, efficient and visual call is achieved based on an ordinary call process in an environment without data service.

The invention relates to a short-range wireless network using a CDMA technology based on frequency shift keying. In a CDMA-based wireless network, after being subjected to spread spectrum, signals ofa sending end are transmitted to a receiving end through a wireless channel, and demodulated and detected; a zero correlation zone ZCZ sequence is used as a spread spectrum address code; a quasi-synchronization CDMA system resisting multi-address interference and having excellent performance is realized; quasi-synchronization delay is controlled within 1 bit; binary frequency shift keying is usedas a modulation and demodulation manner; the zero correlation sequence has ideal correlation characteristics in a zero correlation window near the zero delay; and the spread spectrum sequence can reduce multi-address interference of a QS-CDMA system to the minimum, even completely eliminate. The communication network in the invention has high robustness and anti-fading capability; system implementation is simple; compared with the CDMA technology of a 3G mobile network, the cost is very cheap; and implementation is easily carried out.