A frequency spectrum detection system including: a frequency-scan light source, a phase modulator, an optical filter, an optical fiber, a photodetector, a power divider, an electric amplifier, a combiner, an electric filter, and an oscilloscope. The frequency-scan light source, the phase modulator, the optical filter, the photodetector, and the electric amplifier form a ring-shaped optoelectronic oscillator resonant cavity, which is configured to generate a frequency-scan signal. The combiner is configured to receive a signal to be measured. The phase modulator is configured to modulate the combined electrical signal onto a frequency-scan optical signal. The optical filter is configured to selectively attenuate or amplify one sideband of double sidebands of the double-sideband phase-modulated optical signal. The photodetector is configured to detect a signal filtered by the optical filter.

An adjusting system and an adjusting method for equalization processing are provided. Frequency band energies of sound receiving signals are obtained. The frequency band energies correspond to different frequency bands, respectively. Target gains corresponding to frequency bands are determined according to the frequency band energies. Frequency responses of filtering processing with respect to a plurality of center frequencies are obtained. Equalization gains corresponding to the frequency bands and having the least gain error are determined. The gain error is related to a difference between the amplitude obtained after the equalization gains are reflected on the frequency responses corresponding to the filtering processing and the target gains. The equalization gains are inputted into the filtering processing according to the corresponding frequency bands. Accordingly, the impact of the filtering processing can be reduced.

An adjusting system and an adjusting method for equalization processing are provided. Frequency band energies of sound receiving signals are obtained. The frequency band energies correspond to different frequency bands, respectively. Target gains corresponding to frequency bands are determined according to the frequency band energies. Frequency responses of filtering processing with respect to a plurality of center frequencies are obtained. Equalization gains corresponding to the frequency bands and having the least gain error are determined. The gain error is related to a difference between the amplitude obtained after the equalization gains are reflected on the frequency responses corresponding to the filtering processing and the target gains. The equalization gains are inputted into the filtering processing according to the corresponding frequency bands. Accordingly, the impact of the filtering processing can be reduced.

A spectrum analyzer (10) comprises a signal input or receiver (11) for receiving a signal, an A/D converter (12) configured to sample the received signal and generate a data stream of IQ-data, a digital processing circuit (13) for generating compressed data from the data stream of IQ-data, and a data interface (19) for outputting the compressed data from the spectrum analyzer (10).

A spectrum analyzer (10) comprises a signal input or receiver (11) for receiving a signal, an A/D converter (12) configured to sample the received signal and generate a data stream of IQ-data, a digital processing circuit (13) for generating compressed data from the data stream of IQ-data, and a data interface (19) for outputting the compressed data from the spectrum analyzer (10).

An apparatus for measuring radio frequency power is described that comprises at least one measurement path for small bandwidth and at least one measurement path for wide bandwidth. Further, the apparatus has an analysis and measurement unit connected with the at least two measurement paths. The analysis and measurement unit is configured to process the at least one small bandwidth signal and the at least one wide bandwidth signal. Further, a method of analyzing a radio frequency signal is described.

An apparatus configured to acquire S-parameters of a communications channel includes a physical interface configured to transmit and receive signals through a communications channel under test, a processor, configured to execute instructions that, when executed cause the processor to: send a first data pattern from the transmitter through the communications channel at a first data rate; acquire a first waveform corresponding to the first data pattern and determine a first pulse response; calculate a first transfer function from the first pulse response; send a second data pattern from the transmitter through the communications channel at a second data rate; acquire a second waveform corresponding to the second data pattern and determine a second pulse response; calculate a second transfer function from the second pulse response; and combine the first and second transfer functions to determine an S-parameter of the communications channel.

The present invention relates to a processing of digitally measured signals. When sampling a measurement signal with a predetermined sampling rate, aliasing effects may occur, if a Nyquist condition is violated. For this purpose, the present invention suggests to analyze a frequency spectrum of a signal and to compare the frequency components of the spectrum with the setting of a measurement apparatus, in particular a sampling rate of the measurement apparatus. If a measurement signal comprises frequency components which may violate the Nyquist condition, an alert may be generated to adapt the set of the measurement arrangement.

A spectrum processing apparatus includes: a spectrum obtainer configured to obtain an optical spectrum from a light that is scattered or reflected from a subject; and a processor configured to split the optical spectrum into a plurality of bands, determine, based on a predetermined measurement accuracy for measuring a biosignal from the light, one or more key bands from the plurality of bands, and obtain the biosignal from the determined key bands.

A spectrum processing apparatus includes: a spectrum obtainer configured to obtain an optical spectrum from a light that is scattered or reflected from a subject; and a processor configured to split the optical spectrum into a plurality of bands, determine, based on a predetermined measurement accuracy for measuring a biosignal from the light, one or more key bands from the plurality of bands, and obtain the biosignal from the determined key bands.