A digital receiver comprising at least two reception pathways, the method carries out a digital inter-correlation of the signals obtained as output from at least two filters of different central frequencies and different ranks, the rank and the central frequency of the filters being chosen as a function of a determined frequency-wise search domain. For a determined search domain, the various sampling frequencies of the reception pathways are chosen so that the ambiguous frequencies resulting from the spectral aliasings vary as a monotonic function of the true frequency of the signals.

A method for operating a data processing system to compute the response of a DUT to a modulated input signal is disclosed. The method includes determining a set of parameters for a first model of the DUT from a plurality of measurements of output values from the DUT, each output value includes a measurement of a gain and phase shift provided by the DUT when the DUT is stimulated with a single tone input signal having a frequency in a frequency range determined by the modulated signal. The method also determines a second model that characterizes noise generated by the DUT at the single tone input signals. A performance parameter for an output signal that would be obtained by applying the modulated input signal to an input of the DUT, and receiving the output of the DUT is then determined from the first and second models.

A graphical display for displaying spectrum analyzer data that represents detected signal levels for frequencies in an identified frequency span includes a signal level axis that represents a range of detected RF signal levels for the spectrum analyzer data and a frequency axis that represents an identified frequency spectrum span for the spectrum analyzer data. Frequency ranges in the identified frequency span having a high concentration of detected RF energy are automatically graphically expanded and displayed on the frequency axis of the graphical display while frequency ranges having a lower concentration of detected RF energy are simultaneously, automatically graphically condensed and displayed on the first frequency axis of the graphical display.

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.

Nonlinear distortion of a device under test (DUT) is detected by obtaining measurements of a multi-tone input signal from a signal generator to a DUT, to obtain a measured multi-tone input signal. Measurements are also obtained of a multi-tone output signal from the DUT that is generated based on the multi-tone input signal, to obtain a measured multi-tone output signal. A correlated part of the measured multi-tone output signal that is correlated with the measured multi-tone input signal is determined insofar as the correlated part corresponds to a frequency response function of the DUT.

Disclosed is a channel-selective RF power sensor having a coupler and a channel-selective power measurement circuit. The said coupler is configured to obtain a sample of energy travelling on a main transmission line and provide the sample of energy to the channel-selective power measurement circuit. The sample of energy has a channel of interest. The channel-selective power measurement circuit is configured to measure RF energy information for the channel of interest in the sample of energy. Also disclosed is a method of measuring RF energy information for a channel of interest. The method includes providing a channel-selective RF power sensor and a main transmission line and obtaining a sample of energy from the main transmission line using a coupler of the channel-selective RF power sensor.

The present invention provides a filter bank circuit capable of measuring or testing a frequency band, a spectrum analyzer, a signal analyzer, a signal generator using the filter bank circuit, and a method for controlling the filter bank circuit. A filter bank circuit 10 includes, for example, a one-pole two-throw changeover switch 20 and filter groups G1 and G2, each of which has m filters. The passbands of the filters included in each filter group do not overlap with each other, and the adjacent passbands of the filters included in all the filter groups overlap with each other.

The present invention provides a filter bank circuit capable of measuring or testing a frequency band, a spectrum analyzer, a signal analyzer, a signal generator using the filter bank circuit, and a method for controlling the filter bank circuit. A filter bank circuit 10 includes, for example, a one-pole two-throw changeover switch 20 and filter groups G1 and G2, each of which has m filters. The passbands of the filters included in each filter group do not overlap with each other, and the adjacent passbands of the filters included in all the filter groups overlap with each other.

An RF signal detection device, including: a first threshold crossing detection circuit comprising an input coupled to an input of the RF signal detection device; a first energy detection circuit comprising an input coupled to the input of the RF signal detection device; a second threshold crossing detection circuit comprising an input coupled to an output of the first energy detection circuit; and further including a control circuit configured to: carry out, by the first threshold crossing detection circuit, detection of at least a first threshold crossing frequency in a predetermined RF frequency band; and carry out, by the first energy detection circuit, energy detection in the predetermined RF frequency band; and carry out, by the second threshold crossing detection circuit, detection of at least a second threshold crossing frequency of a first energy signal delivered as an output from the first energy detection circuit; and determine, at least from the first and second threshold crossing frequencies and the first energy signal, whether a single RF signal is present in the RF frequency band.