434 results about "Intensity modulation" patented technology

The invention relates to microwave-free sensor technology with NV centers in diamond. In contrast to the prior art, the intensity of the pump radiation is not PWM-modulated, but monofrequency and sinusoidally modulated. Further measures, such as the use of semiconductor-based pump radiation sources and operation with an offset, prevent the formation of harmonics in the temporal intensity profile of the pump radiation irradiating the NV centers in the sensor element. This allows the sensor system to use the phase shift to determine measured values ​​of external physical parameters such as magnetic flux density, acceleration, temperature, etc., within a recognized and disclosed frequency range of the intensity modulation of the pump radiation, thereby minimizing the influence of noise from the pump radiation source. The galvanic isolation does not need to be compromised by cables from additional sensors.

The invention relates to a phase-sensitive optical time domain reflectometer based on multi-frequency reference switching. Continuous laser generated by a continuous laser is divided into a local path and a detection path through an optical coupler; the local path is input to the polarization coherent receiving module, the detection path is incident to a light intensity modulator driven by the signal generation circuit module, and the light intensity modulator is converted into a multi-frequency pulse laser sequence with intensity modulation; the multi-frequency pulse laser sequence enters the sensing optical fiber to be measured through the optical circulator; generated Rayleigh backscattered light and local continuous laser are subjected to beat frequency coherent receiving in a polarization coherent receiving module through a circulator; and the signal acquisition circuit adopts a demodulation algorithm to compensate phase drift and sensitivity difference of detection pulse demodulation signals with different frequencies so as to realize dynamic strain sensing. Compared with the prior art, the phase drift and the sensitivity difference between the frequencies are extracted to realize the compensation of the interleaved signals, and the method does not depend on the fixed reference frequency, so that the robustness and the adaptability of the system in a complex environment are remarkably enhanced.

The invention relates to a phase-sensitive optical time domain reflectometer based on a parallel frequency division multiplexing sequence. Continuous laser is divided into a local path and a detection path through an optical coupler; the local path is input to the polarization coherent receiving module, the detection path is converted into a pulse laser sequence with intensity modulation through a light intensity modulator driven by a radio frequency signal provided by the signal generation circuit module, and the radio frequency signal is composed of two frequency division multiplexing sequences with difference; the pulse laser sequence enters the sensing link to be measured to generate Rayleigh backscattered light, and the Rayleigh backscattered light and local continuous laser are subjected to beat frequency coherent receiving through a circulator; and the signal acquisition circuit is used for sampling and analyzing the interference signal, and performing frequency domain comparison on an interleaving result of the two frequency division multiplexing pulse sequences to eliminate a harmonic frequency and retain a real strain signal frequency. Compared with the prior art, the non-harmonic strain signal measurement is realized, the high-frequency response performance and the high-precision strain measurement capability are excellent, and meanwhile, the long-distance coverage capability is also realized.

The invention relates to microwave-free sensor technology with NV centers in diamond. In contrast to the prior art, the intensity of the pump radiation is not PWM-modulated, but monofrequency and sinusoidally modulated. Further measures, such as the use of semiconductor-based pump radiation sources and operation with an offset, prevent the formation of harmonics in the temporal intensity profile of the pump radiation irradiating the NV centers in the sensor element. This allows the sensor system to use the phase shift to determine measured values ​​of external physical parameters such as magnetic flux density, acceleration, temperature, etc., within a recognized and disclosed frequency range of the intensity modulation of the pump radiation, thereby minimizing the influence of noise from the pump radiation source. The galvanic isolation does not need to be compromised by cables from additional sensors.

The invention discloses a device and a method for detecting dissolved gas in transformer oil based on micro-nano optical fiber, and the device comprises a gas sensor based on micro-nano optical fiber, an interference phase demodulation unit, an inversion unit, a photothermal effect excitation unit for generating and amplifying excitation light, and a detection unit for detecting dissolved gas in transformer oil based on micro-nano optical fiber, the intensity modulation unit is used for applying sinusoidal modulation to the amplified excitation light; coupling the excitation light subjected to sinusoidal modulation into the gas sensor, exciting a fundamental mode and a first high-order mode, generating an evanescent field in a waist region, and exciting gas in oil to generate a photothermal effect to change phases of the fundamental mode and the first high-order mode so as to form a mode phase difference; the detection light generated by the interference phase demodulation unit has interference between a fundamental mode HE11 and a first high-order mode HE12 in the gas sensor, is subjected to phase modulation of different degrees, and converts a modulation phase into an interference signal peak-to-peak value; and the inversion unit performs inversion by adopting a fitting formula according to the interference signal peak-to-peak value to obtain the concentration of the gas in the oil.

The invention discloses a lithium niobate electro-optical modulator based on interdigital electrodes. The lithium niobate electro-optical modulator comprises a coplanar waveguide electrode structure containing periodically arranged interdigital electrodes, two groups of six modulation waveguides, two groups of four optical waveguide delay lines, two groups of multimode interference couplers, an input waveguide, an output waveguide and a pair of coupling gratings. According to the device, an interdigital electrode structure is used for constructing six electro-optical modulation sections in an upper group and a lower group, and optical waveguide delay lines are used for aligning phases of different electro-optical modulation sections to form an upper group of modulation arms and a lower group of modulation arms. An optical signal enters the input waveguide from the coupling grating on the left side, is divided into two beams through the multi-mode interference coupler, is subjected to equal-size and opposite modulation effects on the upper and lower groups of modulation arms, is combined and coupled in the second multi-mode interference coupler to generate an intensity modulation effect, and is output through the output waveguide and the coupling grating. The electro-optical modulator provided by the invention can be further expanded on the number of times of electrode multiplexing, and is compatible with other multiplexing technologies at the same time.

The invention discloses an optical computing array based on micro-ring resonators without a free spectral range, which comprises an on-chip wavelength division multiplexing beam splitting array, an on-chip intensity modulation array, two groups of on-chip wavelength division multiplexing beam combining arrays and an on-chip balance detector, the on-chip wavelength division multiplexing beam splitting array and the on-chip wavelength division multiplexing beam combining array are respectively composed of a group of multiple FSR-free MRRs which share the same bus optical waveguide, each resonator corresponds to an independent wavelength channel, and the on-chip intensity modulator array is composed of a plurality of groups of on-chip MZI modulator arrays. According to the optical calculation array implementation method, independent control and coding calculation of different wavelength channels in a broadband wavelength range are realized by utilizing the single harmonic peak characteristic of the FSR-free MRR array and the wide-spectrum intensity modulation function of the MZI unit, the limitation of a free spectrum range on the optical calculation wavelength channel is eliminated, the higher wavelength parallelism is achieved, and the optical calculation array implementation method has the advantages of being simple in structure and convenient to implement. And therefore, the calculation scale is remarkably improved.

The invention discloses a Fourier photoacoustic gas detection device and method, and belongs to the technical field of gas detection. In order to solve the problems that the anti-interference capability of an existing Fourier transform photoacoustic spectrum on a sound signal is limited and the detection sensitivity is low, the Fourier photoacoustic gas detection device is designed, and a super-continuum spectrum broadband light source is used as an excitation light source of a photoacoustic effect; uniform intensity modulation of wide-spectrum light is achieved through the intensity modulation assembly, and phase modulation is achieved through the interferometer assembly. The broadband interference light emitted through double modulation acts with gas molecules to generate wide-spectrum mixed sound waves, and the quartz tuning fork sound measurement assembly extracts resonance components in the wide-spectrum mixed sound waves and converts the resonance components into electrical signals; the generated electrical signal is processed by the signal amplification assembly, the phase-sensitive demodulation assembly and the Fourier transform assembly in sequence, and component discrimination and concentration inversion of the target gas are realized by the processed signal.

A method and system for optical communication with simultaneous transmission of bits of information and distribution of cryptographic key bits using laser beam intensity modulation in a transmitter and using direct detection in a receiver. A laser beam of a specific optical carrier wavelength is modulated according to a common set of modulation symbols encoding simultaneously information bits and cryptographic key bits, symbols differing in at least one parameter selected from the group with light intensity and time delay, wherein the symbols used to encode different key bits differ in light intensity.

The invention discloses a multi-objective optimization method for a radiotherapy plan, and the method comprises the steps: S1, building a multi-objective optimization model, and enabling the multi-objective optimization model to be used for the multi-objective intensity optimization of a radiotherapy reverse intensity modulation plan, and generating a Pareto solution; step S2, inputting a Pareto solution currently generated by the multi-objective optimization model into a weight search network model, wherein the weight search network model predicts a sub-objective weight of a next round of multi-objective intensity optimization of the multi-objective optimization model according to the current Pareto solution; s3, optimizing a single-target strength optimization problem with sub-target weights through a multi-target optimization model to update a current Pareto solution; and S4, circularly executing the steps S2 to S3 until a Pareto solution generated by the multi-objective optimization model forms a Hausdorff distance dHaus (Zin, Zout) between an upper bound and a lower bound of the Pareto in space, the distance dHaus (Zin, Zout) is less than threshold, and the threshold is a predefined threshold parameter which is greater than 0. According to the invention, a deep learning method is creatively used to solve the problem of constraint weight search in a radiation therapy reverse plan multi-objective optimization method.

The present disclosure relates to the technical field of optical computing, and particularly relates to an intelligent optical computing chip cluster architecture and system. The architecture comprises: a plurality of optical computing chips, and optical path channels are established between the plurality of optical computing chips by using spatial phase adjustment to modulate light beams; and high-speed optical communication and optical diffraction network computing are performed between the plurality of optical computing chips by performing time-domain intensity modulation on the optical path channels. The present disclosure adopting the above scheme can realize the interconnection computing of optical computing chips in the spatial dimension, and does not rely on electricity for information transmission.

A semiconductor light-receiving element (100) according to the present disclosure comprises: a substrate (1); a first mesa structure (30) having at least an n-type semiconductor layer (2, 3), a multiplication layer (4), a p-type electric field relaxation layer (5), a light absorption layer (6), and an i-type semiconductor layer (8) having a larger band gap than the light absorption layer (6), said layers being sequentially formed on the substrate (1); a second mesa structure (31) having at least a window layer (9) having a larger band gap than the light absorption layer (6), the second mesa structure (31) being formed on the first mesa structure (30); and a terrace part (40) comprising the outermost surface of the first mesa structure (30) exposed to the outer-peripheral side of the second mesa structure (31).

The invention discloses an optical fiber laser phased array self-adaptive optical system based on an integrated optical chip. The optical fiber laser phased array self-adaptive optical system comprises a self-adaptive optical fiber coupler array, the integrated optical chip, an optical fiber splitter, a photoelectric detector, a control platform and a high-voltage amplifier. The integrated optical chip comprises an optical fiber coupling interface, a waveguide, a phase shifter, a Mach-Zehnder intensity modulator and the like. The adaptive optical fiber coupler array couples incident light to the optical fiber array, and corrects tilt aberration based on an optimization control algorithm to realize efficient adaptive coupling of spatial light to optical fibers; the sub-beams enter an integrated optical chip through an optical fiber coupling interface, phase and intensity modulation is performed on the sub-beams in the optical chip based on an optimization control algorithm, and co-phase synthesis output of the beams is realized; the output light is divided into two paths by the optical fiber splitter, one path is connected with the photoelectric detector for control, and the other path is connected with the application end. Based on light path reciprocity, the system has a transmitting or receiving and transmitting integrated function, and has important application prospects in the fields of space optical communication, laser energy transfer and the like.

The invention belongs to the related technical field of sensors, and provides a multi-parameter integrated acquisition optical fiber sensor and a monitoring system thereof in order to solve the problem that high-precision monitoring of a static signal and a dynamic signal is difficult to consider by an existing sensor at the same time, a sensing cavity is sequentially divided into a static signal sensing area and a dynamic signal sensing area in the axial direction; the static signal sensing area adopts a multi-core fiber, fiber gratings are respectively engraved on the multi-core fiber, and the wavelength demodulation of the static signal is realized through the central wavelength drift distance of the fiber gratings; the dynamic signal sensing area is provided with a dynamic signal sensing unit, the dynamic signal sensing unit comprises F-P air microcavities formed between the dynamic signal sensing unit and the end faces of all fiber cores of the multi-core optical fiber, and intensity demodulation of dynamic signals is achieved through cavity length changes of the F-P air microcavities. According to the invention, a wavelength modulation and intensity modulation parallel composite demodulation mechanism is adopted, and decoupling acquisition of static strain, temperature and dynamic vibration is realized in a single sensor.

A stimulated Raman photothermal (SRP) microscope for imaging a sample. A first optical source without an optical resonator emits a pump beam. A second optical source emits an intensity-modulated Stokes beam. The Stokes beam is combined with the pump beam to form a combined beam. The combined beam is directed to the sample to induce a thermal effect caused by the stimulated Raman process. A third optical source emits a probe beam, the probe beam is directed to the sample. An optical detector detects modulation of the probe beam after modulation by the sample to measure an SRP signal. Because noise in the pump and Stokes beam do not significantly effect the measurements from the probe beam, these beams can use a high-powered optical parametric amplifier (OPA) source for improved sensitivity and imaging speed compared to SRP microscopes using an optical parametric oscillator (OPO) source.

The invention relates to the technical field of wafer detection, in particular to a wafer surface defect detection system and method.The system comprises an imaging module, the imaging module comprises at least two sets of imaging channels, each imaging channel comprises an imaging camera for collecting light signals and converting the light signals into image signals, and a light modulation assembly is arranged in each imaging channel; the light modulation assembly performs polarization modulation and light intensity modulation on emergent light reflected or scattered by the surface of the wafer; the polarization control module adjusts the rotation angle of the light modulation assembly in each imaging channel; the signal processing module carries out differential operation on different image signals, light rays emitted by the multiple groups of imaging channels are set with different polarization parameters and light intensity parameters through the light modulation assembly, multiple groups of image signals are obtained, and an imaging image about scattered light of the same detection area is formed. The imaging image comprises an image with the defect signal as weak as possible and an image with the defect signal as strong as possible, and the imaging image with the defect signal enhanced can be obtained through differential operation.

The invention relates to an optical fiber photo-thermal spectrum sensing system for simultaneously detecting multi-component dissolved gas in transformer oil, which is suitable for the fields of optical fiber sensing, power system state monitoring and the like and comprises a homodyne interference light path module, a pumping module and a capillary oil extraction module. The invention provides an optical fiber photo-thermal spectrum sensing system for simultaneously detecting multi-component dissolved gas in transformer oil, a broadband light source is combined with FBG filter filtering and AOM intensity modulation as pumping, multi-component gas can be detected, in order to avoid crosstalk among component signals, different modulation frequencies are set for light sources with different wavelengths, and the optical fiber photo-thermal spectrum sensing system can be used for simultaneously detecting multi-component dissolved gas in transformer oil. The simultaneous real-time detection of each component can be realized; in order to concentrate pumping energy to increase sensitivity, a capillary optical fiber with a punched side face is adopted as a detection cavity, and oil circulation between the detection cavity and a transformer oil tank is achieved through an oil pump.

Provided is a time-stretch spectroscopy device capable of restoring an original spectrum without using a high-speed modulation system or reception system even if temporally adjacent pulses overlap after stretching. This time-stretch spectroscopy device comprises: an optical modulator that performs intensity modulation in pulse units on a group of measurement light pulses, which are obtained by irradiating a measurement object having characteristics relating to light transmittance or reflectance with a group of light pulses; a pulse stretcher that performs time stretching on the group of measurement light pulses; and a signal processing device that, with the assumption that the measurement light pulses are sparse as data, performs a reconfiguration estimating pulse signal wavelength components corresponding to the stretched light pulses, which are obtained by individually time stretching the group of measurement light pulses, in light of a superimposition signal synthesized such that a temporal overlap occurs after the time stretching.

The invention relates to the technical field of textile detection, in particular to a textile surface defect detection method and a textile surface defect detection system, which are used for carrying out online detection on a textile of which the surface is coated with a thermosensitive coating, and the method comprises the following steps: applying preset periodic intensity modulation to a detection light source used for online detection, generating a reference sequence serving as a synchronism analysis benchmark; collecting a series of brightness values of the suspected defect points within a preset time period under the periodic intensity modulation aiming at the suspected defect points, which are preliminarily identified, on the surface of the textile, so as to form a brightness response sequence representing the optical response characteristics of the suspected defect points; calculating a time synchronization degree between the brightness response sequence and the reference sequence; by distinguishing the temporary thermal effect artifacts and the real physical defects, the method has the advantages that the temporary optical artifacts and the real physical defects caused by the thermal effect can be effectively distinguished, the false alarm rate is reduced, and the detection accuracy is improved.

The invention relates to the technical field of semiconductors, in particular to a multiplexing-based optical computing chip and a design method thereof.The multiplexing-based optical computing chip comprises a computing area formed by crossing a first waveguide and a second waveguide, and the computing area comprises a branch waveguide connected with the first waveguide and the second waveguide, a beam splitting part, an intensity modulation part and a first signal conversion part are sequentially arranged on the branch waveguide, the beam splitting part is used for splitting optical signals in a specific proportion, the intensity modulation part is used for modulating the signal intensity of the optical signals into a specific value, and the first signal conversion part is used for setting or maintaining the optical signals in a specific mode; the specific mode means that the optical signal has a specific polarization direction and / or a specific order; the second waveguide is provided with a calculation unit for calculating the sum of the optical powers of the plurality of optical signals. According to the multiplexing scheme provided by the invention, the data processing amount of the optical computing chip can be improved.

The invention provides a photoacoustic sensor and a sensing system for trace C4F7N gas detection, and relates to the technical field of C4F7N gas detection. The system comprises a broadband light source used for generating wide-spectrum infrared light; the modulation unit is used for carrying out intensity modulation on the wide-spectrum infrared light; the photoacoustic cell is used for receiving the modulated light beam and exciting C4F7N gas to generate a photoacoustic signal; the sound detector is used for detecting a photoacoustic signal; the signal processing unit is used for processing the photoacoustic signal to obtain the C4F7N gas concentration; the broadband light source is a blackbody radiation source; the photoacoustic cell is a spherical Helmholtz resonant cavity, is of a differential structure and comprises two spherical resonant cavities; and the two sound detectors are symmetrically arranged on the cavity walls of the two spherical resonant cavities. The black-body radiation source is used as a broadband light source, and the differential spherical Helmholtz photoacoustic cell is coupled with the black-body radiation source, so that the system cost and the integration complexity are remarkably reduced on the premise of keeping the advantage of high sensitivity.

The invention relates to a quantum key distribution method and device based on a double-field protocol, and a storage medium, and the method comprises the following steps: carrying out the phase and intensity modulation of an initial laser pulse through a quantum state preparation device, and generating a double-field quantum state sequence containing a first quantum state sequence and a second quantum state sequence; the sequences are subjected to polarization state coding and time division multiplexing through a quantum channel transmission device to form a coded quantum state transmission sequence. The sequence is then subjected to phase compensation and noise suppression to obtain an optimized quantum state sequence. And then, the quantum state measurement device executes Bell state measurement and basis vector selection on the optimized sequence to obtain a measurement result sequence. And finally, the post-processing device performs key extraction and privacy amplification on the measurement result to ensure that a final quantum key is generated, so that the technical problem that the practicability and the transmission distance of a traditional quantum key distribution scheme are greatly limited due to the influence of channel loss and noise interference factors is solved.

An optical transmission apparatus includes: a distributing unit which distributes a laser beam based on a first oscillation frequency; a phase modulator which generates, using the laser beam based on the first oscillation frequency, a phase-modulated signal that is an optical signal phase-modulated in accordance with a modulated signal; a multiplexing unit which multiplexes a laser beam based on a second oscillation frequency and the phase-modulated signal; a detecting unit which generates a frequency-modulated signal by performing detection processing on a result of multiplexing of the laser beam based on the second oscillation frequency and the phase-modulated signal; and an intensity modulator which generates, using the laser beam based on the first oscillation frequency, an optical signal intensity-modulated in accordance with the frequency-modulated signal.

A stimulated Raman photothermal (SRP) microscope for imaging a sample. A first optical source without an optical resonator emits a pump beam. A second optical source emits an intensity-modulated Stokes beam. The Stokes beam is combined with the pump beam to form a combined beam. The combined beam is directed to the sample to induce a thermal effect caused by the stimulated Raman process. A third optical source emits a probe beam, the probe beam is directed to the sample. An optical detector detects modulation of the probe beam after modulation by the sample to measure an SRP signal. Because noise in the pump and Stokes beam do not significantly effect the measurements from the probe beam, these beams can use a high-powered optical parametric amplifier (OPA) source for improved sensitivity and imaging speed compared to SRP microscopes using an optical parametric oscillator (OPO) source.

A semiconductor light receiving element (100) according to the present disclosure comprises: an n-type InP substrate (1); an n-type semiconductor layer (2) formed on the n-type InP substrate (1); a multiplication layer (3) formed on the n-type semiconductor layer (2) and having an InAlAs digital alloy structure in which InAs layers having a layer thickness of 40-170 nm and AlAs layers are alternately laminated; a p-type field relaxation layer (4) formed on the multiplication layer (3) and composed of InP or InAlAs; and an InGaAs light absorption layer (5) formed on the p-type field relaxation layer (4).

A photoacoustic wave measurement device includes a modulated light source that irradiates a measurement target with far-infrared light, which is subjected to intensity modulation; and a measurement unit that measures a photoacoustic wave emitted from the measurement target irradiated with the far-infrared light. The measurement unit includes an airtight chamber that is filled with a gas therein and receives the photoacoustic wave emitted from the measurement target; and a pressure sensor constituting a part of a wall portion that partitions the airtight chamber from the outside.

The invention discloses a high-precision photon digital-to-analog conversion system based on noise shaping, which is characterized in that a mode-locked laser generates an optical pulse sequence, optical pulses enter a dispersive medium, and periodic pulses are processed by using a fractional order Talbot effect, so that the pulse repetition frequency is improved; the Delta-Sigma (Delta Sigma) modulation module processes a preset target signal and shifts noise to a high frequency band based on an oversampling technology and noise shaping to realize conversion from an analog signal to a digital signal; the pulse signal with the repetition frequency increased is input into the electro-optical modulation module to serve as a sampling source, and a digital signal generated by the delta-sigma modulation module is input into the electro-optical modulation module for intensity modulation, so that the optical pulse carries the characteristics of frequency change and noise shaping of the signal, and fusion from electric signal modulation to optical signal modulation is completed; inputting the pulse signal after electro-optical modulation into a photoelectric detector, and converting an optical signal into an electric pulse signal; the electric pulse signal enters a filtering module, noise in the electric signal is filtered out, and an analog signal is obtained.

The present invention provides a laser frequency-swept ranging device and method. The device includes a laser, an electro-optic modulator, a beam splitter prism, a first detector, a second detector, an analog phase detector, a measurement control circuit, and a modulation frequency source. The laser is used to emit a laser signal. The electro-optic modulator is used to intensity-modulate the laser signal to output a modulated signal. The beam splitter prism divides the modulated signal into two paths. One path is received by the first detector to generate a reference signal. The other path is reflected back by the target to be measured and then received by the second detector after being reflected by the beam splitter prism to generate a measurement signal. The analog phase detector is used to detect the phase difference between the reference signal and the measurement signal. The measurement control circuit is used to perform frequency-sweeping control on the output frequency of the modulation frequency source to generate a high-frequency modulated signal that changes according to a preset step size and feedback it to the electro-optic modulator. It is also used to determine two adjacent modulation frequencies by detecting the zero-phase difference signal and calculate the measurement distance of the target to be measured based on the two adjacent modulation frequencies.

The measurement of overlay using a microscope-based sensor is described. This provides, among several advantages, the ability to measure alignment and overlay in a single system. The signal from the sensor is an intensity-modulated fringe pattern (e.g., an interference pattern). The sensor is configured to generate an intensity-modulated fringe pattern based on diffracted radiation received from a first metronome mark on a first layer of the pattern substrate and a second metronome mark on a second layer of the pattern substrate. The intensity-modulated fringe pattern is filtered for the expected fringe period. The overlay value is determined using the amplitude, phase, and / or other parameters of the fringe in the filtered fringe pattern.

The invention discloses a radar signal identification method based on photon parameter mapping. The method comprises the following steps: S1, generating two paths of homologous optical carriers; s2, processing the first path of optical carrier into a linear frequency modulation optical signal; performing intensity modulation on the second path of optical carrier wave by using the radar signal to be measured, and introducing delay inequality between two cross-polarization components of the generated modulation optical signal; s3, after the two paths of optical signals are combined, balanced photoelectric detection is carried out, and electrical filtering and envelope detection are carried out in sequence; s4, inputting the data into a modulation type identification module in a digital domain for modulation type identification; inputting the obtained modulation type time sequence into a state recognition module for state recognition; the modulation type identification module and the state identification module are pre-trained deep learning models. The invention also discloses a radar signal identification device based on photon parameter mapping. According to the method, the radar signal modulation type and state can be accurately and rapidly identified through low-speed analog-to-digital conversion.