2632 results about "Weak signal" patented technology

A system and method for identifying geographical areas which distribute poor radio frequency coverage is provided. The method includes measuring a radio frequency signal of a mobile unit in response to a trigger. The method continues with mapping the location data of the radio frequency signal which represents the positioning of the mobile unit at a given time. The method continues with recording the location data of the mobile unit and storing the location data in a database. The trigger, which prompts the radio frequency measurement, may be a timer expiring, a dropped call, or a mobile power increase signaling a weak signal. In any form, a post processing module may be configured in order to record, store and organize the location data into a report, such as a coverage map. Embodiments of this disclosure will display geographic areas that have poor radio frequency and allow for an administrator to identify trouble spots by a geographical region.

An optical rangefinder based on time-of-flight measurement, radiates pulsed light toward an object (70), and receives reflected light from the object, the receiver operating in a photon counting mode, so as to generate a pulse for a detected photon. There is a variable probability of a photon detection on the receiver, and a controller (370, 380, 390; 365, 470, 475, 380, 390; 570, 580, 590, 390) controls the photon detection probability of the receiver, based on a light level. By controlling the detection probability according to a light level, the receiver can have an increased dynamic range, and without the expense of using optical components. This can apply even while detecting very weak signals since the receiver can still be in a photon counting mode while the detection probability is controlled. The light level can be indicated by an output of the receiver itself, or by another detector external to the receiver.

The invention provides a short distance transmission system for wireless electromagnetic wave signals of a downhole near bit and a short distance transmission method, and belongs to the field of geosteering systems and measurement while drilling instruments in industries such as petroleum, mines and geological prospecting. The automatic gain control technology is adopted in the short distance transmission system for realizing the automatic adjustment of enlargement factors of downhole weak signals. The short distance transmission system comprises a short section receiving assembly and a short section transmitting assembly, wherein the short section receiving assembly and the short section transmitting assembly are respectively provided with a receiving antenna and a transmitting antenna. Due to the fact that radial coupled antennas are adopted, the short distance transmission system is relatively simple in structure. Meanwhile, the short distance transmission system is high in arithmetic speed and can meet demands for real-time transmission of a large number of signals. Moreover, a front end processing module special for the downhole weak signals is utilized for carrying out the automatic gain adjustment to the collected signals, maintaining stable output of the signals and lowering processing difficulty of subsequent signals, and therefore the signal transmission quality is greatly improved.

A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and fine cancellation signals, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.

The invention relates to a monitoring device of high pressure system which is used for electric automobile electromobile or mixing drive automobile, it includes battery manage module supplies a weak signal at the end of the high pressure system, and receive the signal at the other end, through compare the crest value of the signal to judge high pressure system whether or not short circuit or broken fault, in the close process of high pressure system, through compare the relation between the voltage across of high pressure system and voltage across of battery, achieve the safely connect of the high pressure system.

Improper microphone position and speech level on a telephone headset is sensed by comparison of a speech envelope to multiple signal threshold levels. A first threshold is used to determine whether a headset user is talking. A second threshold is used to determine whether a signal level at the microphone is sufficiently strong for proper communication. An indicator is activated when the user is talking and the signal level is too weak. Typically, a weak signal is caused by a mispositioned microphone or a user talking too softly.

An over the air repeater for enhancing wireless communication is provided. The repeater employs a system and method by which strong signals can be prevented from exceeding the repeater's uplink output limits while still providing full operational gain to any concurrently amplified weak signals, while adapting to time slot variations and optionally to frequency hopping variations. Power measurements are performed on each channel with resultant gain changes being performed on delayed versions of those same signals. Digital delay buffers are used to provide adequate processing time to make an accurate determination of the uplink signal levels of each RF carrier. The repeater alternatively monitors the downlink path from the donor base station to determine the frequencies to be processed on the uplink communication.

The invention discloses a multi-target detection method based on short-time Fourier transform and fractional Fourier transform, which belongs to the technical field of the radar target detection. The method comprises the following steps that the short-time Fourier transform is firstly used for conducting the primary detection on a signal, then a binaryzation method is used for processing a primary detection result, phase position of the signal is kept in the processing, the fractional Fourier transform is used for detecting a signal after being restored by the short-time Fourier transform, by adopting multiple methods for combined processing, advantages of overcoming phenomenon that a strong signal side lobe presses a weak signal main lobe, improving the signal-to-noise ratio of the signal to be detected, and solving the problem of the large false alarm possibility which is caused by adopting traditional method to detect the signal at the low signal-to-noise ratio can be realized; and meanwhile, an image contrast method and a gradual elimination method are adopted, multiple strong signals and weak signals with different or identical frequency modulation rates can be detected by utilizing the space and power strength information of the signal, so that the detection probability and the calculation efficiency can be further improved, easiness in project realization is realized, and the method is worth of being adopted and popularized.

The present invention provides systems and methods for navigational signal tracking in low power mode to conserve the power of handheld navigation receivers. In an embodiment, the receiver cycles between sleep and wakeup states. During the sleep state, most of the components of the receiver are powered off to conserve power, and during the wakeup state, the receiver tracks navigational signals. In an embodiment, the duty cycle of the sleep/wakeup states depends on the receiver dynamic state, e.g., whether the receiver is accelerating. In another embodiment, during the wakeup state, the receiver selects a tracking mode based on the signal strength. Under weak signal conditions, a tracking mode using a long integration to track the satellite signal is disclosed. In one embodiment, a tracking mode tracks the navigation signal by performing data aided integration using known or predicted data bits, such as the TLM and HOW words.

The invention discloses a self-adapting random resonance weak signal detection method, which achieves the self-adapting detection of weak periodic signal through combining a matching random resonance and an imposed signal induced random resonance. According to the theory of random resonance, firstly, numerical simulation is processed to receive correspondence between the noise intensity and the frequency of the best matching random resonance of a nonlinear bistable system in a range of extremely low frequency and under the condition of small-signal; and a high-frequency weak signal encountered in a project can be processed by using the change of normalized scale. For the detection of a weak signal with extremely low message-to-noise ratio and large noise intensity, the heights of voltage barriers of the bistable system can be changed by using the induced random resonance, thereby helping a weak eigenfrequency signal to fulfill the transition between voltage barriers, so that the bistable system reaches the random resonance state, thereby achieving the self-adapting detection of the weak periodic signal.

A burst signal detection circuit for detecting the arrival of a burst-like signal, which can accurately detect the burst signal against the DC level variations even in the case where the arriving burst signal is a weak signal, is disclosed. A DC variation removing circuit detects the bottom level of an input signal and removes the DC level variation of the input signal based on the bottom level. An amplitude identifying circuit detects the presence or absence of a burst signal based on the output signal of the DC variation removing circuit. The amplitude identifying circuit includes an amplitude detection circuit for detecting the maximum amplitude of the output signal of the DC variation removing circuit, a threshold level control circuit for controlling the threshold level and a comparator for comparing the output level of the amplitude detection circuit with the threshold level and outputting a detection signal indicating the presence or absence of a burst signal.

The present invention is a method and system for continuously monitoring cardiac output. In a preferred embodiment, the method and system of the present invention comprises a pneumotachograph, differential pressure transducer, and a signal amplifier/conditioner interconnected to a programmed digital computer. A patient, preferably, inserts the pneumotachograph in his mouth or, alternatively, the pneumotachograph is connected to a patient's tracheal cannula. As the patient exhales and inhales the differential pressure transducer measures the drop in pressure as air flows through the pneumotachograph thereby producing a weak electrical signal non-linearly proportional to flow. Next, the weak signal is directed through the amplifier/signal conditioner which increases the amplitude and removes some of the noise contained in the transducer output. A digital computer is then utilized to convert the analog time varying electrical signal into a stream of digital data, store it on disk, display it in real time and processes the signal using an experimentally determined correlation factor and mathematical equations relating the fluctuations in air flow with stroke volume to obtain the cardiac output.

The invention discloses a high-sensitivity magnetic measurement device in an environment field based on disturbance compensation and a realization method thereof. In the method, the low-frequency disturbance compensation in an environment magnetic field is realized by a second feedback branch and a second magnetic flux locking loop, wherein the second feedback branch is composed of a second integrator, a low-pass filter, a second feedback resistor and a feedback coil; and the second magnetic flux locking loop is formed based on the second feedback branch. A super-magnetic conduction sensor established based on the method can realize the high-pass response frequency characteristics for the environment field and the low-pass response frequency characteristics for the circuit noise at the same time, ensures the suppression of the influence of environment field disturbance on SQUID (superconducting quantum interference device) magnetic measurement without influencing the weak signal measurement, and avoids the overflow phenomenon. Based on the super-magnetic conduction sensor, the method is suitable for the application environment in which the frequency of the magnetic field signal tobe measured is higher than the disturbance frequency band (DC-30Hz) of the environment field.

In a relay scheme, a wireless source apparatus, a wireless destination apparatus and a wireless relay apparatus cooperate for handling transmission failures by space/time diverse channels. In the case of the successful direct transmission, reduced or no additional overhead for the relay selection is incurred. Thus, for a good SNR between source and destination, the inventive protocol has similar performance as a standard approach. In the case of a transmission failure e.g., due to small scale fading, a transmission via a different communication path implementing spatial diversity via a selected relay is supported. The device is to only activate the overhearing of signals in case of weak signal quality between sender and receiver. This selection of relay devices is done by demand only. A specific protocol for the reservation of the wireless medium for the entire cooperative communication has been specified.

The invention discloses a target detection method based on Keystone and matched filtering and belongs to the radar weak signal detection technology field. The method comprises steps that firstly, a radar is utilized to emit a chirp signal, pulse compression for a received target echo signal is carried out, and first-order range migration caused by no fuzzy speed of a target is corrected through utilizing Keystone transformation; secondly, a fuzzy speed multiple and acceleration of the target are estimated through utilizing combined two-dimensional matched filtering processing of a distance frequency domain, and first-order range migration caused by the fuzzy speed of the target and second-order range bending and Doppler migration caused by acceleration are corrected and compensated; and lastly, phase-coherent accumulation of target energy is realized through fast Fourier transform, and a peak value of phase-coherent accumulation is utilized to carry out target detection. The method is advantaged in that amplitude and the phase information of target echoes are utilized to carry out long time phase-coherent accumulation, so a radar echo signal-to-noise ratio can be effectively improved, and target detection performance of the radar can be improved.

The invention discloses a binary offset carrier signal tracking loop, which comprises a correlator module, a phase discriminator unit and a filter unit. The correlator module is used for performing demodulation and despread processing on the input intermediate frequency BOC signals, and acquiring multi-path correlation values IIP, IIE, IIL, IQP, IQE, IQL and QIP between local signals and the intermediate frequency BOC signals; the phase discriminator unit is used for detecting the tracking error theta of the carrier phase and the subcarrier phase and measuring the tracking error tau of the spreading codes; and the filter unit is used for performing noise reduction and smoothing on the phase demodulation result, converting the output tracking error into corresponding frequency control words, correspondingly feeding the frequency control words back to the correlator module, tracking the input intermediate frequency BOC signals, and closing the tracking loop. The binary offset carrier signal tracking loop realizes the split tracking of the subcarrier and spreading codes, eliminates the tracking fuzziness of the BOC signals, reduces the requirement on the acquisition precision, improves the tracking performance of weak signals, widens the dynamic range of the loop, and improves the tracking stability of the BOC signals by using the periodicity of the subcarrier.

The invention discloses a high-sensitivity satellite navigation signal capturing method and a system. The system comprises a digital down-conversion module, an average sampling and block accumulation module, an FFT (fast Fourier transform) module, a circumference shifting module, a local PRN (pseudo random noise) code FFT conjugate memory, a complex multiplier module, an IFFT (inverse fast Fourier transform) module, a differential coherence integration module, a peak detection module and a sequential control module. The digital down-conversion module realizes digital down-conversion operation for satellite digital intermediate frequency signals; the average sampling and block accumulation module averagely samples satellite data and completes a block accumulation function; the FFT module searches code phase frequency domains; the circumference shifting module utilizes Doppler circumference shifting search to replace frequency compensation; the local PRN code FFT conjugate memory stores a local PRN code FFT conjugate result; the complex multiplier module realizes signal de-spreading; the IFFT module calculates different code phase coherence results; the differential coherence integration module accumulates differential coherence energy of de-spread satellite signals; the peak detection module realizes signal capturing output; and the sequential control module controls timing sequence of the various modules of the system. Weak signal capturing speed and sensitivity of a satellite navigation receiver are improved, and parameters can be configured flexibly.

The invention relates to a self-adaption stochastic resonance weak signal detecting method based on a particle swarm optimization algorithm. The method comprises the following steps of 1) particle swarm initialization; 2) step-changed stochastic resonance; 3) individual fitness evaluation; 4) particle speed and position updating; 5) termination condition judgment and 6) detection result output. The self-adaption stochastic resonance weak signal detecting method has the advantages that the simplicity is realized, the implementation is easy, the application range is wide, the convergence speed is high, high-frequency weak signals at high-noise background can be effectively detected, and a novel method is provided for stochastic resonance parameter self-adaption selection and practical application in engineering.

The present invention is a method for GPS positioning in a weak signal environment. The method includes obtaining assistance data for a GPS signal from a satellite at a predetermined time, wherein the assistance data including predicted navigation data, Doppler shift and Doppler shift rate and the GPS signal being modulated by a carrier signal, a pseudorandom code and navigation data, estimating a predicted receiving time for the GPS signal reaching the GPS receiver, capturing the GPS signal, converting the GPS signal to an intermediate frequency signal, acquiring a code phase of the pseudorandom code from the intermediate frequency signal by using the assistance data and the predicted receiving time, and obtaining a position for the GPS receiver based on the predicted navigation data and the code phase of the pseudorandom code. To acquire the code phase of the pseudorandom code, the GPS receiver corrects a real time clock to one millisecond accuracy and process the intermediate frequency signal through coherent correlation of one second.

The invention discloses a high-dynamic weak-signal rapid capture method for a direct sequence spread spectrum system, belonging to the field of radio communication. Because a spread spectrum carrier has a chirp signal characteristic under the condition of high-dynamic motion (high-speed and high-acceleration), the high-dynamic weak-signal rapid capture method comprises the steps of: firstly, carrying out carrier Doppler frequency compensation by using a time frequency focusing characteristic of fractional order Fourier transform; secondly, carrying out incoherent accumulation on a spread frequency signal by using an order resolving capacity of the fractional order Fourier transform; and finally, carrying out capture judgment on the signal in an order Fourier domain by using a constant false alarm rate detection technology. According to the invention, the difficulty of incapability of long-time coherent accumulation under the high-dynamic condition in the traditional Fourier transform based rapid capture method is solved; and under the condition of high dynamicity and low signal to noise ratio, the signal to noise ratio is effectively increased and the signal capture time is shortened. In addition, a rapid algorithm exists in the invention and is easy to realize on the engineering in real time.

The invention relates to a storage photoionization ion migration mass spectrum, mainly solving the problems of the complex line spectrum measured and weaker signals obtained by adopting radioactive component as ionization source. It includes acceleration grid electrode, ionization light source, sampling mouth, ionization region, drift region and ion collecting plate, and its character: the ionization light source is vacuum ultraviolet lamp, it sets an ion storage region structure between the ionization and drift regions to replace the ion gate. It has ion storing function, largely enhances monitoring sensitivity, clear migration mass spectrum chart of the matter to be measured, reduces influence of noise and enhances collecting efficiency.

A frequency phase correction system and method are described that provides a receiver with a greater ability to lock onto relatively weak radio frequency signals by determining and estimating an amount of frequency error in a local frequency reference of the receiver, and using the error estimate to maintain frequency coherence with a received signal, thereby allowing tracking over a longer period of time, enabling longer integration times to capture weaker signals without losing frequency coherence.