37 results about "Double side band" patented technology

The present invention is to provide an optical modulating system for generating a signal of a frequency (f0+2fm) and a signal of a frequency (f0−2fm) and suppressing a signal of a frequency (f0) by a DSB-SC modulator.A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f0) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f0) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

Signal egress from a shielding flaw in a cable telecommunication system is detected, even where signals carried by the cable telecommunication system are quadrature amplitude modulated signals that statistically resemble broadband noise by generating a marker signal comprising a double side band, suppressed carrier signal in the fringes of contiguous frequency bands and at a power level which cannot cause perceptible interference with signals in those contiguous frequency bands. The separation of the sidebands comprising the marker signal can unambiguously identify the marker signal and can distinguish between different cable telecommunication systems installed in the same geographic area. The marker signal can be additionally coded by varying the frequency and / or amplitude of the modulating signal used to create the marker signal.

The present invention discloses a method and system for measurement of an optical device on the basis of optical double-side band modulation, belonging to the fields of optical device measurement and microwave photonics technologies. The method provided by the invention employs general optical double-side band modulation signals and optical double-side band signals after Hilbert transform to measure the spectral response of an optical device to be measured, and employs the data processing technology to modulate and obtain the spectral response of an optical device to be measured (including range response and phase response). The present invention further discloses an optical device spectral response measurement system on the basis of optical double-side band modulation. Compared with an optical device spectral response measurement technology in the prior art, the method and system for measurement of an optical device on the basis of optical double-side band modulation have larger dynamic range, wider measurement range and lower cost.

A ATSC compliant digital television (DTV) receiver including an image rejection filter, an interpolator, a numerically controlled oscillator (NCO), a matched filter unit, a frequency converter, and a DC remover. The image rejection filter removes (filters out) an unwanted image signal and an adjacent channel's interference signal from a first intermediate frequency (IF) signal sampled at a first sampling frequency. The interpolator resamples (at a second sampling frequency) a signal output from the image rejection filter and compensates for a predetermined symbol timing offset in response to a first control signal, thereby outputting a second IF signal. The NCO down converts the second IF signal and simultaneously compensates for a predetermined carrier offset in response to a second control signal, thereby outputting a first complex signal. The matched filter unit receives the first complex signal and filters the first complex signal, thereby outputting a second complex signal. The frequency converter generates a third complex signal having a double side band from the second complex signal output from the matched filter unit. The DC remover removes (filters out) a pilot signal from a DC signal included in the third complex signal output from the frequency converter.

The invention discloses a laser measurement method based on double-sideband modulation, which is used for measuring distance information and speed information of an object to be measured simultaneously. The laser measurement method comprises the steps of modulating a linear frequency modulation microwave signal on an optical carrier, and generating a carrier-suppressed double-sideband modulation optical signal; then using the generated double-sideband modulation optical signal as probe light, and transmitting the probe light to the object to be measured; performing frequency beating on an echo signal and a local oscillation optical signal to obtain an electric signal which simultaneously contains time delay information and Doppler frequency shift information of the echo signal, wherein the local oscillation optical signal is obtained by splitting the optical carrier or the double-sideband modulation optical signal; and finally extracting the time delay information and the Doppler frequency shift information of the echo signal from the electric signal, obtaining distance information of the object to be measured according to the time delay information, and obtaining speed information of the object to be measured according to the Doppler frequency shift information. The invention further discloses a laser measurement device based on double-sideband modulation. The laser measurement method and device based on double-sideband modulation can simultaneously realize real-time and accurate measurement for the distance information and the speed information of the object to be measured.

The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signal The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signalin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal perfoin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal performance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsrmance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesa filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier wavea filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier waveposition generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the central position generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the centralcarrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.carrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.

In the present invention, an all digital, multi channel RF transmitter is utilized for a parallel magnetic resonance imaging (MRI) device, MRI signal generation, modulation and amplification are employed entirely digitally in the proposed RF transmitter, which enables each transmit channel to be easily and individually reconfigured in both amplitude and phase. Individual channel control ensures a homogeneous magnetic field in the multi channel RF coil in MRI. Besides the homogeneous magnetic field generation, multi-frequency MRI signal generation is made easy by the present invention with very high frequency resolution. Multi-frequency enables faster image acquisition which reduces MRI operation time. Digital Weaver Single Side Band (SSB) modulation is also incorporated into the all digital transmitter to suppress unwanted bands of Double Side Band (DSB) MRI signals. The power amplifier in the MRI transmitter does not amplify the unwanted band so that SSB modulation leads to higher power efficiency.

The invention discloses a measuring method and system for frequency response of an electro-optical modulator. A light beam splitter divides optical carrier signals into an upper path and a lower path; in the upper path, a Mach-Zehnder modulator modulates microwave signals output by a microwave source 1 to optical carrier waves, and double-side-band signals which inhibit the carrier waves are generated, and serve as pumping signals after being amplified; and in the lower path, the electro-optical modulator to be measured modulates microwave signals output by a microwave source 2 to optical carrier waves, and double-side-band signals are generated. The frequencies of the microwave source 1 and the microwave source 2 are adjusted, so that the double-side-band signals output by the electro-optical modulator to be measured form single-side-band signals in a Brillouin medium. A photoelectric detector converts the single-side-band signals into electric signals, an amplitude-phase receiver extracts amplitude and phase information from the electric signals, and combined response of the electro-optical modulator to be measured and the photoelectric detector are obtained; and the frequency response of the electro-optical modulator to be measured is obtained by removing the frequency response of the photoelectric detector.

The invention provides a double side band frequency diversity array radar system and an object positioning method thereof and belongs to the technical field of radar signal processing. The double side band frequency diversity array radar system consists of N array elements that are linearly and uniformly arranged at an interval, N is a positive integer, and each array element comprises an emitting part and a receiving part. The emitting part comprises a modulation signal generator, a double side band modulator and an emitting antenna, wherein an output end of the modulation signal generator is connected with an input end of the double side band modulator, and an output end of the double side band modulator is connected with the emitting antenna. The receiving part comprises a receiving antenna, a filter group and a positioning calculation unit, wherein the filter group consists of two narrow band filters that are different in frequency, the receiving antenna is connected with input ends of the two narrow band filters, and output ends of the two narrow band filters are connected with an input end of the positioning calculation unit.