Abstract: Vector modulation is illustrated. A method includes receiving an input signal. The input signal is split into a first 0° output and a 90° output. The first 0° output is split into a second 0° output and a first 180° output using a continuous transmission line. The 90° output is split into a third 0° output and a second 180° output using a continuous transmission line. The second 0° output, the first 180° output, the third 0° output, and the second 180° output are modulated. The modulated second 0° output, the first 180° output, the third 0° output, and the second 180° output are recombined to produce an output signal, where all four of the modulated second 0° output, the first 180° output, the third 0° output, and the second 180° output are used to create the output signal.

Abstract: A self-reset ADC may take a set of temporally equidistant, modulo samples of a bandlimited, analog signal, at a sampling rate that is greater than ?e samples per second, where ? is Archimedes' constant and is Euler's number. The bandlimited signal may have a bandwidth of 1 Hertz and a maximum frequency of 0.5 Hertz. These conditions of sampling rate, bandwidth and maximum frequency may ensure that an estimated signal may be recovered from the set of modulo samples. This estimated signal may be equal to the bandlimited signal plus a constant. The constant may be equal to an integer multiple of the modulus of the centered modulo operation employed to take the modulo samples.

Abstract: A system and method for duplexing radio frequency signals for full-duplex transmission and reception by an antenna. The system comprises a signal coupler comprising an antenna node configured to be connected to the antenna, an input node for receiving radio frequency signals for transmission by the antenna, an output node for outputting radio frequency signals received by the antenna, and a coupling node. The system further comprises a variable impedance element connected to the coupling node to reduce interference between the signals for transmission by the antenna and the signals received by the antenna, the variable impedance element comprising a variable phase shifter connected to a variable attenuator.

Abstract: A unit cell for a resistive mixer includes a plurality of active devices arranged in series, wherein each of said plurality of active devices having a different output conductance. A resistive mixer includes a plurality of active devices connected in series with one another to form a unit cell.

Abstract: A frequency and data synchronization control system through the 8VSB SFN DTx modulation prevents the deterioration of the digitally broadcasted receiving sensitivity caused by a discrepancy of the frequency or data between the receiver of the digital broadcasting signal and the distributed translator or between distributed translators.

Abstract: A single sideband mixer is constructed with digital logic elements such as T-type flip-flops and inverters and with FETs, and the resulting mixer circuit simultaneously improves control over the frequency resolution, noise floor and operating frequency range. The use of this group of elements also allows the mixer circuit to be easily realized in an integrated circuit.

Abstract: A single side band (SSB) mixer includes an in-phase SSB mixer unit and a quadrature-phase SSB mixer unit. The in-phase SSB mixer unit generates an in-phase output current, and includes a first transformer load in which a portion of a quadrature-phase output current flows. The quadrature-phase SSB mixer unit generates the quadrature-phase output current, and includes a second transformer load in which a portion of the in-phase output current flows. The SSB mixer may be used in a wide frequency band without degrading frequency selectivity.

Abstract: A single side band (SSB) mixer includes an in-phase SSB mixer unit and a quadrature-phase SSB mixer unit. The in-phase SSB mixer unit generates an in-phase output current, and includes a first transformer load in which a portion of a quadrature-phase output current flows. The quadrature-phase SSB mixer unit generates the quadrature-phase output current, and includes a second transformer load in which a portion of the in-phase output current flows. The SSB mixer may be used in a wide frequency band without degrading frequency selectivity.

Abstract: A method and apparatus is disclosed herein for transmitting data wirelessly.

Abstract: A phase tracking system includes a source of an input signal representing a received symbol. A phase rotator has a first input terminal which is responsive to the input signal, a second input terminal which is responsive to a phase correction signal, and an output terminal which produces a phase adjusted output signal. A decision element generates an ideal signal representing the received symbol in response to the phase adjusted output signal. A phase adjuster, which has full phase wrap-around capability, generates the phase correction signal in response to the phase difference between the phase adjusted output signal and the ideal signal.

Abstract: A modulator for radio-frequency signals designed an entirely digital modulator has two mixer stages connected in series. The first mixer stage implements with a relatively low first sample rate a frequency mixing with a first oscillator frequency that is adjustable with high precision. The second mixer stage implements a frequency mixing with a significantly higher second sample rate and with a relatively coarsely adjustable second oscillator frequency. The downstream second mixer stage, in the case of a single mixer stage, the mixer stage, has at least two phase accumulators that are incremented with the higher second sample rate but with different incremental values. The output signal of at maximum one of the phase accumulators is evaluated at any point in time.

Abstract: An IF receiver receives a tapped portion of a modulated communication signal. A processor, local with respect to the IF receiver, receives an interrupt from a main processor instructing it to evaluate the power levels of desired and undesired components of the communication signal. The interrupt may be sent for a variety of reasons, such as according to a predetermined schedule, or in response to changes in a communication network, such as new equipment installation and temperature changes. The local processor instructs the IF receiver to tune it's LO so that the evaluation range of the receiver and feedback loop to parameter-adjustable components includes the frequency, or frequencies, of a specified signal component. The local processor evaluates the power level of the specified signal component. Based on the evaluation, the local processor instructs parameter-adjustable signal processing components to alter parameters to optimize characteristics of the communication signal for transmission.

Abstract: A modulator for radio-frequency signals designed an entirely digital modulator has two mixer stages connected in series. The first mixer stage implements with a relatively low first sample rate a frequency mixing with a first oscillator frequency that is adjustable with high precision. The second mixer stage implements a frequency mixing with a significantly higher second sample rate and with a relatively coarsely adjustable second oscillator frequency. The downstream second mixer stage, in the case of a single mixer stage, the mixer stage, has at least two phase accumulators that are incremented with the higher second sample rate but with different incremental values. The output signal of at maximum one of the phase accumulators is evaluated at any point in time.

Abstract: An IF receiver receives a tapped portion of a modulated communication signal. A processor, local with respect to the IF receiver, receives an interrupt from a main processor instructing it to evaluate the power levels of desired and undesired components of the communication signal. The interrupt may be sent for a variety of reasons, such as according to a predetermined schedule, or in response to changes in a communication network, such as new equipment installation and temperature changes. The local processor instructs the IF receiver to tone it's LO so that the evaluation range of the receiver and feedback loop to parameter-adjustable components includes the frequency, or frequencies, of a specified signal component. The local processor evaluates the power level of the specified signal component. Based on the evaluation, the local processor instructs parameter-adjustable signal processing components to alter parameters to optimize characteristics of the communication signal for transmission.

Abstract: In an AM system directed to commercial broadcasting, a pure unmodulated (CW) carrier signal and two sideband signals are generated and processed separately as three independent signals that are summed as output of a final linear mixer. The sideband signals are derived independently utilizing audio spectrum-sharing based on complementary comb filtering, quadrature phase-shifting at both audio and carrier sideband frequencies, and exclusive alternate toggling at a designated switching rate between the two sidebands so that at any instant in time only one of the two sidebands is present along with the continuous carrier. The overall performance provides the capability of advantageous modulation beyond the conventional 100% modulation limit.

Abstract: The present invention relates to a single side band modulator for splitting a signal into a first split signal and a second split signal 90 degrees out of phase with the first split signal. A first double balanced mixer modulates the first split signal and includes a transformer, a modulating signal input, and a first diode ring. The transformer connects the first diode ring to a quadrature hybrid. A second double balanced mixer modulates the second split signal and includes a transformer, a modulating signal input, and a second diode ring. The transformer of the second double balanced mixer connects the second diode ring to the quadrature hybrid. The first and second diode rings are connected in parallel and are connected to a third transformer which performs the function of a power combiner.

Abstract: A method of and apparatus for digitally generating a broadband signal comprising a plurality of CW or quadrature modulated signals having incrementally related frequencies wherein said plurality of signals are centered about a center RF frequency is disclosed. The invention provides for generating a first and second composite baseband signal each comprising a linear combination of N sinusoids, or N modulated signals each modulated in quadrature so as to achieve a desired instantaneous phasor value for each of the RF signals. The invention further provides for modulating in quadrature the first and second composite baseband signals on a local oscillator signal having a frequency equal to the center RF frequency.

Abstract: A system of and method for reducing or eliminating any unwanted sideband component in a signal derived from the output of a quadrature modulator. An unwanted sideband detector detects the unwanted sideband in the output of the quadrature modulator, and responsive thereto, a correction circuit corrects a baseband signal prior to inputting it to the quadrature modulator. In one embodiment, the unwanted sideband detector is an envelope detector.

Abstract: Circuits for removing clock related artifacts in an offset QAM generated VSB signal includes a transmitter arrangement and a receiver arrangement. In the transmitter, a detector detects the artifacts and a correlator determines whether the artifacts repeat over two symbols or over four symbols. A signal indicative of the artifacts is used to control processing circuits for adjusting the ratios and levels of the I and Q signal components of the QAM signal for substantially eliminating the artifacts. In the receiver, the received VSB signal is divided into four parallel signals. Each parallel signal is processed to develop an average symbol level that is subtracted before the parallel signals are recombined. The four symbol repeat rate artifacts reflect a DC offset of the VSB signal symbols, which are both positive-going and negative-going and which therefore average to zero for random signals. Averaging is done over N symbols where N is a power of 2.

Abstract: A digital signal processing vestigial-sideband television modulator receives a television signal. The present invention digitizes the television signal to generate a video signal and a digital processor processes the video signal to generate a complex baseband signal. The complex baseband signal is converted into an in-phase baseband signal and a quadrature baseband signal and modulated to respectively generate a modulated in-phase baseband signal and a modulated quadrature baseband signal. The modulated in-phase baseband signal and the modulated quadrature baseband signal are combined to produce a vestigial radio frequency television signal. The undesired sideband of the vestigial radio frequency television signal is tapped, filtered, and, subsequently, the power level of the undesired sideband is detected. Any imbalance in the modulation process is compensated by using the detected power level of the undesired sideband.

Abstract: A quadrature vestigial sideband (QVSB) communication system provide bandwidth efficient data transmission using cross coupled data signaling during both transmit and receive having controlled intersymbol interference. The QVSB modem includes cross coupled arm transmit and receive data filtering on both of the I&Q channels providing a bandwidth efficient QVSB spectra. A quadrature crosstalk maximum likelihood sequence estimator implements a Viterbi decoding algorithm for providing estimated data sequence outputs. The receiver is a coherently aided demodulator synchronized by a synchronization loop providing time and phase references using the estimated data sequence outputs.

Abstract: An IC card, an IC card processor, and an IC card system are simply arranged to perform full-duplex data exchange efficiently using a frequency band in such a manner that a transmission signal sent from the IC card processor is received by an antenna, the transmission signal is demodulated, and a response signal to be sent from the antenna is formed by modulating a main carrier having the same frequency as a main carrier of the transmission signal with a response data sequence in such a manner that a sideband of the response signal does not overlap a sideband of the transmission signal along the frequency axis.

Abstract: An analogue phase shifter with vector modulator is envisioned. The analogue phase shifter has an input stage that provides the generation of a pseudo-basis of four vectors. The analogue phase shifter has a multiphase filter. The analogue phase shifter has an output stage that controls the amplitde of the basis vectors, and acts to recombine them. The input stase is made with a phase opposition signal generator and a multiphase filter. The input stase is made of four variable attenuators. The attenuators are for separate control of the amplitude of each of the basis vectors. The output stage also has a common output providing the summation of four quadrature channels. In one case, the output stage includes two differential amplifiers. In another case the quadrature channels are connected to the common output through buffer amplifier stages, each followed by a summation capacitor.

Abstract: In the broadcast band having a plurality of channels allocated therein, by using high-side injection and low-side injection as described herein, the noise introduced into the channel by the local oscillator signal can be minimized. The local oscillator signal in combination with the intermediate frequency determines the frequency of the channel signal being produced by the transmitter. The selected high-or low-side injection determines whether the bulk of the power is introduced into the combination frequency signal (i.e., the channel) above or below the local oscillator frequency, thereby moving the local oscillator frequency outside the broadcast band. The non-selected sideband is even further outside broadcast band.

Abstract: In an SSB transmitter, a problem such that the central frequency of a BPF for extracting one of sideband signals from the modulated signals obtained by modulating a carrier frequency signal by an input sound signal is changed by temperatures, causing a drop in suppression ration and a deterioration in sound is solved. The microcomputer circuit 23 determines the change of the central frequency (−&Dgr;&agr;) of the BPF 5 from the compensation table related to the BPF 5 stored in the ROM 32 based on a temperature information of the BPF 5 detected by the temperature sensor 21; controls local oscillators 4a and 7a that output modulated signals and VHF band signals to the balanced modulator 3 and the mixer 6; and changes the frequency of each signal by −&Dgr;&agr; from the standard condition.

Abstract: In accordance with the invention, a single sideband mixer includes first and second all-pass 90° phase shifters. Each phase shifter produces two outputs of substantially equal amplitude but subject to a phase angle error (&thgr;) indicative of a deviation from quadrature of the two outputs. The phase angle errors of the first and second phase shifters are designed to be equal and to track each other over different ambient and operating voltage conditions. In one embodiment, the outputs of the first phase shifter are coupled via a cross switch to the inputs of two mixers and the outputs of the second phase shifter are fixedly connected to the inputs of the two mixers. The outputs of the two mixers are combined to produce an output whose frequency is a function of either the sum or the difference of first and second input frequency signals respectively applied to the first and second phase shifters.

Abstract: An image reject circuit comprises a local oscillator 26 for producing a local oscillator signal. A tunable phase shifting network 29 has inputs 1, 3 for receiving the local oscillator signal and producing an output in-phase (I) signal 13, 25 and an output quadrature (Q) signal 15, 27. A first amplitude detector 33 determines the amplitude of the output I signal, while a second amplitude detector 35 determines the amplitude of the output Q signal. A comparator 37 determines the difference between the amplitudes of the output I and Q signals, to produce a tuning signal for tuning the phase shifting network 29 to bring the difference between the amplitudes of the output I and Q signals towards a desired level. Preferably, the tunable phase shifting network 29 (shown in FIG. 4) comprises a combination of tunable capacitive, resistive and inductive elements.

Abstract: In an SSB transmitter, a problem such that the central frequency of a BPF for extracting one of sideband signals from the modulated signals obtained by modulating a carrier frequency signal by an input sound signal is changed by temperatures, causing a drop in suppression ration and a deterioration in sound is solved.

Abstract: A method and system are provided for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band. The analog monophonic component of the composite signal may be received by conventional AM-band audio receivers. In certain embodiments, the analog signal is a single-sideband large-carrier or vestigial-sideband large-carrier signal, and the composite RF signal includes a digital signal whose spectrum is substantially confined in one inner sideband. In other embodiments, a baseband digital signal is combined with an analog monophonic audio signal and transmitted in upper inner and lower inner sidebands using nonlinear compatible quadrature amplitude modulation (NC-QAM). Additional digital signals' spectrum occupies the lower outer and upper outer sidebands.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A circuit for reducing phase noise in a transmitted radio signal includes a first phase-locked loop circuit including a first controlled oscillator generating a first output signal at a first desired frequency, and a first phase comparator developing a first phase error signal to control the first controlled oscillator, the first error signal representative of phase differences between the first output signal and the first desired frequency. A second phase-locked loop circuit includes a second controlled oscillator generating a second output signal at a desired frequency of transmission related to the first desired frequency, and a second phase comparator developing a second phase error signal representative of phase differences between the first output signal and the desired frequency of transmission.

Abstract: A method and system are provided for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band. The analog monophonic component of the composite signal may be received by conventional AM-band audio receivers. In certain embodiments, the analog signal is a single-sideband large-carrier or vestigial-sideband large-carrier signal, and the composite RF signal includes a digital signal whose spectrum is substantially confined in one inner sideband. In other embodiments, a baseband digital signal is combined with an analog monophonic audio signal and transmitted in upper inner and lower inner sidebands using nonlinear compatible quadrature amplitude modulation (NC-QAM). Additional digital signals' spectrum occupies the lower outer and upper outer sidebands.

Abstract: A method of and apparatus for effecting single sideband modulation which mixes and sums the quadrature and in-phase components of a baseband signal with the in-phase and quadrature components of an intermediate frequency (IF) signal to form in-phase and quadrature components of a sum signal having a frequency equal to the sum of the frequencies of the baseband and intermediate frequency signals and which mixes and sums the quadrature and in-phase components of an RF carrier signal with the in-phase and quadrature components of the sum signal to form a single-sideband signal.

Abstract: A modulating reflector circuit arrangement comprising a transistor configured by means of a feedback arrangement upon operation within a linear region of the transistor's current/voltage characteristic to reflect an incoming amplitude modulated signal with an increased amplitude and a modulator operable to modulate power to the transistor with a periodic waveform in which the reciprocal of the period of the periodic waveform is the required sideband frequency of the reflected signal and the waveform is selected such that the arrangement reflects a substantially single sideband signal.

Abstract: A method and apparatus for reducing peak-to-average power ratio in a paging transmitter broadcasting an independent sideband amplitude modulation protocol is disclosed. A digital signal, for example a digital voice signal, is provided to a control gain generator which generates a digital gain sequence. The digital gain sequence is such that during peak values in the digital signal the gain is low and during low values in the digital signal the gain is high. The digital gain sequence is multiplied with the digital signal to compress the dynamic range of the digital signal.

Abstract: A digital signal processing device and method for vestigial sideband (VSB) modulation of a digital signal. A 2.sup.n -ary digital signal d.sub.i is provided to a baseband shaping filter which samples the signal to provide a baseband signal which has real and imaginary portions Re(S.sub.bb (kT)) and Im(S.sub.bb (kT)), where ##EQU1## The VSB signal is provided with perfect sideband suppression without using analog filters. The digital signal processing device and method is characterized by requiring minimal bandwidth in the shaping filter.

Abstract: A VSB modulator receives a stream of data at a 10.76 MHz constant symbol rate and converts it to a 6 MHz bandwidth signal centered at 44.0 MHz. The incoming data is interpolated by three to generate three data images and a digital filter selects the image embracing the range of 5.38 to 10.76 MHz. A sine X/X correction is added to compensate for the loss experienced in the D/A converter. The signal for the D/A converter is filtered and mixed with a 35.93 MHz oscillator output to produce data about the 44.0 MHz IF frequency. A SAW filter rejects all but the desired data.

Abstract: A single sideband modulator circuit for modulating an optical signal with an RF signal to provide a frequency shift to the optical signal. The modulator circuit utilizes a dual path modulator having an electrical terminal and two optical terminals. An RF signal is provided to the electrical terminal and an optical signal is provided to each optical terminal so that the optical signal input to one terminal travels in the direction of the RF signal to produce an output optical signal having a carrier band and a single sideband, and the optical signal input to the other optical terminal travels in the opposite direction of the RF signal to produce an output having only a carrier band. A coupler adds the resulting optical output signals so that the carrier bands are cancelled, leaving only the sideband.

Abstract: A communication system having a modulation system for transmitting a symbol set via a single side-band modulated carrier and a demodulation system for recovering the in-phase and quadrature signals from the modulated carrier. The modulation circuit receives M symbol values and generates M time domain samples for each of the in-phase and quadrature signals. The in-phase and quadrature signals can then be combined to generate the single side-band modulated carrier. The modulation circuit includes a transform circuit for generating M transformed symbol values by computing the transform of the M symbol values. A polyphase filter bank having 2M FIR filters is used to process the output of the transform circuit. Each filter has g taps, where g is an integer greater than 1. The outputs of the polyphase filters are combined with the outputs of the polyphase filters generated from a previously received set of M symbols to generate the M time-domain signal values of the in-phase signal.

Abstract: A Single-Sideband (SSB) modulator includes:a demultiplexer for successively distributing an A/D converted digital signal x(t) to L sequences x.sub.1 (t.sub.1), x.sub.2 (t.sub.2)... ...x.sub.L (t.sub.L) in accordance with a sampling period t, an adder including L/2 adders for adding constants to x.sub.i (t.sub.i) of the demultiplexer, where i is either an even or an odd number; a phase shift network system comprising L/2 phase shift networks for making a 90-degree phase difference between the outputs of the adder and x.sub.i (t.sub.i) of the demultiplexer; a timing signal generator for generating timing signals expressed by A(-1).sup.(KL)/2+n and/or A(-1).sup.((K-1)L)/2+n in accordance with the sampling period t; a multiplier including L/2 pair of multipliers for multiplying the outputs of the phase shift network system by the outputs of the timing signal generator; a multiplexer for selecting the outputs of the multiplier in accordance with the sampling period t.

Abstract: The present invention provides a system and method in which an arbitrary information-modulated signal is efficiently amplified to high power levels. The arbitrary information-modulated signal is received at a low power level and is separated into elemental signals. In a preferred embodiment, a frequency/phase information signal and an amplitude information signal are the elemental signals which collectively represent the essential information in the original information-modulated signal. The circuit uses the elemental signals to provide an amplified replica of the original information-modulated signal. The amplification preferably, though not necessarily, involves using the digital amplitude modulators disclosed in U.S. Pat. No. 4,804,931, U.S. Pat. No. 5,260,674, or U.S. Pat. No. 5,367,272.

Abstract: The invention provides various embodiments of a balanced modulator, each of which involves one or more individual amplitude modulators which, individually, do not provide suppressed-carrier outputs. A first embodiment employs a single amplitude modulator whose carrier input is selectively delayed by a half wavelength, depending on the polarity of the input modulating signal, and whose amplitude input receives the absolute value of the modulating input signal. A second embodiment involves summation of the outputs of two amplitude modulators whose carrier inputs are responsive to carrier signals offset by a half carrier wavelength and whose modulating signal inputs are responsive only to signals of respectively opposite polarity. Further, quadrature amplitude modulation (QAM) modulators are provided by a combination of the above-described modulators.

Abstract: A digital single sideband modulator (10) includes a relatively complex CMOS NCO (14) that drives a relatively simple ECL frequency translator (30). The frequency translator (30) outputs a digital signal that is converted to analog by a D/A (44) and then filtered in a bandpass filter (46) having a pass band including a frequency of twice the NCO's clock frequency. The NCO (14) generates a modulated intermediate frequency NCO signal having quadrature components. The frequency translator (30) multiplies real and imaginary components of the NCO signal by real and imaginary components of digitized SIN, COS sampling functions (48, 50). The resulting products are added together. The adding operation is performed by a multiplexer (32), whose selection input is driven at twice the carrier frequency, and the multiplying operations are performed by a selective negation circuit (34), that is driven at the carrier frequency.

Abstract: A local frequency generator employing a single crystal oscillator, latches and direct digital synthesizer circuits digitally produces all signals needed in the transmitter channel of a MRI system to generate MRI transmitter RF pulses. The local frequency generator is operable in both the single side band and double side band modes and has the capability of switching between the modes. The generator is constructed with a phase resetting capability for providing the plural output frequencies needed for making plural MRI slices.

Abstract: An improved modulator circuit for mixing a modulation signal with a carrier signal includes first and second harmonic mixers which are operative to produce modulated output signals at an output frequency corresponding to both the sum and the difference of the modulation signal frequency and the even harmonic frequencies of the carrier signal frequency. In one configuration employing a 90.degree. hybrid, the output signals of the harmonic mixers are combined to produce a single sideband modulated output signal. A novel harmonic mixer circuit is also provided along with demodulator circuits and methods of modulating and demodulating modulation signals.

Abstract: A digital circuit having a first section for converting a low-frequency signal into a sampled single sideband signal, coupled to a second section for separating the sampled SSB signal into its two components, the phase and envelope components.

Abstract: Apparatus and method for effecting single sideband suppressed carrier modulation suitable for small, hand-held, high-frequency cellular radio transmitters such as those used at 900 mHz. A local oscillator generates a signal at 0.8 the frequency of the desired carrier. The generated frequency is counted down to produce an IF that is 0.2 the frequency of the desired carrier and the IF is mixed with the baseband signal to produce a modulated IF. The modulated IF is then mixed with the first generated signal to generate the modulated carrier signal. Advantageously, all of the foregoing components can be provided on the same integrated circuit chip.

Abstract: In this invention, in order to generate a VSB modulation signal from a digital baseband signal, an in-phase component of a modulation signal having a frequency spectrum having a high-frequency component whose level is half that of its low-frequency component, and an orthogonal component of the modulation signal of a high-frequency component having a frequency spectrum whose level is half that of the low-frequency component are generated from the baseband signal. The in-phase component and the orthogonal component are multiplied with carrier signals to obtain a carrier in-phase component and a carrier orthogonal component. The carrier in-phase component and the carrier orthogonal component are synthesized to obtain a VSB modulation signal.

Abstract: In a vestigial sideband modulator, an i.f. signal is modulated with a video input and the extreme part of one of the sidebands is removed to provide the right frequency response shape for transmission. The signal for transmission is usually produced by mixing the i.f. signal with an oscillator signal known as the heterodyne signal which differs from the desired carrier frequency by the i.f. frequency, and filtering the signal with a subsequent channel filter to remove any unwanted heterodyne oscillator components and the unwanted sum or difference product. To avoid the need for such a channel filter, the filtered video-modulated i.f. signal is demodulated to quadrature baseband components using the i.f. oscillator, and quadrature components at carrier frequency are modulated with these baseband components to produce on combination a v.s.b. modulated video output at carrier frequency.

Abstract: A single sideband radio system. The system comprises a transmitter and a receiver. The transmitter comprises a transmitter baseband processing portion for generating a first baseband signal comprising first, second, and pilot components and modulating the first baseband signal in inverse proportion to the strength of the first component of the first baseband signal and an RF output stage for generating and transmitting a single sideband signal comprising first, second, and pilot portions corresponding to the first, second, and pilot components of the modulated first baseband signal. The receiver comprises an RF input stage for receiving the single sideband signal and a receiver baseband processing portion for generating a second baseband signal comprising first, second, and third components corresponding to the first, second, and third portions of the single sideband signal and for correcting the second baseband signal based on the pilot component of the second baseband signal.