Abstract: A method for generating a frequency-modulated signal with high receivability quality, comprising the steps of: before sending an input modulating signal to a modulator, modifying the input modulating signal so as to compensate for distortions which will be introduced in the modulated signal receiving section.

Abstract: The system for recovering symbol timing offset and carrier frequency error from an orthogonal frequency division multiplexed (OFDM) signal includes a receiver circuit for receiving an OFDM modulated signal representing a series of OFDM symbols, and providing a received signal to an output thereof. A peak development circuit is included for developing a signal having a plurality of signal peaks representing symbol boundary positions for each received OFDM symbol, where each of the signal peaks is developed responsive to an amplitude and phase correspondence produced between the leading and trailing portions of each of the received OFDM symbols. The system includes a circuit for enhancing the signal peak detectability, which includes a circuit for additively superimposing and then filtering the signal peaks, to produce an enhanced signal peak having an improved signal-to-noise ratio.

Abstract: A digital VSB transmission system that is able to send supplemental data along with MPEG image/sound data is enclosed. The system initially encodes the supplemental data symbol to generate a parity bit, and it multiplexes the parity bit with a predefined sequence and transmits the multiplexed data to a receiver. The system is compatible with the existing ATSC 8T-VSB receivers that are already on the market. It can have advantages over the other type of VSB transmission systems that transmit only the predefined sequence. In addition, the system according the to the present invention results a improved robustness against ghost and noise signals in a channel compared to systems using only the ½ rate convolutional encoding.

Abstract: The invention is an apparatus and method for using electromagnetic energy as the means of automatic data collection (ADC). The communication system that comprises the invention utilizes frequency modulated (“FM”) sideband electromagnetic energy to enable full duplex communication with another communication device. In one embodiment one of the communication devices is passive and the carrier is used to power the passive device. In another embodiment the communication devices are active and the carrier is suppressed to increase range or decrease power constraints, as the application requires.

Abstract: Disclosed is a frequency conversion circuit with sideband suppression in which a first mixer receives an in-phase signal (IFi) and is driven by a local oscillator having an in-phase (0°) oscillator signal (LOi), and produces two sideband signals (LO+IF, LO−IF). A second mixer receives a quadrature phase frequency signal (IFq+) and is driven by a local oscillator having a quadrature (180°) oscillator signal (LOq), and produces two sideband signals (LO+IFq, LO−IFq). One of the sidebands from the second mixer is 180° out of phase with respect to the same sideband from the first mixer. A signal combiner then receives and combines the two sidebands from the first mixer and the two sidebands from the second mixer, the signal combiner suppressing one sideband and enhancing the other sideband. In preferred embodiments, the mixers comprise MOSFET transistors and the signal combiner comprises capacitive elements.

Abstract: A data communication apparatus according to the present invention can be used both in one-wave mode and two-wave mode, and includes: first and second tuning circuits (1, 2); a power supply circuit (3) connected to first tuning circuit (1) for generating power by a signal received by first tuning circuit (1); an information processing circuit (15) connected to first tuning circuit (1) or second tuning circuit (2) through a switching circuit (6) and including a detection circuit (7), a decoder (8), an encoder (10) and the like. Information processing circuit (15) includes a switch control circuit (14) detecting if the mode of the received radio wave is one-wave mode or two-wave mode in accordance with an output from first tuning circuit (1) and controlling switching circuit (6) such that detection circuit (7) is connected to one of first and second tuning circuits (1, 2).

Abstract: A range gated microwave motion sensor having adjustable minimum and maximum detection ranges with little response to close-in false alarm nuisances such as insects or vibrating panels. The sensor resolves direction of motion and can respond to target displacement in a selected direction and through a selected distance, in contrast to conventional hair-trigger motion sensors. A constant false alarm rate (CFAR) detector prevents false triggers from fluttering leaves, vibrating machinery, and RF interference. The sensor transmits an RF pulse and, after a modulated delay, mixes echo pulses with a mixer pulse. Thus, the echo pulses are modulated at the mixer output while transmit and mixer pulse artifacts remain unmodulated and easily filtered from the output. Accordingly, the sensor only responds to echoes that fall within its minimum and maximum range-gated region, and not to close-in or far-out objects.

Abstract: A process for transmitting mixed analog and digital signals. A composite signal is transmitted whose frequency spectrum is composed of a first analog spectrum representative of the amplitude of single-sideband modulation and of a second spectrum composed of multi-subcarriers. The two spectra occupy two disjoint frequency bands. The device may be used for simultaneous broadcast of the same program or its reception by analog or digital receivers.

Abstract: An SSB radio communication system and radio apparatus applicable to ultra high frequencies such as a VHF band and UHF band. In the transmitting side, a carrier wave is amplitude modulated by modulation input signals which comprise a constant amplitude, sine wave shaped reference pulse having a predetermined width and period and a sine wave shaped modulation pulse signal having an amplitude representing two- or multi-value digital values having the same width as the reference pulse signal and which are formed based on the amplitude of the reference pulse signal, and the modulated pulse signals are transmitted on a single side band, while in its receiving side the gain of received signals is automatically adjusted based on the reference pulse signal that is the value of the peak of the received signals.

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 technique for amplitude modulating a carrier without producing side-bands is disclosed. In a preferred embodiment, a signal carrier is directly modulated and no energy side-bands are produced. This is accomplished by amplitude quantizing the data or information to be transmitted at the carrier rate or frequency and then resetting the amplitude of the carrier during one of the two 0-crossing times for each cycle of the carrier.

Abstract: An integrated transceiver circuit (10) includes a single side-band mixer (12) and a phase locked loop (30). The phase locked loop (30) includes a phase detector (32) coupled to a voltage controlled oscillator (36) via a summing circuit (33) and a low pass filter (34). A feedback signal from the voltage controlled oscillator (36) is transferred to the phase detector (32) through a counter (38). Either a phase modulation signal or a frequency modulation signal are inputs of summing circuit (33) and modulate the transmitter carrier signal generated by the voltage controlled oscillator (36). The carrier signal generated at an output terminal (40) of the transmitter tracks the frequency of the local oscillator signal that is supplied at an input terminal of the single side-band mixer (12) in the receiver.

Abstract: A point to multipoint two-way communications systems in which a base station transmits to a remote station ("outstation") on a frequency derived by the base station from the frequency of a previous transmission received by said base station from said outstation.

Abstract: A front end circuit for an RF dual band GSM/DCS phone includes a first channel including an elliptical high-pass filter, a first SAW filter, and a low noise amplifier and a second channel including a second SAW filter and a second low noise amplifier. The output of each channel is alternately switchable to a single-side band mixer circuit. This front end circuit arrangement provides significantly reduced cost and part count over other approaches.

Abstract: A system of vehicle identification with a first interrogator that uses a Lower SideBand (LSB) receiver to receive a modulated signal from a vehicle transponder and a second interrogator that uses an Upper SideBand (USB) receiver to receive another modulated signal. The two interrogators are adjacent to each other at a toll plaza, and operate at different carrier frequencies to force a signal frequency bandgap between communication signals in adjacent vehicle lanes.

Abstract: A method for decoding a suppressed-carrier modulated signal in the presence of a pilot tone, comprising the steps of:extracting the pilot signal from the modulated signal;obtaining the suppressed carrier by multiplying the pilot signal by the pilot signal in quadrature;adjusting the level of the suppressed carrier; andreconstructing the modulating signal.

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: The method for generating a modulated television signal involves performing a first filtering and a second filtering to obtain two signals, one having a passband that is equal to complete passband and the other one having a passband that is equal to the sideband to be suppressed. The signal having a complete passband is amplitude-modulated with a video carrier, obtaining a first signal. The signal having a passband equal to the sideband to be suppressed is then divided into a first component and a second component, and the first component is phase-shifting by 90.degree. with respect to the second component. The first component is modulated with a video carrier that is phase shifted by 90.degree., obtaining a second signal. The second component of the signal having a passband equal to the sideband to be suppressed is modulated with the video carrier, obtaining a third signal. The second and third signals are then subjected to an algebraic sum, obtaining a fourth signal.

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 modulation and demodulation scheme for video signals may be used for HDTV signals using VSB-PAM, analog NTSC signals using VSB-AM and digital video signals using QAM. VSB-PAM modulation and demodulation may be performed using in-phase and quadrature baseband filters. By adjusting the filter taps, a single modulator structure may be used for QAM and VSB-PAM modulation. Similarly, a single demodulator structure may be used for QAM and VSB-PAM demodulation. This demodulator may also be used for VSB-AM modulation.

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: The method envisages performing a first filtering and a second filtering of a video signal to obtain two signals, one signal having a passband that is equal to the complete band and a bandwidth that is a function of the frequency, and another signal whose passband is equal to the side band to be suppressed, and amplitude-modulating the signal having a complete passband with a video carrier, obtaining a first signal. The signal whose sideband is equal to the band to be suppressed is phase-shifted by 90.degree. and modulated with the video carrier phase-shifted by 90.degree., obtaining a second signal. The algebraic sum of the first signal and of the second signal obtains a third signal that represents the television signal having the desired side band.

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 television signal receiver for processing an HDTV signal transmitted in a vestigial sideband (VSB) format includes input complex filters shared by a timing recovery network (30) and a carrier recovery network (50). The filter network includes a pair of upper and lower band edge filters (20, 22) mirror imaged around the upper and lower band edges of the VSB signal for producing suppressed subcarrier AM output signals. The timing recovery network includes a phase detector (28, 38, 62) and responds to an AM signal derived from the two filters (via 26) for synchronizing a system clock (CLK). The carrier recovery network (50) also includes a phase detector (54, 60, 62, 64), and responds to outputs from one or both of the filters for producing an output error signal (.DELTA.) representing a phase/frequency offset of the VSB signal. The error signal is used to reduce or eliminate the offset to produce a recovered baseband or near baseband signal.

Abstract: Apparatus and method (10) for recovering timing information from a vestigial sideband (VSB) modulated signal generate a left hand component signal and a right hand component signal from the received signal, and filters B.sub.1 (f) and B.sub.r (f) (12, 14) filter the left hand and right hand component signals respectively. The filtered signals are then multiplied together without taking the complex conjugate of either signal, as in band edge component maximization (BECM). The generated output signal may be used in a feedback loop to regulate the sample rate of an analog to digital converter (32).

Abstract: A method for fabricating a micro-field emission gun including the steps of providing an insulator slab, formed with a penetrating hole acting as a passage of an electron beam, upon a gate electrode of the micro-field emission gun, such that the penetrating hole is aligned with an emitter of the micro-field gun, bonding an insulator slab upon the gate electrode by means of an anodic bonding process, and providing an acceleration electrode on the insulator slab such that the acceleration electrode covers a surface of said insulator slab facing away from said gate electrode, except for a passage of the electron beam.

Abstract: A method and apparatus for mitigating effects of multipath fading, interference, and noise in a single sideband (SSB) signal transmitted by a radio communication system and demodulated by a portable subscriber unit (122) utilizing a demodulator (304) compensated by a pilot signal power (406). The apparatus performs the mitigation process by calculating (708) a pilot fading threshold in addition to a muting threshold. When samples of the mean pilot signal power fall below the fading threshold, the compensation of the demodulated signal is adjusted (714). In addition, when the mean analog message signal power falls below the muting threshold, the samples included in the predetermined portion of the message are muted (718).

Abstract: In a communication system for data transmission from a moving vehicle to a stationary beacon (1) which has a transceiver in which a signal is broadcast by the beacon (1) and received by an antenna (5, 5') of an on-board unit (4) of the vehicle and after a modulation with a data signal is transmitted back again to the beacon (1), where the data are extracted from the returned signal, the reliability of transmission for the data is increased by providing that the on-board unit (4) has at least two modulators (6, 6'), with which independently of one another the received signal is modulatable with the data signal and can be transmitted back in different ways. The transmission in different ways of the signals modulated independently of one another can be done by means of spatial separation of the antennas (5, 5') and/or by means of polarizing the broadcast signals differently from one another.

Abstract: A system for communicating data between an aircraft and ground unit over conventional amplitude modulated (AM) voice radio channels employs a data collection unit for collecting data desired to be transmitted, such as global positioning system (GPS) data, altitude, or aircraft identification information which is encoded by a data encoder. A gating means senses when the microphone of the AM transmitter is keyed, and passes the encoded data and the voice signals to the existing AM modulator of the AM voice transceiver. This results in a transmitted signal received by a receiving unit, such as a ground unit, which separates the received signal into an AM modulated voice signal and a AM data signal. The AM voice signal is demodulated by normal means into an audible signal, with the AM data signal being decoded by a data decoder into data.

Abstract: In an amplitude-modulated broadcast transmitter for various types of modulation, particularly DSB (double sideband), SSB (single sideband) and ISB (independent sideband), of at least one AF signal to be transmitted, the sum and the difference is formed from the two input channels (7a, 7b). Either the sum or the difference is subjected to a Hilbert transformation in a Hilbert transformer (12). From these signals, an amplitude signal is formed in an amplitude processor (22) and a phase signal is formed in a cyclic sampler (21) and a phase conditioner (23). The amplitude signal is used for anode modulating the transmitting tube (5) and the phase signal is used for grid modulating the transmitting tube. The amplitude-modulated broadcast transmitter for various types of modulation has the advantage that the three types of modulation ISB, DSB and SSB can be set by allocating the AF signals to be transmitted to the two input channels (7a, 7b).

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 a transparent tone-in-band (TTIB) single-sideband-modulated communication system used to communicate digital data; to compensate for variations due, eg, to doppler shift of the pilot tone in the received signal, during the sweep of the frequency of a local oscillator used to tune the receiver, the output of a narrow band filter is monitored for the presence of the expected pilot tone. When the pilot tone appears to be present, the sweep is interrupted and the error rate of the demodulated digital signal is tested, the sweep being resumed if an excessive error rate is encountered.

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.

Abstract: A page party system for use in industrial environments, having a plurality of stations joined by a page line and by a single party line for providing multiple full-duplex conference calls over the single party line. Multiple full-duplex conferencing is achieved by combining single sideband suppressed carrier amplitude modulation and frequency division multiplexing.

Abstract: A sideband receiver that locks to a pilot component of a received signal. The pilot component is down-converted and then up-converted prior to phase comparing the pilot component information to provide a lock function. The receiver architecture allows monolithic integration of the receiver on a single integrated circuit (401).

Abstract: A system of transmission with amplitude modulation for the transmission of signals of all types, analog and/or digital, requiring high performance characteristics with respect to the noise induced by the transmission channel, comprising, at transmission, means for the suppressed carrier amplitude modulation of a useful signal and means for the amplitude modulation, in phase quadrature with said modulated useful signal, of a service signal, making it possible, at reception, to remove the ambiguity on the polarity of the demodulated useful signal. Thus it enables the transmission of signals in suppressed carrier modulation mode, hence with a good signal-to-noise ratio, without losing the polarity of the signal. The transmitters and receivers according to the invention also enable the transmission and reception of the signals modulated in SCAM, VSBAM or VSBSCAM modes.

Abstract: Phase or frequency modulators which utilize phase generators rather than se shifters to produce low frequency input voltages to single side band modulators. Two phase generators are used to supply the two low frequency input ports of a single side band modulator of the 90.degree. phase shift/side band cancellation type, with the voltage dividers of one phase generator being adjusted so that its output is displaced 90.degree. in phase from the output of the other phase generator.

Abstract: A radio transceiver is disclosed for use in an SSB communication system having FM data capability. The dual-mode radio transceiver of the present invention includes a receiver capable of demodulating and deriving AFC from either (a) the voice channel having voice messages transmitted via single sideband amplitude modulation with a pilot carrier, or (b) the data channel having high speed data messages transmitted via narrowband frequency modulation in the same channel bandwidth. Furthermore, the dual-mode radio transceiver includes a transmitter capable of transmitting one of either of the above types of modulation on the appropriate channel, as determined by information received from the high speed data messages transmitted on the control channel.

Abstract: In the case of a method for the generation of an amplitude-modulated ISB transmission signal from different AF signal (NF1,2), the signal vectors are split into signal components (x1,y1 and x2,y2, respectively), components sums (X,Y) are formed from the signal components and an amplitude signal (A(t)) and a harmonic phase signal are derived from the component sums. Amplitude signal and phase signal are then further processed separately and combined at the single transmitting tube (43) by combined amplitude modulation and phase modulation into the final transmission signal.

Abstract: In transparent tone-in-band communication systems a notch in the frequency band is usually formed and then the resulting spectrum is translated in frequency to an intermediate frequency range as part of the transmission process. In a transmitter of the present invention a more simple arrangement is used in which the notch is formed directly in an intermediate frequency range by using mirror filters to divide an input signal into two portions and supply respective mixers, each having one output sideband in the intermediate frequency range. The mixers receive different reference frequencies and the mixer outputs are supplied to a summing circuit whose output is passed to a band pass filter to remove the unwanted sidebands. The original frequency spectrum is restored at the receiver by mixer processes of shifting the two selected sidebands similar to, but the inverse of, those used in the transmitter.

Abstract: A compressed single side band communication system and method in which the audio signal is compressed prior to pre-emphasis and thereafter summed with a pilot tone for further compression prior to transmission. Initially, only the pilot tome is transmitted at full rated power to aid in acquisition of the signal by the receiver. Thereafter, the transmitter ALC is disabled and the pilot tone is attenuated. The receiver adjusts the frequency characteristics of the pilot tone filter and phase lock loop filter in the detector as a function of lock-up. The delay after loss of lock-on in reverting to wide band pilot tone and wideband loop filters is varied as a function of signal strength. The pilot tone may be frequency modulated for tone coded squelch, with the modulating source being located in the return end of the phase lock loop filter. A unique filter is provided to insure acquisition of the pilot tone.

Abstract: An SSB pulse modulator which attenuates unwanted even harmonics of the carrier frequency without expensive filtering. The modulator comprises two pairs of comparators (12, 14 and 16, 18), and the sine and cosine components of the carrier signal are modulating signal [a(t)] and the Hilbert transform [a(t)] thereof are applied to respective ones of the comparators. EX-OR gates (20, 22) multiply together the outputs of each pair of comparators (12, 14 and (16, 18), the multiplied outputs being combined with each other in a signal combining arrangement (24). Each pair of the comparators produces the unwanted even harmonics, which are then attenuated by subtraction from each other in the combining arrangement.

Abstract: An improved system and method for modulation, demodulation and signal processing for single sideband communications systems which provides correction for the adverse effects of rapid fading characteristics in a mobile environment. The system provides modulation through a modified Weaver modulator in which the audio input is processed to produce an output in the form of an upper sideband having a pilot tone in a spectral gap at approximately midband. The receiver includes a modified Weaver demodulator and a correction signal generating circuit which processes the received faded audio input and pilot tone to produce a correcting signal. The correcting signal is mixed with the received signal to regenerate unfaded versions of both the signal and pilot by removing random amplitude and phase modulations imposed on them by the fading.

Abstract: A communication system which uses a transmitter and a receiver. The transmitter divides a band of interest in the frequency spectrum into upper and lower portions, and frequency translates one of these portions in order to provide a frequency notch between the portions. The receiver of the system includes a receiver processor which receives the upper and lower portions, and which restores the original frequency spectrum. The receiver processor at least partially determines the final position of the restored portion.

Abstract: Several forms of a novel amplitude-modulated (AM) signal format are disclosed. Circuits of several types for generating the desired special vestigial-sideband (SVSB) AM waveforms are discussed. The principal form of the SVSB modulation provides for a reduction in transmitted signal bandwidth compared with standard double-sideband techniques plus very linear amplitude characteristics with simple synchronous detectors. Circuits according to the invention may also include means for dynamically varying signal bandwidth to accommodate special applications.

Abstract: When modems are used in SSB systems a problem arises in controlling variable data rates. If a transparent tone-in band system is used, the notch in the band transmitted will be required for a control signal for the SSB receiver. The present invention allows a further possibility for transmitting control signals, for instance one representative of data rate, by varying the width of the notch in the transmitter and determining notch width in the receiver. The notch width is controlled by frequencies applied to two mixers and reference signals for these mixers are derived by respective multipliers from a clock signal. In a receiver the process of restoring the original frequency spectrum also employs two mixers receiving signals from two oscillators. The frequency of one of the oscillators is controlled to ensure that lower and upper portions of the restored spectrum have the correct frequency and phase relationship.

Abstract: A broadcast transmitter with single-sideband modulation for transmitting a message with a band width and carrier power which is lower in comparison with double-sideband modulation. To be able to operate a high-power single-sideband transmitter with only one transmitting tube, a single-sideband modulator (1) is used which generates, as a function on a modulating LF signal (2), a zero-phase modulator amplitude signal (9) which amplitude-modulates the anode (23) of an RF output stage tube (26) via a digital/analog converter (21), constructed as a switching amplifier with pulse step modulation, and an RF filter (22). The single-sideband modulator (1) also supplies a modulator phase signal (19) which is preferably not amplitude-dependent and which is fed to the control grid of the RF output stage tube (26), if necessary via a frequency converter (25).

Abstract: A communication system which uses a transmitter and a receiver. The transmitter divides a band of interest in the frequency spectrum into upper and lower portions, and frequency translates one of these portions in order to provide a frequency notch between the portions. The receiver of the system includes a receiver processor which receives the upper and lower portions, and which restores the original frequency spectrum. The receiver processor at least partially determines the final position of the restored portion.