Abstract: A system and method for providing a multi-layer, high density wireless communication architecture is disclosed. An example of a transceiver module is provided to better demonstrate this system and method. The transceiver module comprises a transmitting layer having a top portion and a bottom portion. A filter layer having a top portion and a bottom portion is also provided, wherein the top portion of the filter layer is adjacent to the bottom portion of the transmitting layer. A logic layer having a top portion and a bottom portion is provided, wherein the top portion is adjacent to the bottom portion of the filter layer and wherein logic is located on the bottom portion of the logic layer. A series of via structures of connected at specific locations of the transceiver module to allow for electrical connections between the transmitting layer and the filter layer, and the filter layer and the logic layer. Shield layers are also provided to prevent harmful electronic coupling between layers.

Abstract: One embodiment of the present invention is a method for providing security for a transmission of information in an ADSL environment using a DMT modulation technique. The order of the frequency orthogonal subchannels used in the DMT technique is scrambled according to a permutation cipher. The key for this scrambling operation is scrambled with the subscriber's public key, and is encoded according to a CDMA technique for transmission through the ADSL channel approximately concurrently with the information. The encoded key and the DMT data subblocks are recovered from the secured transmission. The encoded key is decoded according to the CDMA technique to generate the decoded key. The decoded key is used to assign an order to the subblocks of data.

Abstract: A radio communication apparatus having maximized channel capacity, and a method thereof, preferably includes a transmitter having a plurality of transmitting antennae, wherein each transmitting antenna transmits on a channel using a transmission power that is allocated and a base-band signal that is modulated according to a feedback signal from a receiver. The feedback signal is preferably derived in the receiver using an algorithm that analyzes and processes a previously received signal from the plurality of transmitting antennae. Only information on the amount of transmission power to be allocated to a first transmitting antenna from the plurality of transmitting antennae is fed back. Therefore, the channel capacity may be maximized while minimizing the amount of information in a feedback signal. Further, decoupling conversion is not required, thereby reducing the size and cost of manufacturing hardware.

Abstract: A method and apparatus for increasing the capacity of a multiple-input and/or multiple-output system. Each sub-stream of a primary data stream is stratified to produce a processed sub-stream whose strata can be separated out and decoded with an acceptable error rate. A sub-stream can be stratified by dividing it into a plurality of sub-stream-components that are processed to obtain strata, with each stratum representing one of the sub-stream-components. The strata are then combined to obtain the processed sub-stream. Stratifying allows a particular processed sub-stream's strata have different transmit features from each other, such as different bit rates, or different power levels, or both. This reduces the interference for some of the strata of each processed sub-stream since as stratum are separated out and decoded they are no longer interference for the other strata. Thus, allowing for a higher overall bit rate for the processed sub-streams.

Abstract: At least two publicly visible electronic displays are carried by a moving vehicle, each of which displays is positioned to be visible from a different external position relative to the vehicle. Separate messages can be displayed on the differently positioned displays. The selection of different messages for showing on different displays can be made as a function of differences between viewers who are likely to see the different displays. Such selections can be based on demographic information. The displays can include a side display that can better be seen from a position to the side of the vehicle, and a back display that can better seen from a position behind the vehicle. Messages considered more appropriate for pedestrians or more appropriate for rapid viewing can be shown on the side display, and those considered more appropriate for drivers behind the vehicle or for longer viewing can be shown on the back display.

Abstract: An IF local generating circuit for a broadband communication system using a plurality of carriers is disclosed. In the present invention, one IF phase locked loop converts the IF signals to baseband signals by a downward processing of frequency in the receiving end of the broadband portable terminal.

Abstract: A communication method, transmitter, receiver, and cellular ratio communication system. When the high priority data and the low priority data are transmitted at the same time in the multi-carrier communication, a processing in accordance with the priority is performed to decode data accurately. At the transmitting side, the high priority symbols and the low priority symbols are alternately positioned and each symbol of the differential symbol stream obtained by differential-modulating the high priority data based on the differential phase is assigned to sub-carrier. The transmission signal in which the sub-carriers on which high priority symbols are superimposed and the sub-carriers on which low priority symbols are superimposed are positioned alternately is transmitted.

Abstract: An adaptive array antenna transceiver apparatus provides: a local signal generator 24 that outputs a signal having a frequency that corresponds to the difference between the reception frequency and the transmitting frequency; a coupler 15 that separates and extracts a part of the signals from the output of the transmitters 13; a switch 21 that selects the signal output from any one of the transmitters 13; a frequency converter 22 that converts the frequency of the signal selected by the switch 21; and a switch 23 that inputs signals output by the frequency converter 22 and selectively outputs them to any one of the plurality of paths.

Abstract: In the conventional diversity reception, information included in each non-selected signal does not contribute to an improvement in the reliability of communications, and transmitting power has been dissipated to satisfy required communication quality. Owing to the setting of encoding in respective base stations to injection, signals each including the same contents, which are received by a mobile station, are used for increasing the reliability of communications without depending on the number of the signals which were capable of being received by the mobile station, to thereby reduce transmitting power for satisfying required communication quality.

Abstract: A traffic information warning system for conveying first and second messages regarding a traffic situation from a traffic advisory site is disclosed. The system comprises a transmitter adapted for placement at the advisory site and a receiver. The transmitter includes an oscillator for transmitting a first carrier signal and a second carrier signal. The first carrier signal has a first discrete carrier frequency and the second carrier signal has a second discrete carrier frequency. The first and second discrete carrier signal frequencies are located at a frequency location. The first message of a traffic situation is reflective of the specific frequency locations of the first and second discrete frequencies. A modulator modulates the first carrier signal with a modulating signal reflective of the second message regarding the traffic situation. The second carrier signal comprises an unmodulated signal.

Abstract: A communication method, and a processing in accordance with the priority can be performed with a simple configuration even in the case of the communication of the multi-carrier method. The sub-carriers on which high priority data is superimposed and the sub-carriers on which low priority data is superimposed are positioned alternately to be transmitted. At the receiving side, the reception symbol stream in which symbols are lined on the frequency axis is obtained by performing a predetermined reception processing. The delayed symbol stream in which the reception symbol stream is delayed for a predetermined time is added to the reception symbol stream to extract the signal components relating to the high priority data, so that the high priority data is decoded.

Abstract: A system provides transmit diversity with feedback to enhance the reception of communication signals at a wireless communication terminal. Multiple antennae are provided at the base station. The multiple antennae transmit multi-carrier information signals such as OFDM including pilot tones. The wireless communication terminal receives the pilot tones and performs processing on those tones to detect the relationship between the information signals transmitted from the various antennae of the base station. A feedback signal, based on the comparison of the pilot tones communicates back to the base station information about the channels of the respective transmit antennae to the terminals. The base station modifies the transmission processing associated with the various transmit antennae based upon the feedback signal. The modified processing improves the reception of the information signals at the wireless communication terminal.

Abstract: A selective messaging system controller (105) and analogous methods arranged to schedule messages and control transmitters in a messaging system (100) having a service area so as to enhance a reuse factor, includes: a network port (102) for accepting message requests that is coupled to a processor (131) for forming a first plurality of messages, including an associated zone ID (407) for each message, scheduled for concurrent transmission, during a first time period, within a first coverage pattern (503) that creates interference areas (525) and a second plurality of messages scheduled for concurrent transmission, during a second time period, within a second coverage pattern (505) that provides coverage for a portion of the interference areas; the processor further coupled to a transmitter port (106), for sending the pluralities of messages to the transmitters and controlling these transmitters; and a receiver port (109) for receiving a registration message including one coverage zone ID that identifies a cove

Abstract: A multicarrier transmission system (100) routes data symbols from a data source (142) to a multicarrier modulator (145). Each modulator (201, 202, 203) within the multicarrier modulator (145) is coupled to a corresponding gain adjuster (211, 212, 213) that distributes the available transmit power across various subcarriers. Power distribution, is determined in part, upon the noise sensitivity of the transmitted information. In accordance, data stream symbols of like sensitivity are grouped (520) and transmitted during defined time intervals. Each such group is assigned a unique transmission power level (530). At any given moment in time, all subcarrier transmission power levels will have an identical amplitude, thereby mitigating the impact of subchannel-to-subchannel interference.

Abstract: The present invention relates to an arrangement for transmitting a radio-frequency signal at two different frequency bands and for receiving at two different frequency bands. The arrangement can be applied for instance to a transceiver of a radio communications system operating at two different frequency bands, or to a transceiver meant to be used in connection with two different radio communications systems. One of the ideas of the invention is that one and the same filter (72), belonging to the RF front end of the antenna circuit, is used for filtering interference from at least two signals located at different frequency bands, in which case the number of filters (72, 75) can be reduced. By means of the solution suggested in the invention, also the number of controllable switches (73) provided on the signal path of the RF front end can be minimized.

Abstract: Multiple diversity used in a fading or shadowed error prone, framed, random access channel enhances the probability of successful transmission and reduces delays. This is important, for example, in mobile telephone service, in which traffic channels are only assigned on a speech spurt basis. Selected control messages (such as reverse allocation requests and deallocation requests) are transmitted with multiple diversity. More particularly, an identical control message is transmitted at multiple instants in time (such as three), each transmission occurring on a different carrier frequency, and each transmission occurring at a randomly selected power level.

Abstract: Subscriber units (14) can roam from zone (A) to zone (B) and accurately compile fragments of a message that includes fragments transmitted from both zones. Preferably, a subscriber unit (14) assigns different markers to fragments received from different zones. When the subscriber unit senses that a received message includes fragments from different zones, it correlates a number of characters of a fragment received from one zone (A) to a similar number of characters in a fragment received from a different zone (B). If a complete match is not found, the fragments are combined as part of a message. If a match is found, a further comparison looks for additional matches between fragments and, finding such additional matches, erases one copy of duplicate characters.

Abstract: A two-way communication system for communication betweeen a system network and a mobile unit. The system network includes a plurality of base transmitters and base receivers include in the network. The base transmitters are divided into zonal assignments and broadcast in simulcast using multi-carrier modulation techniques. The system network controls the base transmitters to broadcast in suimulcast during both systemwide and zone boundaries to maximize information throughout. The preferred mobile unit inlcudes a noise detector circuit to prevent unwanted transmissions. The system network further provides an adaptive registration feature for mobile units which controls the registration operation by the mobile units to maximize information throughout.

Abstract: A system and method for frequency dehopping of spread spectrum communication signals includes a downconverter having two mixer stages, each mixer stage providing coarse frequency dehopping. The local oscillator injection frequency of each mixer stage is selectable by way of a plurality of relatively easily generated tones. The output of the second mixer stage is sampled by an analog-to-digital converter to enable fine tuning dehopping to be performed in the digital domain and subsequently demodulated in a demodulator circuit.

Abstract: In the method for parameterizing at least one receiving device and a receiving device for a radio station, a plurality of decorrelated signals are received by an intelligent antenna device. Antenna weighting factors for suppressing received disturbances and channel coefficients for balancing out the differences in transit time of different signal components of a received signal are determined simultaneously. During a training sequence, test data present in the receiving device is rated in a channel model with channel coefficients and received test data is rated with antenna weighting factors and superposed to form antenna data or model variables. The minimizing of the deviation of antenna data and model variables is performed with the exclusion of the trivial solution. The method is suitable in particular for base stations in mobile radio systems.

Abstract: In a multi-carrier system, the pilot carrier which is transmitted between two stations for synchronisation purposes, is re-allocated to a new frequency whenever it is disturbed by noise or a single frequency disturber in the vicinity thereof. A less noisy frequency is selected by means of a specific criterion to be fulfilled, for instance based on signal to noise ratio measurements performed for all carriers in the multi-carrier system.

Abstract: A paging system includes a site control module for storing paging data and activating a plurality of transmitters simultaneously in response to a transmission approval signal to transmit the stored paging data synchronously. The device includes a paging terminal for encoding paging data to transmit and generating a transmission approval signal upon completion of transmitting the paging data; a plurality of site control modules connected to the paging terminal via a private communication line, for storing the paging data in a memory prepared therein and generating the stored paging data upon receiving the transmission approval signal; and a plurality of transmitters for converting the paging data output from the site control modules into a radio paging signal to transmit; whereby the paging data is transmitted simultaneously in synchronism with the transmission approval signal.

Abstract: The invention relates to the organization of phase references in a data transfer system based upon the multiplexing of orthogonal frequency components, when transmissions in the system are composed of relatively short symbol sequences. In accordance with the invention, in the first symbol (OS1) of the sequence differential phase-shift keying between elementary signals is carried out, based upon a phase reference (Ref) transmitted in one or several subfrequency bands (fc) and upon a phase shift chain propagated one subfrequency thereof at a time. In each subfrequency band in the subsequent symbols of the sequence phase-shift modulation refers to the elementary signal of the preceding symbol of the same subfrequency band. The invention may be applied with benefit to digital cellular network systems which employ the OFDM method.

Abstract: The system operates in a wireless communication system (200) which has a plurality of wireless communication channels (501, 502) controlled by a switching center (212) and the system includes an intelligent peripheral (30) in communication with the switching center (212) and an inverse multiplexer (38) responsive to the intelligent peripheral (30). The inverse multiplexer (38) separates a broadband communication signal (100) into a plurality of portions (301, 302) and the intelligent peripheral (30) causes the switching center (212) to transmit a first portion (301) of the broadband communication signal (100) over a first wireless communication channel (501) and to transmit a second portion of the broadband communication signal (302) over a second wireless communication channel (502). The switching center (212) controls the first wireless communication channel (501) independently of the second wireless communication channel (502).

Abstract: A communication system that provides dual frequency communication using a single superheterodyne receiver that receives both the desired frequency and the image frequency of a transmitted signal. If communication cannot be established on a desired frequency, the transmitter switches to the image frequency while the receiver frequency remains constant.

Abstract: The dual band code division multiple access radio of the present invention operates on multiple frequencies simultaneously on either transmit or receive. The transmit path operates by splitting the transmit intermediate frequency (IF) path (103) and mixing the IF to two different transmit frequencies using two frequency synthesizers (140 and 145). The receive path (104) has two RF channels (116 and 117) that are mixed with the frequencies generated by the synthesizers (140 and 145) and summed into one IF strip. Thus the radio of the present invention can perform a soft hand-off between frequencies while communicating with both base stations simultaneously. Additional mixing paths and synthesizers can be added if it is desired to communicate with more than two base stations simultaneously.

Abstract: An apparatus and a method for transmitting and receiving a signal having multiple tones for obviating destructive interference between a groundwave and a skywave of the signal. The multiple tones have a frequency offset that is calculated so that the destructive interference nulls for each of the tones occurs at different range distances from the transmitter thereby extending the distance over which at least one of the tones can be reliably received.

Abstract: The dual band code division multiple access radio of the present invention operates on multiple frequencies simultaneously on either transmit or receive. The transmit path operates by splitting the transmit intermediate frequency (IF) path (103) and mixing the IF to two different transmit frequencies using two frequency synthesizers (140 and 145). The receive path (104) has two RF channels (116 and 117) that are mixed with the frequencies generated by the synthesizers (140 and 145) and summed into one IF strip. Thus the radio of the present invention can perform a soft hand-off between frequencies while communicating with both base stations simultaneously. Additional mixing paths and synthesizers can be added if it is desired to communicate with more than two base stations simultaneously.

Abstract: A method and apparatus for single signal, multiple channel digital information transfer through pulses with time slot allocation. The apparatus consists of one or more transmitting devices and one or more receiving devices. Multiple source signals are each allocated a unique time slot between successive synchronization pulses. Digital signals from each source are converted to analog information pulses synthesized from a combination of a fundamental frequency wave and a finite number of its harmonics. The total signal, which consists of successive synchronization pulses interspersed with information pulses for each signal source, each within its allocated time slot, is transmitted to the receivers. Each receiving device extracts the fundamental frequency and harmonic components through the use of narrow bandpass, high Q filters for each information pulse in its time slot and uses the known algorithm to reproduce the input digital signals.

Abstract: In a remote-control communication system, a signal generating unit includes a first signal transmitter for transmitting a first signal at a first frequency, such as UHF, a second signal transmitter for transmitting a second signal at a second frequency, such as an infrared frequency, that is diverse from the first frequency; a keyboard for generating an information signal containing a given message, which is modulated onto both the first signal and the second signal; wherein both the first and second modulated signals are transmitted in response to a key of the keyboard being pressed to generate the information signal. A receiver for the system includes a microcontroller for processing the given message to control a given operation of an electronic communication apparatus; a UHF detector and demodulator unit and an infrared detector and demodulator unit, which respectively detect and demodulate the first and second modulated signals to provide the information signal containing the given message.

Abstract: A method for broadcasting information in a cellular communication system comprising at least one base station with an antenna array and a plurality of mobile stations is disclosed. The common information is preprocessed to create orthogonal signals. The orthogonal signals are then beam formed so that the orthogonal signals are delivered to the different elements in the array antenna. The orthogonal signals are transmitted and then received at at least one mobile station. The signals are then processed at the mobile station to decipher the common information from the orthogonal signals.

Abstract: The invention provides a means by which a radio system in a multipath propagation environment may improve the probability of successful reception of a message by the application of diversity. It is applicable to such applications as paging, cordless telephones, cellular telephones, and radio identification tags. The transmitter sends the message repeatedly, each repetition transmitted from a different antenna. The antennas are separated so that multipath fading of the signal arriving at the receiver from each transmit antenna is substantially uncorrelated with the multipath fading of the signal arriving at the receiver from the other transmit antennas. The receiver examines the radio channel for an incoming message for a time period long enough for it to potentially receive the message from each antenna.

Abstract: The present invention provides an improved cellular communications system which reduces the dynamic range of a received multicarrier signal. The cellular communications system includes at least one cell site. A base station cooperating with an antenna is positioned within the cell site and is configured to communicate with at least one wireless terminal. A receiver is positioned within the base station for receiving multicarrier signals. Within the receiver is positioned a dynamic range-reducing multicarrier signal processor which reduces the dynamic range of a received multicarrier signal.

Abstract: A traffic information warning system for conveying traffic information from a traffic advisory site to a vehicle is disclosed. The traffic warning site comprises an emergency vehicle, a roadside hazard, or the like. The system comprises a transmitter adapted for placement at the advisory site and a receiver adapted for placement at the vehicle. The transmitter includes a first oscillator for transmitting a first carrier signal having a first carrier frequency and a second oscillator for transmitting a second carrier signal having a second carrier frequency. The first carrier frequency and the second carrier frequency are spaced apart by a predetermined frequency difference. The transmitter also includes a modulator for modulating both carrier signals with an identical modulating signal reflective of a traffic situation.

Abstract: A two-way communication system for communication between a system network and a mobile unit. The system network includes a plurality of base transmitters and base receivers included in the network. The base transmitters are divided into zonal assignments and broadcast in simulcast using multi-carrier modulation techniques. The system network controls the base transmitters to broadcast in simulcast during both systemwide and zonal time intervals. The system network dynamically alters zone boundaries to maximize information throughput. The preferred mobile unit includes a noise detector circuit to prevent unwanted transmissions. The system network further provides an adaptive registration feature for mobile units which controls the registration operations by the mobile units to maximize information throughput.

Abstract: A cellular base station (10) in a digital cellular system employs transmitting circuitry in which voice signals (15) are processed at a low frequency level (12) into two separate paths. A first of the low frequency signals is variably delayed (20), and the first and the other low frequency signals are upconverted to radio frequency level (16,22) for transmission over independent time-spaced transmission paths (26,28) to cellular receivers. A receiver downconverts and demodulates the radio frequency diversity signals, and then combines the demodulated diversity signals to generate an equalized combination diversity signal for receiver output processing.

Abstract: The present invention provides a system for determining, and correcting for, channel-induced distortion in transmitted wideband carrier signals. During a synchronization, or sounding mode, known as the preamble mode, a wideband signal consisting of a number of tones, which may be those of geometric harmonic modulation (GHM), each having a phase of zero are transmitted to a receive unit. At the receive unit, the phases for each tone are extracted. Since each tone is at a different frequency, a snapshot of the change in phase over a number of frequencies can be determined. These phase changes are employed in determining the generalized phase distortion over frequency equation which is used to remove the phase distortion induced by the channel before decoding of the signal. The device then operates in its traffic mode thereby transmitting information to a receive unit which uses the phase distortion information to remove phase distortion induced by the channel and then decode a message signal.

Abstract: A traffic carrier waveform W.sub.n (.PHI.,R;t) being the product of a number of tones is employed in transmitting blocks of information from a transmit unit to a receive unit. The tones are geometrically increasing multiples of a frequency of a fundamental tone. Each tone incorporates a tone phase. The selection of these tone phases uniquely identifies each transmitted signal. The tone phases also is used as a `key` in converting a message signal into a direct wide spectrum signal for communication. To insure that third parties do not decode the transmitted message, the tone phases are transformed to seed phases by a method known to both the transmit and receive units, but not to third parties. The seed phases are then transmitted by intermittent preamble carrier waveform to the receive unit which transforms these into the tone phases and decodes the message signal. The seed phases may be dynamically changed according to a sequence known or generated by both the transmit unit and receive unit.

Abstract: The present invention provides a novel frequency Interlaced Geometric Harmonic Modulation (IGHM) system. The IGHM system operates in two modes, a preamble mode and a traffic mode. During the preamble mode, n+1 frequencies are each offset by a predetermined phase in a transmit unit and passed through a channel to a receive unit. The set of phases is used as the spreading code in the transmit unit, and also acts as an `address` of desired receive units. The receive unit monitors preamble signals to determine the phases. When it recognizes a set of phases, or `address`, which pertains to itself, the receive unit stores the phases and uses these phases to despread and decode the appended message. After the preamble mode is finished, the IGHM modulator enters the traffic mode and requests the message to be transmitted from the message source.

Abstract: The present invention provides a novel Geometric Harmonic Modulation (GHM) system. The GHM system operates in two modes, a preamble mode and a traffic mode. During the preamble mode, n+1 frequencies are each offset by a predetermined phase offset in the transmit unit and passed through a channel to a receive unit. The set of phase offsets is used as the spreading code in the transmit unit, and also acts as an `address` of receive units to transmit to. The receive unit monitors preamble signals to determine the phase offsets. When it recognizes a set of phase offsets, or `address`, which pertains to itself, the receive unit stores the phase offsets and uses these phase offsets to despread and decode the appended message. After the preamble mode is finished, the GHM modulator enters the traffic mode and requests the message to be transmitted from the message source. A traffic carrier waveform is created by multiplying tones, each having its specific phase offset.

Abstract: The present invention provides a novel Geometric Harmonic Modulation (GHM) method. The GHM method functions in two modes, a preamble mode and a traffic mode. During the preamble mode, n+1 frequencies are each offset by a predetermined phase in a transmit unit and passed through a channel to a receive unit. The set of phases is used as the spreading code in the transmit unit, and also acts as an `address` of intended receive units. The receive unit monitors preamble signals to determine the phases. When it recognizes a set of phases, or `address`, which pertains to itself, the receive unit stores the phases and uses these phases to despread and decode the appended message. After the preamble mode is finished, the GHM modulator enters the traffic mode and requests the message to be transmitted from the message source. A traffic carrier waveform is created by multiplying tones, each having its specific phase. An analog or binary message is encoded by modulating the traffic carder waveform.

Abstract: A method for communication of information is described. The method provides for a much greater number of communication channels than available with conventional technologies. The number of communication channels that can be obtained is of the order of n.sup.2, where n is the number of physical channels available. Further, the method provides robustness in the presence of noise, interference, path delays, and other adverse environmental conditions. It is also compatible with a number of privacy insuring methods, and has an inherent resistance to casual prying.

Abstract: A traffic information warning system for conveying traffic information from a traffic advisory site to a vehicle is disclosed. The traffic warning site comprises an emergency vehicle, a roadside hazard, or the like. The system comprises a transmitter adapted for placement at the advisory site and a receiver adapted for placement at the vehicle. The transmitter includes a first oscillator for transmitting a first unmodulated carrier signal at a first frequency and a second oscillator for transmitting a second unmodulated carrier signal at a second frequency. The first and second frequencies define the traffic information. The receiver includes a detector for detecting the first and second signals and an announcing device for announcing the traffic information.

Abstract: Apparatus and a method for generating all of the assignable carrier frequencies in the FM broadcast band and for frequency modulating the generated carriers includes a generator of a train of pulses having a crystal-controlled repetition frequency and a specific pulse shape which together produce a spectrum of odd harmonics of the pulse repetition frequency whose separation in frequency is identical to that of the assignable carrier frequencies. This pulse train is then mixed with a 98.0 MHz sine wave to translate the spectrum to the FM band. Simultaneous modulation of all the carriers is achieved by frequency modulating the 98.0 MHz sine wave, whereby the same modulation is imparted simultaneously to all of the carriers.

Abstract: A method for simultaneously imposing a single modulating signal on a number of constant frequency carriers includes applying the single modulating signal and all of the carriers to a doubly-balanced mixer circuit that produces sideband signals that are uncontaminated by the carriers. The sideband signals thus produced are then combined with signals proportional to the carriers in a linear circuit to obtain an output signal equivalent to a signal that would result from combining separately modulated carriers.

Abstract: In a transmitting section, a modulator modulates a first carrier with data o be transmitted, thereby producing a modulated output f.sub.m, a local oscillator generates a local oscillating signal to be used as a second carrier f.sub.LO, a mixer mixes the modulated output and the local oscillating signal, thereby generating waves of different frequencies. These waves include an upper side band wave f.sub.LO +f.sub.m and a lower side band wave f.sub.LO -f.sub.m. A transmitting antenna radiates electromagnetic waves into the air, which includes the waves of different frequencies generated by the mixer. In a receiving section, a receiving antenna receives the electromagnetic waves, a diversity section extracts at least one of the upper side band and lower side band waves f.sub.LO +f.sub.m, f.sub.LO -f.sub.

Abstract: A device for the reception of digital data broadcast at a high bit rate for reception by mobile receivers is disclosed. The device operates under adverse conditions of multiple propagation corresponding to the Rayleigh process and imperfect frequency tuning to minimize the inter-symbol interference in the frequency domain. The device receives a digital signal having digital elements distributed in the frequency-time space f-t and transmitted in the form of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of digital elements and broadcast simultaneously. The device includes a module for transposition by a local oscillator, baseband filtering and analog-digital conversion, a temporal windowing module for the selection of the useful samples and a mathematical transformation module, the temporal windowing module applying a Nyquist window type of temporal window with non-zero roll-off.

Abstract: A method for the contactless transmission of information between a transmitter/receiver unit and a transponder.

Abstract: According to this invention, a modulator modulates a carrier serving as a fundamental wave with data to be transmitted, thereby to generate a modulated output including at least the fundamental wave and double wave thereof. A transmitting antenna radiates electromagnetic waves into the air, and the electromagnetic waves include the fundamental wave and the double wave included in the modulated output generated by the modulator. A receiving antenna receives the electromagnetic waves including the fundamental wave and the double wave radiated from the transmitting antenna. A diversity section generates an output having a diversity effect on the basis of the fundamental wave and the double wave included in the electromagnetic waves received by the receiving antenna. A demodulator demodulates the output having the diversity effect and generated by the diversity section, thereby to output data corresponding to the data to be transmitted.

Abstract: In a QAM communications system, a novel synchronizing sequence of symbols added to the information channel simplifies acquisition of timing and synchronization by a receiver. Such synchronization vectors provide signals for improved AFC control signal generation.