Abstract: A broadcast transmitting and receiving system includes a receiver having multiple tuners. A data tuner receives a data stream indicating the type of programming being broadcast by one or more stations. Based on information in the data stream, the frequency of operation of a sound tuner is adjusted to provide the user with a desired type of programming. Various modes of operation are provided, some employing a user interface and others being operable without user intervention.

Abstract: A radio data reception system operates within a host processing system such as a personal computer and receives FM broadcast transmissions encoded with either RDS or MBS digital data modulated upon a subcarrier frequency. The radio data reception system operates in one of three modes to interpret the RDS or MBS digital data. A first mode of operation provides a user of the radio data reception system with complete FM stereo tuner functions displayed on a monitor. The radio data reception system receives and decodes RDS data transmissions in the FM stereo tuner mode and displays the RDS data on the monitor. In second and third modes of operation, the radio data reception system receives and processes MBS digital data. In the second mode of operation, the MBS data is used by the host processing system to monitor pages received by a user of the system.

Abstract: In accordance with the present invention, an RFID system has a homodyne receiver having two outputs; the in-phase or I output and the quadrature or Q output. The modulated backscattered signal is composed of an information signal, modulated onto a single frequency subcarrier signal, generating a modulated subcarrier signal; this modulated subcarrier signal is then backscatter modulated onto the incoming RF signal. To demodulate this modulated backscattered signal, the I and Q outputs are combined using an IQ combiner. This IQ combiner introduces a 90.degree. phase shift, with respect to the frequency of the subcarrier signal, onto one of the demodulator outputs and then combines the outputs of the demodulator.

Abstract: Pager data is transmitted at different subcarrier frequencies on different FM broadcast channels. The subcarrier frequency of the pager data is selected to avoid conflicts with signals transmitted from other systems. The pager receiver decodes data at any one of the multiple subcarrier frequencies according to the active subcarrier used on the currently tuned broadcast channel. In one embodiment, the subcarrier frequency of the pager data is contained in control packets of a time division multiplexed data frame. The receiver decodes the control packets to determine which broadcast frequencies and associated subcarrier frequencies contain potential pager signals. The receiver accordingly searches the identified broadcast frequency and automatically reconfigures a circuit demodulator to decode data packets at the identified subcarrier frequencies.

Abstract: A system and method of information dissemination that permits the user to listen to the specific content of information when and where he or she wants to. A radio or television receiver system receives information from a FM subcarrier, a television vertical blanking interval transmission, a television separate audio program transmission or a dedicated channel and stores the transmitted information in a memory. A user interface allows selection from the memory of the stored information via a set of menus controlling a hierarchical database, so as to access particular items of information. Typically the system includes RAM and/or a storage medium such as a digital audio tape,a magneto-optical mini-disk, a magnetic disk or optical disk, sufficient to store information for 10 hours of audio. A decompression device, accepts the accessed compressed digital audio information items which may have been encrypted and transforms them into spoken speech.

Abstract: The invention involves a method of transmitting a control signal that is synchronized in time with a radio program signal. The control signal may be used, for example, in a receiver to restore dynamic range reduction that occurred at the transmitter. The method includes the steps of forming a first supplemented signal by inserting the control signal and a first time-reference signal into a data stream of a radio data signal such as an RDS signal. A second supplemented signal is formed by adding a second time-reference signal to the radio program signal. The first and second time-reference signals are correlated in time. The first and second supplemented signals are transmitted.

Abstract: An FM broadcasting signal carrying multiplex character data transmitted from a radio broadcasting station is automatically preset in an FM receiving apparatus. An FM broadcasting signal is received, and a frequency information of the received FM broadcasting signal is temporarily memorized in a memory. It is judged whether a PLL lock signal is produced by a clock signal reproducing circuit during a demodulation process of the FM broadcasting signal whose frequency information is memorized in the memory. When it is determined that the PLL lock signal is produced by the clock signal reproducing circuit, it is determined that the FM broadcasting signal carries multiplex character data, and the frequency information of said FM broadcasting signal is preset to the FM receiving apparatus.

Abstract: An on-board unit includes at least one receiving and transmitting antenna for a bidirectional transmission of data which works in accordance with the transponder method. To compensate for interference fading, a high-frequency amplifier is connected in an incoming circuit to the demodulator/modulator, through which the transmission range of the transmission distance is improved as well. The same amplifier and the demodulator/modulator can be used in downlink and uplink operation. In uplink operation, the demodulator/modulator can alternatively subject the carrier signal to amplitude shift keying or phase shift keying.

Abstract: A receiver for receiving multiplexed text broadcasts includes a receiving circuit for receiving multiplexed text broadcasts that provide information including at least one program with at least one page formed with multiplexed data comprising a plurality of blocks each provided with a block identity code followed by a data packet, a memory for storing the multiplexed data received by the receiving circuit, a display device for displaying the information, a plurality of receive counters for receiving the block identity code and counting the block identity code for a predetermined number thereof for managing the display timing of the page of the program for being determined when the program is defined to display the page after a decided period of time from the reception of the multiplexed data, and a circuit for allotting the receiving counters by allotting the idle one of a plurality of the receiving counters for counting each of the block identity codes of the multiplexed data overlappingly received within th

Abstract: A system for receiving a radio signal representing a radio program comprises at least first and second radio receiver units. Each receiver unit receives the radio signal at a respective frequency and produces a respective radio program signal. All of the radio program signals represent the same radio program. A decoder decodes a control signal, such as an RDS signal, from each of the radio program signals. A control device processes the control signals to determine the delay between the radio program signals. The control device uses the delay information to modify a a variable delay in the signal path of at least one radio program signal until the radio program signals are synchronized. The synchronized radio program signals are combined, e.g., by fading the signals together, to produce a resultant radio program signal.

Abstract: The system allows radio broadcast listeners to use a telephone to connect to a database that contains prerecorded audio descriptions (e.g. spoken text and/or music) of material played by the radio station. The database is indexed by the radio station's program schedule or play list to allow the user to select a particular audio description of interest (e.g. the song currently airing, the song last played, etc.). Hearing the audio description over the telephone insures the listener that the requested selection is in fact correct. Using the telephone DTMF touch tone controls the listener can place an order to purchase the selected material over the telephone.

Abstract: A method of multicarrier modulation using co-located transmitters to achieve higher transmission capacity for mobile paging and two-way digital communication in a manner consistent with FCC emission mask limits. Co-location of the transmitters obviates the need for stringent, symmetrical subchannel interference protection and provides for a wider range of operating parameters, including peak frequency deviation, bit rate, and carrier frequencies, to obtain optimal transmission performance.

Abstract: Two separate subcarriers are used to transmit portions of a single message to one or more receivers on an FM radio signal. The synchronization and addressing data necessary to identify the message to a target receiver is located in the first subcarrier. The second subcarrier, in turn, consists almost entirely of raw message data. Thus, transmitting multiple subcarriers substantially increases the overall data transmission payload when transmitting digital messages. Because each subcarrier is located within a different frequency band, the communication system is also adaptable to different subcarrier allotments in the FM baseband.

Abstract: A modulated backscatter communication system (e.g., an Electronic Shelf Label (ESL) system) includes a central node (e.g., a ceiling node) and one or more remote nodes (e.g., ESL tags). The central node transmits a downlink radio signal which is reflectively modulated at a remote node to produce a modulated reflected radio signal. At the remote node, a precise-frequency subcarrier signal is modulated with an uplink information signal to produce a modulated signal which is used to produce the modulated reflected radio signal. At the central node, the modulated reflected radio signal is received, detected and narrowband filtered to obtain the modulated subcarrier signal which is then demodulated to obtain the uplink information signal, with great immunity to close to carrier downlink radio noise and fluorescent light backscatter interference.

Abstract: In a multiple access network a main station is to be capable of distinguishing signals transmitted by sub-stations to the main station. A method of realising this is the use of SCMA (SubCarder Multiple Access). According to this method the signal to be transmitted is modulated on a subcarrier having its own frequency and then modulated on a main carrier in each sub-station. In prior-art multiple access network the distribution signals which are to be transmitted to the sub-stations by the main station are modulated each on its own distribution subcarrier and then applied to a shared distribution modulator. For diminishing the requirements posed on the high-frequency properties of the electronic components necessary for the network, the subcarriers for distribution signals and return signals are selected to lie in the same frequency band.

Abstract: This invention pertains to a method for operating a radiotelephone for receiving digitally encoded broadcast messages from a radio channel, and also to a radiotelephone that operates in accordance with the method. The method includes a first step of operating a user interface (19, 20, 22) for inputting information to a controller (20) of the radiotelephone, the information specifying at least one category of broadcast message to be received. In response to the inputted information, a second step receives a broadcast message that belongs to the at least one category. A third step stores all or a portion of the received message in a memory (21) of the radiotelephone. A fourth step selectively displays (19) all or a portion of the stored message. In a presently preferred embodiment of this invention the message is received from a short message service broadcast channel.

Abstract: A radio transmitter (103) transmits a cycle (320) including a digital portion (330) generated by frequency modulating a radio carrier with a digital signal and an analog portion (440) generated by amplitude modulating a radio carrier with an analog signal. A selective call radio (106) frequency demodulates the digital signal; amplitude demodulates the analog signal; decodes a message address (510); generates a quality signal indication (643) while a quality assessment signal (420) is being received; processes an information signal (550) in response to a message received signal (641); records at least one measurement of the quality assessment signal (420) during the quality signal indication (643); determines a signal quality level of the information signal (550) from the at least one measurement of the quality assessment signal (420); and generates a sensible alert in response to the signal quality level.

Abstract: A system and method of information dissemination that permits the user to listen to the specific content of information when and where he or she wants to. A radio or television receiver system receives information from an FM subcarrier, a television vertical blanking interval transmission, a television separate audio program transmission or a dedicated radio channel and stores the transmitted information in a memory. A user interface allows selection from the memory of the stored information via a set of menus controlling a hierarchical database, so as to access particular items of information. Typically the system includes RAM and/or a storage medium such as a digital audio tape, a magneto-optical mini-disk, a magnetic disk or optical disk, sufficient to store information for 10 hours of audio. A decompression device accepts the accessed compressed digital audio information items (which may have been encrypted) and transforms them into spoken speech.

Abstract: The present invention provides for an analog and/or digital radio broadcast transmission system and radio receiver therefor, which includes a control signal having an item of control information concerning another, different type of transmission/receive system. The receiver is a hybrid receiver able to receive both types of signals. When the same program material is available on both of the different systems, the control signal is used for switching the different systems so that the receiver receives the program on the system which provides the best reception.

Abstract: A radio information broadcasting and receiving system consisting of three major parts: an FM transmitter station with subcarrier multiplexing capability, an FM receiver apparatus with subcarrier demodulation capability, and a computer connected in combination with the receiver apparatus. The FM transmitter station includes sources of main programming signals first digital data signals and second digital data signals. The first and second digital data signals are modulated by subcarrier 1 and subcarrier 2 frequencies respectively and are mixed with the main program signal and then transmitted. The transmitted signals are received by a receiver apparatus including an FM receiver circuit and an FM demodulator circuit for receiving the broadcast signal and demodulating it. The demodulated main program audio frequency signal is applied through a filter/deemphasis circuit and amplifier to speaker to provide an audio output.

Abstract: A broadcast system includes a device to compare program material to be transmitted with a database of known material, and to transmit along with the program material data corresponding to that program material. A corresponding receiving system stores the data in memory and displays, at the selection of the user, the data corresponding to the program material. The user selectively stores the data on a magnetic recording card for electronic coupon or other uses. Various modes of operation are selectable by the user, and the data may be used as electronic coupons, or to control attached equipment, or to sound alarms, or for other applications. Broadcast of the associated data commences earlier than that of the program material so that such data are available for display on a receiver when the program material is first received. The receiver is connectable to remote terminals for the collection of information relating to a user's pattern of storing and accessing the broadcast data.

Abstract: A warning system for alerting a person to an emergency situation which includes a transmitter responsive to a visual or acoustic alerting system for transmitting an alarm signal on an RF carrier and a control signal on a sideband of the carrier. A tuneable receiver for receiving commercial broadcasts in a normal operating mode transfers to an emergency mode upon detection of the control signal and converts the alarm signal to an acoustic signal. In one embodiment, the visual or acoustic alerting system is a siren and light system of an emergency vehicle. In this embodiment, a transceiver is preferably included for dedicated communications among emergency vehicles. The range of both the transmitter and transceiver complement and are substantially the same as the effective range of the visual or acoustic alerting system.

Abstract: A system for broadcasting audio music and broadcasting lyrics for display and highlighting substantially simultaneously with the occurrence of the lyrics in the accompanying audio music is provided. The system includes a audio music source that provides a data output and a analog audio signal output. A computer receives the data output by the music source and generates lyric text data and lyric timing commands. A subcarrier generator generates a subcarrier signal carrying the lyric text data and lyric timing commands. An FM transmitter broadcasts a composite signal that combines the analog output of the music source with the subcarrier signal. A lyric display unit receives the composite signal, separates and decodes the subcarrier signal and displays and highlights lyrics according the lyric text data and lyric timing commands decoded from the subcarrier signal.

Abstract: A radio program distribution system for creating custom recordings containing a requested plurality of musical programs. The system stores digital copies of musical programs and can selectively copy the programs onto custom recordings. Each participating broadcaster transmits program information to the system about each broadcasted program, and the system creates an entry in a database identifying the program, the time, the date and the broadcaster of each broadcast by a participating broadcaster. The system is connected to a telephone network, allowing customers to call into the system and request a custom recording containing desired musical programs. The customer requests which musical programs are desired by giving the time, date and broadcaster of when the program was heard on the radio.

Abstract: A system and method of information dissemination that permits the user to listen to the specific content of information when and where he or she wants to. A radio or television receiver system receives information from an FM subcarrier, a television vertical blanking interval transmission, an active picture area television transmission a television separate audio program transmission or a dedicated radio channel and stores the transmitted information in a memory. A user interface allows selection from the memory of the stored information via a set of menus controlling a hierarchical database, so as to access particular items of the information. Typically the system includes RAM and/or a magnetic storage medium such as a digital audio tape, a magneto-optical mini-disk, a magnetic disk or optical disk, sufficient to store information for several hours of audio output. A decompression device accepts the accessed compressed digital audio information items and transforms them into audible speech signals.

Abstract: RDS data broadcast method and apparatus is disclosed that provides dynamic sequencing and parallel formating to improve access to and the reliability of Radio Data System (RDs) services. Dynamic sequencing permits receivers not adapted to display the textual information that is broadcast as radiotext under the RDS standard to display that radiotext information, automatically.Dynamic control of complex day-parting schedules minimizes data selection and coding errors and delays, provides priority access to the station's data channel and provides transparent scheduling of real-time data entries, while protecting against losses of real-time entries through overflow.

Abstract: An FM stereo radio data-system receiver has a front end including an FM discriminator that produces a composite signal composed of an AM stereo signal, including a 19 KHz pilot, and an AM digital-data signal. A dual-bandwidth phase locked loop (PLL) locks onto the pilot and serves both, as the decoder of the stereo portion of the composite signal, and as a generator of a strong stable 38 KHz carrier for use in regenerating the bit rate clock signal and for decoding the data-symbol signal of the digital-data portion of the composite signal. Advantages include economy of circuitry, a simpler and less costly high pass filter, and greater reliability in the decoding of the data signal.

Abstract: A broadcast system includes a device to compare program material to be transmitted with a database of known material, and to transmit along with the program material data corresponding to that program material. A corresponding receiving system stores the data in memory and displays, at the selection of the user, the data corresponding to the program material. The user selectively stores the data on a magnetic recording card for electronic coupon or other uses.

Abstract: A communication system (100) is provided for transmitting data to mobile receivers utilizing a subcarrier within a commercial FM channel of a radio station (55). The data transmitted is first encoded in encoder (112), utilizing a forward error correction code. The sequence of the encoded data is altered in interleaver (116), subdivided into a plurality of subframes, in framing and synchronization circuit (120), which also adds channel state bits to each subframe. The framed data is modulated onto the subcarrier in the differential quadrature phased shift keying modulator (130), the output of which is coupled to the FM modulator (52) of radio station transmitter (50). The transmitted radio frequency signals may be received by a vehicle antenna (12) for coupling to the vehicle's FM receiver (80). The modulated subcarrier is recovered from the FM demodulator (84) of the receiver (80), the modulated subcarrier being demodulated to recover the encoded digital data therefrom.

Abstract: Receiver having an RF input for applying an RF input carrier thereto, which receiver is coupled to a phase-locked loop (PLL) whose signal path incorporates a phase detector, a loop filter, a controlled amplifier and a controlled oscillator, and a signal generator for generating a local auxiliary pilot and a pilot detector for detecting the local auxiliary pilot, a first input of which is coupled to the signal path of the PLL between an output of the phase detector and a control input of the controlled oscillator, a second input is coupled to an output of the signal generator and an output is coupled to a control input of the controlled amplifier via a selection device.

Abstract: A relay satellite receives, from stations on the ground, modulated high-frequency signals situated in two different frequency bands. One of the modulations is narrow band and the other broad band. The satellite retransmits a multiplexed signal resulting from the phase modulation, of a sub-carrier consisting of the signal modulated by the narrow band modulation. The phase modulation is performed using signals drawn from the signals that carry the broad-band modulation. The user stations receive this multiplexed signal and extract therefrom, by filtering, the narrow band modulated sub-carrier, which can be used for phase-demodulating the multiplexed signal in order to recover signals which carry the broad-band modulation.

Abstract: A wide band, wide area FM-SCA radio system has a central station that transmits multiple audio signals and digital data signals through a satellite network to FM stations participating in the system. Each FM station demodulated and time multiplexes the audio and digital signals with a control signal to form a first baseband waveform having a frequency range corresponding to the SCA frequency bandwidth.The first baseband waveform and a regular FM baseband waveform are combined into a composite band waveform that is single-sideband modulated onto the station carrier for retransmission to FM-SCA receivers in the coverage area.Each FM-SCA receiver demodulates the received signal and separately processes the regular FM signal, the FM-SCA audio signals, and the FM-SCA digital data signals. A user interface is provided for audio output selection.

Abstract: A system for broadcasting audio music and broadcasting lyrics for display and highlighting substantially simultaneously with the occurrence of the lyrics in the accompanying audio music is provided. The system includes a audio music source that provides a data output and a analog audio signal output. A computer receives the data output by the music source and generates lyric text data and lyric timing commands. A subcarrier generator generates a subcarrier signal carrying the lyric text data and lyric timing commands. An FM transmitter broadcasts a composite signal that combines the analog output of the music source with the subcarrier signal. A lyric display unit receives the composite signal, separates and decodes the subcarrier signal and displays and highlights lyrics according the lyric text data and lyric timing commands decoded from the subcarrier signal.

Abstract: A radio receiver receives FM subcarrier transmissions, and stores the transmitted textual information in a random access memory. The information is typically news, weather, sports, entertainment or other information of interest. A user interface allows selection from the memory of the stored information via a set of menus controlling a hierarchical database, so as to access particular items of information. A speech synthesizer accepts the accessed textual information items and transforms them into spoken speech. The user interface is either by voice or a single or multi-position switch allowing scanning through and selection from the menu items.

Abstract: In a radio receiver having a device for decoding radio data signals, which are divided into groups each with a predetermined number of bits and contain a program identification code, and having a device for switchover for switchover from a received frequency to an alternative frequency, by briefly switching over to the alternative frequency, a plurality of data samples are taken from various groups and at various times within the groups of the radio data signal that is received at the alternative frequency. The data samples are compared with a program identification code stored in memory.

Abstract: A process for generating an entertainment audio signal interrupted by advertising audio signals in which pilot signals associated with the advertising audio signals cause switching between the entertainment audio signals and the advertising audio signals makes it possible to broadcast different radio programs of the desired acoustic quality in a shop by means of a carrier frequency. To this end, a high-frequency control signal is generated from advertising audio signals and pilot signals which precede or follow the advertising audio signals. The control signal and preferably the entertainment audio signal are modulated to a high-frequency carrier signal, possibly with several channels, for the separate recovery of the signals. The modulated carrier signal is transmitted, the transmitted carrier signal is demodulated and, if necessary, the signals are separated from each other. The pilot signals of the transmitted control signals are monitored for the presence of fading or flashback conditions.

Abstract: A broadcast and reception system provides a segmented broadcast signal for providing regional traffic information and a receiver adapted to receive selected segments of that broadcast. The segmented broadcast signal includes a number of segments which each include a tone sequence, a digital regional code, a digital duration code, and an audio segment. The receiver monitors selected regional traffic segments and converts the selected audio segment to a form compatible with a standard automotive radio. Thus, a user can selectively monitor regional traffic information without having to listen to reports from regions of no interest to him. Alternatively, the selected traffic information can automatically override normal radio listening.

Abstract: A multiplication circuit for use in an FM television transmitter and receiver is provided. The multiplication circuit includes a limiting circuit for limiting a subcarrier supplied thereto and a dividing circuit coupled to the limiting circuit and dividing the output of the limiting circuit by a predetermined factor. A mixer is coupled to the dividing circuit and mixes the output of the dividing circuit with the subcarrier.

Abstract: Apparatus for demodulating information signals frequency-modulated on an RF carrier signal carrying spectral components within the audio frequency range, a pilot carrier signal having an imparted phase shift from the phase of the transmitted pilot carrier signal, and amplitude-modulated spectral components having another imparted phase shift in a subcarrier channel frequency range above the audio frequency range. The apparatus includes a demodulator for demodulating the frequency-modulated information signals to provide a detected composite signal which includes a detected pilot carrier characterized by an imparted phase shift due to the effects of multipath reception, and detected amplitude modulated spectral components exhibiting another multipath induced phase shift.

Abstract: An apparatus and method is described for transmitting, receiving and communicating program data signals which are combined with digital data signals. Preferably, the present invention compresses 30 digital audio signals, multiplexes them with title, track, artist, record label, year, etc., program information, and transmits the combined signals via satellite to a receiving station. The receiving station demultiplexes the signals and sends them via a cable distribution system to a subscriber's digital music tuner. This tuner further demultiplexes and decodes the signals so that the digital audio signals may be converted to analog and output for listening, while the corresponding data signals are communicated to the subscriber. In an alternative preferred embodiment, the program data signals are transmitted to a remote control receiver where they are displayed. The system described in the present invention may be used for transmitting video, software or games with program data to subscribers.

Abstract: A receiver, adapted to the reception of identification data in accordance with the RADIO DATA system (RDS) and having only one tuner, effects the acquisition of the identification code of an alternative channel by sampling the alternative channel during periods in which the audio output of the receiver is muted. These periods are of such a short duration that they are not noticed by the listener.

Abstract: A broadcast receiver or monitor unit receives and decodes items of information pertaining to broadcast program material, such as the title of a broadcast musical piece, the artist name, tape/CD catalog number, and the like. The information items can be displayed on a panel simultaneously with the broadcast. Upon entry of a memory command, the receiver stores the decoded items of information data in a memory. Sets of stored information data relating to selected broadcasts can later be retrieved from the memory and recorded in a predetermined format on paper strips or coupons by a printer device.

Abstract: A microwave system is provided for the broadcast of multiple channels of audio programming to a wide listener base, in which noise-free transmission of multiple audio channels is accomplished through microwave transmission followed by down converting the received signal to television band frequencies, accomplished in one embodiment through the use of a single MDS channel.

Abstract: A baseband signal communication apparatus includes a transmission unit and a reception unit. The transmission unit superposes a subcarrier on one value of a baseband signal consisting of binary values, modulates a carrier with the baseband signal on which the subcarrier is superposed, and transmits the baseband signal as a transmission signal wave. The reception unit demodulates the baseband signal having the subcarrier superposed thereon by using a demodulator upon reception of the transmission signal wave, extracts the subcarrier from the demodulated signal by using a bandpass filter, and demodulates the baseband signal by causing a detector to detect an envelope of the subcarrier.

Abstract: An FM subcarrier receiver of the type useful for detection of a relatively high frequency subcarrier signal transmitted on an FM carrier which includes baseband and relatively high frequency signals is disclosed. It comprises radio frequency circuitry for providing a radio frequency signal having frequency modulated baseband and subcarrier components. High pass filter circuitry receives the output of the radio frequency circuitry. A tuned circuit receives the output of the high pass filter. It comprises a first inductor and a first capacitor tuned substantially to the frequency of the subcarrier which one wishes to detect. A second tuned circuit is tuned to the subcarrier which one wishes to detect. The second tuned circuit comprises a second inductor and a second capacitor. The first and second inductors comprise ferrite cores and are positioned with respect to each other to allow magnetic coupling therebetween.

Abstract: A spread spectrum system provides bidirectional digital communication on a vacant television (TV) channel for simultaneous use by more than 75,000 subscribers using time and frequency division multiplex signals locked to horizontal and vertical sync pulses of an adjacent channel Host TV station. The system, whose operation is analogous to a radar system, comprises (1) the Host TV station to send down-link sync and data pulses to subscribers during the horizontal blanking interval (HBI), (2) subscriber "transponders" which detect those signals and transmits up-link "echo" data pulses only during the HBI to eliminate interference to TV viewers, and (3) a central receiver which also uses the host TV sync pulses to trigger range gates to detect the up-link data pulses.

Abstract: The present invention provides a pager system which integrates a plurality of transmitters which operate at different frequencies. Some of the transmitters transmit paging messages using FM subcarrier signals (termed FM-SCA signals) and some transmit messages using a modulated carrier (termed RCC signals). The receiver includes two front ends. One front end receives and demodulates FM-SCA signals and one front end receives and demodulates RCC signals. Each paging message is transmitted on both FM-SCA transmitters and on RCC transmitters. The signals on each of the transmitters are slightly off set in time. When an assigned time slot occurs, one receiver turns on and attempts to receive a message, if it does not receive an appropriate signal, it tunes to another station that is in a stored list of stations. If the next station has an RCC flag associated therewith the RCC receiver rather than the FM-SCA receiver is operated. The entire process is controlled by a microprocessor which is a part of the system.

Abstract: A system for facilitating link continuity and prompt supervisory control in a communication system with discontinuous transmissions comprising varying the carrier power in a first communication unit and varying frequency deviation of a modulating signal to provide a continuous signal detectable by a second communication unit, where continuous monitoring at the second communication unit allows for rapid detection and reaction to received supervisory control signals through the use of continually comparing the received supervisory signal to an expected signal and qualifier signal to enhance the reaction time of the second communication unit.

Abstract: A message is transmitted on a subcarrier of a main carrier frequency of a radio station. The message is displayed simultaneously with the audible reproduction of the radio program. The message is capable of being displayed dynamically by having different portions thereof sequencing through the display device until the entire message is concluded and/or using a variety of possible display attributes, such as scrolling and flashing. One feature involves scanning the radio band for a station that carries the message. Scanning of a plurality of subcarriers at each station is also performed. One embodiment transmits the message during the "dead time" of other programming normally transmitted on the same subcarrier. The alphanumeric characters of the message are preferably converted prior to transmission into a signal with an average value of zero. The converted characters are decoded at the receiver.

Abstract: The present invention provides a technique and system for modifying the modulation of the 66.5 kHz subcarrier in such a way that its spectrum will not overlap that required by the 57 kHz subcarrier, while at the same time maintaining compatibility with existing subcarrier receivers. A special signal is created whose spectral shape is asymmetrical with respect to the 66.5 kHz subcarrier. In the frequency domain, the lowest frequency part of the symmetrical spectrum is cut off, flipped about the carrier frequency and then added to the highest frequency part of the spectrum. This technique and system takes advantage of the fact that the receiver, with which the system is designed to operate, uses a sampling process which products frequency aliasing.