Abstract: Disclosed are a key updating method and device, and a master Transmission Point (TP). The method includes: receiving a key parameter for generating a data encryption key of a TP in a virtual cell (S102); and generating the data encryption key of the TP in the virtual cell according to the key parameter and a cell Identity (ID) of the virtual cell (S104). By means of the key updating method and device and the master TP, the problem about key updating of different TPs in a virtual cell is solved.

Abstract: Systems (100) and methods for selectively controlling access to data streams communicated from a first communication device (FCD) using a timeslotted shared frequency spectrum and shared spreading codes. Protected data signals (1301, . . . , 130S) are modulated to form first modulated signals (1321, . . . , 132S). The first modulated signals are combined with first chaotic spreading codes to form digital chaotic signals. The digital chaotic signals are additively combined to form a protected data communication signal (PDCS). The PDCS (136) and a global data communication signal (GDCS) are time division multiplexed to form an output communication signal (OCS). The OCS (140) is transmitted from FCD (102) to a second communication device (SCD) over a communications channel. The SCD (106, 108, 110) is configured to recover (a) only global data from the OCS, or (b) global data and at least some protected data from the OCS.

Abstract: Provided is a radio communication base station device which can prevent damage of ARQ control in an ARQ in which a response signal (ACK/NACK) channel is shared by a plurality of mobile stations. In the device, a repetition unit (106) repeats a response signal inputted from a modulation unit (105) so as to obtain a plurality of identical response signals and outputs the plurality of response signals to a scrambling unit (107). The scrambling unit (107) scrambles the identical response signals by using a scrambling code corresponding to a mobile station ID number inputted from an allocation information generation unit (101) (that is, a scrambling code unique to each of mobile stations) and outputs the scrambled response signals to an S/P unit (108).

Abstract: The subject matter described herein includes methods, systems, and computer readable medium for scrambled communication of data to, from, or over a medium. According to one aspect, the subject matter described herein includes a method for communicating data in scrambled form to or over a medium. The method includes receiving analog or digital data to be transmitted to or over a medium. The method further includes modulating samples representing at least signal using the analog or digital data to produce data modulated signal samples. The method further includes scrambling the data modulated signal samples using a predetermined scrambling algorithm. The method further includes transmitting the scrambled data modulated signal samples to or over the medium. The method further includes descrambling samples received from the medium using the inverse of the predetermined scrambling algorithm to obtain the unscrambled modulated signal samples, which can then be demodulated to retrieve original data.

Abstract: An information carrier for holding user information, the information carrier comprising access information in the form of access information bits for accessing the user information, the access information bits being stored on the information carrier in a variation of a parameter, which variation is detectable by integration detection. The access information bits are scrambled according to a pre-determined scrambling method. By scrambling the access information bits according to a pre-determined scrambling method, detection of the access information is not possible as long as the scrambling method is not known. Using the integration detection technique, the only way to obtain the access information is by knowing how the signal obtained after reading-out the area comprising the access information bits must be processed. In this way illegal retrieval of the user information is further prevented.

Abstract: This invention allows connection of an apparatus with a low security level without lowering the security level of a network even when such apparatus issues a connection request. This invention is directed to an access point which makes wireless communications with a station using an encryption method (AES). Upon reception of a connection request message including information indicating an encryption method (WEP) that can be used by a station, the access point checks if the encryption method (WEP) recognized based on the received connection request message is different from the encryption method (AES). When it is determined that the two encryption methods are different, the access point launches a controller which makes wireless communications with the station using that encryption method (WEP).

Abstract: A method for decrypting multicast data by a mobile station in a wireless communication system is described. The method includes receiving an identifier of a group from a base station, receiving parameters for generating a group traffic key from the base station, wherein the parameters include an authentication key for the group, a group security seed and a counter, performing a key derivation function to generate the group traffic key based on the identifier and the parameters and decrypting multicast data using the group traffic key.

Abstract: A communication system 10 includes a head end 12. The head end communicates with a system gateway 26. A plurality of user devices 28 is coupled to the gateway 26 that includes a memory device 94 for storing content therein. The gateway 26 receives the plurality of first encrypted signals and stores the signals in the memory device 94. The storing in the memory device 94 may be performed after further encryption. One of the user devices 28 generates a request for content and communicates the request to the gateway 26. The gateway 26 communicates content corresponding to the request to the user device 28.

Abstract: A wireless station (A) is operated in a power-save mode, in which the station is alternately in power-ON and power-OFF states to reduce power consumption. Wireless station (A) computes at least some future time instances at which another wireless station (B) is expected to start transmitting control messages. Wireless station (A) is ensured to be in the power-ON state in corresponding time intervals encompassing durations of at least some of such future transmissions of control messages by wireless station (B), and is thereby enabled to receive the control messages. In an embodiment, the control messages correspond to group key message updates in which values of a decryption key are transmitted, wireless station (A) being a wireless client, wireless station (B) being an access point, with wireless stations (A) and (B) operating in a wireless network consistent with IEEE 802.11 specifications, and communication between wireless stations (A) and (B) being encrypted.

Abstract: A wireless station (A) is operated in a power-save mode, in which the station is alternately in power-ON and power-OFF states to reduce power consumption. Wireless station (A) computes at least some future time instances at which another wireless station (B) is expected to start transmitting control messages. Wireless station (A) is ensured to be in the power-ON state in corresponding time intervals encompassing durations of at least some of such future transmissions of control messages by wireless station (B), and is thereby enabled to receive the control messages. In an embodiment, the control messages correspond to group key message updates in which values of a decryption key are transmitted, wireless station (A) being a wireless client, wireless station (B) being an access point, with wireless stations (A) and (B) operating in a wireless network consistent with IEEE 802.11 specifications, and communication between wireless stations (A) and (B) being encrypted.

Abstract: An approach is provided for minimizing co-channel interference in a communication system is disclosed. A header of a first frame is scrambled based on a first unique word. A header of a second frame is scrambled based on a second unique word. The first frame including the corresponding scrambled header and the second frame including the corresponding scrambled header are transmitted, respectively, over adjacent co-channels of the communication system. Each of the frames further includes a payload and a pilot block. The payload and the pilot block of the first frame are scrambled based on a first scrambling sequence. The payload and the pilot block of the second frame are scrambled based on a second scrambling sequence. The above arrangement is particularly suited to a digital satellite broadcast and interactive system.

Abstract: A system for transmitting quantum information includes a sending unit including an encoder configured to encode a carrier with quantum information by setting a quantum state of the carrier, the quantum state determined according to the combination of a first component and a second component, and a receiving unit including a decoder configured to perform a measurement on the carrier using a measurement basis selected to cancel the second component and decode the quantum information from the carrier.

Abstract: A method is provided for tamper detection of a transmitted signal. The method is comprised of generating a first digital data signal having a first data rate. The method is also comprised of generating a second digital data signal having a second data rate. The method is further comprised of concurrently transmitting the first digital data signal at a first carrier frequency using a first modulation format and the second digital data signal at a second carrier frequency using a second modulation format. The method includes selecting the second carrier frequency and a bandwidth of the second digital data signal so that the second digital data signal is contained within a frequency spectrum defined by a bandwidth of the first digital data signal. The method also includes verifying an integrity of the first digital data signal at a remote receiver based on defection at the remote receiver of the second digital data signal. A system (100) is also provided for generating a tamper-protected transmitted signal.

Abstract: Various embodiments of the present invention are directed to scrambling-descrambling systems for encrypting and decrypting electromagnetic signals transmitted in optical and wireless networks. In one aspect, a system (1302) for scrambling electromagnetic signals comprises a first electronically reconfigurable electro-optical material (1402) positioned to receive a beam of electromagnetic radiation including one or more electromagnetic signals encoding data. The beam is transmitted through the electro-optical material (1402) and a two-dimensional speckled pattern (1410) is introduced into the cross-section of the beam such that data encoded in the one or more electromagnetic signals is scrambled.

Abstract: Data is encrypted onto an electromagnetic beam by providing an electromagnetic beam having a signal component having a modal state, wherein the signal component is susceptible to accumulation of a geometric phase, and a reference component, transmitted along a path over at least part of which the signal component accumulates a geometric phase by transformation of its modal state from a first to a second modal state, from the second to at least one further modal state, and then back to the first modal state; and modulating with the data the geometric phase so accumulated, by modulating the modal state transformations. Data is decrypted from a received electromagnetic beam by corresponding processing of the received electromagnetic beam and by comparing an overall phase of the signal component with an overall phase of the reference component so as to retrieve the modulation.

Abstract: Methods and apparatus, including computer program products, are provided for channel estimation. In one aspect, there is provided a receiver including a demodulator for decoding a signal including at least one of a transmission parameter signaling (TPS) carrier and a data carrier. The receiver further includes a channel estimator, coupled to the demodulator, for determining a channel estimate for the TPS carrier. Moreover, the receiver includes an interpolator, coupled to the channel estimator, for determining, based on the determined channel estimate for the TPS carrier, another channel estimate for the data carrier. Related systems, methods, and articles of manufacture are also disclosed.

Abstract: A method and system for securing transfer, storage, and playback of media content. The method and system relate to securing transfer, storage, and playback of all types of media content, including television, music, electronic games, and other types of electronic data.

Abstract: Wireless communication apparatus (WAP) which comprises means of receiving data streams (312, 313, 314, 315, 316, 317) each at least partly requiring a cryptographic processing operation, a cryptographic module (320) comprising a crypto-processor (301), and management means configured to deliver at least some of the data streams to the crypto-processor (301) according to an order of priority defined from the data types and cryptographic processing types assigned to each data stream.

Abstract: A system and method for providing an encrypted media stream to clients includes a plurality of remote multiple media stream manager and provider (RMP) units to receive a plurality of source media streams. The RMP units modulate the source media streams to provide a plurality of modulated media streams; encrypt the modulated media streams to provide a plurality of encrypted and modulated media streams; de-modulate the encrypted and modulated media streams to provide a plurality of encrypted and demodulated media streams; and transmit the encrypted and demodulated media streams over a high speed network.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to analyze an audio-video data stream to determine watermark appropriate information for the audio-video data stream. The second circuit may be configured to communicate the watermark appropriate information either in-band with or out-of-band from a bit stream communicating the audio-video data.

Abstract: A data communication apparatus which improves security against eavesdropping is provided for secret communication using Y-00 protocol. In a data transmitting apparatus 101, a multi-level code generation section 111 generates, based on key information 11, a multi-level code sequence 12 in which a signal level changes so as to be approximately random numbers. A multi-level processing section 112 generates a multi-level signal 13 having a plurality of levels each corresponding to a combination between information data 10 and the multi-level code sequence 12. A level conversion section 113 divides the plurality of levels of the multi-level signal 13 into several groups, and allocates one level of a converted multi-level signal 21 to a plurality of levels included in each of the several groups in an overlapped manner. The level conversion section 113 then converts the multi-level signal 13 into the converted multi-level signal 21.

Abstract: Systems (100) and methods (400) for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and shared spreading codes. The methods involve generating a first product signal (FPS) by spreading first symbols of a first amplitude modulated (AM) signal using a first spreading code (SC). The methods also involve generating a second product signal (SPS) by spreading second symbols of a complimentary AM signal using a second SC. The FPS (124) and SPS 126 are combined to form a protected data communication signal (PDCS) including first data recoverable by a receiver (106). A global data communication signal (GDCS) is combined with PDCS (128) to form an output signal (140) having a spread spectrum format. The GDCS is generated using a digital modulation process and includes second data recoverable by a plurality of receivers (106, 108).

Abstract: Methods and apparatus for converting original data into a plurality of sub-bands using wavelet decomposition; encrypting at least one of the sub-bands using a key to produce encrypted sub-band data; and transmitting the encrypted sub-band data to a recipient separately from the other sub-bands.

Abstract: A base station of a wireless communication system includes: a base station side data generation portion generating a number of sets of scramble data which are different from each other while the number of sets of the scramble data is the same as or more than the number obtained by multiplying the number of the sub-channels used in said overall wireless communication system by the number of the subcarriers; a base station side storage portion which stores the scramble data; a base station side upper layer control portion which outputs both transmission data for a terminal at other end of a communication and information of sub-channels; a base station side lower layer control portion which, based on the information of the sub-channels, controls the base station side storage portion to output scramble data corresponding to the sub-channels; a base station side scramble portion which conducts a multiplication operation between the transmission data output from the base station side upper layer control portion and

Abstract: The method and system of the invention provide a variety of techniques for using a selected alias and a selected personal identification entry (PIE) in conjunction with use of a transaction card, such as a credit card, debit card or stored value card, for example. A suitable number or other identification parameter is selected by the account-holder as an alias. The account-holder is then required to choose a PIE for security purposes. The alias is linked to the account-holder's credit card number via a database. When the account-holder enters into a transaction with a merchant, the physical card need not be present. The account-holder simply provides his or her alias and then the PIE. This can be done at any point of sale such as a store, catalog telephone order, or over the Internet. The alias and PIE are entered and authorization is returned from the credit card company.

Abstract: Provided is a radio communication base station device which can prevent damage of ARQ control in an ARQ in which a response signal (ACK/NACK) channel is shared by a plurality of mobile stations. In the device, a repetition unit (106) repeats a response signal inputted from a modulation unit (105) so as to obtain a plurality of identical response signals and outputs the plurality of response signals to a scrambling unit (107). The scrambling unit (107) scrambles the identical response signals by using a scrambling code corresponding to a mobile station ID number inputted from an allocation information generation unit (101) (that is, a scrambling code unique to each of mobile stations) and outputs the scrambled response signals to an S/P unit (108).

Abstract: An assembly of simultaneously transmitted electrically generated signals, which contains a subset of binary spreading-code sequences that are members of a larger set of binary spreading-code sequences available to a particular node of a multi-node communication network. All sequences in the set of spreading-code sequences available to the particular node of the network can be generated by the same configuration of two linear-feedback binary shift registers, where feedback taps of the two linear-feedback binary shift registers correspond to primative polynomials of the same degree over GF(2), the field of two elements.

Abstract: A system and method for secure wireless cryptographic communication among participants in a wireless computing network is presented. This secure communication method is based on a random modulation technique and a domino match. Once the initial modulation scheme is selected, each data transmission includes an indication of what modulation scheme should be used for the next data transmission. If a given number of bits are to be used, the modulation scheme for the final transmission may be limited to complete the bit transfer. The bit value assignments within particular modulation schemes may also be varied for each subsequent transmission.

Abstract: A disclosed base station randomizes downlink physical channels in OFDM radio access by scrambling codes suitable for the respective physical channels. The base station includes a base-station-specific scrambling code generating unit configured to generate a base-station-specific scrambling code for randomizing downlink physical channels; a sector-specific orthogonal sequence generating unit configured to generate a sector-specific orthogonal sequence; and a multiplication control unit configured to determine, for each of the physical channels, whether to multiply the base-station-specific scrambling code by the sector-specific orthogonal sequence based on whether each of the physical channels requires soft combining.

Abstract: A multiplexing technique for optical communications used to create a pseudo-random communications signal in the optical domain such that only the sender and/or receiver can decode the signal. The multiplexing technique may include one or more information-bearing optical signals combined with one or more dynamic pseudo-randomly-generated optical signals to create a combined dynamic subcarrier multiplexed privacy-protected output signal. The information-bearing signal is protocol-independent and can be of mixed type, such as RF, analog, and/or digital. Only the receiver of the privacy-protected signal may decode the pseudo-random signal so as to disclose the information-bearing signal. The present invention may use dynamic subcarrier multiplexing selection based on standard digital encryption and the use of optical range time to ensure synchronization.

Abstract: A method for placing a predetermined number of notch filters in a disc drive servo control system to attenuate noise frequencies, in order of decreasing resonance magnitudes, is disclosed. The method involves calculating an open loop response for a response spectrum of the drive, calculating a notch filter for any noise frequency that exceeds a threshold, mathematically applying the notch filter into the servo control system, recalculating the open loop response and applying another filter for a noise frequency that exceeds the threshold and repeating until no noise frequencies exceed the gain threshold; selecting another frequency range and repeating the same process until a predetermined number of notch filters has been placed in the servo control system.

Abstract: A system and method for wireless cryptographic key exchange among participants in a wireless computing network is presented. This allows the authorized participants in the wireless communication session not have the same key before the wireless computing session begins. This wireless online key exchange/generation is based on a random modulation technique and a domino match. Once the initial modulation scheme is selected, each data transmission includes an indication of what modulation scheme should be used for the next data transmission. If a given number of bits are to be used, the modulation scheme for the final transmission may be limited to complete the bit transfer. The bit value assignments within particular modulation schemes may also be varied for each subsequent transmission.

Abstract: A spread spectrum method and apparatus for protecting and authenticating wirelessly transmitted digital information using numerous techniques. The apparatus may be a wireless code division multiple access (CDMA) communication system, a base station, a wireless transmit/receive unit (WTRU), a transmitter, a receiver and/or an integrated circuit (IC). The wireless CDMA communication system includes a transmitter which steganographically embeds digital information in a CDMA communication signal and wirelessly transmits the CDMA communication signal. The system further includes a receiver which receives the CDMA communication signal and extracts the steganographically embedded digital information from the received CDMA communication signal.

Abstract: A encoding/decoding method and device for a remote controller utilizing a baud rate to encrypt data for transmission. The encoding device includes an encoder encoding an identification code into an encrypted code; and an interpreter interpreting the un-encoded portion of the identification code and the encrypted code into a transmission signal. When the encrypted code is in a first base, the plain code corresponding to the encrypted code will be transmitted with a first baud rate; and when the encrypted code is in a second base, the plain code corresponding to the encrypted code will be transmitted with a second baud rate. The decoding device includes a receiver receiving the transmission signal; a interpreter connected to the receiver interpreting the transmission signal into a received signal; an encoder utilizing the same encoding algorithm as in the transmitter to generate a comparison code; and a processor comparing the received signal and the comparison code.

Abstract: A system and method for encrypting all channels of a wireless spread spectrum communication at the chip level. The PN sequence is encrypted with one or more encryption sequences and then used to spread the signal.

Abstract: Disclosed are a forward multiple scrambling code generating method and apparatus in a communication system. Each base station uses primary scrambling codes and an associated one of secondary scrambling code sets, each consisting of a plurality of secondary scrambling codes. When an n-th one of the primary scrambling codes is to be generated, an initial value of the scrambling code generator is set with a binary value of “n,” so that a desired primary scrambling code is generated using the initial value. When an n-th one of the secondary scrambling codes in an m-th one of the secondary scrambling code sets is to be generated, an initial value of the scrambling code generator is set with a value obtained by shifting the n-th primary scrambling code by m times, thereby generating a desired secondary scrambling code.

Abstract: A mobile host MH and its home network HN correspond to both the Internet Protocol version 4 (IPv4) and the Internet Protocol version 6 (IPv6). An authentication server (RS) is accommodated in the home network HN. A corresponding host H corresponds to the IPv6 and is accommodated in the IPv6 network. In addition, a plurality of relay servers S1, S2 and S3 corresponding to both the IPv4 and the IPv6 are accommodated in the IPv6 network. The respective S1, S2 and S3 extract an IPv6 packet by decapsulating the IPv4 packet received from the mobile host MH via the IPv4 network, and transfers the relevant IPv6 packet to the corresponding host H via the IPv6 network.

Abstract: A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. In an embodiment of the invention employing a Chua circuit as the basic chaotic circuit, the transmitter has a tank circuit portion and a Chua diode portion linked through a resistance. The capacitance of the tank circuit is varied by selectively switching in and out of the tank circuit an auxiliary capacitance isolated by an optoisolator. Switching of the optosiolator is controlled by an information signal to generate a perturbed oscillation in the transmitting circuit. A voltage is tapped from the Chua diode circuit and transmitted to carry the information from the information signal. A receiver in another embodiment applies the transmitted signal to both the tank circuit and Chua diode portions of the receiving circuit. The transmitted signal is applied through a resistor to the Chua diode portion as well as the tank circuit portion.

Abstract: Apparatus and methods are provided for embedding or embedding digital data into an analog host or cover signal. A distributed signal feature of the cover signal in a particular domain (time, frequency or space) is calculated and compared with a set of predefined quantization values corresponding to an information symbol to be encoded. The amount of change required to modify the signal feature to the determined target quantization value is calculated and the cover signal is modified accordingly to so change the feature value over a predefined interval. Information symbols are extracted by the opposite process. In one embodiment, the predefined value is a short term autocorrelation value of the cover signal.

Abstract: Apparatus and methods are provided for embedding or encoding auxiliary signals into an analog host or cover signal. A replica of the cover signal or a portion of the cover signal in a particular domain (time, frequency or space) is generated according to a stego key specifying modification values to specified parameters of the cover signal. The replica signal is then modified by an auxiliary signal corresponding to the information to be embedded, and inserted back into the cover signal. Embedded auxiliary signals are extracted by generating replicas of received signals and correlating the replicas with the received signals.

Abstract: A complex spreading and/or scrambling code sequence generation system uses a first complex code sequence having at least two components and a second complex code sequence having at least two components. The components of the first complex code sequence are respectively mixed with the corresponding components of the second complex code sequence to generate the complex scrambling code sequence. In doing so, an offset between the components of the complex scrambling code sequence is achieved for the same and/or different users. The complex scrambling code sequence can be used for spreading, scrambling, de-spreading or descrambling an information signal.

Abstract: A vehicular emergency awareness system and method is provided. A vehicle is provided with an onboard computer system adapted to receive and process signals generated at an external source. Under predetermined conditions, the emergency awareness system alerts the driver of the vehicle of a proximal hazard or emergency, such as hazardous road conditions, nearby emergency vehicles and the like. In one embodiment, a program product is provided which, when executed by the computer, causes the computer or other devices to process the received signal, determine whether a warning should be provided to the driver and, if so, provide a signal to one or more output devices disposed on the vehicle.

Abstract: A method for encryption and decryption of analog signal, wherein encryption and decryption are performed in analog domain. The transmitter creating digital representations with unique behavior; producing computation instructions for each digital representation; randomly generating analog identification signals with random waveform appearance and yet preserving common behavior as in said digital representation; encryption through partitioning said analog signal and inserting said analog identification signals prior to, in between, and/or after said partitioned analog signal segments. As a result, encrypted analog signal sequence becomes totally destructed to unauthorized receivers.

Abstract: An apparatus and method for improved security in wire or wireless communication systems includes scrambling the audio signal, combining a masking signal with the scrambled audio signal, and then transmitting the scrambled masked signal. To recover the original audio, a receiver must by synchronized and know the characteristics of the masking signal and the scrambling technique. Such a receiver removes the masking signal, descrambles the audio and thus recovers the original audio. Any attempted interception of the communication would hear white noise, and even if the white noise mask where removed, the communication would still have the security level of the scrambling. The mask removes any remnants of the original audio that might be used to try to locate and intercept the communication.

Abstract: Methods and apparatus for providing a secure optical communications link are disclosed. Communications information is encrypted with a security key. An optical beam is then modulated with both the security key and the encrypted communications information, with different modulation schemes being used for each. The dual-modulated optical beam is then transmitted to a receiver. At the receiver, the optical beam is split into first and second optical beams. First and second demodulators are then employed to demodulate the optical beams to recover the encrypted communications information and its data rate, and the security key and its data rate. The encrypted communications information, the security key, and the data rate information are then sent to decryption and timing circuitry which decrypts the encrypted communications information to obtain the original unencrypted communications information.

Abstract: A spread spectrum transmitter for generating a plurality of spread spectrum codes comprises a shift register having a plurality of stages, with a plurality of tap sets connected to selected ones of said stages. Each tap set defines a different spread spectrum code, which may be maximal or non-maximal. Outputs from the tap sets are combined using exclusive-OR gates and fed back to through a table of logic gates to the input of the shift register. A serial data register is loaded from a data stream and clocked periodically into a parallel data register. The parallel data register corresponds to a data symbol and is connected to the table, whereby one of the spread spectrum codes at a time is selected. A code portion of the spread spectrum code up to a designated length is generated for each data symbol. More than one code portion may be simultaneously sent using offset quadrature phase shift keying.

Abstract: An electronic paging system and method for transmitting paging signals over a broadcast network, such as a standard pre-existing commercial radio broadcast system, adds paging signals to a normal radio baseband signal for non-interferential co-transmission therewith over the existing standard radio broadcast transmission system. A telephone interface receives paging information via normal telephone lines. The paging information is used to pseudo-randomly frequency-hop a frequency-synthesized signal which is added to the baseband audio of a standard commercial radio signal. This composite signal is then used to modulate the standard commercial radio broadcast carrier in the normal manner. Mobile pagers, or "beepers," receive and selectively decode (i.e. pseudo-randomly frequency-dehop) the standard commercial broadcast signal to determine whether and which pager is being summoned, i.e. addressed.

Abstract: Audio signals are descrambled by double sideband modulating the scrambled audio signal with a modulation carrier having a carrier frequency slightly above the highest audio signal present in the scrambled audio. This produces a double sideband signal that is passed through a low pass filter which in turn is modulated by a second carrier frequency lower than the first carrier signal by an amount equal to the offset spectrum of the original scrambled signal. The first low pass filter nulls out any residual carrier from the first modulator that results from the of intermodulation of the two modulation frequencies that would be audible at its descrambler output. The modulators used are low noise switch type modulators that improve the signal to noise ratio in the descrambled signal over the previously used linear modulators. The use of switch type modulators provides a lower cost device with improved performance.

Abstract: A method and apparatus for the identification and verification of audio transmission segments, such as may be broadcast by a radio station, consists of the generation of a data stream corresponding in duration to the length of the program segment and including both cumulative time data and segment identification data. The data stream is combined with the program segment to which it relates in a manner in which the data is inaudible on conventional reception apparatus and which does not significantly degrade the audio quality of the program segment. A reception facility is provided to extract the data stream from the recorded audio and compare the data therein with reference data for the transmission, including intended length and time of the segment. By such a comparison verification of the broadcast can be accomplished.

Abstract: An apparatus and method for high speed transmission of data over a transmission line/medium/network telephone, wherein this high speed is achieved by simultaneously, or in a timed and marked relationship, transmitting multiple bits of data over parallel frequencies rather than serially transmitting one bit of data at a time over one frequency.