Abstract: A digital decision feedback equalizer is disclosed in which compensation for the post-cursors of the impulse response of the transmission channel is divided up into two regions. A first region encompasses the initial rapidly changing unpredictable transient response, possibly oscillatory, of the transmission channel. A fast acting, close-tracking linear filter is used to compensate for this largely unpredictable initial transient. The second region of the impulse response is the slowly changing, easily predictable asymptotic tail of the impulse response. This second region can be compensated for by a relatively slow acting, simple pole-zero filter. Together, the two equalizer sections provide an overall equalizer design far less complicated and less expensive than an equalizer based on a single linear compensating filter.

Abstract: A system and method for communicating a vehicle with a calling party are disclosed in which even when a communication circuit is interrupted during a data communication of the system with the calling party such as a base station due to a worse circuit condition, the calling from the system to the calling party is carried out without operation of a switch for activating the system to start calling so that the communication with the calling party is restarted. The communication data includes a vehicle identification code (ID information) and/or instantaneous position of the vehicle.

Abstract: An umbrella with a hollow interior shaft with a canopy attached at the top portion of said shaft. An audio signal source is attached to the shaft of the umbrella and speaker assemblies are attached to the inside of the canopy of the umbrella. The speaker assemblies are electronically coupled to the audio signal source by wires that are run through the hollow interior of the shaft and exit at the top portion of the shaft and run along the flexible support ribs of the umbrella canopy.

Abstract: A tuner having a programmable frequency divider which selects a broadcast station in accordance with a frequency division number, and a broadcast station selecting device. The selecting device includes an input device for inputting information representing a broadcast station; a memory means for storing information representing a plurality of broadcast stations and for storing frequency division numbers respectively corresponding to the stored information; and a control circuit for reading from the memory he stored frequency division number corresponding to the inputted information by the input device, and for supplying the read frequency division number to the programmable frequency divider so that the programmable frequency divider will select a broadcast station in accordance with the supplied frequency division number.

Abstract: An apparatus and method for selecting a number of cellular radio channels to be boosted in a given geographical area provides either F1-F1 or F1-F2 operation. The signals can be boosted at the same frequency with input to output isolation being achieved by the use of directive transmit and receive antennas physically positioned to achieve sufficient isolation. Each signal is individually filtered, amplified, and recombined for transmission. Any number of signals may be accommodated depending upon the number of retransmission channels available. Apparatus is also provided to retransmit a signal at a different frequency from that at which it is received. A tag, typically an audio tone or diminished signal amplitude gap, may be selectively applied to boosted retransmitted signals in order that they may be recognized as such.

Abstract: A data communication system in which video data is digitized, compacted, and transmitted by a frequency modulated radio station having a subsidiary communication authorization. The data is broadcast on a subcarrier channel to a radio receiver, which is connected to a microcomputer. This microcomputer generates a visual graphic display on a screen, and performs various other functions, such as error checking and permitting the user to alter the display. One application of the invention is real time monitoring of visual information by a remote receiving station. Furthermore, the invention may include a receiver that is turnable, thereby providing data to a mobile receiving station, such as an airplane. Although the invention is especially useful for monitoring weather information, it is adaptable for use with any visual graphics data that is desired to be transmitted via FM subcarrier frequencies.

Abstract: Means and structure for encoding binary data ensures that, on average, the encoded data provides a balanced data stream having an equal number of logical one and logical zero bits. An indicator bit of known value is appended to N data bits, forming a group of N+1 bits. The polarity of this group is determined, i.e. whether the group contains more ones than zeros. The cumulative polarity of all bits sent over the communication link is also maintained. When the polarity of the group is the same as the cumulative polarity, all bits in the group are inverted and the inverted group is transmitted. Otherwise the bits in the group are transmitted in their original form. To decode the transmitted bits, the bit stream is framed to separate each series of N+1 bits. The value of the indicator bit on the receiver side of the communication link indicates whether the group has been inverted. If the group has been inverted, it is reinverted on the receiver side of the link to provide the N data bits in their original form.

Abstract: A combination battery pack and low profile antenna arrangement for use in conjunction with a two-way portable transceiver includes an enclosure containing an electrical battery with positive and negative electrodes. A pair of terminals are attached to the outer surface of the enclosure and are coupled to the positive and negative electrodes. A low profile antenna structure is disposed within the enclosure and includes a feed point for coupling RF energy to and from the antenna structure. An antenna coupling arrangement is electrically coupled to the feed point for coupling RF energy into and out of the enclosure.

Abstract: An AM/FM band selector is provided for selecting AM and FM bands by a single band switch. By using only a single band switch, power consuming parts are eliminated so that power consumption of the selector is reduced. Also, impulse noise which occurs when selecting bands and switching on and off the power source is removed to provide an efficiently operating AM/FM band selector. The AM/FM band selector having a single band switch prevents simultaneous selection of AM and FM bands.

Abstract: A programming station for use in programming and servicing two-way radios that include replaceable hardware elements. Both user-only and programming station-assisted steps are simultaneously displayed in a predetermined order. The steps may only be accomplished in a fixed allowed order.

Abstract: A digital pulse receiver is disclosed in which the transmitted signal is recovered from the received signal by using a decision feedback equalizer to estimate and then remove the intersymbol interference. A second decision feedback equalizer is used to estimate the timing of the sampling pulse. An optimum timing phase is derived by driving the sampling clock with a phase adjustment signal optimizing the amplitude of the sampling pulse relative to the next preceding pre-cursor pulse. The signal recovery decision feedback equalizer and the timing recovery decision feedback equalizer share the same tapped delay line to provide a fully digital pulse receiver operating at the baud rate to provide an optimum sampling phase.

Abstract: A rotatable contactless RF signal coupler, which couples RF signals between an antenna and an RF signal processor in a portable radio, along with an antenna capable of operating in two modes is described herein. Specifically, the signal coupler includes a transformer that is primarily located within the hinge formed by the housing of the radio and a rotatable flip portion. Substantially constant inductive coupling is maintained in the coupler regardless of rotation. The antenna is capable of operating in a narrow band and a wide band mode to afford antenna operation through varied conditions.

Abstract: A field telephone system having a widely dispersed set of telephone lines including a page line pair and a party line pair, audio processing equipment including telephone handsets, handset amplifiers, receiver amplifiers and paging speaker amplifiers is designed to have improved voice transmission by provision of a narrow band FM carrier system. The FM carrier system includes a device for generating a carrier frequency signal, a modulator for modulating the carrier frequency with an audio signal derived from one of the handsets at a transmitting station and circuitry for transmitting the modulated signal over a line pair to a receiving station. The receiving station includes circuitry responsive to the transmitted signal and the carrier frequency signal for extracting the audio component of the transmitted signal and for processing the extracted audio signal and for providing the processed audio signal to a handset at the receiving station.

Abstract: Self-programming scanning receiver having superheterodyne circuitry, microprocessor controlled synthesized frequency tuning circuitry, frequency validation means, a learn mode to invoke the frequency validation means for all frequencies tunable by the tuning circuitry, listen mode for scanning of frequencies learned in the learn mode, and an ignore mode for erasing frequencies from permanent memory.

Abstract: A method for communicating with a plurality of hosts connected to an X.25 network and for selectably using a character as a control character or a data character. Each character received from the X.25 network is inspected to determine if it is one of a set of reserved characters. If so, the character is encoded before being sent to its final destination. Data intended for the X.25 network is inspected for the presence of a predetermined control character. If the control character is present, the next character is inspected to determine whether it is a command character or an encoded data character. If this next character is an encoded data character, it is decoded and provided to the X.25 network. If this next character is a command character, then the command is executed. The method allows the use of any character as either a command character or data character. Data transfer between the DTE and DCE is assigned a PAD and a virtual channel number which corresponds to a particular host on the X.25 network.

Abstract: A watch type paging receiver which may be put on person's wrist by a belt includes a body on which a display device such as a liquid crystal display device is provided. An inverted F-shaped main antenna is implemented by a part of the display device. A loop antenna is provided in addition to the main antenna and implemented by the belt. The main and loop antennas are selectively rendered active depending upon the level of a received signal. Even when the length of the belt is changed to suit person's wrist, accurate matching is established on the basis of the resulting length of the belt. A primary battery in the form of a solar battery and a secondary battery are associated with the receiver body and the belt, respectively. A vibration source which is adapted for tactual alerting forms a part of the belt.

Abstract: A digital demodulation apparatus which has a detector (11) for receiving transmission signals (S.sub.in) modulated under a multivalue quadrature amplitude modulation method in accordance with a honeycomb signal structure point arrangement. The detector produces I channel and Q channel demodulation signals. The apparatus also includes a discriminator (13) which converts the analog demodulation signals (Sa) to digital demodulation signals (Sd), a memory (21) which successively receives said digital demodulation signals (Sd) and reproduces corresponding original data. The read only memory (21) stores data representatives of the honeycomb signal structure point arrangement, and stores polarity bits (P) and error bits (.epsilon.) of the signal points.

Abstract: A method and apparatus for identifying a radio transmitter. The transient frequency or phase history of the turn-on characteristics of a transmitter is detected and digitized. The history can be analyzed by a microprocessor operating a computer program to gather transient phase information from an unknown transmitter and to classify the transmitter in accordance with a transient characteristic.

Abstract: A simulcast broadcast system wherein two signals (103 and 106) intended for simultaneous broadcast are transmitted from a source site (100) to remote sites (200) discrete from one another. At the remote sites, the two signals are separately processed, including the introduction of appropriate delay (305 and 312), prior to combining them for broadcast in conjunction with other remote sites. One or more monitoring sites (400) can also be provided to monitor reception coherence within the system and to provide operating measurement information to allow automatic control of various simulcast system parameters, including delay.

Abstract: A jammer includes means for receiving a local radio transmission and means for determining the frequency of the local radio transmission. Monitoring circuits are arranged to detect the end of the local radio transmission and only then to trigger the transmission of a jamming signal by jamming signal transmitting means. In this manner the jammer jams local reception of the response of a non-local station to the detected local transmission. The jammer is able to jam effectively using a low power signal. The reduction in the power-consumption of the jammer makes it particularly suitable for use as a leave-behind jammer for military applications.