Abstract: A system which improves coverage in overlapping coverage areas between two type-A or type-B cellular radio telephone systems is able to direct a subscriber unit in the overlapping coverage area to the home or primary system, thereby minimizing the subscriber unit's roaming-type expenses. The system includes a control channel receiver, a control unit, and a control channel transmitter/receiver pair, in combination with a transmit/receive antenna. The system transmits a control channel, which is associated with the home system, into the overlapping region. The control channel is intended to be the strongest channel in that region. Any subscriber units in the region associated with the home system which respond to that control channel will be directed to other control channels associated with the home system. Those subscriber units will receive service from the home system, as opposed to the foreign system which may provide other strong control channels in the overlapping coverage area.

Abstract: A booster usable in a radio telephone communication system can amplify and repeat both analog and digital representations of communications. The unit monitors control channel communications going to subscriber units and reverse control channel responses from subscriber units. When a digital traffic channel assignment is detected, the booster directs the subscriber unit to a different traffic channel pair. The booster communicates with the subscriber unit on the traffic channel pair assigned by it to the subscriber unit. The booster communicates with the cell site on the channel pair assigned by the cell site. Digitized communications from the subscriber unit are amplified only during the associated time intervals. Hence, other communications in different time intervals on the same message channel are not effected. Analog conversations and other message channels can be simultaneously boosted and retransmitted.

Abstract: An omni-directional, collinear, vertical base station antenna having an adjustable or variable radiation beam tilt capability. Terminations at the drive or feed points are provided by an adjustable, capacitive coupling structure at the feed points between the conductive elements of a feed structure and a radiator assembly for adjusting the physical position of the feed points and thereby the phase of the feed points relative to the upper and lower portions of the antenna to alter the deflection angle of the radiation produced. A signal feed, having first and second conductive feed elements, is connectable to a signal feed line to couple a signal between the feed line and the radiator assembly.

Abstract: An apparatus and method which can provide a private cellular system within an area already served by a public cellular system include a receiver for receiving RF control signals from the public system. The public system control signals are converted to saturation level control signals from the private system. Subscriber units to be serviced by the public system are directed thereto. Those associated with the private system can be serviced directly.

Abstract: A system and method for handing back a movable transceiver to a different cell site from the original cell site includes circuitry for sensing signals from the movable transceiver which are transmitted on a modified frequency as well as circuitry for translating those signals back to their originally assigned frequencies without changing the detected field strength of the signal, in combination with circuitry for forwarding the translated signals to the different cell site for hand-off evaluation. The method includes sensing the received signals, translating the received signals to an originally assigned frequency based on either a fixed offset or other provided information concerning the translation along with a step of continually updating those frequencies which are to be retranslated.

Abstract: A multi-resonator notch filter incorporates a variable impedance transmission line with impedance values going from a relatively low value and increasing upward to a relatively high value then back down to a relatively low value again. A plurality of resonant cavities is coupled to the relatively high central impedance line section of the filter at odd multiples of quarter wavelength intervals. Other resonators can be coupled to lower impedance sections of the transmission line. The locations of selected resonators on the quarter wavelength intervals can be altered thereby increasing and decreasing the nominal quarter wavelength intervals of selected internal pairs by a predetermined amount thereby providing acceptable levels of performance with fewer resonators.

Abstract: A diversity receiving apparatus includes first and second antennas and circuitry for selecting one antenna or the other. Control circuitry analyzes signal strength received from the selected antenna and determines when the antennas should be switched. The antennas are switched when the received signal strength falls below a running average thereof; the received signal strength falls below a threshold value; or a predetermined time has elapsed since the antennas have been switched. The antennas are switched when the received signal strength falls below a running average thereof; the received signal strength falls below a threshold value; or a predetermined time has elapsed since the antennas have been switched.

Abstract: An adjustable cellular mobile antenna assembly capable of being mounted on a vehicle in which the angular orientation of the antenna whip or radiator is adjustable relative to the surface on which it is mounted. The antenna member of an adjustable antenna includes a whip or radiator and a support portion. The support portion includes a bottom member, suitably shaped to be receivable in a base attached to the vehicle. The antenna member is angularly adjustable relative to the base and is retained in such a selectable position by a retaining member adapted to engage and interact with both the antenna member and the base and to retain the antenna member in the angular position selected. The antenna assembly is designed to receive and connect to a cable to provide an uninterrupted electrical connection between a transceiver and the antenna whip over all of its angular positions.

Abstract: A system and a method for extending coverage of a cell site in a cellular radio telephone system include a plurality of repeaters or boosters which are spaced through the region where increased coverage is desired. A first booster is in radio communication with the transceiver for the cell site. The remaining boosters are linked together, by radio transmissions, in a series configuration with only one of those linked to the first booster. A movable transceiver operating in the extended area of coverage is in radio communication with the closest booster unit and, via the serial chain of boosters in communication with the controlling cell site. As the movable unit moves along the extended area of coverage from one booster area to another, it is automatically picked up by the approaching booster and dropped by the receding booster while continuing to be in communication ultimately with the cell site via the series coupled booster chain.

Abstract: A cellular communication system booster has plural narrowband and wideband channels each having down mixers, local oscillators, IF filters, and amplifiers for amplifying communication signals. On a narrowband channel preferably not in use, and preferably in a time-multiplexed manner, a reference signal of known signal strength is substituted at the output amplifier in lieu of a normal communications signal. When this amplified reference signal is broadcast at the output antenna a portion of the signal is feed back to the input antenna due to imperfect isolation between the antennas. This feedback signal is measured by a Radio Signal Strength Indicator (RSSI) circuit at the point of its receipt into the IF filter of the narrowband channel. The measured signal strength serves as a measurement of signal isolation/feedback between the antennas.

Abstract: An apparatus for detecting excessive output power from a cellular radio telephone system booster includes input circuitry for receiving incoming radio frequency signals from a mobile source. Amplifiers are provided for amplifying the radio frequency signals either directly or by means of intermediate frequency channels. The output power amplifiers have variable gain. Circuitry detects when the transmitted radio frequency signals exceed a predetermine threshold and reduce the amplifier gain accordingly.

Abstract: A method for optimizing antenna orientation in a cellular radio telephone system with respect to a predetermined criterion of signal level includes the steps of orienting the antenna in a selected direction, sensing a selected received signal in a predetermined frequency range, mixing the selected received signal with the control signal so as to generate a corresponding intermediate frequency signal in an intermediate frequency transmission path, measuring a selected parameter of the intermediate frequency signal and then altering the orientation of the antenna while subsequently repeating the required steps. The preferred antenna orientation can be determined by examining the results of the various measurements and selecting an antenna orientation which maximizes the signal level of the desired received signal.

Abstract: A multi-resonant notch filter incorporates a stepped impedance transmission line with impedance values going from a relatively low value and increasing upward to a relatively high value then back down to a relatively low value again. A plurality of resonant cavitites is coupled to the relatively high central impedance line section of the filter. Other resonators can be coupled to lower impedance sections of the transmission line.

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: 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 are 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.

Abstract: A system for coupling a plurality of telephones or local units to a remote land line telephone system includes a line interface associated with each of the telephones or local units. Each of the line interfaces is in turn coupled to an audio switch matrix. Outputs and inputs to and from the audio switch matrix are coupled to a 4 to 2 wire hybrid, a tone interface hybrid and a computer based control unit. The control unit includes a programmed microcomputer with interface circuits enabling it to communicate with and to control the line interfaces and the audio switch matrix. The computer also includes interface circuits enabling it to communicate with and control a radio transceiver. The radio transceiver is in radio frequency communication with a corresponding radio transceiver remotely located and coupled to the remote land line telephone system. Communications with the remote land line telephone system can be initiated by any of the local units.

Abstract: A mobile antenna system for use at frequencies in and above the 800 MHz band having a collinear radiator mounted on one surface of a dielectric such as the window of a vehicle and a tunable coupling circuit disposed internally of a conducted housing mounted on the opposite surface of the dielectric which acts as a counterpoise for coupling RF energy between the radiator and a transmission line connected to a suitable transceiver.