Abstract: An antenna for use with a shippinconductive elements shunt fed to an exterior metallic surface of the container. As a result, electromagnetic field energy is radiated or detected by coupling to currents flowing in the surface of the container, rather than by direct coupling to the radio waves themselves. The shunt fed antenna forms a feed system for the mobile structure. It performs best when mounted on a lower plane of the container adjacent a vertical side, but may be mounted on the vertical side itself in applications where the containers are intended to be stacked upon one another or where vertical polarization properties are desired.

Abstract: A low power miniature repeater station is located on a vehicle such as a train, cargo ship, cruise ship or other vehicle which is expected to carry multiple paging receivers. The repeater station receives paging messages that originate as satellite signals and rebroadcasts them in the immediate vicinity of the vessel. The rebroadcast may typically be over a single FM carrier frequency or in the form of a subcarrier signal. The repeater includes an FM scanning receiver that samples the radio band and enables the rebroadcast of signals only if FM subcarrier signals are not detected within the vicinity of the vehicle. As the vehicle re-approaches a populated area, continued scanning of the radio band eventually detects the presence of subcarrier signals and shuts down the repeater to ensure that it will not interfere with licensed terrestrial broadcasters.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and frequency at which the RBSs can expect to receive data from the field units. A network hub or message operations center (MOC) coordinates the operation of the paging systems and RBSs from a central location. For example, the MOC determines an available HF frequency and time for a particular field unit to transmit, and then issues the request for data to the field unit using the existing paging network infrastructure. The field units make use of paging receivers, and an HF transmitter to report remote data such as a geoposition or other sensor data when requested to do so.

Abstract: A two-way communications system provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. A network hub or mission operation center (MOC) coordinates the operation of the paging systems and RBSs from a central location. The paging network infrastructure is used as an outbound link over which each of the field units is regularly provided with a outbound data message containing information on the available frequencies and time slots the field units can use to transmit inbound data messages to the RBSs. If any of the field units desires to transmit data to MOC, the field unit selects an available frequency from the outbound data message, and transmits its data at the selected available frequency and time.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and HF frequency at which the RBSs can expect to receive inbound data from the field units. A network hub or mission operation center (MOC) determines a radio frequency which is expected to be propagating and clear at the time that a particular field unit is to use the frequency as an inbound link. The MOC then issues the request for data to the field unit using an existing inexpensive wireless system such as the paging network infrastructure.

Abstract: An automatic antenna tuner which conjugately matches the impedance of an electrically small antenna to the impedance of a transmit amplifier output stage by using a pi-type impedance matching network with adjustable capacitive circuit components which are preferably implemented using a low cost escapement mechanism. During an initial set up tuning procedure, a resistive Wheatstone bridge detector is disposed between the output of the power amplifier and the input to the pi network, to feedback a measure a degree of match of the pi network to a controller. The capacitive elements in the legs of the pi network are then electromechanically adjusted under the operator of the controller until an optimum setting is found. These initial impedance values are determined for each frequency in an operating range and then stored in a non-volatile memory.