Abstract: A duplex microwave radio communication and telemetry system for transmitting analog and digital data between fixed stations as well as to mobile stations wherein the microwave oscillator is stabilized by utilizing a free running oscillator which is controlled in frequency with the incoming modulation input and the output of the free running oscillator is supplied to a phase comparator and to a multiplier and the multiplier supplies an output to a mixer which also receives a portion of the input from the microwave oscillator and supplies an input to the phase comparator to provide a control signal for controlling the frequency of the microwave oscillator.

Abstract: In one illustrated embodiment involving a railway communication system, about ten send-receive stations form a transmission section operating at one pair of frequencies in the range above one gigahertz, the stations being arranged at about one kilometer intervals along the route for radio communication with mobile stations moving therealong. A next succeeding similar transmission section operates at a different pair of send and receive frequencies above one gigahertz. All of the stations of a given transmission section may be in communication with a main station by means of a parallel cable connection. A central station then may communicate with mobile stations via the respective main stations. In another embodiment, the stations are implemented as microwave relay stations linked to a main station by the same antenna system used for communication with the mobile stations.

Abstract: A method and device for increasing security with respect to transmission faults in an information-transmission system, particularly for the railroad field, in which an interrogation device and a passive response device are movable relative to one another, and the interrogation device transmits an interrogation signal, which can be periodically swept through a predetermined frequency band, preferably in the microwave range, and which during a read operation, receives during several periods from the passive response device, a frequency-selectively reflected interrogation signal, in accordance with a k-digit information item to be transmitted, which signal forms the response signal, with the response signals being suitably identified and one of a series thereof, preferably that with the least errors therein, being suitably through-connected for subsequent utilization, in which not only is the response signal with the fewest errors utilized, but of the signals having the same minimum number of errors, that respon

Abstract: A device for increasing security with respect to transmission faults in an information transmission system, particularly for the railroad field, in which an interrogation device and a passive response device are movable relative to one another, and the interrogation device transmits an interrogation signal, which can be periodically swept through a predetermined frequency band, preferably in the microwave range, and which during a read operation, receives during several periods from the passive response device, a frequency-selectively reflected interrogation signal, in accordance with a k-digit information item to be transmitted, which signal forms the response signal in which the interrogation device is provided with means for amplifying each response signal, until there is reached a predetermined threshold level of the low-frequency portions of the response signals, which are below the frequency of the periodic interrogation sweep, with the amplification that the low-frequency portions thereafter being so r

Abstract: An answering device in a system for automatic wireless transmission of an item of information coded by a plurality of frequencies is disclosed herein. An interrogation device movable with respect to the answering device transmits an interrogation signal having a frequency which periodically varies within a predetermined microwave frequency band. The answering device has a plurality of microwave resonators, each of which has a fixed frequency. A microwave diode is coupled to each of the resonators for preventing a response to the interrogation signal by either damping or detuning the resonator fixed frequency when a control voltage is applied. The control voltage means connected to each of the microwave diodes switches certain of the resonators to an inoperative condition to establish a set of frequencies at which the resonators will respond which corresponds to the information to be transmitted.