Did You Know...
...When G.G. Hubbard learned of his future son-in-law's invention, he called it "only a toy." His daughter was engaged to a young man named Alexander Graham Bell.
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| Number | Title | Issue Date |
| 6234428 | Selective data transmission process and device for communication systems used in traffic engineering A process is disclosed for communication systems used in traffic engineering and having an earthbound transponder for each corresponding track section. The transponders transmit first data through a first path of transmission to polling machines arranged ... | 05/22/2001 |
| 5554982 | Wireless train proximity alert system A wireless train proximity alert system provides a constant warning signal to warn vehicles approaching a train crossing when a train is also approaching the crossing. The system includes a transceiver, positioned on the train itself or at the side of the... | 09/10/1996 |
| 5136225 | Device for guiding vehicles on a virtual track A vehicle guidance system for guiding a vehicle on a virtual track includes a waveguide connected to a member emitting electromagnetic radiation at a frequency between 1 and 100 kHz and disposed on the axis of the track to be followed. At least one set of... | 08/04/1992 |
| 4910793 | Two-way transmission system for ground/mobile station communications Information is transmitted at microwave frequencies, the ground station being connected to a waveguide (25) and the station aboard a railway vehicle being connected to an antenna (26). Each station comprises a microwave generator (19) supplying a carrier,... | 03/20/1990 |
| 4232318 | Duplex microwave radio communication system 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 contro... | 11/04/1980 |
| 4207569 | Railroad radio frequency waveguide Disclosed is a waveguide for conducting radio frequency signals along a railroad line comprising the ballast, ties and rails of the railroad line. If the waveguide is utilized for intra-train communication, the wheels, axles and under-vehicle parts of the... | 06/10/1980 |
