Telecommunications – Transmitter – Mobile or portable
Patent
1983-09-22
1986-09-16
Bookbinder, Marc E.
Telecommunications
Transmitter
Mobile or portable
455103, 455127, 455128, H04B 104
Patent
active
046126678
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an emergency transmitter having a first transmission means for a first frequency, and a second transmission means for a second frequency. The transmission means are accommodated in a floatable housing, and can be connected via a switch with a battery. The transmission means comprise a common quartz or crystal oscillator after which are connected respective frequency multipliers which in turn are respectively connected to driver and final stages. The latter are connected to a transmission antenna which projects out of the housing. Single tone generators are also provided for modulation of the transmitted frequencies. The present invention also relates to an operation method.
DESCRIPTION OF THE PRIOR ART
Emergency transmitters of this general type are known; for example, the radio buoy EB 218 of the company LAWO Geratebau, D-7550 Rastatt-Ottersdorf. These radio buoys transmit on the aircraft frequencies 121.5 MHz (civilian) and 243 MHz (military).
Such emergency transmitters are preferably utilized for rescue from emergencies at sea, and make possible a large area search and rescue action with the aid of aircraft. Due to the signal radiated from the emergency transmitter, bearings can be taken on the position of the emergency transmitter with the aid of aircraft and helicopters even at a great distance, so that even during conditions of poor visibility, and especially at a great distance, the position of damaged craft can be determined.
Although the heretofore known emergency transmitter operates satisfactorily, it is, however, still relatively large and therefore cannot be optimally used in many situations. Weight and size play a considerable role especially when the emergency transmitter must be carried constantly by the person to be protected.
These two parameters (size and weight) cannot be arbitrarily reduced, since especially the supply battery for the emergency transmitter must have a sufficient capacity in order on the one hand to enable a reliable operation over a certain minimum time period, for example 36 hours, and on the other hand so that the radiated transmission power does not become too small since then the maximum range is reduced.
SUMMARY OF THE INVENTION
An object of the present invention, by special measures, without changing the range or the maximum duration of operation, is to achieve a reduction of the energy delivered by the battery and hence its size by nearly half. Conversely, without changing the power of the battery, these measures make possible a corresponding increase of the range and/or the maximum duration of operation.
These objects are realized by associating a fixed-cycle control device with the first and second transmission means of an emergency transmitter of the aforementioned general type. This fixed-cycle control device alternately sets the two transmission means into operation.
In contrast with the state of the art, the two emergency frequencies thus are not radiated simultaneously, but rather are radiated alternately, so that the power which is to be delivered by the battery, and which is essentially determined by the transmission stage, only has to suffice for one transmission means, while with the state of the art the battery must simultaneously supply both transmission means and therefore must deliver twice as much power.
Pursuant to further advantageous specific embodiments of the present invention, the fixed-cycle control device may include a counter which is triggered by a fixed-cycle signal generator having a fixed repetition frequency; the counter may have two outputs which during the cycle of the repetition frequency each emit a rectangular signal pulse which are out of phase relative to one another per a given period of time. The fixed-cycle signal generator may be formed by a ramp signal generator having connected thereto a differentiator and/or a pulse shaper. The ramp signal generator may also have connected thereto a tone frequency oscillator, the frequency of which can be controlled so tha
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patent: 3500209 (1970-03-01), Fletcher et al.
patent: 3566235 (1971-02-01), Rose et al.
patent: 3617894 (1971-11-01), Benoit
patent: 3723881 (1973-03-01), Burton
patent: 3870959 (1975-03-01), Wootton
patent: 4110709 (1978-08-01), Day, Jr.
Autoflug GmbH
Bookbinder Marc E.
LandOfFree
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