Boots – shoes – and leggings
Patent
1981-11-16
1984-12-11
Krass, Errol A.
Boots, shoes, and leggings
364480, 364484, 364514, 364825, 246 8, 246167R, 307354, 307520, 328137, 328167, 340 47, 340 48, G01R 1900, G06G 702, H04B 106
Patent
active
044882386
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to amplitude selection circuits and, more particularly, to selection stages for selecting the alternating signal of greater amplitude between two signals of different predetermined frequencies, the mean amplitudes of which may vary.
Such a selection stage finds application notably in devices for information transmission, by rail, between a railway track and a set of vehicles circulating in the same direction on that track, and along which tracks there are in succession a number of information transmission zones wherein the useful information signal carrier frequencies alternate from one zone to the following zone. In such a device, any crosstalk must have no influence on the correct reception of signals on board a railway vehicle circulating within a given zone.
The mean amplitude of the signals emitted in each zone may vary in a significant way between the upstream and downstream end of the zone, so that simple limit detectors cannot be used to eliminate the signals emitted in adjacent zones. The ratio of the amplitude of the useful signal to that of the interference signal, however, always remains greater than one, whatever the respective amplitudes may be.
An object of the invention, accordingly, is to provide a new and improved signal amplitude selection system that improves upon the possible influence of such crosstalk and enables novel elimination of undesired signals in adjacent transmission zones as in railway systems and the like.
A further object is to provide a novel selection stage of more general applicability, as well; and other objects will be hereinafter pointed out and delineated in the appended claims.
In summary, according to one aspect of the invention, the selection stage for the alternating signal of greater amplitude between two signals of different predetermined frequencies whose respective amplitudes differ, comprises an operational amplifier; filter means having an input and an output and being switchable to eliminate, selectively, signals of one or the other of the predetermined frequencies; means for applying the sum of the two signals to the respective inputs of the operational amplifier and the filter means; counter means for counting the pulses in the output signal from the operational amplifier resulting from zero crossings in the input signal thereto, the output signal from the counter means having a period corresponding to that of the signal of greater amplitude; and a control circuit connected to the output of the counter means and to the filter means, the control circuit being responsive to the output signal from the counter means for causing the filter means to switch to eliminate the signal of lower amplitude, whereby the signal of greater amplitude is applied to a processing device connected to the output of the filter means. The control circuit may include a selector of the period of the output signal of the counter such as is described, for example, in French Pat. Nos. 2,176,266 and 2,313,812.
The invention will be better understood, and other goals advantages and characteristics will become more clear through the reading of the following description, to which is appended the accompanying drawing, the single FIGURE of which represents schematically a device for the processing of the signal of greater amplitude provided by a selection stage conforming to the present invention in best or preferred mode.
Referring to the drawing, a device is shown for information processing, such as aboard railway vehicles circulating on tracks equipped with an information transmission device utilizing two predetermined carrier frequencies alternating from one zone to the following. A coil 1 constitutes the element for reception by induction of the useful information-bearing signal, emitted, for example, by mean of an insulated conductive loop winding placed between the rails of the track within a transmission zone, not represented in the FIGURE.
Since such a zone may extend to several kilometers in length, it is evident that the useful signal received by
REFERENCES:
patent: 3314026 (1967-04-01), Maynard
patent: 3743935 (1973-07-01), Alt
patent: 3760278 (1973-09-01), Narbaits-Jaureguy et al.
patent: 3868575 (1975-02-01), Narbaits-Jaureguy et al.
patent: 3973746 (1976-08-01), Ball
Laurent Daniel M.
Salmon Jean P.
Jeumont-Schneider Corporation
Krass Errol A.
Teska Kevin J.
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