Telecommunications – Transmitter and receiver at separate stations – Single message via plural carrier wave transmission
Patent
1992-02-18
1994-10-11
Urban, Edward F.
Telecommunications
Transmitter and receiver at separate stations
Single message via plural carrier wave transmission
455 88, 455 92, 455103, 34082554, 342 51, H04B 159
Patent
active
053555210
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for the contactless transmission of information.
BACKGROUND OF THE INVENTION
The Swedish Patent Specification No. (Swedish Patent Application 8802230-6), having a corresponding U.S. Pat. No. 5,251,235, describes apparatus for the contactless transmission of information over a serial twin-cable data bus, comprising a clock line and a data line connected to a transmitter, a receiver and a demodulator. The transmitter includes an oscillator and a modulator which is intended to modulate the signal generated by the oscillator in response to the clock line signals and data line signals respectively. The invention defined in said Patent Specification is characterized in that the modulator is constructed to carry out on the signal generated by the oscillator two significantly separated modulation steps which do not coincide in time, therewith to form two mutually independent signal channels, of which a first is intended for data signals and the other is intended for the clock signals. The demodulator is constructed to demodulate signals which are received by the receiver and which have been modulated in the aforesaid manner and also to recreate said two signals. The demodulator has a clock-line output and a data-line output.
The aforesaid Patent Specification defines a method of separating data and clock lines, by using pauses in transmission as information carriers, wherewith, e.g., switching or marking of levels in the clock line triggers a first modulation step, which constitutes a short transmission pause, whereas switching or marking of levels in the data line triggers a second modulation step which constitutes two rapid, sequential transmission pauses.
SUMMARY OF THE INVENTION
The present invention provides a novel and useful method for application in such data buses or other data links, such as to enable the signals transmitted from the master side to be used as control oscillators on the slave side, and therewith to enable the slave side to transmit signals which are received on the master side without the signals transmitted from said master side disturbing the reception of the signals, transmitted from the slave side and without the occurrence of zero settings, or so-called nodes, in the signal from the slave side.
The present invention thus relates to a method for the contactless transmission of information between a transmitter/receiver unit and a transponder, the transmitter/receiver unit comprising oscillators, transmitter and receiver antennas, a modulator and a detection circuit, and the transponder including a transmitter/receiver antenna, a modulator and a detection circuit. The invention is characterized in that the transmitter/receiver unit is caused to transmit a first and a second carrier wave which have mutually different frequencies (f1, f2); in that the difference frequency is formed in the transponder; in that a third signal having the difference frequence (f3) is caused to be divided to a fourth signal having half the difference frequency (f4); in that the fourth signal is caused to modulate the two carrier waves received in the transponder by being applied to a diode or like device, such that the received carrier waves are reflected back to the transmitter/receiver unit; in that the signal received in the transmitter/receiver unit is mixed down with one of the first or the second carrier wave frequencies; and in that each of the two sidebands on respective sides of the carrier wave frequency with which said mixing is effected are brought forward, said sidebands differing from the last mentioned carrier wave frequency by a frequency which is equal to half the difference frequency (f4), wherein that sideband of said sidebands which has a frequency that lies between the carrier wave frequencies is a combined sideband which is caused to have an amplitude which differs from the amplitude of the other sideband, and wherein the pair of sidebands are filtered and the information content of the sidebands detected in the dete
REFERENCES:
patent: 4075632 (1978-02-01), Baldwin et al.
patent: 4896371 (1990-01-01), Kahn
patent: 5128669 (1992-07-01), Dadds et al.
Berglind Eilert
Henoch Bengt
Henoch Bengt
Urban Edward F.
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