Radio system for data transmission with passive terminal station
First Claim
1. A radio system for alternately transmitting by microwaves first and second digital data signals between first and second data processing units connected to said radio system, said first data signal being transmitted by said first unit to said second unit during first data transmission periods and said second data signal being transmitted from said second unit to said first unit during second data transmission periods,said system comprising transmitting and receiving central and terminal stations,said transmitting and receiving central station being connected to said first unit for emitting to said terminal station a first microwave modulated in amplitude by said first data signal during said first transmission periods and a second unmodulated microwave during said second transmission periods,said transmitting and receiving terminal station being connected to said second unit for emitting a third two-phase-state microwave modulated by said second data signal during said second transmission period,said terminal station comprising one transmitting and receiving antenna having first and second ports, andmicrowave detecting and modulating means connected to said first antenna port via a transmission line for (a) detecting the amplitude of said first microwave emitted by said central station during said first transmission periods thereby recovering said first data signal and (b) deriving said third microwave from said second microwave received by said antenna during said second transmission periods and retroreflected from an end of said transmission line connected to said detecting and modulating means, said end of said transmission line being respectively in short-circuit and in open-circuit according to the logic level of said second digital data signal.
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Accused Products
Abstract
The radio system embodying the invention comprises a central station and a passive terminal station. First and second data signals are transmitted between data processing units respectively connected to the central and terminal stations. The terminal station comprises a same low-cost circuit associated with a square two-dimensional antenna for detecting the amplitude of a first incident microwave emitted by the central station thereby recovering the first data signal and deriving, in response to the first microwaves, a microwave modulated in phase by the second data signal by means of a retroreflection of a second incident microwave. This second incident microwave is emitted by the central station to the two-dimensional antenna of the terminal station. The terminal station is of very simple design, is compact and can therefore be included as well as the corresponding data processing unit in a contact-free chip card.
14 Citations
13 Claims
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1. A radio system for alternately transmitting by microwaves first and second digital data signals between first and second data processing units connected to said radio system, said first data signal being transmitted by said first unit to said second unit during first data transmission periods and said second data signal being transmitted from said second unit to said first unit during second data transmission periods,
said system comprising transmitting and receiving central and terminal stations, said transmitting and receiving central station being connected to said first unit for emitting to said terminal station a first microwave modulated in amplitude by said first data signal during said first transmission periods and a second unmodulated microwave during said second transmission periods, said transmitting and receiving terminal station being connected to said second unit for emitting a third two-phase-state microwave modulated by said second data signal during said second transmission period, said terminal station comprising one transmitting and receiving antenna having first and second ports, and microwave detecting and modulating means connected to said first antenna port via a transmission line for (a) detecting the amplitude of said first microwave emitted by said central station during said first transmission periods thereby recovering said first data signal and (b) deriving said third microwave from said second microwave received by said antenna during said second transmission periods and retroreflected from an end of said transmission line connected to said detecting and modulating means, said end of said transmission line being respectively in short-circuit and in open-circuit according to the logic level of said second digital data signal.
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8. A radio system for alternately transmitting by microwaves first and second digital data signals between first and second data processing units connected to said radio system, said first data signal being transmitted by said first unit to said second unit during first data transmission periods and said second data signal being transmitted from said second unit to said first unit during second data transmission periods,
said system comprising transmitting and receiving central and terminal stations, said transmitting and receiving central station being connected to said first unit for emitting to said terminal station a first microwave modulated in amplitude by said first data signal during said first transmission periods and a second unmodulated microwave during said second transmission periods, said transmitting and receiving terminal station being connected to said second unit for emitting a third two-phase-state microwave modulated by said second data signal during said second transmission period, said terminal station comprising one transmitting and receiving antenna having a port, and microwave detecting and modulating means connected to said port for (a) detecting the amplitude of said first microwave emitted by said central station during said first transmission periods thereby recovering said first data signal and (b) deriving said third microwave from said second microwave received by said antenna during said second transmission periods, said detecting and modulating means including a component that is selectively activated to be (a) an amplitude detector during said first transmission periods and (b) a two phase state modulator during said second transmission periods, said component being connected to said port via a transmission line during said first and second transmission periods, said component directing detected amplitude modulated replicas of the first data signal on the line to the second data processing unit during said first periods, said component responding to binary values of the second data signal to supply modulated waves having two phases representing the second data signal to the line during the second periods.
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11. A system for alternately transmitting by modulated waves first and second digital data signals between first and second data processing units connected to said system, said first data signal being transmitted by said first unit to said second unit during first data transmission periods and said second data signal being transmitted from said second unit to said first unit during second data transmission periods,
said system comprising transmitting and receiving central and terminal stations, said transmitting and receiving central station being connected to said first unit for emitting to said terminal station a first wave modulated in amplitude by said first data signal during said first transmission periods and a second unmodulated wave during said second transmission periods, said transmitting and receiving terminal station being connected to said second unit for emitting a third two-phase-state wave modulated by said second data signal during said second transmission period, said terminal station comprising one transmitting and receiving structure having a port, and detecting and modulating means connected to said port for (a) detecting the amplitude of said first wave emitted by said central station during said first transmission periods thereby recovering said first data signal and (b) deriving said third wave from said second wave received by said structure during said second transmission periods, said detecting and modulating means including a component that is selectively activated to be (a) an amplitude detector during said first transmission periods and (b) a two phase state modulator during said second transmission periods, said component being connected to said port via a transmission line during said first and second transmission periods, said component directing detected amplitude modulated replicas of the first data signal on the line to the second data processing unit during said first periods, said component responding to binary values of the second data signal to supply modulated waves having two phases representing the second data signal to the line during the second periods.
Specification