Method for wireless data transmission
A method and apparatus for wireless data transmission is provided between a base station and a backscatter-based transponder, in which the transponder generates a presence signal after initialization or at predetermined time intervals, independent of data transmitted by the base station. The presence signal is generated by phase modulation and backscattering of a carrier signal transmitted by the base station.
1. A method for wireless data transmission, the method comprising the steps of:
providing a base station and a backscatter-based transponder, the base station and the backscatter-based transponder transmitting wirelessly between one another; and
generating a presence signal by a transmitting portion of the transponder as soon as said transponder enters a transmission range or response range of a carrier signal from said base station independent of data transmitted on said carrier signal by the base station,
wherein the data is transmitted by the base station via amplitude modulation including a succession of a plurality of field gaps between amplitude signals,
wherein the presence signal is generated by phase modulation and backscattering of said carrier signal that is transmitted by the base station, said presence signal having a substantially constant amplitude,
wherein a receiving portion of said transponder detects said data generated by said base station and detects said presence signal generated by said transmitting portion of said transponder,
wherein the transponder receives the data while the presence signal is being transmitted,
wherein said receiving portion of said transponder is configured to differentiate between the data from the base station and the presence signal generated in said transmitting portion of the transponder, and
wherein the transponder stops sending the presence signal when the transponder receives a command signal from said base station.
2. The method according to claim 1 , wherein the transponder is provided with operating power exclusively by the carrier signal.
3. The method according to claim 2 , wherein the transponder is initialized when the operating power is sufficient for supplying the transponder.
4. The method according to claim 1 , wherein the presence signal is generated by modulation of the carrier signal with a subcarrier.
5. The method according to claim 1 , wherein the presence signal contains a transponder identification.
6. The method according to claim 1 , wherein a configuration command transmitted by the base station and/or a transponder-internal memory contains one or more parameters for setting the presence signal.
7. The method according to claim 6 , wherein a frequency and/or a pulse duty factor of a modulation signal, with which the carrier signal is modulated, is set by at least one parameter.
8. The method according to claim 7 , wherein the frequency and/or the pulse duty factor is derived from a transponder-internal oscillator clock.
9. The method according to claim 6 , wherein the generation of the presence signal is released or suppressed by the at least one parameter.
10. The method according to claim 1 , wherein the transponder ends the transmission of the presence signal, when a prescribable maximum time has elapsed and/or the transponder receives a command.
11. The method according to claim 1 , wherein a frequency of the carrier signal is within the UHF frequency range.
12. A transponder comprising:
an antenna for receiving a carrier signal that is transmitted by a base station, the transponder receiving the carrier signal within a transmission range of the base station; and
a presence signal generation unit having a transmitting unit and a receiving unit wherein said transmitting unit generates a presence signal as soon as said transponder enters a transmission range or response range of a carrier signal from said base station by phase modulation and backscattering on the basis of the carrier signal transmitted by the base station, the presence signal having a substantially constant amplitude and the presence signal being generated independently of data transmitted by the base station,
wherein said receiving unit of said transponder detects said data generated by said base station and detects said presence signal generated by said transmitting unit of said transponder,
wherein the data is transmitted by the base station via amplitude modulation including a succession of a plurality of field gaps between amplitude signals,
wherein the transponder receives the data while the presence signal is being transmitted,
wherein said receiving unit of said transducer is configured to differentiate between the data from the base station and the presence signal generated in said transmitting unit of the transponder, and
wherein the transponder stops sending the presence signal when the transponder receives a command signal from said base station.