Transmitter and a method for transmitting data
View Patent ↗An excitation reference source (F C ) is split through a 90 degree splitter. One output from the splitter is fed to the LO port of a mixer. Data is fed to the mixer's IF port and causes PRK modulation of the LO port's signal. The output of the mixer at the RF port is a PRK modulated quadrature signal. This is attenuated and added back onto the reference by a zero degree combiner ready for transmission to the transponder.
1. A device adapted to receive a modulated signal and derive therefrom a data signal, the device comprising:
an antenna adapted to receive the modulated signal and, in response thereto, produce a first signal;
means for deriving, from the first signal, a local oscillator signal;
means for deriving a second signal by passing a further portion of the first signal through a delay means; and
wherein the local oscillator signal and the second signal are used to demodulate the first signal and obtain an indicative data signal.
2. The device as claimed in claim 1 , wherein a phase locked loop is used to derive the local oscillator signal.
3. The device as claimed in claim 2 , wherein the phase locked loop is a low loop bandwidth phase locked loop.
4. The device as claimed in claim 1 , wherein a mixer is used in demodulating the first signal.
5. The device as claimed in claim 1 , wherein a multiplier is used in demodulating the first signal.
6. The device as claimed in claim 1 , wherein the first signal is used as a source of power for the device means.
7. The device as claimed in claim 1 , wherein the device is a Radio Frequency Identification Device.
8. The device as claimed in claim 1 , wherein the device is a passive device.
9. The device as claimed in claim 1 , wherein the device is a transponder.
10. A method of demodulating a modulated signal received by a device and deriving therefrom a data signal, the method comprising the steps of:
receiving the modulated signal and producing a first signal;
deriving, from the first signal, a local oscillator signal;
deriving a second signal by passing a further portion of the first signal through a delay means; and
demodulating the first signal using the local oscillator signal and the second signal to obtain an indicative data signal.
11. The method as claimed in claim 10 , wherein a phase locked loop is used to derive the local oscillator signal.
12. The method as claimed in claim 11 , wherein the phase locked loop is a low loop bandwidth phase locked loop.
13. The method as claimed in claim 10 , wherein a mixer is used in demodulating the first signal.
14. The method as claimed in claim 10 , wherein a multiplier is used in demodulating the first signal.
15. The method as claimed in claim 10 , wherein a low pass filter is used to filter out high frequency signal components and pass the demodulated data signal.
16. The method as claimed in claim 10 , wherein the first signal is used as a source of power for the device.
17. A method of demodulating a modulated signal received by a device and deriving there from a data signal, the method comprising the steps of:
receiving the modulated signal and inducing into an antenna of the device, an antenna voltage signal;
amplifying the antenna signal;
providing a portion of the amplified signal to a phase locked loop to filter off sidebands and creating a first signal;
passing another portion of the amplified signal through a delay means and creating a second signal; and
XORing the first and second signals to provide indicative data.
18. The method as claimed in claim 17 , wherein the antenna signal is amplified by squaring the signal by a Schmitt trigger device.
19. The method as claimed in claim 17 , wherein the phase locked loop is a low bandwidth phase locked loop device.
20. The method as claimed in claim 17 , wherein the data is detected using a floating point comparator device.