Interrogator for electronic identification system
AssigneeBritish Technology Group Inter-Corporate Licensing Limited
InventorJos Scheelen
Life of this patent
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Abstract
Interrogator for an electronic identification system having a first oscillator arranged to vary in frequency in accordance with the frequency of a received signal, a second oscillator arranged to vary in accordance with the frequency of the first oscillator after a delay of a number of cycles of the received signal, a phase discriminator for detecting the phase difference between respective output signals of the first and second oscillators and a phase-change detector arranged to determine the frequency at which the phase changes occur. In this way, a modulation frequency of the received signal can be determined.
Claims9
An interrogator for an electronic identification system, comprising:
- a first oscillator arranged to vary in frequency in accordance with the frequency of a received signal;
- a second oscillator arranged to vary in accordance with the frequency of the first oscillator after a delay of a number of cycles of the received signal;
- phase discriminator means to detect the phase difference between respective output signals of the first and second oscillators;
- and
- phase-change detection means for determining the frequency at which the phase changes occur and thereby determining a modulation frequency of said received signal.
An interrogator for an electronic identification system, comprising:
- a first oscillator arranged to vary in frequency in accordance with the frequency of a received signal;
- a second oscillator arranged to vary in accordance with the frequency of the first oscillator after a delay of a number of cycles of the received signal;
- a phase discriminator for detecting the phase difference between respective output signals of the first and second oscillators;
- and
- a phase-change detector for determining the frequency at which the phase changes occur and thereby determining a modulation frequency of said received signal.
Dependencies are inferred from the claim text.