Methods and apparatus for phase change detection using a resonator
Disclosed is a microwave cavity resonator used as a phase change (phase modulation) to intensity change (intensity or amplitude modulation) converter. Certain aspects and embodiments include resonant circuits, such as a resistor, inductor and capacitor (RLC) circuit. Certain aspects and embodiments convert changes in phase to changes in output voltage to perform analog demodulation of a phase modulated microwave carrier. Certain aspects and embodiments use resonance when the reactive components of the circuit (capacitive and inductive components) are equal in magnitude and 180 degrees out of phase with one another, thereby cancelling out the reactance component of the circuit's impedance.
1. A communications receiver comprising:
an input to receive a phase modulated radio frequency (RF) input signal;
a resonator coupled to the input and configured to receive the phase modulated RF input signal and to produce an electrical output signal having characteristics representative of a phase modulation of the phase modulated RF input signal, the resonator including a resistor, inductor, and capacitor (RLC) circuit, the RLC circuit having a series arm including an inductive component connected in series with a capacitive and a resistive component; and
signal processing circuitry configured to receive and process the electrical output signal to produce a decoded information signal.
2. The communications receiver of claim 1 , wherein the electrical output signal has amplitude variations that correspond to the phase modulation of the phase modulated RF input signal.
3. The communications receiver of claim 2 , wherein the electrical output signal is a voltage and the amplitude variations are voltage spikes.
4. The communications receiver of claim 1 , wherein the input is an antenna.
5. A communications receiver comprising:
an input to receive a phase modulated radio frequency (RF) input signal encoded with information;
at least one resonator coupled to the input and configured to receive the phase modulated RF input signal, to internally resonate signal energy in response to receiving the phase modulated RF input signal, and to produce an electrical output signal having a steady-state amplitude and amplitude variations, corresponding to deviations from the steady-state amplitude, that are representative phase transitions in the phase modulated RF input signal, the resonator including a resistor, inductor, and capacitor (RLC) circuit, the RLC circuit having a series arm including an inductive component connected in series with a capacitive and resistive component; and
signal processing circuitry configured to receive and process the electrical output signal to produce a decoded information signal.
6. The communications receiver of any one of claim 5 , wherein the electrical output signal is a voltage and the amplitude variations are voltage spikes.
7. The communications receiver of any one of claim 5 , wherein the input is an antenna.
8. A communications receiver comprising:
an input to receive a phase modulated radio frequency (RF) input signal encoded with information;
a resistor, inductor, and capacitor (RLC) resonant circuit coupled to the input and configured to receive the phase modulated RF input signal, the RLC circuit including a series combination of an inductive component, a capacitive component, and a resistive component, wherein a voltage sum of a first voltage across the inductive component and a second voltage across the capacitive is representative of a phase modulation of the phase modulated RF input signal; and
signal processing circuitry coupled to the RLC circuit and configured monitor the voltage sum to produce a decoded information signal.
9. The communications receiver of claim 8 , wherein the voltage sum includes voltage spikes corresponding to phase transitions in the phase modulated RF input signal.