1. A tunable, switchable electromagnetic filter comprising:
an electromagnetic resonator having a first end and a second end;
a switch coupled to the second end of the resonator and to ground;
an impedance element coupled to the first end of the resonator, wherein the resonator, the switch and the impedance element comprise a switchable filter;
a ferroelectric tunable component electromagnetically coupled to the switchable filter;
a tuning control signal generator for generating a tuning signal, coupled to the ferroelectric tunable component;
a switching control signal generator for generating a switching signal, coupled to the switch.
2. The filter of claim 1, further comprising a microelectrical mechanical switch.
3. The filter of claim 1, further comprising a voltage source coupled to the component.
4. The filter of claim 1, further comprising a ferroelectric capacitor.
5. The filter of claim 1, further comprising a voltage source coupled to the switch.
6. The filter of claim 1, further comprising a ferroelectric capacitor having a quality factor at about 1.9 GHz equal to about 50 or greater.
7. The filter of claim 1, further comprising a second resonator coupled to the first resonator and wherein the impedance element is coupled between the first and second resonators.
8. The filter of claim 7, further comprising:
an input capacitor coupled at a first end of the input capacitor to an input port of the filter and at a second end of the output capacitor to the impedance element and the first resonator; and
an output capacitor coupled at a first end of the output capacitor to an output port of the filter and at a second end of the output capacitor to the impedance element and the second resonator.
9. The filter of claim 8, further comprising a second tunable ferroelectric component coupled to the filter.
10. The filter of claim 9, wherein the impedance element, the input capacitor and the output capacitor comprise, respectively, a third, a fourth and a fifth tunable ferroelectric component.
11. The filter of claim 7, wherein the first and second resonators comprise monoblock resonators.
12. The filter of claim 1, wherein the filter resonates at a frequency between about 1850 MHz and about 1910 MHz.
13. The filter of claim 1, wherein the filter resonates at a frequency between about 1930 MHz and about 1990 MHz.
14. The filter of claim 1, wherein the filter resonates at a frequency between about 824 MHz and about 849 MHz.
15. The filter of claim 1, wherein the filter resonates at a frequency between about 869 MHz and about 894 MHz.
16. The filter of claim 1, wherein the filter resonates in a half wave mode.
17. The filter of claim 1, wherein the filter resonates in a quarter wave mode.
18. A tunable, switchable electromagnetic filter comprising:
an electromagnetic resonator;
a first switch coupled to the resonator and to ground;
an impedance element coupled to the resonator, wherein the resonator, the first switch and the impedance element comprise a switchable filter;
a ferroelectric tunable component electromagnetically coupled to the switchable filter;
a second switch electromagnetically coupled to the ferroelectric tunable component and to a ferroelectric component, switchable between a first configuration wherein the ferroelectric component is coupled to the ferroelectric tunable component, and a second configuration wherein the ferroelectric component is not coupled to the ferroelectric tunable component;
a tuning control signal generator for generating a tuning signal, coupled to the ferroelectric tunable component;
a switching control signal generator for generating a first switching signal, coupled to the first switch; and
a second switching control signal generator for generating a second switching signal coupled to the second switch.
19. The filter of claim 18, further comprising a second ferroelectric component electromagnetically coupled to the second switch wherein the second ferroelectric component is coupled to the ferroelectric tunable component in the second configuration.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1.-20. (canceled)
21. A method for determining a noise parameter on an input optical signal having a data-carrying signal contribution and a noise contribution within an optical signal bandwidth, the method comprising:
obtaining at least two optical spectrum traces from said input optical signal, said optical spectrum traces being taken under different conditions such that they show different non-zero signal-to-noise ratios;
mathematically discriminating said signal contribution from said noise contribution within said optical signal bandwidth using said optical spectrum traces;
determining an in-band noise level on said input optical signal from the discriminated noise contribution; and
determining the noise parameter from the determined in-band noise level, the noise parameter being indicative of the noise contribution within the optical signal bandwidth.
22. The method as claimed in claim 21,
wherein the signal contribution and the noise contribution have mutually different degrees of polarization and wherein said obtaining at least two optical spectrum traces comprises:
producing at least two samples of the input optical signal, under different polarization analysis conditions, states of polarization of the two samples being arbitrary relative to said input optical signal such that they show non-zero signal-to-noise ratios; and
acquiring an optical spectrum of each one of the first and the second samples to obtain said optical spectrum traces.
23. The method as claimed in claim 21, wherein said noise contribution within said optical bandwidth varies slowly in wavelength compared to said data-carrying signal contribution, and optical spectrum traces are obtained using different integration widths to provide said different conditions, a second one of the integration widths being larger than a first one of the integration widths.
24. The method as claimed in claim 23, wherein said obtaining comprises:
acquiring an optical spectrum measurement of said input optical signal;
convoluting the acquired measurement with a first convolution window having a width corresponding to the first integration width to obtain a first optical spectrum trace, and convoluting the acquired measurement with a second convolution window having a width corresponding to the second integration width to obtain the second optical spectrum trace.
25. The method as claimed in claim 24, wherein said discriminating comprises subtracting said optical spectrum traces from one another to obtain a difference trace, a value of said difference trace at a central wavelength of said optical signal being representative of said optical noise.
26. The method as claimed in claim 21, wherein said noise parameter comprises an optical signal to noise ratio of the input optical signal, determined using the determined in-band noise.
27. The method as claimed in claim 21, further comprising outputting the determined noise parameter.
28. The method as claimed in claim 24, wherein a spectral shape of one of said signal contribution and said noise contribution is known within said optical signal bandwidth, said discriminating is performed by assuming said spectral shape.
29. A method for determining a noise parameter on an input optical signal having a data-carrying signal contribution and a noise contribution within an optical signal bandwidth, said signal contribution being mostly polarized and said noise contribution being mostly unpolarized, the method comprising:
acquiring a first and a second optical spectrum trace of the input optical signal corresponding to respective first and second polarization analysis conditions, said first and second polarization analysis conditions being mutually different and arbitrary relative to said input optical signal such that said optical spectrum traces show mutually different non-zero signal-to-noise ratios;
mathematically discriminating said signal contribution from said noise contribution within said optical signal bandwidth based on said optical spectrum traces; and
determining said noise parameter from the discriminated noise contribution, the noise parameter being indicative of the noise contribution within the optical signal bandwidth.
30. The method as claimed in claim 29, wherein said acquiring a first and a second optical spectrum trace of the input optical signal comprises:
polarization beam splitting said input optical signal into at least two samples, said samples having mutually orthogonal states of polarization; and
acquiring an optical spectrum of each one of said samples to obtain said first and second optical spectrum traces.
31. The method as claimed in claim 30, wherein said discriminating comprises:
subtracting said first and second optical spectrum traces from one another to obtain a difference optical spectrum substantially proportional to an optical spectrum of said signal contribution;
estimating an optical spectrum of said signal contribution using said difference optical spectrum;
determining an optical spectrum of said input optical signal from at least one of the first and second optical spectrum traces; and
determining a level of said optical noise by subtracting the estimated optical spectrum of said signal contribution from the determined optical spectrum of said input optical signal.
32. The method as claimed in claim 31, wherein said first and second optical spectrum traces each have a signal contribution and a noise contribution and wherein said performing calculations further comprises estimating a factor K related to a proportion between the signal contributions of said first and said second optical spectrum trace for use in said estimating an optical spectrum of said input optical signal.
33. The method as claimed in claim 29, wherein said acquiring a first and a second optical spectrum trace of the input optical signal comprises:
power splitting said input optical signal into a first and a second sample;
polarization analyzing said first sample and acquiring an optical spectrum of the polarization analyzed first sample to obtain said first optical spectrum trace; and
acquiring an optical spectrum of said second sample to obtain said second optical spectrum trace, wherein said second sample is not polarization analyzed.
34. The method as claimed in claim 29, wherein said noise parameter comprises an optical signal to noise ratio of the input optical signal, determined using the discriminated signal and noise contributions.
35. The method as claimed in claim 29, further comprising outputting the determined noise parameter.
36. A system for determining a noise parameter on an input optical signal within an optical signal bandwidth, the system comprising:
an input for receiving said input optical signal comprising a data-carrying signal contribution and a noise contribution within said optical signal bandwidth, said signal contribution and said noise contribution having mutually different degrees of polarization;
a polarization optics arrangement for obtaining a first and a second sample of the input optical signal under mutually different polarization analysis conditions such that at least one of the first and the second sample is polarization analyzed, a state of polarization of the at least one polarization analyzed sample being arbitrary relative to a state of polarization of the input optical signal;
an optical spectrum analyzer for acquiring a first and a second optical spectrum trace respectively of the first and second samples, the first and second optical spectrum traces showing mutually different non-zero signal to noise ratios;
a spectrum processor adapted for mathematically discriminating said noise contribution in said input optical signal within said optical signal bandwidth based on said first and second optical spectrum traces; and
a noise calculator for evaluating said noise parameter within the optical signal bandwidth from the discriminated noise contribution.
37. The system as claimed in claim 36, wherein said spectrum processor comprises a differentiator for calculating, from said optical spectrum traces, a difference optical spectrum substantially indicative of said signal contribution; and a noise solver for evaluating said noise contribution using calculations involving said optical spectrum traces and said difference optical spectrum.
38. The system as claimed in claim 36, wherein said polarization optics arrangement comprise a polarization beam splitter for splitting said input optical signal into said first and second samples, said samples having mutually orthogonal states of polarization.
39. The system as claimed in claim 36, further comprising a polarization disturbing device for disturbing a state of polarization of said input optical signal to vary the signal to noise ratio on at least one of said optical spectrum traces such that the first and second optical spectrum traces show different signal to noise ratios.
40. The systems as claimed in claim 36, wherein said noise parameter comprises an optical signal to noise ratio of the input optical signal, determined using the discriminated signal and noise contributions.