A reflectometer for use in measuring scattering (S-)parameters for a device under test (DUT) includes a test port, a radio frequency (RF) output signal source, and a local oscillator (LO) signal. The LO signal is used to downconvert the RF output signal to an incident IF signal. The reflectometer is useable as a first reflectometer with a second reflectometer such that the first and second reflectometers are phase synchronized by a synchronization signal. Phase and magnitude of transmission S-parameters of the DUT are measurable when the first reflectometer is used with the second reflectometer. The roles of the first and second reflectometers are reversible to allow for measurement of forward and reverse parameters. Further, the synchronization signal can be provided by one reflectometer to the other (or both can receive a separately generated synchronization signal) via a wire or fiber optic cable, for example, or via a wireless connection.

A method of calibrating a setup comprises: performing at least one calibration of the setup, thereby obtaining calibration data; setting a quantity representing forward tracking to be equal with a quantity representing reverse tracking; solving a system of equations having at least an unknown quantity representing the forward tracking or the reverse tracking, thereby obtaining at least one equation having the unknown quantity squared; creating based on the calibration data obtained two phase over frequency relationships for the respective quantity; determining two lines having a linear change in phase over frequency for the phase over frequency relationships created; extrapolating the lines determined to a frequency of 0 Hz; and determining the respective quantity by selecting one line of the lines extrapolated that is closer to a phase of zero, 2π or a multiple thereof at the frequency of 0 Hz.

A detecting method for detecting an output impedance angle of an inverter includes controlling an inverter to output a second voltage signal and a current signal based on a first voltage signal; calculating an active power and reactive power based on the second voltage signal and the current signal; and calculating an output impedance angle of the inverter based on the product of the active power and a first amplitude parameter, the product of the active power and a second amplitude parameter, the product of the reactive power and the first amplitude parameter, and the product of the reactive power and the second amplitude parameter. The first amplitude parameter corresponds to a first amplitude of the first voltage signal, and the second amplitude parameter corresponds to the first amplitude of the first voltage signal and a second amplitude of an AC voltage.

A detecting method for detecting an output impedance angle of an inverter includes controlling an inverter to output a second voltage signal and a current signal based on a first voltage signal; calculating an active power and reactive power based on the second voltage signal and the current signal; and calculating an output impedance angle of the inverter based on the product of the active power and a first amplitude parameter, the product of the active power and a second amplitude parameter, the product of the reactive power and the first amplitude parameter, and the product of the reactive power and the second amplitude parameter. The first amplitude parameter corresponds to a first amplitude of the first voltage signal, and the second amplitude parameter corresponds to the first amplitude of the first voltage signal and a second amplitude of an AC voltage.

Methods and apparatus are provided for detection path design for reflection coefficient estimation. In one novel aspect, a hardware-based phase estimator estimates a phase shift between the forward path signal and the reverse path signal. In one embodiment, a data selector is used to pass only signals above a magnitude threshold. In another embodiment, a modified phase unwrap algorithm stores an unwrapping correction for subsequent samples and updates the stored unwrapping correction upon processing of each sample processed. In another novel aspect, mixed hardware and software solutions are used. In one embodiment, the reference signal and the detection signals are matched such that the modulation signal interference is removed. In some embodiments, one or two power detectors and a cross-correlator are used. In yet another embodiment, two detection measurement paths are used to obtain the reflection coefficient. In one embodiment, fractional timing offset is estimated to obtain the reflection coefficient.

Methods and apparatus are provided for detection path design for reflection coefficient estimation. In one novel aspect, a hardware-based phase estimator estimates a phase shift between the forward path signal and the reverse path signal. In one embodiment, a data selector is used to pass only signals above a magnitude threshold. In another embodiment, a modified phase unwrap algorithm stores an unwrapping correction for subsequent samples and updates the stored unwrapping correction upon processing of each sample processed. In another novel aspect, mixed hardware and software solutions are used. In one embodiment, the reference signal and the detection signals are matched such that the modulation signal interference is removed. In some embodiments, one or two power detectors and a cross-correlator are used. In yet another embodiment, two detection measurement paths are used to obtain the reflection coefficient. In one embodiment, fractional timing offset is estimated to obtain the reflection coefficient.

Provided herein are systems, methods and apparatuses for a Biomarker sensor.

An S-parameter of a reference impedance is determined and converted to a desired mode of operation. Example modes of operation include a single-ended input output mode, a differential input output mode, and a common input output mode. The complex values of the impedance at each port as a function of frequency can be computed using the novel closed-form quadratic S-parameter equation which utilizes the concept of matched networks by setting the reflections and re-reflections to zero through S-parameter renormalization. Using the S-parameter renormalization, the insertion loss corresponding to zero reflections and re-reflections is calculated. Based on the determination of the matching impedance used to reduce the reflections and re-reflections to zero, a parameter of a circuit comprising the network may be modified to reduce noise.

An S-parameter of a reference impedance is determined and converted to a desired mode of operation. Example modes of operation include a single-ended input output mode, a differential input output mode, and a common input output mode. The complex values of the impedance at each port as a function of frequency can be computed using the novel closed-form quadratic S-parameter equation which utilizes the concept of matched networks by setting the reflections and re-reflections to zero through S-parameter renormalization. Using the S-parameter renormalization, the insertion loss corresponding to zero reflections and re-reflections is calculated. Based on the determination of the matching impedance used to reduce the reflections and re-reflections to zero, a parameter of a circuit comprising the network may be modified to reduce noise.

A measurement system and a method of removing effects of instability of the measurement system while measuring at least one S-parameter of a device under test (DUT) are provided. The method includes initially determining a characteristic of the measurement system, including identifying a location of an instability in the time domain of the measurement system; determining a change of the characteristic of the measurement system while connected to the DUT; and compensating for the determined change of the characteristic of the measurement system while connected to the DUT by removing effects of the determined change on measurements of the at least one S-parameter of the DUT.