A frequency measurement system and method of a radio frequency (RF) signal. The frequency measurement system includes: a magnetic field source module, a light source module, an excitation module, a complementary metal-oxide-semiconductor (CMOS) camera, and a signal processing module; the excitation module is disposed in the magnetic field; the excitation module is disposed on an output light path of the light source module; the CMOS camera is disposed on an output light path of the excitation module; and the CMOS camera is connected to the signal processing module; the light source module is configured to emit a laser; the CMOS camera is configured to capture an excitation image when the laser enters the excitation module to which a to-be-tested RF signal is applied; and the signal processing module is configured to determine a frequency of the to-be-tested RF signal according to the excitation image.

A buried perimeter loop wire break detector with a base unit and probe unit. The base unit injects different frequencies into the two ends of the loop wire and the probe unit detects the frequencies at a test location along the wire. If a signal is not detected, that indicates the direction toward the break. By halving the distance along the wire toward the break and retesting, the location is quickly determined. Both frequencies and amplitude are measured, sometimes with amplification, both earth and wired grounds may be employed, and a micro-ohmmeter measures resistance of the loop wire to indicate satisfactory operation.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.

A buried perimeter loop wire break detector with a base unit and probe unit. The base unit injects different frequencies into the two ends of the loop wire and the probe unit detects the frequencies at a test location along the wire. If a signal is not detected, that indicates the direction toward the break. By halving the distance along the wire toward the break and retesting, the location is quickly determined. Both frequencies and amplitude are measured, sometimes with amplification, both earth and wired grounds may be employed, and a micro-ohmmeter measures resistance of the loop wire to indicate satisfactory operation.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.

A pulse measurement device is provided, including a first signal source, a second signal source, two microwave resonators, two mixers, and a signal processing unit. The first signal source and the second signal source output a first high-frequency signal and a second high-frequency signal, respectively. Each of the microwave resonators generates an electric field according to the first high-frequency signal, and senses a variation in the electric field which is interfered by a pulse to obtain a sensing signal. Each of the mixers is coupled to one of the microwave resonators, to mix the sensing signal and the second high-frequency signal to output a down-converted signal. The signal processing unit respectively demodulates amplitudes of the down-converted signals of the two mixers to obtain amplitude signals.

A pulse measurement device is provided, including a first signal source, a second signal source, two microwave resonators, two mixers, and a signal processing unit. The first signal source and the second signal source output a first high-frequency signal and a second high-frequency signal, respectively. Each of the microwave resonators generates an electric field according to the first high-frequency signal, and senses a variation in the electric field which is interfered by a pulse to obtain a sensing signal. Each of the mixers is coupled to one of the microwave resonators, to mix the sensing signal and the second high-frequency signal to output a down-converted signal. The signal processing unit respectively demodulates amplitudes of the down-converted signals of the two mixers to obtain amplitude signals.

Conventional frequency detection circuits have a disadvantage that the circuit scale increases as the frequency of a reception signal to be detected increases.

A frequency detection circuit includes: a first signal source for outputting a first clock signal; a second signal source for outputting a second clock signal having the same frequency as but a different phase from those of the first clock signal; a first sample hold circuit for undersampling a reception signal using the first clock signal; a second sample hold circuit for undersampling the reception signal using the second clock signal; and a frequency calculating circuit for calculating the frequency of the reception signal using a phase difference between output signals of the first sample hold circuit and the second sample hold circuit.