Overview of Nexense Technology.

Background
Nexense has made a scientific discovery that has enabled us to develop a unique and advanced sensor technology that links the measurement of all physical parameters to time, the one common basis for all physical phenomena.
Our state of the art sensor technology has a signal- to-noise ratio (SNR) of up to 190 dB, 22 bit resolution, digital output without an ADC, and the ability to make measurements without the need for any direct contact, in a non intrusive and non emissive manner. Our unique sensor technology enables us to provide all of these attributes at a cost far below the typically high prices of regular, advanced, precision measuring instruments.

How it works
Nexense measurement technology utilizes a technique that measures a range of physical parameters as a function of time. Using specially developed sensors and equipment, our devices measure the time it takes an energy wave to propogate through a specific, given medium.
When viewed as a function of time, all physical parameters can be measured to a level of accuracy previously unattainable other than by using extremely complicated and costly equipment.
An energy wave is repeatedly transmitted from one point in the object to a receiver at another location in the object.
A predetermined reference point is detected in the cyclically repeating energy wave at the second location. The frequency of transmission of the energy wave is continuously and automatically altered in a closed loop controlled by the specific characteristic of the measured component. This change in frequency is used to produce a measurement of the physical parameter.

This measurement is accomplished in two stages. In the first stage, the measured parameter acts upon the transit time of the wave. In the second stage, the transit time is converted to a frequency. In a typical application, a transmitter and a receiver are placed on or within a specific medium. The transmitter can emit any type of cyclically repeating energy wave. Depending on the application, this wave could be acoustic, radio, light, or magnetic and can be transmitted through any medium, including air, silicone, metals, liquids, or gases.
The parameter acting on the medium (force, pressure, temperature, etc.,) causes a minute displacement of the medium or a change in its natural velocity coefficient (the speed at which the energy wave travels through the medium) and thus causes an actual or virtual displacement of the transmitter and receiver. Virtual displacements can result from a temperature change. For example, an acoustic wave at 5000 m/s through metal will experience a change in its velocity as the temperature changes. As the transducers shown in Figure 1 are displaced, the transit time of the frequency changes.

Figure 1.

In most physical
measurements, the transmitter
and receiver are displaced.
The minute displacement is
measured with extreme precision.

Generally speaking, the transit time gives complete information regarding displacement and temperature. However, measuring transit time directly presents some challenges. First, to directly measure the transit time of a single pulse we need a resolution of a few picoseconds. Second, when sending the pulse signal, the received signal needs to be strongly amplified in order to obtain a rectangular shape.
To obtain the time-stabilized signal, Nexense uses a specially designed time-to- frequency converter. In effect, this is an electrical oscillator with a delay line, i.e., the transmitter and receiver are connected to the electrical feedback loop. The receiver’s signal is amplified and then passed to a high-speed comparator that produces a square signal. The comparator’s output is connected to the transmitter. Immediately after receiving the signal, the transmitter sends it back through the medium (or channel), completing the feedback loop (see Figure 2).

Figure 2.

The comparator circuit converts
the frequency to a square wave output

Any electrical circuit has noise. If the hysteresis of the comparator is sufficiently low, the noise signal will pass through the feedback loop. However, the resonant transmitter and receiver loop will only select frequencies within their bandwidth.
There are two ways to initiate the oscillations in the loop: an artificial pulse or a pulse that appears when power is switched on. Because of the resonant features of the transducers, a group of several pulses will be obtained on the receiver output and then sent to the channel via the transmitter synchronizing the phase. On each following pass, the pulses will have greater duration until finally the continuous frequency (a standing wave) is established in the loop.

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