Signal-to-noise ratio improvements

Signal-to-noise ratio improvements

September 13, 2019

Every year we create stronger, faster, better electronics to make it easier and faster to access critical process information. With the introduction of our new printed circuit boards (PCBs), we are proud to introduce improvements to bring you the fastest, most accurate, mass flow devices on the market.

Fully redesigned circuit board for improved efficiency

Sensors detect changes to the flow environment and quickly calculate the desired values. These values can be displayed on the front display, or sent through the communication protocol to a DAQ, PLC, desktop computer, or other means of data collection. Alicat devices are designed to take analog signals from temperature and pressure sensors and convert them into digital counts.

Lower noise and less shift

Our newest release converts data in a way that reduces the sensitivity to external effects, and helps minimize system noise, thereby maximizing the signal to noise ratio (SNR) and reducing the error value. The chart below shows the bits gained in our SNR by upgrading the circuitry:

The large-scale improvement of 4.5–5 bits SNR (that’s a 20 to 30 times increase) can be seen in the lowest measurable flow of our mass flow devices. From the moment the sensor detects a change in the environment and sends a signal through our device, the amount of uncertainty of the final value drops dramatically due to the drop in noise in the system.

Improvements in circuitry lead to an increase in processing speed and functionality, impacting the complexity of control logic complexity and on-board alarms and subsequent actions. This also affects the degree to which the full scale range can be adjusted and even the ability to update the firmware via a serial interface.

These improvements allow for a higher resolution sampling of the sensor data and less shift when subjected to different temperatures and pressures. This results in increased accuracy, resolution, and repeatability of the data displayed. By decreasing noise and improving upon the analog output, device signal is less susceptible to error across the full voltage/current span. The SNR of higher flow rates sees a smaller improvement due to flow-generated noise, which is created by the true raw signal from the sensor and cannot be improved upon with improvements to the PCB.

Improved functionality includes:

  • Improved accuracy and turndown ratios
  • Floating point full range scales
  • Ability to upgrade or downgrade firmware in the field on 8V and above

We are constantly finding ways to improve how our devices interact with the environment and strive to get as close as possible to the real world values. Alicat works with our customers to ensure that you can extract every bit of performance possible from your Alicat units. The overall impact of the improved PCB is the increase in the signal to noise ratio, which in turn provides a final value that is closer to the actual real world value. By striving toward a perfect system, our analysis of flows will see less and less error, opening up applications that require more precise and accurate information, and opening doors to a whole new world we haven’t even begun to discover.

Note: It is important to note that a system’s signal to noise ratio is dependent on the bandwidth it is measured over. Bandwidth can be described as the dynamic range of a system, and is defined as the ratio between the smallest and the largest signals that can be measured. Resolution, or precision, is the smallest input signal that will change the digital output, and it refers to the number of output bits that a converter can generate per conversion.

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