Sensors have long seen use in a vast range of applications. These have encompassed consumer electronics products like smartphones and smart home devices, as well as automotive systems, medical equipment for patient monitoring, industrial automation, and other vital purposes.
We could go on and on, but you probably get the idea. When it comes to enabling systems to detect and measure physical properties – thereby allowing for automation, optimised efficiency, improved safety, and real-time monitoring – sensors exert a profound impact on almost every facet of 21st-century life.
So, this makes it very unfortunate when in one of the aforementioned contexts, unwelcome sensor noise occurs. You might be anxious to combat this problem with a particular project you’re working on, to help ensure a noisy sensor doesn’t damage your efforts to attract outside investment.
How Does Sensor Noise Arise, And Why Is It Such a Problem?
Sensor noise can happen due to a combination of internal and external factors. Examples of the former include thermal noise, amplifier noise, and dark current. Meanwhile, examples of the latter can encompass electromagnetic interference from nearby equipment, as well as radio frequency interference, and/or the inherent randomness of the environment being measured.
Whatever the exact culprits may be for the sensor noise you are witnessing with your project, it can be extremely frustrating. When any of the aforementioned factors introduce unwanted variations into the signal, sensor data can be corrupted, and the true signal obscured. As a result, the reading produced by the sensor may be less precise than the true measurement.
Prospective Investors May Be Put Off by Noisy Sensor Issues
From the point of view of wooing potential investors, noise on sensor lines can make your prototypes look unpolished, thereby undermining confidence in your project.
If a would-be investor sees that your product gives erratic readings, this will indicate to them that there are certain technical challenges still to be ironed out.
It will therefore greatly help restore their confidence if you can pinpoint and remedy the cause of the signal noise, with a well-judged hardware tweak.
So, What Solution Could You Employ for This Problem?
When it comes to simple solutions, introducing a resistor-capacitor (RC) low-pass filter could well be “the one”. It can attenuate (block) high-frequency noise, while leaving your signal of interest untouched, given that it allows frequencies below a certain “cutoff frequency” to pass.
The term “cutoff frequency” refers to the point at which a filter begins to reduce a signal’s strength. A low-pass filter, then, is different to a high-pass filter, which allows frequencies above its cutoff frequency to pass, at the same time as attenuating all lower frequencies.
If, then, you decide to use an RC low-pass filter to solve your noisy sensor issue, you can use the cutoff frequency formula, fc = 1 / (2πRC). In this formula, fc refers to cutoff frequency, while R means resistance, and C is capacitance.
The RC low-pass / high-pass calculator on the website of the electrical component store RS, and the explanatory notes, can help make this process easier to understand.
The 5 Design Steps to Perform This Filter Fix
Here, then, is a step-by-step design guide:
- Use an oscilloscope or data logger to measure your sensor’s dominant noise frequencies
- Decide on a cutoff that is at least twice your desired signal bandwidth
- Calculate R and C from fc = 1 / (2πRC)
- Prototype on breadboard or solder small SMD (surface-mount device) parts onto a breakout board
- Re-measure noise spectrum to confirm attenuation.
There you have it; the “fix” you can perform on your hardware to not only help remedy any sensor noise problems you are experiencing, but also demonstrate to prospective investors that you are detail-oriented and determined to deliver the best possible readiness for your product.
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