Provide and explain 2 hardware and 2 software methods for re

Solution

For removing noise,

the hardware methods which can be used are:

1) Using shielded cables

Proper use of shielded cables in a data acquisition system will help minimize common mode electrostatic noise. Theoretically, when a shield surrounds a signal wire(s), the signal wire will capacitively couple to the shield but cannot capacitively couple to any conductors outside the shield. Now, this works both ways and can be used to keep electrostatic noise out of the conductors within a shield cable but can also be used to keep electrostatic noise contained within the shield.

As a rule of thumb, all measurement signals need to be connected to the system using shielded cables, but it is also important to use shielded cables on power cables in the system that contain signals with high frequency time varying signals to minimize their effect on other parts of the system. This typically includes devices that are being driven by pulse width modulated signals such as the cables that connect variable frequency drives to their respective motors, solenoids that are switched during data acquisition, and solenoids that are driven by PWM signals.

When using shielded cables, one must ensure that shield is properly terminated. Typically, only one end of a shied is terminated, and is terminated at the zero-signal reference potential (common) for the signals contained within a shield. In special circumstances shields may be terminated at both ends but care must be taken that there is no difference in potential between either ends of the shield, because if there is, a ground loop will be induced.

2) Proper grounding should be done.

Proper grounding and ground bonding in the design and installation phases is essential for reducing unwanted noise issues in the DAQ system. Establishing a ground plane can help reduce noise and ensure that all circuits within a system have the same reference potential for comparing different signals and voltages. This ground plane appears to most signals as an infinite ground potential where every point on its surface is at the same potential for all frequencies.

All grounding is designed to establish a low-impedance ground-fault return path to the power source, which is necessary for actuating the overcurrent protection device. To accomplish grounding of all components, the cables and accessories used to acquire data are effectively bonded to the ground plane, which is then bonded to the system earth ground in order to provide a return path for any ground faults. This also provides a zero potential reference to minimize electrical noise from high frequency RF sources.

(Ref: https://www.winemantech.com/blog/top-8-ways-to-deal-with-noise-in-data-acquisition-and-test-systems/)

the software methods which can be used are:

1) Signal smoothing

Smoothing usually reduces the noise in a signal. If the noise is \"white\" (that is, evenly distributed over all frequencies) and its standard deviation is s, then the standard deviation of the noise remaining in the signal after one pass of a rectangular smooth will be approximately s/sqrt(m), where m is the smooth width. If a triangular smooth is used instead, the noise will be slightly less, about s*0.8/sqrt(m). Smoothing operations can be applied more than once: that is, a previously-smoothed signal can be smoothed again. In some cases this can be useful if there is a great deal of high-frequency noise in the signal. However, the noise reduction for white noise is less in each successive smooth. For example, threepasses of a rectangular smooth reduces white noise by a factor of approximately s*0.7/sqrt(m), only a slight improvement over two passes.

2) Using statistical methods like median and median absolute deviation.