What is the signal-to-noise ratio?

In analog & digital communications, a signal-to-noise ratio, often written S/N or SNR, is a measure of the strength of the desired signal relative khổng lồ background noise (undesired signal). S/N can be determined by using a fixed formula that compares the two levels và returns the ratio, which shows whether the noise màn chơi is impacting the desired signal.

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The ratio is typically expressed as a single numeric value in decibels (dB). The ratio can be zero, a positive number or a negative number. A signal-to-noise ratio over 0 dB indicates that the signal cấp độ is greater than the noise level. The higher the ratio, the better the signal quality.

For example, a Wi-Fi signal with S/N of 40 dB will deliver better network services than a signal with S/N of trăng tròn dB. If a Wi-Fi signal"s S/N is too low, network performance can be impacted because it becomes more difficult for devices khổng lồ distinguish the desired signal from the noise. This can result in dropped packets và data retransmissions, leading khổng lồ lower throughput và higher latency.

Noise includes any unwanted disturbance that degrades the quality of the desired signal. It can include thermal, quantum, electronic, impulse or intermodulation noise, as well as other forms of noise. Environmental factors, such as temperature và humidity, can also affect noise levels.

If the noise is significant enough in comparison to lớn the desired signal -- that is, S/N is low -- it can disrupt a wide range of data transfers, including text files, graphics, telemetry, applications, và audio and đoạn phim streams.

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A low signal-to-noise ratio can result in dropped packets & data retransmission on a network.

Communications engineers always strive lớn maximize S/N. Traditionally, this has been done by using the narrowest possible receiving-system bandwidth consistent with the data tốc độ desired. However, there are other methods. For example, engineers might use spread spectrum techniques to lớn improve system performance, or they might boost the signal output power to increase S/N.

In some high-level systems, such as radio telescopes, internal noise is minimized by lowering the temperature of the receiving circuitry to near-absolute zero (-273 degrees Celsius or -459 degrees Fahrenheit). In wireless systems, it is always important khổng lồ optimize the performance of the transmitting and receiving antennas.

How vì chưng you calculate the signal-to-noise ratio?

The signal-to-noise ratio is typically measured in decibels & can be calculated by using a base 10 logarithm. The exact formula depends on how the signal and noise levels are measured, though.

For example, if they"re measured in microvolts, the following formula can be used:

S/N = 20 log10(Ps/Pn)

Ps is the signal in microvolts, và Pn is the noise in microvolts.

However, if the signal và noise are measured in watts, the formula is slightly different:

S/N = 10 log10(Ps/Pn)

The letter phường is often used in these formulas khổng lồ indicate power.

When Ps equals Pn, S/N will be 0. A ratio of 0 dB indicates that the signal is competing directly with the noise level, resulting in a signal that borders on unreadable. In digital communications, this can cause a reduction in data tốc độ because of frequent errors that require the transmitting system to lớn resend data packets.

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When Ps is greater than Pn, S/N will be positive. Ideally, Ps should be much greater than Pn to minimize noise interference. As an example, suppose that Ps equals 10 microvolts and Pn equals 1 microvolt. Because 10 divided by 1 equals 10, the following formula can be used lớn calculate S/N:

S/N = đôi mươi log10(10) = đôi mươi dB

A ratio of đôi mươi dB means that the signal is clearly readable. If the signal is much weaker but still above the noise level -- say, 1.3 microvolts -- S/N is much lower, in this case, only 2.28 dB:

S/N = 20 log10(1.3) = 2.28 dB

This is a marginal situation that could impact network performance, although it"s not the worst possible situation. When Ps is less than Pn, S/N is negative, a low signal-to-noise ratio. In this type of situation, reliable communication is nearly impossible, và steps should be taken lớn increase the signal level, decrease the noise cấp độ or implement a combination of both.


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