Signal to Noise Ratio And Its Calculation

Signal to Noise Ratio And Its Calculation

Listening to music in the car, I realized that every note had a different detail, which made me deeply appreciate and love music. This is also why my interest in Science and Technology grew overnight. Furthermore, compact Disc (CD) and car sub-woofer were the new technology in sound which further increased my curiosity in the field.

Before CDs and subwoofers, audiophiles used to prefer vinyl for its clear and HiFi sound quality. There is still a debate whether vinyl has the edge over CDs regarding sound quality. However, CDs were a clear winner over cassette tapes regarding quality and clarity. As there is a demand for high-resolution video in today’s market, compact discs had the same allure back then.

With CDs came car audio CD receivers appreciated for their superior sound and clarity in audio. This clarity and HiFi sound was achieved through an enhanced signal to noise ratio (SNR). The difference in sound quality using SNR was acknowledged even by casual listeners. As a result, SNR has become critical in signal transmission devices besides its importance in the audio industry. Below is a comprehensive guide on SNR and how to calculate it to guarantee accuracy.

Signal to Noise Ratio

Before we delve into the technicalities and calculation of SNR, it is crucial to understand what SNR does. In simple terms, signal to noise ratio enhances a specific signal while reducing the background noise in the other. As a result, the audio is made clearer and easy to comprehend for the listener. SNR is also a typical parameter used in science and engineering studies. In technical terms, SNR is a ratio between signal and noise power calculated in decibels (dB). Anything higher than 0dB is considered a good quality sound as the signal is more powerful than the noise.

The best way to explain SNR to the general public is by comparing it with daily life. For example, you and your friend are sitting in a crowded restaurant and chatting. Other people are also having conversations, but their speech and voice pattern are similar to yours, making it difficult for your friend to differentiate. This differentiation is exactly what an SNR does; it clarifies a particular note while reducing the noise from the unwanted one.

Importance of SNR

Signal to noise ratio technology is an essential one in today’s world. The importance of SNR can be best described when using a frequency which is transmitting sensitive data where errors are unacceptable, but other frequencies are disturbing the flow. Naturally, with this much noise, the receiver will not be able to differentiate between signals. This is where the high signal to noise ratio shows its actual colour. It will isolate the desired frequency while reducing noise from the others. As a result, you will receive the transmission clear and without any errors. This technology is also the basis of all wireless devices as it only enhances the desired frequency while blocking out the rest.

Basic Calculation of SNR

In simple terms, SNR calculation is finding the difference between desired frequency and the unwanted one. Therefore, identifying the main signal strength is vital before moving on to the noise signal. For example, if a radio receives a signal at -70 dBm (decibels per milliwatt) and the noise at -90 dBm, the SNR is 20 dBm. Therefore, the signal strength of your wireless device would be considered 20 dB, which is standard signal strength. Following is a complete SNR requirement compared to its values;

  1. 5 dB to 10 dB is a weak signal strength that makes the noise level of other frequencies indistinguishable.
  2. 10 dB to 15 dB is where a wireless connection is made, but it’s unreliable.
  3. 15 dB to 25 dB can make the connection, but it’s poor.
  4. 25 dB to 40 dB is good signal strength.
  5. 41 dB and higher is considered an excellent signal strength to establish a connection.

Advanced SNR Calculation

Calculating SNR can either be simple or complicated, depending on the data. As explained previously, if the device shows the values in decibels, the calculation is simple. However, it becomes complicated when other parameters express the signal strength. You have to divide the specific signal with a noise one and then take a common logarithm of the result using the formula log ( S ÷ N ). Remember, if the signal strength is expressed by watts, you will multiply it by 20, and in case the unit is voltage, it will be multiplied by 10. For example, if the noise value (N) is 2 microvolts and the signal (S) is 300 millivolts, the formula would look like 10 log (.3 ÷ .000002), which equates to 63 dB.

Channel Capacity and SNR formula

SNR is extensively used in wireless devices and networks such as Bluetooth, Wi-Fi, 4G and 5G. As these networks primarily use radio signals, there is a maximum channel capacity. Additionally, by enhancing SNR, their channel capacity can also be increased. In short, bandwidth, SNR and channel capacity directly impact the communication channel capacity. Claude Shannon first discovered this during World War II, and modern-day scientists and engineers refer to it as the Shannon-Hartley theorem. The formula used to calculate channel capacity is;

C = W log2(1 + S/N)

Where C is the channel’s capacity, S is the average signal power, N is the average noise power, and W is bandwidth. The value of S, N and W set the transmission rate limits.

The accurate calculation of signal to noise ratio is crucial to the efficient working of any wireless technology. This also offers a window into device performance, design and functionality for the user. Before manufacturing, any wireless device undergoes extensive SNR calculations for maximum efficiency and reliability. SNR can make all the difference in receiving accurate and on-point information during pressure situations, any discrepancies and the data will be compromised and unusable. Therefore, use the above formulas to properly and accurately configure signal to noise ratios in your wireless devices for greater efficiency and clarity.






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