dB to power ratio conversion**The power P _{2} is equal to the reference power P_{1} times 10 raised by the gain in G_{dB} divided by 10**. P

Generally, a signal with an SNR value of **20 dB or more** is recommended for data networks where as an SNR value of 25 dB or more is recommended for networks that use voice applications.

Shannon's formula **C = 12log(1+P/N)** is the emblematic expression for the information capacity of a communication channel.

SNR (**Signal to Noise Radio**) is actrually not a ratio but a decibel (dB) value measures the difference between the signal strength and the background noise. For instance, the signal strength is -56 dBm, noise is -86 dBm, the SNR is 30dB. SNR is also an vital factor to be considered during deployment.

6 Receiver bandwidth. The size of the receiver BW used for signal acquisition affects the rate of data acquisition (i.e. **BW = 1/Δt**) and the frequency range of each image pixel (e.g. 100 kHz/128 pixels ~780 Hz/pixel).

The half-power or 3-dB bandwidth is the width of the range of positive frequencies where a peak value at zero or infinite frequency (low-pass and high-pass signals) or at a center frequency (bandpass signals) is attenuated to 0.707 the value at the peak.

The power of a signal is **the sum of the absolute squares of its time-domain samples divided by the signal length**, or, equivalently, the square of its RMS level. The function bandpower allows you to estimate signal power in one step.

Q-factor: In LCR Circuit, **the ratio of resonance frequency to the difference of its neighbouring frequencies so that their corresponding current is 1/2 times of the peak value**, is called Q-factor of the circuit. Formula: Q=R1CL.

**how to improve receiver sensitivity**

- A smaller bandwidth could be used.
- The loss in the preselect filter or switch could be reduced.
- The noise figure of the LNA could be improved.
- The LNA gain could be increased reducing the effect of the mixer on.
- A lower NF in the mixer would also improve the system NF.

The receiver bandwidth is **the range of frequencies used during the reception of RF pulses**. During the reception phase the readout gradient receives a range of frequencies and converts it into an MR signal using an analogue digital converter (ADC).

dB to power ratio conversion**The power P _{2} is equal to the reference power P_{1} times 10 raised by the gain in G_{dB} divided by 10**. P

To achieve a reliable connection, the signal level has to be significantly greater than the noise level. **An SNR greater than 40 dB is considered excellent**, whereas a SNR below 15 dB may result in a slow, unreliable connection.

Noise figure is **a metric used to indicate the quality of amplifiers**. It is the decibel representation of the noise factor that determines the sensitivity of the amplifier is decreased to an incoming signal due to its internal noise.

What is ENR? ENR refers to **Excess Noise Ratio** which is 10 log {(Th-290)/290} essentially a normalized measure of how much the noise source is above thermal in its power. At high ENRs > 15 dB the density of power can be approximated by adding the ENR to -174 dBm/Hz.

If you have the signals in decibels (dB), **subtract noise from the signal**. If your calculations are in watts, use the power signal-to-noise ratio formula SNR = 20 × log(signal / noise) . If your calculations are in volts, use the voltage signal-to-noise ratio formula SNR = 10 × log(signal / noise) .

Noisecom's noise diodes are **the fundamental building blocks for analog noise systems**. They are categorized for performance characteristics that enhance their broadband noise output and flat spectral response. All Noisecom noise diodes can deliver symmetrical white Gaussian noise and flat output power versus frequency*.

**A measure of power spectral density**. It provides a ratio of the power in one Hertz of bandwidth, where power is expressed in units of dBm.

The bandwidth of a signal is **the difference between the upper and lower cutoff frequencies in a continuous band of frequencies**.

Bandwidth is measured between the 0.707 current amplitude points. The 0.707 current points correspond to the half power points since **P = I ^{2}R**, (0.707)

Dated : 21-May-2022

Category : Education