The bandwidth of the detector is then defined as the frequency at which the response drops to 50% of its value at DC. On a log scale, this is the -3 dB point of the voltage spectrum, and it is referred to as the voltage bandwidth.
The specific detectivity D* is the detectivity normalized to a unit detector area and detection bandwidth; one can calculate it by multiplying the detectivity with the square root of the product of detector area (in square centimeters) and the detector bandwidth (in Hz).
In physics, quantum noise refers to the uncertainty of a physical quantity that is due to its quantum origin. In certain situations, quantum noise appears as shot noise; for example, most optical communications use amplitude modulation, and thus, the quantum noise appears as shot noise only.
Minimum Detectable Optical PowerThe NEP of a detector is the optical power incident to. the detector that needs to be applied to equal the noise. power from all sources in the detector; in other words, NEP is the optical power that results in an SNR of 1 [2].
e·quiv·a·lent pow·'er. the power equal to an infinitely thin lens as measured on an optical bench.
If some detector has a voltage rather than a current output, one can define its responsivity as the ratio of output voltage and optical power. This leads to units of V/W (volts per watt).
Which of broad classifications of noise are most difficult to treat? Explanation: Noise which is generated inside the receiver is very much difficult to handle. 5.
A ratio of 10-15dB is the accepted minimum to establish an unreliable connection; 16-24dB (decibels) is usually considered poor; 25-40dB is good and a ratio of 41dB or higher is considered excellent.
Basically, a low figure means the network adds very little noise (good) and a high noise figure means it adds a lot of noise (bad). The concept fits only those networks that process signals and have at least one input and one output port. Figure 1, below, provides the fundamental expression for noise figure.
In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system, where noise is defined as any signal other than the one being monitored.
Noise Figure is defined as the ratio of signal to noise ratio at the output to that at the input. In other words, NF= (s/n)i/(s/n)o. Where (s/n)I is the signal to noise ratio at the input, and (s/n)o is the signal to noise ratio at the output of the device under test.
Noise factor: The noise factor can be derived simply by taking the SNR at the input and dividing it by the SNR at the output. As the SNR at the output will always be worse, i.e. lower, this means that the noise factor is always greater than one.
Editorial Team - everything RFThe Noise Floor is the signal created from adding up all the unwanted signals within a measurement system. The noise floor consists of noise from a number of sources which includes thermal noise, atmospheric noise and noise from components used to make the measurement system.
Noise Figure (NF) is probably the most commonly used Figure-of-Merit quantifying receiver noise performance. NF can be calculated as the ratio of the sum of the available source and receiver input referred noise power to the available source noise expressed in dB.
Noise Figure (NF) is the Noise factor converted to Decibel (dB). It is a measure of degradation of the signal to noise ratio (SNR), caused by components in the RF signal chain, for a given bandwidth. It is the increase in noise power of a device from the input to the output that is greater that the signal gain.
In the specific case of a photodetector, responsivity measures the electrical output per optical input. The responsivity of a photodetector is usually expressed in units of either amperes or volts per watt of incident radiant power.
The sensitivity of the receiver is dictated by its noise figure, the bandwidth of the signal, and the carrier-to-noise ratio (CNR) at which the desired signal can be decoded with acceptable error rate.
Effective Receiver Sensitivity – Effective Receiver Sensitivity (ERS) Figure 2, also called operational sensitivity, is the sensitivity as seen in the real world when connected to the antenna. When the receiver or receive system is connected to the antenna it picks up external RF noise and possibly interfering signals.
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.
Analog receiver sensitivity is measured by monitoring the SINAD level as the RF signal power is lowered. The RF input power resulting in 12 dB SINAD is typically considered the specified sensitivity of the receiver. For a digital receiver, the key performance measure is BER (Bit Error Rate).
What is the two basic specifications of a receiver? Explanation: Sensitivity and selectivity are the two key specifications for any receiver, which is used for the purpose in communication.
Explanation: The figure of parameter G/T0 is called as receiver sensitivity.
Because receiver sensitivity indicates how faint an input signal can be to be successfully received by the receiver, the lower power level, the better. When the power is expressed in dBm the larger the absolute value of the negative number, the better the receive sensitivity.
Further, the noise figure of a receiver can be improved through the addition of an external LNA placed between the receive antenna and the receiver. NuWaves offers several LNA modules in the NuWaves product line, including the µHILNATM, providing low noise gain solutions from 2 MHz to 10 GHz.
6.3 Superheterodyne receiver. The superheterodyne receiver is the most common configuration for radio communication. Its basic principle of operation is the translation of all received channels to an intermediate frequency (IF) band where the weak input signal is amplified before being applied to a detector.
