Table of Contents
How do you calculate NEP in ecology?
NEP = GPP – ER, with GPP = gross primary production. NEP refers to production (= positive when the ecosystem is a CO2 sink, negative for a CO2 source) while NEE is a flux (= negative when the ecosystem is acting as a CO2 sink, positive for a CO2 source).
What is NEP photodiode?
Noise-equivalent power (NEP) is a measure of the sensitivity of a photodetector or detector system. It is defined as the signal power that gives a signal-to-noise ratio of one in a one hertz output bandwidth.
How is detector noise calculated?
Average Detector Noise is calculated by dividing the data into segments (specified in the processing method) and averaging the values for each segment. Many of the calculations compare the actual value of the data point and the predicted value of the data point based on the least-squares line.
What is detection bandwidth?
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.
What is the cutoff wavelength of a photodetector?
The long end of the spectral response of GaAs photodiodes is limited by the bandgap energy of GaAs which is 1.42eV (corresponding to about 870nm). Hence incoming light with a wavelength beyond that limit (i.e. light with a larger wavelength) will not be absorbed as GaAs is transparent for such wavelengths.
What is the cut-off wavelength for Na?
1) 1.67 eV 2) 504 nm A sodium surface is illuminated with light having a wavelength of 300 nm.
What is the cut-off wavelength?
The second order mode cut-off wavelength (commonly shortened to cut-off) refers to the wavelength above which the fiber is single-mode; only at wavelengths above the cut-off will the fiber guide be single-mode. The cut-off wavelength is the wavelength at which an optical fiber becomes single-mode.
Which of the following is used for long wavelength detector design?
The most prevalent long wavelength photon detectors use doped germanium in the photoconductive mode. Recent work on other materials systems such as extrinsic germanium or GaAs impurity band conduction detectors has shown promise.
What is meant by cut off wavelength of a metal?
(a) The cutoff wavelength is the wavelength where the incoming light has barely enough energy to free an electron, i.e. all of the photon’s energy goes into overcoming the work function barrier.
Which wavelength of light would you choose to allow single mode?
The mode field diameter is ‰ˆ 9.2 Î¼m at 1310 nm, or 10.4 Î¼m at 1550 nm. The single-mode cut-off is at ‰ˆ 1260 nm….
Is it true that receiver sensitivity depends on channel bandwidth?
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.
On which factors the minimum detectable signal depends?
To establish the minimum detectable signal (MDS) of a receiver we require several factors to be known. As a numerical example: A receiver has a bandwidth of 100 MHz and noise figure of 1.5 dB and the physical temperature of the system is 290 kelvins.
How do I know the sensitivity of my receiver?
To calculate receiver sensitivity, we add the overall noise figure of the receiver to the noise floor. This quantifies the noise floor at the input to the demodulator. The signal must be higher than the noise floor by the carrier to noise ratio required for a desired signal quality.
Why is my receiver sensitivity negative?
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.
What is a common receiver sensitivity level range?
Receiver sensitivity is a measure of the minimum signal strength that a receiver can detect. It tells us the weakest signal that a receiver will be able to identify and process. The typical range for receiver sensitivity of various RF modules is from -50 to -100 dBm.
How do I increase the sensitivity of my receiver?
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.
Which parameter is referred to as receiver sensitivity?
Explanation: Noise figure is a parameter that represents the noisiness of a two port network or device such as an amplifier, compared with a reference noise. Explanation: The figure of parameter G/T0 is called as receiver sensitivity.
Why receiver sensitivity is so important for optical module?
Maximum input optical power indicates the maximum receive optical power of the receiver. Receiver sensitivity and overload point are both critical facets of optical power. If the input optical power is less than the receiver sensitivity, it is too weak to ensure that equipment receives signals.
What parameter enables a receiver to detect the weakest possible signal level?
Dynamic Range d. Fidelity 2. It is a receiver parameter that is used to measure the ability of the receiver to accept a given band of frequencies and reject all others.
Why is local oscillator frequency kept higher?
As a listener tunes across the broadcast band, the local oscillator is also tuned in synchronism so as to precisely produce a single-frequency signal (essentially an unmodulated carrier signal) which is higher in frequency by 455 kHz in comparison to the incoming signal.
What is the standard value for intermediate frequency if in AM receivers?
around 455 kHz
Which quantity is used for comparing the noise performance of receivers?
5. Which of the following is the most generally used term for comparing amplifier noise characteristics? Explanation: Noise factor measures degradation of signal to noise ratio which is caused by components in radio frequency (RF) signal chain.