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What is the selectivity of a receiver?
Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.
How is radio selectivity measured?
Selectivity is usually measured as a ratio in decibels (dB), comparing the signal strength received against that of a similar signal on another frequency. If the signal is at the adjacent channel of the selected signal, this measurement is also known as adjacent-channel rejection ratio (ACRR).
How does bandwidth affect selectivity?
Q Factor and Selectivity As we reduce the bandwidth of our filter Q increases, the skirts become steeper and our filter becomes more selective. A band pass filter increases in selectivity as Q increases.
What is frequency selectivity in communication?
Wave filters are needed to select specific frequencies and to reject others. In low-frequency communication applications, frequency selectivity is achieved by the use of discrete capacitors and inductors arranged in resonant circuits.
What is the correct order of the components in a radio receiver?
In the simplest type of radio receiver, called a tuned radio frequency (TRF) receiver, the three functions above are performed consecutively: (1) the mix of radio signals from the antenna is filtered to extract the signal of the desired transmitter; (2) this oscillating voltage is sent through a radio frequency (RF) …
What is difference between sensitivity and selectivity?
Sensitivity refers to a radar detector’s ability to pick up police signals at the greatest distance. Selectivity refers to the detector’s ability to filter out signals that are not true police signals, yet operate on the same frequencies as police radar (i.e. security alarms, garage doors, automatic doors, etc.).
What is the purpose of bandwidth?
Network bandwidth is a measurement indicating the maximum capacity of a wired or wireless communications link to transmit data over a network connection in a given amount of time. Typically, bandwidth is represented in the number of bits, kilobits, megabits or gigabits that can be transmitted in 1 second.
What is bandwidth and selectivity?
As the bandwidth is taken between the two -3dB points, the selectivity of the circuit is a measure of its ability to reject any frequencies either side of these points. A more selective circuit will have a narrower bandwidth whereas a less selective circuit will have a wider bandwidth.
What is sensitivity of a receiver?
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.
Why if is used in superheterodyne receiver?
Intermediate frequencies are used in superheterodyne radio receivers, in which an incoming signal is shifted to an IF for amplification before final detection is done. Conversion to an intermediate frequency is useful for several reasons. It’s easier to make sharply selective filters at lower fixed frequencies.
Why do you need selectivity in a superheterodyne?
A variety of selectivity and filter requirements are applicable for superheterodyne receivers. Selectivity of the front end is required to ensure sufficient image rejection, and the filters in the IF provide the main adjacent channel rejection.
How does a superheterodyne receiver convert a signal?
The superheterodyne receiver uses one or more mixers and local oscillators to convert the received signal channel to another frequency band for more convenient filtering and amplification. A detrimental by-product of this frequency transfer process is the susceptibility of the receiver to unwanted signals on other frequencies.
What is the intermediate frequency of a superheterodyne?
Although today the new frequency, called the intermediate frequency or IF, may be either higher or lower than the RF frequencies, early superheterodyne receivers always down-converted RF signal to a lower IF frequency (IF < RF).
Which is radio receiver has the best selectivity?
Superheterodyne receiver: The superheterodyne radio receiver has been in widespread use for many years, and it is still widely used for many high performance applications as well as for broadcast, television, communications and others. A variety of selectivity and filter requirements are applicable for superheterodyne receivers.