Question

What is the function of a band pass filter used in a modulator for obtaining AM signal?

Answer 1

A band-pass filter (BPF) is a device that allows frequencies within a specific range to pass while rejecting (attenuating) frequencies outside that range. Well-designed bandpass filters, with the appropriate bandwidth for the mode and speed of communication being utilised, increase the number of signal transmitters that may exist in a system while reducing interference or signal rivalry in both sending and receiving applications.

Complete answer:
A bandpass filter is an electrical device or circuit that enables signals between two frequencies to pass but rejects signals from other frequencies. Wireless transmitters and receivers mainly employ bandpass filters. The main purpose of such a filter in a transmitter is to reduce the output signal's bandwidth to the absolute minimum required to transmit data at the given speed and in the desired format.

A bandpass filter in a receiver allows signals within a certain range of frequencies to be heard or decoded while blocking signals at undesired frequencies. A bandpass filter also improves a receiver's signal-to-noise ratio (sensitivity).The output produced by square law device is passed to band pass filter which rejects the dc and the sinusoids of frequencies wm, 2 wm and 2 wc and retains the frequencies wc, wc -wm and wc + wm}$ The output of band pass filter is an AM wave.

In wireless transmitters and receivers, bandpass filters are commonly employed. The main purpose of such a filter in a transmitter is to keep the output signal's bandwidth inside the transmission band. This eliminates the possibility of the transmitter interfering with other stations.

Note: A bandpass filter in a receiver allows signals within a certain range of frequencies to be heard or decoded while blocking signals at undesired frequencies. Signals received at frequencies beyond the receiver's tuned band might overwhelm or harm the receiver. They can also produce undesired mixing products that fall out of band and interfere with the desired signal. Wideband receivers are especially vulnerable to this type of interference. A bandpass filter also improves a receiver's signal-to-noise ratio and sensitivity.