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Analysis and Simulation of Filters: Tuning a Radio

Description| How it works| Low Pass Filter| Tuning a Radio




Radio signals from different stations are sent out with different frequencies. A reciever radio set is tuned to a desired station using an RLC circuit which works as a second order filter. This filter has a peak in its frequency response, which is used in tuning the set to a desired frequency. This type of filter is called a resonant filter.

To model and study such a filter, we use the entries as shown below.

Filter for tuning Radio

The frequency response of this filter shows a sharp peak at its resonant frequency (~1 rad/sec).

Resonant Filter

We will now input a signal consisting of a mix of frequencies into this filter. The input signal is given by SIN(x)+2*SIN(0.1*x)+2*SIN(10*x). The desired signal of frequency 1 rad/s is weaker than the other 2 signals, but as can be seen below, the resonant filter is able to extract it.

Tuning radio