Functional Specification and Design of FM Radio Frequency Channels

Part I:
Specify the functional specification and design using different FM radio frequency channels
from 88MHz and 108MHz.
(i) The overall FM repeater system explanation and its function
The FM radio is a terrestrial communication system that transmits the radio waves on
land. The transmission is done at the broadcasting station where the information or the
message signal is encoded and transmitted within a band limited frequency. The system,
thereafter, encodes the signal using matching x-former and transmits it through the antenna.
The antenna is placed on a tower which is of great length depending on the distance it is

meant to project the signal. The antenna is set to have a specific power and gain value which
determines the distance a signal will travel before it loses most of its energy. There are two
sections of the FM radio: the transmitter end and the receiver end. These two perform the
encoding and decoding of message signals respectively. In a practical case, the signal is
transmitted by a broadcasting radio station or a telecommunication company and an user
equipment or a mobile equipment such as a cell phone or radio gadget receives the signals
and processes them to get the transmitted message. The FM radio repeater system has several
components that constitute the transmitter and the receiver.
FM transmitter block
The FCC in the USA is responsible for allocating frequencies to different service
providers and broadcasting stations. The FM transmission sends out radio waves into the
terrestrial atmosphere for them to be received by another antenna or the end users. The
transmitter block obtains a digital message and modulates it using the Frequency shift keying
technique and it sends the signal to the matching x-former and later connects it to the
antenna. The signal power determines how far the signal transmitted propagates before losing
too much energy.
In this project, the FM range provided is,
RF frequency=96.8 MHz
Station name=oli 96.8 FM
adjacent channel=96.3 MHz∧97.2 MHz
FM receiver block
The digital up-converter is comprised of the following DUC cascaded objects of three
interpolation filters and an oscillator that up converts the interpolated signal to a specified pass-
band frequency.