Frequency selection and control of FM broadcast transmitters using a two-modulus prescaler

• Main Author: Mappatao, Gerino P.
• Format: text
• Published: Animo Repository 2007
• Subjects: Phase-locked loops; FM broadcasting; Signal Processing; Systems and Communications
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/8504
• Institution: De La Salle University

A technique and a system are presented and described that offer simple, economical and convenient method f stabilizing and programming the carrier frequency of an FM broadcast transmitter. The system employs the common phase locked loop method of frequency programming and control but uses a two-modulus prescaler instead of a fixed modulus prescaler as part of the counter divider section contained in the feedback loop. With the use of the two modulus prescaler , frequency programming is easy for a transmitter to operate at a particular frequency anywhere between 88.1 MHz to 107.9 MHz using only one reference frequency. The system described here has a resolution (channel separation) of 50 kHz instead of the ideal 200 kHz. The carrier frequency stability is good and satisfies the standard stability and other frequency related requirements stated in the KBP (Kapisanan ng mga Brodkaster sa Pilipinas) Technical Standards and Operating Requirements for Broadcast Stations in the Philippines.