The Problem

1. The Problem There currently exist several devices which allow people to transmit sound from their portable music devices to car radios. Often when driving between cities, the unused radio frequency in one city might be used by a broadcasting station in the next. This interference requires the user to retune the radio and transmitter. Senior Project – Electrical Engineering – 2007Automatically Tuned MP3 Transmitter for VehiclesDaniel Fishman, Michael Thylur and Saim JafriAdvisor – Prof. Hassib The Solution An automatic tuning transmitter will help reduce frustration for drivers and provide safer car rides. To do this, an automatic FM radio frequency scanner will have to be designed which distinguishes between used and unused stations. A phase-locked loop system with a digital divide-by-n chip will be used to scan through the FM range, and a microcontroller will be used to decide which stations are unused, displaying an unused station on a seven segment display. System Block Diagram Frequency synthesizer Detector Super heterodyne Receiver PLL Output Voice or Display Microcontroller Frequency Synthesizer Energy Detector Generates a desired frequency by changing reference frequency and divide-by-n value Microcontroller reads detected peak values from envelope detector and finds unused station Divide-by-n Components Controlled by microcontroller. Divisor determined by 16 jam inputs -TLC2933 and LM565 Phase locked loop -CD4059A Divide-by-N counter - PMB2313T Prescaler -8051 Microcontroller -Superheterodyne receiver