FM Radio Receiver

You can always hook up to radio stations for listening to music or daily news bytes. All that is required is a FM Radio receiver at your end. Here is a project from Cornell University which is a perfect guide to design one on your own. So, one can have fun while making this music player besides adding a star in the workbook.

This project is a low-cost, user friendly FM radio receiver. It has a wide range of functionalities such as:

· Frequency Tuning

· Scanning up or down for the next station with a strong signal

· Set ups for 3 radio stations which will be available later for quick tune

· Adjust the scanning threshold to pick up stronger or weaker stations

AIROHA100 IC which is a single chip FM receiver is used. This receiver first receives the incoming radio frequency signal and then demodulates it. For the demodulation process, the signal is first passed through a low noise amplifier followed by a frequency mixer. These functionalities are integrated on the AIROHA IC itself. The receiver output is then given to the speaker via audio jack for listening to radio. The receiver can perform other functions like tuning, scanning etc with a user interface keypad. A 4×4 keypad is used where every key is assigned a specific task. Keyboard output is send to microcontroller ATMega644 for processing. The ATmega644 is the central processing unit which communicates with the FM receiver IC, keypad and the LCD unit.

The communication protocol used to communicate with AIROHA100 is I2C. The I2C protocol requires only two signals: clock and data. The registers on the AIROHA100 needs to be initialized before starting the communication. FM radio signals are broadcast on a carrier frequency within the range of 8.5 MHz to 108.0MHz. As per the U.S standards every station is provided with a window of .2MHz to broadcast their signal but in order to comply with international standards, users are allowed to tune up or down by .01 MHz increments.