AN APPARATUS, METHOD AND ARTICLE OF MANUFACTURE FOR CARRIER FREQUENCY COMPENSATION IN AN FM RADIO RECEIVER

摘要

A method, apparatus and article of manufacture for compensating for carrierfrequency error is disclosed. An FM signal is receivedfrom an antenna and the received FM signal is provided to receiver. Thereceiver takes the FM signal at the carrier frequency and outputsa baseband signal. This baseband signal is then processed by a DSP whichprovides carrier frequency compensation and decoding toproduce a data stream that a microprocessor provides to a host device.Frequency differences between the FM carrier frequency and thefrequency used to demodulate the FM signal can shift the DC bias level of thebaseband signal. The DSP compensates for such frequencydifference by using a receive compensation value and applying it to eachreceived signal sample. When transmitting, data to be transmittedis provided from the host device to the DSP via a microprocessor. The DSPprovides encoding and carrier frequency compensation of thedata to provide a baseband signal to a transmitter that modulates the basebandsignal to produce an FM signal at a desired carrier frequency.Frequency differences between the desired FM carrier frequency and thefrequency used to modulate the baseband signal can produce errorsin receiver systems. The DSP compensate for such a frequency difference byusing a transmit compensation value and applying it to eachencoded signal sample.