Automatic frequency control in a radio communication receiver

A radio frequency (RF) communication device for processing a received, frequency modulated (FM) RF signal having binary message information, the binary message information comprising at least a synchronizing portion, the RF communication device comprising:

• a receiver for receiving the RF signal and converting the received RF signal into a converted signal;
• a demodulator, coupled to said receiver, for generating the binary message information represented by binary states;
• bit clock generating means for generating a bit clock indicating bit periods within the binary information;
• synchronization correlating means, coupled to said demodulator, for generating a synchronization command signal when the synchronization portion of the binary information correlates to a predetermined synchronization pattern;
• a frequency counter, coupled to said receiver and said bit clock generating means, for measuring the frequency of the converted signal and further for determining the associated binary state of the binary message information for each of a plurality of the bit periods indicated by the bit clock generated by the bit clock generating means;
• measurement storage means for storing the converted signal frequency measurements;
• a frequency control generator, coupled to said measurement storage means and said synchronization correlating means, for generating a frequency control signal in response to the synchronization command signal being generated, the frequency control signal generated being a function of the stored converted signal frequency measurements and the associated binary states;
• and
• a controllable local oscillator, coupled to said frequency control generator and to said receiver, for supplying a local oscillator signal to the receiver, the local oscillator signal having a frequency being controlled by the frequency control signal.

A selective call radio frequency (RF) communication device for processing a received, frequency modulated (FM) RF signal having binary message information, the binary message information comprising at least a synchronizing portion, an address portion, and a message portion, said selective call radio frequency communication device comprising:

• a receiver for receiving and converting the RF signal into a converted signal, said receiver being a zero intermediate frequency (IF) quadrature receiver, and wherein the converted signal comprises two orthogonal zero IF channel signals;
• a controller coupled to said receiver, comprising:
• an address memory for storing a predetermined address;
• a demodulator coupled to said receiver for generating the binary message information, represented by binary states;
• a bit clock generating means, coupled to said demodulator, for generating a bit clock indicating the bit periods of the binary message information;
• synchronization correlating means, coupled to said demodulator, for generating a synchronization command signal when the synchronization portion of the binary message information correlates to a predetermined synchronization pattern;
• an address detector, coupled to said demodulator and said bit clock generating means, for generating an address detection signal when the address portion of the binary message information matches a predetermined address;
• an alert device for indicating the receipt of the binary message information in response to the address being detected;
• a frequency counter, coupled to said receiver and said bit clock generating means, for measuring the frequency of the converted signal and further for determining the associated binary state of the binary message information for each of a plurality of the bit periods indicated by the bit clock generated by said bit clock generating means;
• measurement storage means, coupled to said frequency counter, for storing the converted signal frequency measurements;
• and
• a frequency control generator, coupled to said measurement storage means and said synchronization correlating means, for generating a frequency control signal in response to the synchronization command signal being generated, the frequency control signal generated being a function of the stored converted signal frequency measurements and the associated binary states;
• and
• a controllable local oscillator coupled to said frequency control generator and to said receiver, for supplying a local oscillator signal to said receiver, the local oscillator signal having a frequency controlled by the frequency control signal.