RADIO COMMUNICATION TERMINAL DEVICE, AND AUTOMATIC FREQUENCY CONTROLLING METHOD

• Main Authors: SASAKI AKIRA, YOKONAGA HIROYUKI, IZUMI KEIKO, FUJITA SHOICHI
• Format: Patent
• Language: English
• Published: 08.01.2009
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; MULTIPLEX COMMUNICATION; PICTORIAL COMMUNICATION, e.g. TELEVISION; SELECTING RESONANT CIRCUITS; TRANSMISSION; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION; TUNING RESONANT CIRCUITS

PROBLEM TO BE SOLVED: To reduce deterioration of receiving performance due to a rapid change in frequency as well as to maintain a high receiving performance in a normal state by performing automatic frequency control with a high follow-up capability when performing a specific processing which would disturb a reference frequency. SOLUTION: A quadrature detection portion 106 performs a quadrature detection of a received signal by a control signal generated by an NCO 116. A specific processing execution notification portion 112 notifies a timing to issue an execution order for a specific processing which would cause a change in reference frequency. A frequency error detection portion 114 detects a frequency error. Under an instruction from a TV tuner AFC loop constant controlling portion 113, when executing the specific processing which would cause a change in reference frequency, a variable loop filter 115 sets a time constant smaller than one in a case that the specific treatment is not executed, and passes a frequency error signal and integrates it. The NCO 116 generates a control signal having a predetermined oscillation frequency from the integrated frequency error signal. COPYRIGHT: (C)2009,JPO&INPIT