System and method for harmonic interference avoidance in carrier recovery for digital demodulation

A method of controlling a synthesizer so as to avoid interference comprising the steps of:

• Determining an offset frequency value by which to offset a down converted carrier frequency;
• locking on to said down converted carrier frequency, said locking performed in conjunction with a wide sweep of a frequency band containing said down converted carrier frequency;
• and
• tuning said synthesizer to offset the down converted carrier frequency by the offset frequency value so as to avoid the interference.

A method of controlling a synthesizer so as to avoid interference comprising the steps of:

• synthesizing a first frequency for down converting a received carrier signal to a first intermediate frequency;
• synthesizing a second frequency offset from the first frequency for down converting the received carrier to a second intermediate frequency;
• and,
• alternating between synthesizing the first frequency and synthesizing the second frequency until a demodulator is locked onto one of the received carrier signal at the first intermediate frequency or the received carrier signal at the second intermediate frequency.

A method of avoiding interference comprising the steps of:

• controlling a voltage controlled oscillator to sweep over a wide frequency band for a down converted carrier signal;
• detecting the presence of interference in said down converted carrier signal via the presence of a false lock indication;
• locking on to said down converted carrier signal;
• determining an offset frequency so as to offset the down converted carrier signal;
• offsetting the down converted carrier signal by the offset frequency;
• controlling said voltage controlled oscillator to sweep over a narrow frequency band for the down converted signal offset by the offset frequency;
• and
• locking onto the down converted signal offset by the offset frequency.