Elimination of spurious signals in double conversion tuner using a dynamic intermediate frequency and a preselected crystal reference frequency

A method for use with a double conversion tuner that generates a first intermediate frequency (IF) signal in response to an input signal and a first local oscillator (LO) signal, generates a second IF signal in response to the first IF signal and a second LO signal, and generates the first and second LO signals in response to a crystal reference frequency, the method for eliminating spurious signals in an IF output bandwidth of the tuner, said method comprising the steps of:

• selecting a crystal reference frequency that generates spurious signals only outside of the IF output bandwidth;
• and,
• (i) using two or more frequency values to determine a frequency of the first IF signal;
• (ii) identifying spurious signals produced by the first IF signal at the determined frequency;
• and
• (iii) if no spurious signals produced by the first IF signal at the determined frequency are in the IF output bandwidth, setting the first IF signal to the determined frequency;
• otherwise
• (iv) repeating steps (i)-(iii).