System and method for rejecting image signals

• Main Authors: SEIDEL, MARK N, GLAS, JACK, BANU, MIHAI, TARSIA, MAURICE J, DEC, ALEX, WANG, HONGMO
• Format: Patent
• Language: English; French; German
• Published: 02.07.1997
• Edition: 6
• Subjects: BASIC ELECTRONIC CIRCUITRY; DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TOANOTHER; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION

A method and apparatus process an input signal along two paths so as to reject image signals created during processing. On the first path (A,E,F,D2) the input signal is mixed (in 647) with a first component (from 606) of a first local oscillator (605) signal to generate a first signal at a first, non-zero intermediate frequency, the first signal is filtered, (in 664), and the filtered first signal and a first component (from 618) of a second local oscillator (619) signal are mixed (in 667) to generate a second signal at a second intermediate frequency, wherein the second intermediate frequency is higher than the first intermediate frequency. On the second path (A,B,C,D1 ) the input signal is mixed (in 607) with a second component (from 606) of the first local oscillator (605) signal to generate a third signal at the first intermediate frequency, the third signal is filtered (in 614), and the filtered third signal and a second component (from 618) of the second local oscillator (619) signal are mixed (in 617) to generate a fourth signal at the second intermediate frequency. An output signal is generated (by 630) as a function of the fourth signal and the second signal in which output signal the image signals have been reduced.