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April 24, 2012


George Storm

In order to be meaningful, I would have thought that the term "Zero IF" would need to refer to performing the demodulation itself at baseband. Such demodulation requires that two mixed signals are available at baseband - the so-called InPhase and Quadrature components.
This system of course carries out the demodulation at the 10.7-MHz IF.
This is of course no criticism of the technique itself - merely that the definition used here for "Zero IF" would cause nearly every FM demodulation system I have either designed or tinkered to be redefined as being a hybrid ZIF (or DZIF).

Victor Koren

The '614 with '612 is a single conversion receiver. The '615 with '612 is a double conversion receiver. Many years ago I was given a NE604 (forerunner of the '614) pre-production sample for evaluation.

Carl Schwab

DZIF response----The oscillator of the ILOD IS the second oscillator. Recall the rational of the dual conversion receiver what the FIRST IF (10.7 MHz) solved the image problem while the SECOND IF @ 455 KHz solved the adjacent channel selectivity problem. In DZIF the second oscillator is at 10.7 MHz so that adjacent channel interference, either above or below can be handled by a LPF, Low Pass Filter. So in DZIF the 455 KHz function is now handled at baseband. The mixer for the second conversion is the phase detector part of ILOD. IT WORKS.

BTW Victor you are correct about the '614 vs '615. That is why I used the '614.

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