doppelumsetzungstuner with a first if filter without a precise frequency

摘要

Disclosed are systems and methods which utilize a relatively low cost first IF filter in a dual conversion tuner circuit. A preferred embodiment first IF filter is provided using a filter arrangement having a relatively high tolerance. Accordingly, preferred embodiment systems are designed such that they can accommodate the range of first IF frequencies that the large tolerance filter may provide. One aspect of this accommodation may include providing a means by which the system may detect the location of the passband of the IF filter in the spectrum. Another aspect of the accommodation for the range of first IF frequencies may include adjusting the first IF frequency utilized by the dual conversion tuner to match the passband of the IF filter. Additionally or alternatively, the passband of the first IF filter itself may be tuned, such as to provide a passband more near a desired IF frequency.