Television providers have moved significantly toward cable and satellite technology for providing content to users, but terrestrial transmission still has significant usage worldwide. Analog television signals are still utilized in many areas of the world, and are also utilized in portions of digital provider networks.
Receivers introduce undesirable impairments to a signal when the signal is being amplified, filtered or downconverted. For example, direct conversion receivers (also referred to as “DCR”, “zero IF receivers”, or “ZIF receivers”) are a very efficient way of implementing a radio receiver. However these receivers introduce a variety of impairments to a signal which can degrade overall performance of the system. Most notably, DC offset and signal image due to imbalances in the complex signal path, often referred to as “I/Q mismatch,” may corrupt the downconverted signal. Existing methods for performing DC offset cancellation (DCOC) and I/Q calibration (IQ cal) can be effective at mitigating these problems. However, for signals which require very high signal to noise ratio such as analog TV signals, the residual impairment due to the limitations of these techniques can still leave visible artifacts in the analog picture screen.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.
USPTO Backgrounds
USPTO Backgrounds