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US 2002/0177423 A1Published application
Tuner and method of aligning a tuner
AssigneeZarlink Semiconductor Inc.
InventorNicholas Paul Cowley
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AssigneeZarlink Semiconductor Inc.
InventorNicholas Paul Cowley
Estimating the term…
A tuner comprises a first frequency changer with a mixer and local oscillator. The output of the frequency changer is connected to a first intermediate frequency filter, whose output is connected to a second frequency changer. The output of the frequency changer is connected to the usual second intermediate frequency filter and to an amplitude detector. A reference oscillator is connectable under control of a controller via a multiplexer to the input of the mixer. During an alignment mode of the tuner, the reference signal from the oscillator is supplied to the mixer and the local oscillators and are controlled by the controller to sweep across a frequency range encompassing all possible pass frequencies of the filter. The controller monitors the output of the detector so as to establish the frequency response of the filter. Frequency offsets are then stored in the synthesizers and so as to center each channel during a reception mode on the actual center frequency of the filter.
A tuner comprising a first frequency changer having a first local oscillator, a first intermediate frequency filter for filtering a signal from said first frequency changer, a detector for detecting an amplitude of a signal filtered by said first filter, a reference oscillator for supplying a reference signal, and a controller arranged, during an alignment mode of said tuner, to supply said reference signal to said first frequency changer, to vary a frequency of at least one of said first local oscillator and said reference oscillator, to monitor said amplitude detected by said detector so as to determine an actual first intermediate frequency of said first filter, and to adjust said first local oscillator so as to convert, during a reception mode of said tuner, each selected channel to said actual first intermediate frequency.
A method of aligning a tuner of the type comprising a first frequency changer having a first local oscillator and a first intermediate frequency filter for filtering a signal from said first frequency changer, said method comprising the steps of:
Dependencies are inferred from the claim text.