Diplexer for television tuning systems
AssigneeRCA Corporation
InventorGerald E. Theriault
Life of this patent
Estimating the term…
Abstract
A diplexer comprises a first frequency selective filter coupled between its first input terminal and a circuit point, a second frequency selective filter coupled between the circuit point and its output terminal, and third frequency selective filter coupled between its second input terminal and the circuit point. The first filter selects frequencies higher than a first frequency and the second filter selects frequencies lower than a second frequency which is higher than the first frequency. The third filter selects frequencies lower than a third frequency which is lower than the first frequency. In a television receiver, the first and second filters serve as a bandpass filter for the UHF band, and the third filter passes the VHF and CATV bands.
Claims16
Apparatus for diplexing electrical signals comprising:
- first and second input terminals, and an output terminal;
- fist frequency selective filter means having an input connection to which said first input terminal is coupled and having an output connection coupled to a circuit point, said first filter means for selecting signals at frequencies higher than a first predetermined frequency;
- second frequency selective filter means having an input connection coupled to said circuit point and having an output connection coupled to said output terminal, said second filter means for selecting signals at frequencies lower than a second predetermined frequency higher than said first frequency;
- third frequency selective filter means having an input connection to which said second input terminal is coupled and having an output connection coupled to said circuit point, said third filter means for selecting signals at frequencies lower than a third predetermined frequency lower than said first frequency, each of said first and third frequency selective filter means providing a respective signal path between its input connection and said circuit point, said respective signal path being without switching means for selecting one of said signal paths to the exclusion of the other of said signal paths;
- frequency mixing means having a first connection to which said output terminal is coupled for receiving first signal therefrom, having a second connection for receiving a frequency signal, and having a third connection at which a signal at an intermediate frequency between said first and third frequencies is developed;
- and
- means for applying said frequency signal to said second connection to shift the frequency of said first signal to said intermediate frequency.
Dependencies are inferred from the claim text.