Modulator system

Claim 2

A modulator system comprising: a source of video information signals, a source of radio frequency carrier signals tunable to a plurality of different frequencies, each frequency of said plurality of frequencies being selected to be within a different television channel to which a television receiver tuner may be tuned; a modulator coupled to said source of radio frequency carrier signals and having an input terminal and an output terminal; means connected between said source of video information signals and said modulator input terminal for coupling said video information signals to said modulator input terminal such that double sideband modulated radio frequency carrier signals are developed at said modulator output terminal; a tunable attenuator filter coupled between said modulator output terminal and an other terminal, said filter tunable to a plurality of frequencies, each frequency of said plurality of frequencies having a fixed relationship to a corresponding frequency of said plurality of frequencies to which said source of radio frequency carrier signals is tunable; and control means coupled to said source of radio frequency carrier signals and said attenuator filter for controlling the tuning of both said source of radio frequency carrier signals and said attenuator filter such that the tuning of said attenuator filter tracks the tuning of said source of radio frequency carrier signals to develop vestigial sideband modulated radio frequency carrier signals at said other terminal.

Claim 3

A modulator system as defined in claim 1 wherein said modulator is a balanced amplitude modulator, and including a source of frequency modulated audio information signals coupled to said modulator input terminal, said frequency modulated audio information signals having a center frequency of 4.5 MHz

Claim 4

A modulator system as defined in claim 1 wherein said tunable attenuator filter includes a parallel tuned circuit connected in series between said modulator output terminal and said other terminal.

Claim 5

A modulator system as defined in claim 3 wherein said attenuator filter includes a reactive element connected in series with a diode, said diode coupled to said control means and when biased for conduction connecting said reactive element in said attenuator filter tuned circuit to alter said tuned circuit resonant frequency.

Claim 6

In a video playback system of the type wherein television signals recorded on a record medium are detected and processed to provide signals for use in a television receiver having a tuner tunable to a plurality of television channels and coupled to an antenna terminal, a modulator system comprising: a source of video information signals; a source of radio frequency carrier signals tunable to a plurality of different frequencies, each frequency of said plurality of frequencies being selected to be within a different television channel to which a television receiver tuner may be tuned; a modulator coupled to said source of radio frequency carrier signals and having an iNput terminal and an output terminal; first means connected between said source of video information signals and said modulator input terminal for coupling said video information signals to said modulator input terminal such that double sideband modulated radio frequency carrier signals are developed at said modulator output terminal; a tunable attenuator filter coupled between said modulator output terminal and an other terminal, said filter tunable to a plurality of frequencies, each frequency of said plurality of frequencies having a fixed relationship to a corresponding frequency of said plurality of frequencies to which said source of radio frequency carrier signals is tunable; control means coupled to said source of radio frequency carrier signals and said attenuator filter for controlling the tuning of both said source of radio frequency carrier signals and said attenuator filter such that the tuning of said attenuator filter tracks the tuning of said source of radio frequency carrier signals to develop vestigial sideband modulated radio frequency carrier signals at said other terminal; and second means connected between said other terminal and said television receiver antenna terminal for coupling said vestigial sideband modulated audio frequency carrier signals to said antenna terminal for processing in said television receiver tuner.

Claim 7

In a video playback system of the type wherein television signals recorded on a record medium are detected and processed to provide signals for use in a television receiver having a tuner tunable to a plurality of television channels and coupled to an antenna terminal, a modulator system comprising: a source of video information signals; a source of radio frequency carrier signals tunable to a plurality of different frequencies, each frequency of said plurality of frequencies being selected to be within a different television channel to which a television receiver tuner may be tuned; a modulator coupled to said source of radio frequency carrier signals and having an iNput terminal and an output terminal; first means connected between said source of video information signals and said modulator input terminal for coupling said video information signals to said modulator input terminal such that double sideband modulated radio frequency carrier signals are developed at said modulator output terminal; a tunable attenuator filter coupled between said modulator output terminal and an other terminal, said filter tunable to a plurality of frequencies, each frequency of said plurality of frequencies having a fixed relationship to a corresponding frequency of said plurality of frequencies to which said source of radio frequency carrier signals is tunable; control means coupled to said source of radio frequency carrier signals and said attenuator filter for controlling the tuning of both said source of radio frequency carrier signals and said attenuator filter such that the tuning of said attenuator filter tracks the tuning of said source of radio frequency carrier signals to develop vestigial sideband modulated radio frequency carrier signals at said other terminal; and second means connected between said other terminal and said television receiver antenna terminal for coupling said vestigial sideband modulated audio frequency carrier signals to said antenna terminal for processing in said television receiver tuner.

Claim 8

A modulator system as defined in claim 5 wherein said modulator is a balanced amplitude modulator and including a source of frequency modulated audio information signals coupled to said modulator input terminal, said frequency modulated audio information signals having a center frequency of 4.5 MHz.

Claim 9

A modulator system as defined in claim 5 wherein said second means connected between said other terminal and said television receiver antenna terminal is a coaxial cable.

Claim 10

A modulator system as defined in claim 5 wherein said tunable attenuator filter includes a parallel tuned circuit connected in series between said modulator output terminal and said other terminal.

Claim 11

A modulator system as defined in claim 8 including a reactive element connected in series with a diode, and wherein said control means includes a switch coupled to said diode and operable to cause said diode to be biased into and out of conduction, said diode when biased into conduction connecting said reactive element in said attenuator filter tuned circuit to alter said tuned circuit resonant frequency, and said switch additionally connected in a resonant circuit associated with the tuning of said source of radio frequency carrier signals and operable to cause a change in the operating frequency of said source of radio frequency carrier signals.