Two-way CATV system
View Patent ↗A two-way CATV system is easy of maintenance, stable of a transmission quality and capable of restraining inter-modulation distortion noises of downstream RF signal carriers which are caused by non-linearity of electric contact members of coaxial connectors among upstream ingress noises becoming a problem when performing communications services by utilizing a CATV transmission path. The two-way CATV system comprises at least one bidirectional amplifier provided on a CATV transmission path for connecting a CATV center station to a subscriber home, a bias voltage superposing element for superposing, with a bias voltage, a downstream signal transmitted along a coaxial transmission path subordinate to an amplifier at the terminal among the bidirectional amplifiers, and a bias current adjusting load element, provided at the end of the coaxial transmission path, for setting the bias current corresponding to an application of the bias voltage superposed by the bias voltage superposing element.
1. A two-way CATV system comprising:
at least one bidirectional amplifier provided on a CATV transmission path for connecting a CATV center station to a subscriber home;
bias voltage superposing means for superposing, with an AC frequency bias voltage within a bidirectional amplifier at the terminal of said at least one bidirectional amplifier, a downstream RF frequency signal transmitted along a coaxial transmission path subordinate to the bidirectional amplifier at the terminal; and
bias current adjusting load means, provided at the end of said coaxial transmission path, for setting an AC frequency bias current corresponding to an application of the AC frequency bias voltage superposed by said bias voltage superposing means and for flowing a uniform AC frequency current on said coaxial transmission path; and
wherein said bias current adjusting load means includes an inductive element in series with a resistance element coupled by a parallel connection to a terminating resistance element, wherein said inductive element is selected so that the resistance of the coupled current adjusting load means and terminating resistance element approximates the resistance of the terminating resistance element for RF signals.
2. A two-way CATV system comprising:
at least one bidirectional amplifier provided on a CATV transmission path for connecting a CATV center station to a subscriber home;
bias voltage superposing means for superposing, with an AC frequency bias voltage within a bidirectional amplifier at the terminal of said at least one bidirectional amplifier, a downstream RE frequency signal transmitted along a coaxial transmission path subordinate to the bidirectional amplifier at the terminal; and
bias current adjusting load means, provided at the end of said coaxial transmission path, for setting an AC frequency bias current corresponding to an application of the AC frequency bias voltage superposed by said bias voltage superposing means and for flowing a uniform AC frequency current on said coaxial transmission path; and
wherein said bias current adjusting load means includes an inductive element in series with an impedance circuit couple by a parallel connection to a terminating resistance element, wherein said impedance circuit includes a capacitive element coupled by a parallel connection to a second inductive element or a second capacitive element, and wherein said inductive element is selected so that the resistance of the coupled current adjusting load means and terminating resistance element approximates the resistance of the terminating resistance element for RF signals.
3. A two-way CATV system according to claim 1 , wherein said AC frequency bias current is set at a level to overcome a diode effect of a coaxial connector in the coaxial transmission path.
4. A two-way CATV system according to claim 1 , wherein said AC frequency bias current is set at a level to match a maximum branch output current level of the bidirectional amplifier.