Information Resources, Inc.

Other

W Andrew Wright, Jr

Gerald J Eskin

Ned W Cogswell

A signal splitter circuit accepts an input signal and conveys the input signal to two output ports. The circuit operates with minimal attenuation, throughout a very wide bandwidth, and also effectively isolates the output ports from each other. The signal from the input port is coupled to an autotransformer, and the ends of the autotransformer are connected to the respective output ports. A bridge load circuit which includes a transformer winding and a load connected in parallel, is inductively coupled to the autotransformer. The bridge load circuit has no connection to the splitter circuit, other than through the inductive coupling. The splitter circuit also includes inductors in series with the output ports and capacitors in parallel with the output ports. The circuit provides a balanced bridge circuit which cancels signals traveling between the output ports, and the inductors and capacitors provide impedance matching between the input port and output ports. The arrangement of the bridge load circuit places the leakage inductance of the autotransformer outside the effective path of the bridge load circuit, so that the leakage inductance cannot cause unwanted and unpredictable phase shifts at high frequencies.

CATV signal splitter

A fast tuning subsystem includes a tuner for selecting a channel, with a voltage controlled oscillator having a control input for determining the channel frequency the tuner selectively receives. A predictor supplies a selected predicted voltage signal from memory to the control input of the oscillator to slew the channel frequency at a rapid slew rate to the frequency corresponding to the selected predicted voltage signal. An error detector generates a tuning error signal indicative of the tuning error of the tuner off the frequency for the selected channel. The tuning error signal is combined with the selected predicted voltage signal to provide a control signal for adjusting the channel frequency to reduce the tuning error. The subsystem also similarly controls the amplitude of the received channel. The tuning subsystem automatically and from time to time changes the signals stored in the memory for respective channels to signals corresponding to the control signals applied after long term feedback. The feedback provides successively a correction mode and a station-keeping mode. The correction mode provides correction of any error in tuning of an acquired channel fast enough that the correction is substantially imperceptible to the eye and any residual error is substantially imperceptible to the eye. The station-keeping mode operates slowly enough to filter out noise and spurious signals and maintain any residual error below a predetermined limit over long periods of time.

Fast tuning control for a television system

A signal matching signal substitution system includes a tuner for selectively receiving signals in respective television channels with an input gain control for controlling the signal output level of the tuner. The system substitutes television signals in a substitute channel in lieu of normal signals in a normal channel selected by a viewer. The system has a component for determining the input signal level of currently received signals in a currently received channel and generating a current amplitude signal. A set point generator is responsive to the current amplitude signal corresponding to the normal channel most currently received for providing a set point for the output signal level. A gain control signal generator is responsive to the set point and the signal output level for generating a gain control signal maintaining the output level at the set point. The set point may be set at a predetermined fixed level when the current amplitude signal corresponding to the most current normal channel is relatively high and is set at progressively lower levels when the current amplitude signal corresponding to the most current normal channel is below a transition level. The set point at the progressively lower levels is noise limited to provide substantially equal signal to noise ratios in the signal output of the tuner in both the normal and the substitute channels upon signal substitution. The set point is gain limited to the maximum signal output achievable by the gain control for the normal channel.

Signal matching signal substitution

A signal substitution system for cable television applies substitute television program signals in at least one substitute channel to the transmission cable along with signal substitution control signals. The signal substitution control signals include a plurality of different terminal command signals and a plurality of different event command signals. Each of the terminal command signals includes a respective panelist address signal for identifying a respective panelist receiving station and a plurality of event identification signals identifying respective events. Each of the event command signals includes a respective event address signal corresponding to a respective event and a normal channel identification signal for identifying a normal channel into which a substitute television program is to be switched. A controller at each panelist receiving station responds to the signal substitution control signals by selectively switching a substitute television program into a normal channel. The controller stores event signals corresponding to the event identification signals of the respective terminal command signal. When a received event address signal corresponds to a local event address signal and the received normal channel identification signal corresponds to a channel select signal selected by the viewer, a substitute channel is substituted for the channel selected by the viewer for a period determined by the event command signals.

Cable television with multi-event signal substitution

A signal substitution system for cable television applies substitute television program signals in at least one substitute channel to the transmission cable along with singal substitution control signals. The signal substitution control signals include a plurality of different terminal command signals and a plurality of different event command signals, each of the terminal command signals including a respective panelist address signal for identifying a respective panelist receiving station, and each of the event command signals including a normal channel identification signal for identifying a normal channel into which a substitute television program is to be switched. A controller at each panelist receiving station responds to the signal substitution control signals by selectively switching a substitute television program into a normal channel. The controller includes a generator of a local panelist address signal and a substitute channel selector for producing a substitute channel select signal corresponding to a substitute channel. A first comparator compares the received panelist address signal of each terminal command signal with the local panelist address signal and produces a first match signal when the signals match. A second comparator compares the received normal channel identification signal with a channel select signal selected by the viewer and produces a second match signal when the signals match. In response to the first and second match signals a substitute channel is substituted for the channel selected by the viewer for a period determined by the signal substitution control signals.

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Bethlehem, PA, United States of America

W Andrew Wright, Jr