Abstract: A polling pattern generator system for use in a CATV system including a polling pattern generator and a passive data monitor. The polling pattern generator periodically generates polling pattern signals each of which has a specific address code for calling a corresponding terminal unit and a command code for requesting a designated answer from the called terminal unit. The passive data monitor compares an up data signal outputted from the terminal unit in response to the command code with the designated answer requested by the command code and judges whether or not an operational state of the terminal unit is acceptable from the resultant comparison output. The passive data monitor sets the address code in the designated terminal unit.

Abstract: A polling pattern generator system for use in a CATV system including a polling pattern generator and a passive data monitor. The polling pattern generator periodically generates polling pattern signals each of which has a specific address code for calling a corresponding terminal unit and a command code for requesting a designated answer from the called terminal unit. The passive data monitor compares an up data signal outputted from the terminal unit in response to the command code with the designated answer requested by the command code and judges whether or not an operational state of the terminal unit is acceptable from the resultant comparison output. The passive data monitor sets the address code in the designated terminal unit.

Abstract: A two-way CATV system having a substantial number of terminals incorporates a central processor and transmitter system which continually interrogates the terminals at high speed, monitoring changes of usage of premium programs and other data while also permitting central control of access to restricted premium programs. For inexpensive but reliable intercommunication, short, fixed word length digital messages are frequency multiplexed onto the cable in both upstream and downstream directions, and subscriber groups are controllably selected in turn, with each subscriber being scanned in what may be an arbitrary order by transmission of unique private messages which are recognized at the terminal and in response to which previously prepared fixed length messages are immediately transmitted in return.

Abstract: An output waveform of a manually operable tuning pulse generator of an electronic preset type tuning control device of a tuner using varactor diodes for a multi-band radio receiver is improved by using Schmitt trigger circuit means which may be provided with a trigger level checking circuit, both being provided as IC.

Abstract: In a bidirectional CATV system, in which interrogations and commands to terminals for individual subscribers occur at high speed, the status of individual terminals is checked rapidly and reliably without interfering with other transmissions. In response to diagnostic commands from the head end unit, the terminal responds with a message that is unlike the usual transmission, and identifies the status established in response to prior commands. The head end unit is thereby without delay able to ascertain not only that the prior commands were correctly transmitted and received but that the appropriate actions were taken in response thereto.