Abstract: A gain variance and ingress reduction system reduces the overall ingress of interferers for an entire CATV system return transmission path and allows a reduction in subscriber terminal return transmitter power. The system places a calculated loss at each subscriber tap location. By placing these losses at each subscriber location, the headend receives a more consistent return transmission path gain thereby reducing the terminal return transmitter power range requirement. In addition, the losses reduce return transmission path ingress.

Abstract: Selective off-premises jamming for premium CATV service is provided by using continuously running fixed-frequency oscillators (19.1-19.n) for generating jamming signals at each of a plurality of distribution locations (13). The frequency of each oscillator corresponds to the frequency of one of the premium channels. A remotely controlled switched network is provided at each distribution location for applying jamming signals only to those TV channels of the subscriber lines (14) upon which the corresponding subscriber (15) is not entitled to receive premium signals. Since jamming signals are not applied to the TV channels upon which subscribers are entitled to receive premium TV programs, there is no need for de-scrambling apparatus at the various subscriber locations. In various embodiments, the switched network may be an array of switches (20.1-20.n), an array of filter traps (32.1-32.n) or an array of parallel connected band-pass filters (41.1-41.n).

Abstract: An echo canceller stores echo signals in a plurality of sample and hold circuits. These echo signals are selectively switched to the input of a summing amplifier for subtraction from a data plus echo signal. A training sequence detector is utilized to detect the statistical occurrence of a predetermined training signal embedded within a stream of data. The echo canceller requires no analog to digital conversion or digital processer and operates at very high speeds. The circuit may be implemented in integrated circuit form at very low cost.

Abstract: A method of encoding data into a frame, includes the step of providing a frame having a plurality of byte locations for storing a plurality of bytes each associated with one of the byte locations. The value of the initial byte location of the frame is stored in a temporary register. An address of a first byte location having zero value is stored in the initial byte location of the frame. A continuation bit associated with the address of said first byte location is set. The value of the initial byte is stored in the first byte location. The non-zero valued bytes of information are stored in their associated byte locations of the frame. When the initial byte location contains zero, the last location containing an address of a zero valued byte repeats the previous address having a zero valued byte.

Abstract: Stochastic Time Division Multiplexing (STOTDM) is disclosed. in STOTDM data packets are preceded by a flag word. Each data packet appears in a frame of data packets in a predetermined order. If there is no data to be placed in the packet location, only the flag is transmitted and the data location is allocated to other data. By using a fixed length frame, synchronous data packets can be placed near the beginning of the frame and packets which are not timing sensitive may follow them. A variable length frame may also be used wherein data from a plurality of sources are once again ordered and preceded by a flag word or bit. The flag may be used to indicate whether or not the packet location is filled or this may be determined by control packets. Variable length frames may be accommodated as long as the average bandwidth required to transmit the data does not exceed the channel bandwidth.