摘要:
In a digital broadcast communications system, a higher priority component and a lower priority component are broadcast from a transmitter to a receiver. Each of these components generates a main and a supplemental signal, and each supplemental signal is advanced in time with respect to the corresponding main signal. The main and supplemental signals for both the higher and lower priority components are combined into a single signal, which is broadcast to a receiver. In the receiver, the time advanced supplemental signals are stored in a buffer to time align them with their corresponding main signals. Both main signals are processed in the normal manner in the receiver, and are also monitored to detect a fading event. When a fading event is detected, the corresponding buffered supplemental signals are substituted for the faded main signals and normal processing continues.
摘要:
An apparatus for use in a cable system comprises a port for receiving a downstream cable transmission; a demodulator for receiving an upstream signal for providing a demodulated signal; and a modulator for modulating the demodulated signal for providing a downstream signal for addition to the received downstream cable transmission.
摘要:
A cable network tap comprises a first port for coupling to an upstream portion of a cable network and for receiving a downstream signal; a second port for coupling to a downstream portion of the cable network and receiving an upstream signal; and a filter for filtering at least one of the downstream signal and the upstream signal. The filter has a bandwidth that is adjustable in accordance with a plurality of cable network bandwidth configurations, each cable network bandwidth configuration allocating bandwidth differently between upstream communications and downstream communications over at least a portion of the cable network.
摘要:
A remodulator system includes a source of an input transport packet stream and an input packet buffer coupled to the input transport packet stream source. The input packet buffer generates a status signal indicating whether it is: full, empty, or neither empty nor full. An output packet stream generator is coupled to the input packet stream buffer and responsive to an output clock signal, and generates the output packet stream in synchronism with the output clock signal. A variable output clock signal generator generates the output clock signal responsive to a control signal, and a control signal generator generates the control signal in response to the status signal.
摘要:
A system for receiving a plurality of broadcast channels transmitted with different polarizations includes a first demodulator for demodulating a first channel having a first polarization to produce a first demodulated channel signal, and a second demodulator for demodulating a second channel having a second polarization, opposite to the first polarization, to produce a second demodulated channel signal. An adaptive interference cancellation network, coupled to the first and second demodulators, cancels interference, derived from the second channel, in the first demodulated channel signal to produce a received signal.
摘要:
A digital high definition television receiver equalizer system includes an input adaptive feed forward filter (FFF 20), a carrier recovery network (46), and a slicer (40) in addition to an adaptive decision feedback filter (DFF, 30) for removing intersymbol interference. At the beginning of a blind equalizing interval the FFF is not adapted and the DFF operates as a linear filter with adapted coefficients for equalizing post-ghosts. Afterwards in the blind interval the FFF coefficients are adapted blindly for equalizing pre-ghosts. In a subsequent decision-directed mode the slicer output is used for adapting both the FFF and DFF non-linearly.
摘要:
An apparatus for use in a cable system comprises a first port for use in coupling to a portion of a cable network for receiving an upstream signal having a frequency spectrum including a first frequency band; and a reflector for reflecting the received upstream signal back downstream via the first port; wherein the first frequency band is different from those frequency bands used by a head-end of the cable network for Internet communications.
摘要:
An implementation provides a transmitter that separates sequential portions of data in a first set of data by time intervals allowing a power saving mode (1005). The transmitter transmits the sequential portions of data separated by respective time intervals having lengths configured to allow a receiver to enter and exit a power saving mode between receiving sequentially transmitted portions of data from the first set of data (1010). The transmitter separates sequential portions of data in a second set by time intervals that are not of sufficient length to allow a receiver to enter and exit a power saving mode during the time intervals (1015). The second set of data is then transmitted (1020).
摘要:
A satellite television ground system, particularly for a make or break satellite television signal system, includes an outdoor unit and an indoor unit that are in communication with each other via a single coaxial cable and an optional separate single conductor for power. The satellite television ground system is operative to measure and reverse frequency conversion errors utilizing DSP techniques, allowing for more precise generation and transmission of uplink signals from the satellite television ground system. Control data for the system is sent via a low data rate connection on a power cable thereof, or by a narrowband signaling channel via a coax cable. The system also utilizes a single reference oscillator to drive the various frequency synthesizers and the like. The satellite television ground system utilizes related oscillators for the uplink and downlink sections. Carrier frequency offset in the downlink is measured in a carrier tracking loop part of a television signal demodulator. The carrier frequency offset of the downlink is utilized to synthesize various frequency signals for the uplink and downlink sections to correct frequency errors. For the uplink section, the carrier frequency offset of the downlink is reversed in the uplink. If the uplink is on a different frequency, the measured offset of the system master oscillator can be scaled by different synthesizer ratios.
摘要:
An output packet stream generator in a remodulator system includes a source of a stream of input transport packets and a source of additional packets. A multiplexer is coupled to the input transport packet stream source and the additional packet source and generates the output packet stream. A control signal has a variable characteristic having a first state when an input transport packet should be inserted into the output packet stream and a second state when additional packets should be inserted into the output packet stream. A multiplexer controller conditions the multiplexer to insert an input transport packet into the output packet stream when the control signal has the first state, and an additional packet into the output packet stream when the control signal has the second state.