Abstract: A method and apparatus for isolating a noise intolerant device, e.g., a phase-lock loop of a tuner within a television receiver, from source of noise. In one embodiment, the apparatus isolates a phase-lock loop integrated circuit (IC) from the bus, by providing an isolation buffer that allows the receiver to only pass data to the tuner's phase-lock loop IC when a tune command is issued by a processor. When not being tuned, the IIC lines to the tuner are held HIGH by a buffer until needed again to perform the tuning function. This allows the demodulation circuitry to use a setting for a carrier tracking-loop that optimizes bit error rate performance.

Abstract: A television, such as an HDTV receiver, includes a plurality of signal inputs each of which is adapted to receive television signals comprising a plurality of channels and communicate the received television signals to a processor/tuner for selection of the various channels by a user for viewing on a display of the television. A channel search routine for the detection of channels in the television signal is accomplished on the currently designated signal input rather than on all signal inputs of the television. The channels detected during the search of the currently designated signal input are included in a channel list that is stored in memory of the television. A GUI is preferably used to initiate the channel search and is capable of displaying the detected channels relating to the currently selected signal input. Channel lists for each signal input are updated as the channels are detected.

Abstract: A method and apparatus for isolating a noise intolerant device, e.g., a phase-lock loop of a tuner within a television receiver, from source of noise. In one embodiment, the apparatus isolates a phase-lock loop integrated circuit (IC) from the bus, by providing an isolation buffer that allows the receiver to only pass data to the tuner's phase-lock loop IC when a tune command is issued by a processor. When not being tuned, the IIC lines to the tuner are held HIGH by a buffer until needed again to perform the tuning function. This allows the demodulation circuitry to use a setting for a carrier tracking-loop that optimizes bit error rate performance.

Abstract: A software packet error system for a High Definition Television (HDTV) receiver. A data packet error signal is transferred from a forward error correcting Reed-Solomon decoder to a transport processor. In response to a segment sync signal, the transport processor generates an error signal which appears on a programmable output pin. The software packet error signal is synchronized with the outgoing data packet signal such that each data packet is bracketed or framed by its associating packet error signal. Precession of the start of the data packets forwarded on the transport but relative to the start of the data packets appearing at the output of the decoder occurs as a result of a training packet generated for every 312 data packets. The precession is reset at the beginning of every field and is predictable across the field duration with sufficient accuracy to make the software packet error mechanism feasible.

Abstract: A method and apparatus for reliably detecting MPEG-2 packet sync-byte positions received via a digital transmission system in the event of a packet stream containing a plurality of null packets of a plurality of packets containing a fixed repeating bit pattern and for reliably synchronizing and delivering the MPEG-2 stream broadcast to the receiver transport layer. A Null-Packet Detector compares the content of the current packet with a fixed (or predetermined) bit pattern to detect a null packet to reliably identify the location of the sync-byte of the null packet. a sync-byte position is identified based upon the position of the predetermined fixed bit pattern in the header portion of a plurality of null-packets in the stream.

Abstract: An apparatus (20) such as a television signal receiver provides an AGC function by using multiple feedback sources which provide both narrow band and wide band AGC signals in an adaptive manner. According to an exemplary embodiment, the apparatus (20) includes a tuner (10, 15, 20, 25, 30) operative to generate first and second IF signals. A first demodulator (40) is operative to generate a first AGC signal responsive to the first IF signal. A second demodulator (50) is operative to generate a second AGC signal responsive to the second IF signal. A wide band AGC detector (60) is operative to generate a third AGC signal responsive to at least one of the first and second IF signals. A switch (70) is operative to selectively provide one of the first, second and third AGC signals to the tuner (10, 15, 20, 25, 30) responsive to a predetermined condition.

Abstract: A technique for performing channel detection in a device such as a television signal receiver is capable of quickly determining the analog and/or digital broadcast channels available in a given area. According to an exemplary embodiment, a method for performing channel detection includes tuning a first frequency channel, determining whether a signal parameter associated with the first frequency channel exceeds a predetermined threshold, and enabling a first channel acquisition operation responsive to determining that the signal parameter exceeds the predetermined threshold.

Abstract: A system is described for establishing timing synchronism between a local receiver symbol clock and a transmitter symbol clock. A prescribed number of offset values are calculated for desired symbol timing range, the offset values being grouped substantially symmetrically about a central offset value. Each of the preselected offset values are tested to see if symbol timing recovery lock can be achieved by starting at the central offset value and gradually moving away from such value. Finally, two timing detection algorithms are used and switched between the two algorithms is carried out as desired to maximize the possibility of STR lock.

Abstract: A method and apparatus for identifying a false MPEG-2 packet synchronization lock condition by parsing MPEG-2 packets that may have been incorrectly delineated by a sync-byte checksum-decoder, to detect resulting anomalies. Forcing the restart of the conventional checksum-encoded sync-byte synchronization/lock process upon generating a “resync” command based upon the anomalies detected by a False Lock Detector. Reliably synchronizing and delivering the MPEG-2 stream to the receiver transport layer. The False-Lock Detector circuit compares the content of the currently identified packet header or payload portion of a sync-byte delineated packet with expected values in order to detect a false-lock condition and to eliminate false sync-byte position-candidates from the basis of a “synchronization lock”.

Abstract: The present invention provides a method and apparatus for processing a received television signal comprising one of a first type of television signal and a second type of television signal. Specifically, the method comprises amplifying the received television signal in response to a control signal. If the received television signal comprises the first type of television signal, the RF amplifier gain is reduced when the received television signal exceeds a first signal level. If the received television signal comprises the second type of television signal, the RF amplifier gain is reduced when the received television signal exceeds a second signal level. The second signal level is greater than the first signal level. A concomitant apparatus is also provided. As the first signal level is lower for the first type of television signal, reception of the first type of television signal is improved.

Abstract: A method and apparatus for isolating a noise intolerant device, e.g., a phase-lock loop of a tuner within a television receiver, from source of noise. In one embodiment, the apparatus isolates a phase-lock loop integrated circuit (IC) from the bus, by providing an isolation buffer that allows the receiver to only pass data to the tuner's phase-lock loop IC when a tune command is issued by a processor. When not being tuned, the IIC lines to the tuner are held HIGH by a buffer until needed again to perform the tuning function. This allows the demodulation circuitry to use a setting for a carrier tracking-loop that optimizes bit error rate performance.

Abstract: A television receiver for receiving digital and analog signals that reduces adjacent channel interference when receiving digital signals susceptible to interference caused by a lower adjacent NTSC signal. Upon receiving the digital signal, the receiver heterodynes the digital signal with a local oscillator (LO) signal to produce an intermediate frequency (IF) signal. A microprocessor searches a memory unit for stored information regarding the digital broadcast channel and determines the presence or absence of a lower adjacent NTSC channel. In the case a lower adjacent NTSC channel is present, the microprocessor shifts the frequency of the LO signal causing the IF signal to shift towards the lower band edge of a surface acoustic wave (SAW) filter present in a digital signal processor further attenuating the lower adjacent NTSC channel.

Abstract: Channel acquisition in a digital television signal receiver is improved by determining the carrier tracking loop frequency offsets and the symbol timing recovery offsets for each channel in the television receiver. Offsets are stored in respective EEPROMs for each channel. When a channel is to be acquired in the TV receiver the tune command will be applied to the appropriate EEPROMs and the respective values are conveyed to the VSB demodulator to start acquisition of the channel.

Abstract: A method and apparatus for isolating a noise intolerant device, e.g., a phase-lock loop of a tuner within a television receiver, from source of noise. In one embodiment, the apparatus isolates a phase-lock loop integrated circuit (IC) from the bus, by providing an isolation buffer that allows the receiver to only pass data to the tuner's phase-lock loop IC when a tune command is issued by a processor. When not being tuned, the IIC lines to the tuner are held HIGH by a buffer until needed again to perform the tuning function. This allows the demodulation circuitry to use a setting for a carrier tracking-loop that optimizes bit error rate performance.

Abstract: A multipath signal strength indicator is included in a communications receiver which is responsive to a communications channel subject to a multipath signal. The multipath signal strength indicator includes circuitry for estimating the characteristics of the communications channel and circuitry for storing nominal characteristics of a communications channel free of the multipath signal. Further circuitry calculates the difference between the nominal characteristic and the estimated channel characteristic as the multipath signal strength.

Abstract: A multipath signal strength indicator is included in a communications receiver which is responsive to a communications channel subject to a multipath signal. The multipath signal strength indicator includes circuitry for estimating the characteristics of the communications channel and circuitry for storing nominal characteristics of a communications channel free of the multipath signal. Further circuitry calculates the difference between the nominal characteristic and the estimated channel characteristic as the multipath signal strength.

Abstract: In a receiver for processing a VSB modulated signal containing terrestrial broadcast high definition television information including data packets, the received signal is converted to a digital signal (19), demodulated (22) and equalized by an adaptive channel equalizer (34). An equalized signal is processed by decoding networks including a Reed-Solomon FEC error detecting and correcting network (44). The equalizer filter coefficient step size is dynamically adjusted during the adaption process as a function of the packet error rate. A local microcontroller (60) monitors the packet error rate at the Reed-Solomon error detector and instructs the equalizer to adjust the coefficient step size in a direction to reduce the packet error rate.