Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by changing the amplitude of the legacy data symbols. In exemplary embodiments of the present invention, additional data capacity can be achieved for a COFDM signal which is completely backwards compatible with existing legacy satellite broadcast communications systems. In exemplary embodiments of the present invention, additional information can be overlaid on a legacy COFDM signal by applying an amplitude offset to the legacy symbols. In exemplary embodiments of the present invention, special receiver processing can be implemented to extract this additional information, which can include performing channel equalization across frequency bins to isolate the amplitude modulated overlay signal.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by modulating existing data carriers with a phase and an amplitude offset. In exemplary embodiments of the present invention, additional data capacity can be achieved for an COFDM signal which is completely backwards compatible with existing satellite broadcast communications systems. In exemplary embodiments of the present invention additional information can be overlayed on an existing signal as a combination of amplitude and phase offset from the original QPSK symbols, applied for each information bit of the overlay data. With two additional levels of modulation, a receiver can demodulate the information from each of the previous stages and combine the information into a suitable format for soft decoding. The first stage of demodulation will be recovery of overlay data from the amplitude modulated D8PSK.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by changing the amplitude of the legacy data symbols. In exemplary embodiments of the present invention, additional data capacity can be achieved for a COFDM signal which is completely backwards compatible with existing legacy satellite broadcast communications systems. In exemplary embodiments of the present invention, additional information can be overlaid on a legacy COFDM signal by applying an amplitude offset to the legacy symbols. In exemplary embodiments of the present invention, special receiver processing can be implemented to extract this additional information, which can include performing channel equalization across frequency bins to isolate the amplitude modulated overlay signal.

Abstract: Systems and methods are presented for improving the ability to withstand slow speed mute via diversity transmission while avoiding loss in link level margin. In exemplary embodiments of the present invention, systems and methods are presented for improving resistance to slow speed muting by employing transmit diversity where a second signal is not a replica of the original signal. The second signal can be generated, for example, by using only a COFDM FFT bin that contained the cluster sync bit while setting all other bins to zero. That is, only the spectral portion of interest of the COFDM signal need be utilized. In such exemplary embodiments, the same frequency and time delay offset can be used as in current systems and methods, except that the replica COFDM signal can, for example, consist of only one populated FFT bin.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by modulating existing data carriers with a phase and an amplitude offset. In exemplary embodiments of the present invention, additional data capacity can be achieved for an COFDM signal which is completely backwards compatible with existing satellite broadcast communications systems. In exemplary embodiments of the present invention additional information can be overlayed on an existing signal as a combination of amplitude and phase offset from the original QPSK symbols, applied for each information bit of the overlay data. With two additional levels of modulation, a receiver can demodulate the information from each of the previous stages and combine the information into a suitable format for soft decoding. The first stage of demodulation will be recovery of overlay data from the amplitude modulated D8PSK.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by changing the amplitude of the legacy data symbols. In exemplary embodiments of the present invention, additional data capacity can be achieved for a COFDM signal which is completely backwards compatible with existing legacy satellite broadcast communications systems. In exemplary embodiments of the present invention, additional information can be overlaid on a legacy COFDM signal by applying an amplitude offset to the legacy symbols. In exemplary embodiments of the present invention, special receiver processing can be implemented to extract this additional information, which can include performing channel equalization across frequency bins to isolate the amplitude modulated overlay signal.

Abstract: Systems and methods are presented for digital antenna diversity combining. In exemplary embodiments of the present invention, at least two antenna signal paths can be communicably connected to a receiver. Each antenna signal path can be provided with an RF tuner communicably connected to a demodulator, which can estimate the signal to noise ratio (SNR) and time of arrival of its respective antenna signal. In exemplary embodiments of the present invention, a time alignment circuit can be communicably connected to each antenna signal path, and a maximum ratio combiner can be communicably connected to the time alignment circuit. In operation, the time alignment circuit can use the time of arrival estimate to align the multiple signals and the maximum ratio combiner can use the SNR estimate obtained for each antenna signal to respectively weight each signal and thereby generate a combined output signal.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by modulating existing data carriers with a phase and an amplitude offset. In exemplary embodiments of the present invention, additional data capacity can be achieved for an COFDM signal which is completely backwards compatible with existing satellite broadcast communications systems. In exemplary embodiments of the present invention additional information can be overlayed on an existing signal as a combination of amplitude and phase offset from the original QPSK symbols, applied for each information bit of the overlay data. With two additional levels of modulation, a receiver can demodulate the information from each of the previous stages and combine the information into a suitable format for soft decoding. The first stage of demodulation will be recovery of overlay data from the amplitude modulated D8PSK.

Abstract: Systems and methods are presented for improving the ability to withstand slow speed mute via diversity transmission while avoiding loss in link level margin. In exemplary embodiments of the present invention, systems and methods are presented for improving resistance to slow speed muting by employing transmit diversity where a second signal is not a replica of the original signal. The second signal can be generated, for example, by using only a COFDM FFT bin that contained the cluster sync bit while setting all other bins to zero. That is, only the spectral portion of interest of the COFDM signal need be utilized. In such exemplary embodiments, the same frequency and time delay offset can be used as in current systems and methods, except that the replica COFDM signal can, for example, consist of only one populated FFT bin.

Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by changing the amplitude of the legacy data symbols. In exemplary embodiments of the present invention, additional data capacity can be achieved for a COFDM signal which is completely backwards compatible with existing legacy satellite broadcast communications systems. In exemplary embodiments of the present invention, additional information can be overlaid on a legacy COFDM signal by applying an amplitude offset to the legacy symbols. In exemplary embodiments of the present invention, special receiver processing can be implemented to extract this additional information, which can include performing channel equalization across frequency bins to isolate the amplitude modulated overlay signal.

Abstract: A robust data extension added to a standard 8VSB digital television signal is used to improve the performance of a digital television receiver. The robust data extension is added to a standard 8VSB digital television transmission system by encoding high priority data packets in a rate 1/2 trellis encoder. The high priority data 1/2 trellis encoded packets are then multiplexed with normal data packets and input into the normal data service of an 8VSB system, which further contains a rate 2/3 trellis encoder. The combined trellis encoding results in a rate 1/3 trellis encoding for robust data packets and a rate 2/3 trellis encoding for normal packets. Backward compatibility with existing receivers is maintained for 1) 8VSB signaling, 2) trellis encoding and decoding, 3) Reed Solomon encoding and decoding, and 4) MPEG compatibility. In addition to delivery of robust data for mobile applications, the redundant robust data packets also improve the performance of the receiver in the normal tier of service.

Abstract: Systems and methods are presented for digital antenna diversity combining. In exemplary embodiments of the present invention, at least two antenna signal paths can be communicably connected to a receiver. Each antenna signal path can be provided with an RF tuner communicably connected to a demodulator, which can estimate the signal to noise ratio (SNR) and time of arrival of its respective antenna signal. In exemplary embodiments of the present invention, a time alignment circuit can be communicably connected to each antenna signal path, and a maximum ratio combiner can be communicably connected to the time alignment circuit. In operation, the time alignment circuit can use the time of arrival estimate to align the multiple signals and the maximum ratio combiner can use the SNR estimate obtained for each antenna signal to respectively weight each signal and thereby generate a combined output signal.