Method and apparatus for echo cancellation in digital ATV systems using an echo cancellation reference signal

A method of processing a digital data stream having echo interference from transmission over a transmission path, the digital data stream having a plurality of field syncs and a plurality of segments of symbol spaces between successive ones of the field syncs, the method comprising:

• identifying a plurality of echo cancellation reference signals between the field snycs;
• processing the digital data stream with the echo cancellation reference signals to provide a substantially echo-free digital data stream;
• and
• furnishing the substantially echo-free digital data stream to a digital television receiver;
• wherein the echo cancellation reference signals are of a class of signals substantially defined by
• 7 f ⁢ ( t ) = 1 2 ⁢ π ⁢ ∫ 0 Ω ⁢ [ A ⁢ ⁢ cos ⁢ ( b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω + 1 2 ⁢ π ⁢ ∫ - Ω 0 ⁢ [ A ⁢ ⁢ cos ⁢ ( - b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( - b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω
• A, b and Ω being real numbers.

A system for cancellation of echo interference in a transmitted data stream, comprising:

• means for inserting a plurality of echo cancellation signals into an ATSC VSB digital data stream prior to transmission to generate a transmission digital data stream, the ATSC VSB data stream comprising a plurality of field syncs and a plurality of segments of symbol spaces between successive ones of the field syncs, and the echo cancellation reference signals being inserted between the field snycs and being of a class of signals substantially defined by
• 8 f ⁢ ( t ) = 1 2 ⁢ π ⁢ ∫ 0 Ω ⁢ [ A ⁢ ⁢ cos ⁢ ( b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω + 1 2 ⁢ π ⁢ ∫ - Ω 0 ⁢ [ A ⁢ ⁢ cos ⁢ ( - b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( - b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω
• wherein A, b and Ω are real numbers;
• means for transmitting the transmission digital data stream;
• an equalizer having an input for receiving the transmission digital data stream, the equalizer operatively processing the transmission digital data stream at the input thereof with the echo cancellation reference signals to provide a substantially echo-free digital data stream at an output thereof, and
• a VSB digital television receiver having an input coupled to the output of the equalizer.

A method for cancellation of echo interference in a transmitted data stream, comprising:

• inserting a plurality of echo cancellation signals into an ATSC VSB digital data stream prior to transmission to generate a transmission digital data stream, the ATSC VSB data stream comprising a plurality of field syncs and a plurality of segments of symbol spaces between successive ones of the field syncs, and the echo cancellation reference signals being inserted between the field snycs and being of a class of signals substantially defined by
• 9 f ⁢ ( t ) = 1 2 ⁢ π ⁢ ∫ 0 Ω ⁢ [ A ⁢ ⁢ cos ⁢ ( b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω + 1 2 ⁢ π ⁢ ∫ - Ω 0 ⁢ [ A ⁢ ⁢ cos ⁢ ( - b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( - b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω
• wherein A, b and Ω are real numbers;
• transmitting the transmission digital data stream;
• subsequent to the transmitting step, processing the transmission digital data stream with the echo cancellation reference signals therein to provide a substantially echo-free digital data stream;
• and
• applying the substantially echo-free digital data stream to a VSB digital television receiver.

An ATSC 8 VSB digital television receiver system comprising:

• an equalizer having an input for receiving a transmitted digital data stream comprising a plurality of field syncs, a plurality of segments of symbol spaces between successive ones of the field syncs, and a plurality of macro echo cancellation reference assembly signals between successive ones of the field snycs, each of the macro echo cancellation reference assembly comprising a plurality of blank symbol spaces and at least one echo cancellation reference signal, the equalizer operatively processing the digital data stream at the input thereof with the echo cancellation reference signals to provide a substantially echo-free digital data stream at an output thereof;
• a FIFO register to operatively remove the echo cancellation reference signals from the digital data stream at the output of the equalizer;
• and
• a standard 8 VSB digital television receiver having an input coupled to the output of the FIFO register;
• wherein the echo cancellation reference signals are of a class of signals substantially defined by
• 10 f ⁢ ( t ) = 1 2 ⁢ π ⁢ ∫ 0 Ω ⁢ [ A ⁢ ⁢ cos ⁢ ( b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω + 1 2 ⁢ π ⁢ ∫ - Ω 0 ⁢ [ A ⁢ ⁢ cos ⁢ ( - b ⁢ ⁢ ω 2 ) + j ⁢ ⁢ A ⁢ ⁢ sin ⁢ ( - b ⁢ ⁢ ω 2 ) ] ⁢ ⅇ jω ⁢ ⁢ t ⁢ ⁢ ⅆ ω
• A, b and Ω being real numbers.