Multiresolution digital television broadcast system

Receiver apparatus for receiving signals representing digital images of at least two resolutions including a relatively fine resolution and a relatively coarse resolution, said receiver apparatus comprising:

• means for receiving signals representing signal points which were selected from a signal constellation in a transmitter apparatus, said signal constellation having a plurality of signal-point groups, each signal point group comprising a plurality of signal points which are disposed within the signal-point group in a particular pattern, said signal-point groups being translated versions of one another in said signal constellation, any two neighboring signal points being separated by at least a first distance, at least one signal point within each signal-point group having more than two neighboring signal points separated from said at least one signal point by said first distance;
• first means responsive to said signals for identifying said signal points which were selected, the selected signal points representing said digital images in said relatively fine resolution, said first means including second means for identifying said signal-point groups from which said selected signal points originate, said signal-point groups representing said digital images in said relatively coarse resolution, said first distance being shorter than a second distance between any two neighboring signal-point groups in said signal constellation, a ratio of said first distance to said second distance being pre-selected so that said selected signal points are identifiable by said receiver apparatus within a first radius of said transmitter apparatus and only said signal-point groups are identifiable by said receiver apparatus between said first radius and a second radius of said transmitter apparatus, said first radius being shorter than said second radius.

A system for broadcasting signals representing digital images in at least two resolutions including a relatively fine resolution and a relatively coarse resolution, said system comprising:

• transmitter apparatus comprising
• means for providing a sequence of digital images;
• means for processing said sequence of digital images to provide at least a relatively fine resolution version and a relatively coarse resolution version thereof;
• first means for selecting signal points from a signal constellation having a plurality of signal-point groups, each signal-point group comprising a plurality of signal points which are disposed within the signal-point group in a particular pattern, said signal-point groups being translated versions of one another in said signal constellation, any two neighboring signal points being separated by at least a first distance, at least one signal point within each signal-point group having more than two neighboring signal points separated from said at least one signal point by said first distance, signal points selected by said first means representing said relatively fine resolution version of said digital images, said first means including second means for selecting signal-point groups from which said signal points selected by said first means originate, signal-point groups selected by said second means representing said relatively coarse resolution version of said digital images;
• and
• means for transmitting signals representing said signal points selected by said first means, said first distance being shorter than a second distance between any two neighboring signal-point groups in said signal constellation, a ratio of said first distance to said second distance being pre-selected so that said relatively fine resolution versions are recoverable when said signals are received within a first radius of said transmitter apparatus and said relatively coarse resolution versions are recoverable when said signals are received between said first radius and a second radius of said transmitter apparatus, said first radius being shorter than said second radius;
• and
• receiver apparatus comprising
• means for receiving said signals;
• and
• means responsive to said signals for recovering said digital images of at least said relatively coarse resolution.