Signal processing utilizing a tree-structured array

Abstract

A communication system for sending a sequence of symbols on a communication link. The system includes a transmitter for placing information indicative of the sequence of symbols on the communication link and a receiver for receiving the information placed on the communication link by the transmitter. The transmitter includes a clock for defining successive frames, each of the frames including M time intervals, where M is an integer greater than 1. A modulator modulates each of M carrier signals with a signal related to the value of one of the symbols thereby generating a modulated carrier signal corresponding to each of the carrier signals. The modulated carriers are combined into a sum signal which is transmitted on the communication link. The carrier signals include first and second carriers, the first carrier having a different bandwidth than the second carrier. In one embodiment, the modulator includes a tree-structured array of filter banks having M leaf nodes, each of the values related to the symbols forming an input to a corresponding one of the leaf nodes. Each of the nodes includes one of the filter banks. Similarly, the receiver can be constructed of a tree-structured array of sub-band filter banks for converting M time-domain samples received on the communication link to M symbol values.Signal processing is performed by splitting a signal into subbands using a plurality of filter banks connected to form a tree-structured array. The filter banks are connected so that the signal is split into subbands of different size. The subbands can be designed to approximate the bands of the human auditory system for audio signal processing applications. Reconstruction of signals using a plurality of synthesis filter banks connected to form a tree-structured array is also performed.

1. A communication system for sending a sequence of symbols on a communication link a sequence of symbols having values representative of said symbols, said communication system comprising a transmitter for placing information indicative of said sequence of symbols on said communication link and a receiver for receiving said information placed on said communication link by said transmitter, said transmitter comprising
 a clock for defining successive frames, each said frame comprising M time intervals, where M is an integer greater than 1;  
 a modulator modulating each of M carrier signals with a signal related to the value of one of said symbols thereby generating a modulated carrier signal corresponding to each of said carrier signals that is to be modulated and generating a sum signal comprising a sum of said modulated carrier signals, said modulator comprising a tree-structured array of filter banks having nodes, including a root node and M leaf nodes, each of said values related to said symbols forming an input to a corresponding one of said leaf nodes, each of said nodes, other than said leaf nodes, comprising one of said filter banks; and  
 an output circuit for transmitting said sum signal on said communication link, wherein said carrier signals comprise first and second carriers, said first carrier having a different bandwidth than said second carrier.  
 
     
     
       2. The communication system of  claim 1  wherein said receiver comprises:
 an input circuit for receiving and storing M time-domain samples transmitted on said communication link; and  
 a decoder for recovering said M symbol values, said decoder comprising a tree-structured array of sub-band filter banks, said received M time-domain samples forming the input of a root node of said tree-structured array of said decoder and said M symbol values being generated by the leaf nodes of said tree-structured array of said decoder, each said sub-band filter bank comprising a plurality of FIR filters having a common input for receiving an input time-domain signal, each said filter generating an output signal representing a symbol value in a corresponding frequency band.  
 
     
     
       3. A communication system for sending a sequence of symbols on a communication link, said communication system comprising a transmitter for placing information indicative of said sequence of symbols on said communication link, said transmitter comprising:
 a clock for defining successive frames, each said frame comprising M time intervals, where M is an integer greater than 1;  
 a modulator modulating each of M carrier signals with a signal related to the value of one of said symbols thereby generating a modulated carrier signal corresponding to each of said carrier signals that is to be modulated and generating a sum signal comprising a sum of said modulated carrier signals;  
 an output circuit transmitting said sum signal on said communication link, wherein said carrier signals comprise first and second carriers, said first carrier having a different bandwidth than said second carrier; and  
 a receiver comprising: 
 an input circuit for receiving and storing M time-domain samples transmitted on said communication link; and  
 a decoder for recovering said M symbol values, said decoder comprising a tree-structured array of sub-band filter banks, said received M time-domain samples forming the input of a root node of said tree-structured array said decorder  decoder and said M symbol values being generated by the leaf nodes of said tree-structured array decorder  decoder, each said sub-band filter bank comprising a plurality of FIR filters having a common input for receiving an input time-domain signal, each said filter generating an output signal representing a symbol value in a corresponding frequency band.  
 
 
     
     
       4. The communication system of  claim 3  wherein said modulator comprises a tree-structured array of filter banks having nodes, including a root node and M leaf nodes, each of said values related to said symbols forming an input to a corresponding one of said leaf nodes, each of said nodes, other than said leaf nodes, comprising one of said filter banks. 
     
     
       5. A signal processing method comprising:
 splitting a signal into subbands using a plurality of filter banks connected to form a tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       6. The method of  claim 5 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       7. The method of  claim 5 , wherein the tree-structured array is designed to split a sum of modulated carrier signals. 
     
     
       8. The method of  claim 7 , wherein the tree-structured array is designed to split the sum of modulated carrier signals by transforming the sum of modulated carrier signals into frequency domain symbols, wherein a first frequency domain symbol occupies a first bandwidth and a second frequency domain symbol occupies a second, different bandwidth. 
     
     
       9. The method of  claim 5 , wherein the signal is an audio signal. 
     
     
       10. The method of  claim 5 , wherein at least one of the filter banks is designed to utilize polyphase components. 
     
     
       11. The method of  claim 10 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       12. A signal processing method comprising:
 splitting a signal into sub-bands using a plurality of filter banks connected in a tree-structured array having a first and a second level;    the first level comprising one first level filter bank having more than two filters; and    the second level comprising at least two second level filter banks, each second level filter bank having as input an output from a different filter in the first level, wherein one second level filter bank has a different number of filters than another second level filter bank.   
     
     
       13. The method of  claim 12 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       14. The method of  claim 12 , wherein the signal is a sum of modulated carrier signals. 
     
     
       15. The method of  claim 12 , wherein the signal is an audio signal. 
     
     
       16. The method of  claim 12 , wherein at least one of the filter banks is designed to generate polyphase components. 
     
     
       17. The method of  claim 16 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       18. A signal processing method comprising:
 synthesizing a signal using a plurality of synthesis filter banks connected to form a tree-structured array having greater than two leaf nodes and a root node,    wherein each of the nodes comprises one synthesis filter bank having greater than two filters, with at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       19. The method of  claim 18 , wherein at least one of the synthesis filter banks is designed to utilize polyphase components. 
     
     
       20. The method of  claim 19 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       21. The method of  claim 18 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       22. The method of  claim 18 , wherein the signal is a regenerated time-domain audio signal. 
     
     
       23. The method of  claim 18 , wherein the signal is a sequence of symbols to be transmitted over a communication link. 
     
     
       24. The method of  claim 18 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       25. The method of  claim 18 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       26. A signal processing method comprising:
 synthesizing a signal using a plurality of synthesis filter banks connected in a tree-structured array having a first and a second level,    wherein the first level comprises more than two first level synthesis filter banks, and one first level synthesis filter bank has a different number of filters than another first level synthesis filter bank, and    the second level comprises one synthesis filter bank having more than two filters, the second level having as inputs the outputs of the first level synthesis filter banks.   
     
     
       27. The method of  claim 26 , wherein at least one of the synthesis filter banks is designed to utilize polyphase components. 
     
     
       28. The method of  claim 27 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       29. The method of  claim 26 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       30. The method of  claim 26 , wherein the signal is a reconstructed audio signal. 
     
     
       31. The method of  claim 26 , wherein the signal is a sequence of symbols to be transmitted over a communication link. 
     
     
       32. The method of  claim 26 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       33. The method of  claim 26 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       34. A signal processing system comprising:
 a plurality of filter banks that can connect to form a tree-structured array to split a signal into subbands, the tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       35. The system of  claim 34 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       36. The system of  claim 34 , wherein the signal is a sum of modulated carrier signals. 
     
     
       37. The system of  claim 36 , wherein the tree-structured array is designed to split the sum of modulated carrier signals by transforming the sum of modulated carrier signals into frequency domain symbols, wherein a first frequency domain symbol occupies a first bandwidth and a second frequency domain symbol occupies a second, different bandwidth. 
     
     
       38. The system of  claim 34 , wherein the signal is an audio signal. 
     
     
       39. The system of  claim 34 , wherein at least one of the filter banks is designed to utilize polyphase components. 
     
     
       40. The system of  claim 39 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       41. A signal processing system comprising:
 a plurality of filter banks designed that can connect to form a tree-structured array to split a signal into subbands, the tree-structured array having a first and a second level;    the first level comprising one first level filter bank having more than two filters; and    the second level comprising at least two second level filter banks, each second level filter bank having as input an output from a different filter in the first level, wherein one second level filter bank has a different number of filters than another second level filter bank.   
     
     
       42. The system of  claim 41 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       43. The system of  claim 41 , wherein the signal is a sum of modulated carrier signals. 
     
     
       44. The system of  claim 43 , wherein the sum of modulated carrier signals is transformed into frequency domain symbols, wherein a first frequency domain symbol occupies a first bandwidth and a second frequency domain symbol occupies a second, different bandwidth. 
     
     
       45. The system of  claim 41 , wherein the signal is an audio signal. 
     
     
       46. The system of  claim 41 , wherein at least one of the filter banks is designed to generate polyphase components. 
     
     
       47. The system of  claim 46 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       48. A signal processing system comprising:
 a plurality of synthesis filter banks that can connect to form a tree-structured array to synthesize a signal, the tree-structured array having greater than two leaf nodes and a root node,    wherein each of the nodes comprises one synthesis filter bank having greater than two filters, with at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       49. The system of  claim 48 , wherein at least one of the synthesis filter banks is designed to generate polyphase components. 
     
     
       50. The system of  claim 48 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       51. The system of  claim 48 , wherein the signal is a decompressed audio signal. 
     
     
       52. The system of  claim 48 , wherein the signal is a sequence of symbols to be transmitted over a communication link. 
     
     
       53. The system of  claim 48 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       54. The system of  claim 48 , further comprising a modulator designed to modulate a first symbol onto a carrier having a first bandwidth, and a second symbol onto a carrier having a second, different bandwidth. 
     
     
       55. The system of  claim 48 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       56. The system of  claim 55 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       57. A signal processing system comprising:
 a plurality of synthesis filter banks designed that can connect to form a tree-structured array to synthesize a signal, the tree-structured array having a first and a second level,    wherein the first level comprises more than two first level synthesis filter banks, and one first level synthesis filter bank has a different number of filters than another first level synthesis filter bank, and    the second level comprises one synthesis filter bank having more than two filters, the second level having as inputs the outputs of the first level synthesis filter banks.   
     
     
       58. The system of  claim 57 , wherein at least one of the synthesis filter banks is designed to generate polyphase components. 
     
     
       59. The system of  claim 58 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       60. The system of  claim 57 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       61. The system of  claim 57 , wherein the signal is a regenerated time domain audio signal. 
     
     
       62. The system of  claim 57 , wherein the signal is a sequence of symbols to be transmitted over a communications link. 
     
     
       63. The system of  claim 57 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       64. The system of  claim 57 , further comprising a modulator designed to modulate a first symbol onto a carrier having a first bandwidth, and a second symbol onto a carrier having a second, different bandwidth. 
     
     
       65. The system of  claim 57 , wherein at least one of the synthesis filter banks transforms sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       66. A signal processing system comprising:
 means for splitting a signal into subbands using a plurality of filter banks that can connect to form a tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       67. The system of  claim 66 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       68. The system of  claim 66 , wherein the signal is an audio signal. 
     
     
       69. The system of  claim 66 , wherein at least one of the filter banks is designed to generate polyphase components. 
     
     
       70. The system of  claim 69 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       71. A signal processing system comprising:
 means for splitting a signal into sub-bands using a plurality of filter banks that can connect to form a tree-structured array having a first and a second level;    the first level comprising one first level filter bank having more than two filters; and    the second level comprising at least two second level filter banks, each second level filter bank having as input an output from a different filter in the first level, wherein one second level filter bank has a different number of filters than another second level filter bank.   
     
     
       72. The system of  claim 71 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       73. The system of  claim 71 , wherein the signal is an audio signal. 
     
     
       74. The system of  claim 71 , wherein at least one of the filter banks is designed to generate polyphase components. 
     
     
       75. The system of  claim 74 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       76. A signal processing system comprising:
 means for synthesizing a signal using a plurality of synthesis filter banks that can connect to form a tree-structured array having greater than two leaf nodes and a root node,    wherein each of the nodes comprises one synthesis filter bank having greater than two filters, with at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       77. The system of  claim 76 , wherein at least one of the synthesis filter banks is designed to utilize polyphase components. 
     
     
       78. The system of  claim 77 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       79. The system of  claim 76 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       80. The system of  claim 76 , wherein the signal is a reconstructed audio signal. 
     
     
       81. The system of  claim 76 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       82. The system of  claim 76 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       83. A signal processing system comprising:
 means for synthesizing a signal using a plurality of synthesis filter banks that can connect to form a tree-structured array having a first and a second level,    wherein the first level comprises more than two first level synthesis filter banks, and one first level synthesis filter bank has a different number of filters than another first level synthesis filter bank, and    the second level comprises one synthesis filter bank having more than two filters, the second level having as inputs the outputs of the first level synthesis filter banks.   
     
     
       84. The system of  claim 83 , wherein at least one of the synthesis filter banks is designed to utilize polyphase components. 
     
     
       85. The system of  claim 84 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       86. The system of  claim 83 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       87. The system of  claim 83 , wherein the signal is a reconstructed audio signal. 
     
     
       88. The system of  claim 83 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       89. The system of  claim 83 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       90. An information storage media having stored thereon information that when executed splits a signal into subbands using a plurality of filter banks connected to form a tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node. 
     
     
       91. The media of  claim 90 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       92. The media of  claim 90 , wherein the signal is an audio signal. 
     
     
       93. The media of  claim 90 , wherein at least one of the filter banks is designed to utilize polyphase components. 
     
     
       94. The media of  claim 93 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       95. An information storage media having stored thereon information that when executed splits a signal into sub-bands using a plurality of filter banks connected in a tree-structured array having a first and a second level;
 the first level comprising one first level filter bank having more than two filters; and    the second level comprising at least two second level filter banks, each second level filter bank having as input an output from a different filter in the first level, wherein one second level filter bank has a different number of filters than another second level filter bank.   
     
     
       96. The media of  claim 95 , wherein at least one of the filter banks is designed to utilize cosine modulation. 
     
     
       97. The media of  claim 95 , wherein the signal is an audio signal. 
     
     
       98. The media of  claim 95 , wherein at least one of the filter banks is designed to generate polyphase components. 
     
     
       99. The media of  claim 98 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       100. An information storage media having stored thereon information that when executed synthesizes a signal using a plurality of synthesis filter banks connected to form a tree-structured array having greater than two leaf nodes and a root node,
 wherein each of the nodes comprises one synthesis filter bank having greater than two filters, with at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node.   
     
     
       101. The media of  claim 100 , wherein at least one of the synthesis filter banks is designed to utilize polyphase components. 
     
     
       102. The media of  claim 101 , wherein the polyphase components are generated using a window length of  512  samples. 
     
     
       103. The media of  claim 100 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       104. The media of  claim 100 , wherein the signal is a reconstructed audio signal. 
     
     
       105. The media of  claim 100 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       106. The media of  claim 100 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       107. An information storage media having stored thereon information that when executed synthesizes a signal using a plurality of synthesis filter banks connected in a tree-structured array having a first and a second level,
 wherein the first level comprises more than two first level synthesis filter banks, and one first level synthesis filter bank has a different number of filters than another first level synthesis filter bank, and    the second level comprises one synthesis filter bank having more than two filters, the second level having as inputs the outputs of the first level synthesis filter banks.   
     
     
       108. The media of  claim 107 , wherein at least one of the synthesis filter banks is designed to generate polyphase components. 
     
     
       109. The media of  claim 108 , wherein the polyphase components are generated using a window comprising  512  samples. 
     
     
       110. The media of  claim 107 , wherein at least one of the synthesis filter banks is designed to transform frequency components into polyphase components by cosine modulating the frequency components. 
     
     
       111. The media of  claim 107 , wherein the signal is a decompressed audio signal. 
     
     
       112. The media of  claim 107 , wherein the tree-structured array is designed to synthesize a decompressed audio signal. 
     
     
       113. The media of  claim 107 , wherein at least one of the synthesis filter banks is designed to transform sub-band components into polyphase components by cosine modulating the sub-band components. 
     
     
       114. An information storage media having stored thereon audio information having been split into subbands using a plurality of filter banks connected to form a tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the number of filters in a second leaf node. 
     
     
       115. The media of  claim 114 , wherein the information is audio information. 
     
     
       116. A information storage media having stored thereon audio information having been split into sub-bands using a plurality of filter bands connected in a tree-structured array having a first and a second level;
 the first level comprising one first level filter bank having more than two filters; and    the second level comprising at least two second level filter banks, each second level filter bank having as input an output from a different filter in the first level, wherein one second level filter bank has a different number of filters than another second level filter bank.   
     
     
       117. The media of  claim 116 , wherein the information is audio information. 
     
     
       118. A method of regenerating a signal using a plurality of synthesis filter banks connected to form a tree-structured array having greater than two leaf nodes and a root node,
 wherein each of the nodes comprises one synthesis filter bank having greater than two filters, with at least one of the leaf nodes having a number of filters that differs from the number of filters in a second lead node.   
     
     
       119. The media of  claim 118 , wherein the regenerated signal is an audio signal. 
     
     
       120. A method of reconstructing a signal using a plurality of synthesis filter banks connected in a tree-structured array having a first and a second level,
 wherein the first level comprises more than two first level synthesis filter banks, and one first level synthesis filter bank has a different number of filters than another first level synthesis filter bank, and    the second level comprises one synthesis filter bank having more than two filters, the second level having as inputs the outputs of the first level synthesis filter banks.   
     
     
       121. The media of  claim 120 , wherein the regenerated signal is an audio signal.