Look up table based upsampling and digital filtering
View Patent ↗A system and method are disclosed for processing a signal that includes receiving encoded data including a plurality of input symbols; generating an input symbol set from the plurality of input symbols; looking up a plurality of output samples for the input symbol set; and outputting the plurality of output samples.
1. A method of processing a signal including: receiving encoded data including a plurality of input symbols; generating an input symbol set from the plurality of input symbols; looking up a plurality of output samples that correspond to a plurality of interpolated values of the input symbol set; and outputting the plurality of time shifted output samples; wherein looking up the plurality of output samples includes: finding the outputs in a plurality of lookup tables (LUTs); and selecting an appropriate LUT for a given output sample using a multiplexer.
2. A method of processing a signal as recited in claim 1 wherein the input symbol set includes six symbols.
3. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes finding the outputs in a LUT having a plurality of entries and wherein the plurality of entries in the LUT correspond to time shifted output samples.
4. A method of processing a signal as recited in claim 1 wherein generating the input symbol set from the plurality of input symbols includes storing the input symbol set in a memory device.
5. A method of processing a signal as recited in claim 1 generating the input symbol set from the plurality of input symbols includes storing the input symbol set in a memory device and wherein looking up the plurality of output samples includes finding the outputs in a LUT.
6. A method of processing a signal as recited in claim 1 wherein the plurality of input symbol sets are split into I and Q components and the I and Q components are used as inputs to separate LUTs to obtain the plurality of output samples.
7. A method of processing a signal as recited in claim 1 wherein the plurality of output samples comprise a band limited signal.
8. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes finding the outputs in a LUT and wherein the LUT includes a beginning section and an ending section.
9. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes finding the outputs in a LUT and wherein the LUT includes a beginning section, a middle section and an ending section.
10. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes finding the outputs in a LUT and wherein the LUT is compressed.
11. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes finding the outputs in a LUT and wherein the LUT excludes certain potential input sets.
12. A method of processing a signal as recited in claim 1 wherein the plurality of LUTs are used in conjunction with a state counter.
13. A method of processing a signal as recited in claim 1 wherein looking up the plurality of output samples includes:
finding possible output samples in a plurality of LUTs using a first state counter; and
selecting the output samples from the possible output samples using a multiplexer and a second state counter.
14. A method of processing a signal as recited in claim 1 , further comprising encoding a plurality of inputs to generate the encoded data.
15. A method of processing a signal as recited in claim 1 wherein the plurality of input symbols has a lower clock rate than the plurality of output samples.
16. A method of processing a signal including: receiving encoded data including a plurality of input symbols; generating an input symbol set from the plurality of input symbols; looking up a plurality of output samples that correspond to a plurality of interpolated values of the input symbol set; and outputting the plurality of time shifted output samples; wherein looking up the plurality of output samples includes finding the outputs in a plurality of lookup tables (LUTs) each having a plurality of entries and wherein the plurality of entries in each of the plurality of LUTs corresponds to interleaved output samples.
17. A system for processing a signal including: an input for receiving encoded data including a plurality of input symbols; symbols; a first memory for storing an input symbol set derived from the plurality of input a second memory configured to store a plurality of interpolated time shifted output samples; wherein the plurality of time shifted output samples are obtained by looking up the input symbol set; and wherein the second memory includes a plurality of lookup tables (LUTs) having a plurality of LUT outputs, and a multiplexer configured to select one of the plurality LUT outputs.
18. A system for processing a signal as recited in claim 17 wherein the input symbol set includes six symbols.
19. A system for processing a signal as recited in claim 17 wherein the second memory includes a LUT having a plurality of entries and wherein the plurality of entries in the LUT correspond to time shifted output samples.
20. A system for processing a signal as recited in claim 17 wherein the first memory includes a shift register.
21. A system for processing a signal as recited in claim 17 wherein the first memory includes a shift register and the second memory includes a LUT.
22. A system for processing a signal as recited in claim 17 wherein the selected one of the plurality of outputs results in a band limited signal.
23. A system for processing a signal as recited in claim 17 wherein the second memory includes a LUT and wherein the LUT includes a beginning section and an ending section.
24. A system for processing a signal as recited in claim 17 wherein the second memory includes a LUT and the LUT includes a beginning section, a middle section and an ending section.
25. A system for processing a signal as recited in claim 17 wherein the second memory includes a LUT and wherein the LUT is compressed.
26. A system for processing a signal as recited in claim 17 wherein the second memory includes a LUT and wherein the LUT excludes certain potential input sets.
27. A system for processing a signal as recited in claim 17 wherein the plurality of LUTs are used in conjunction with a state counter.
28. A system for processing a signal as recited in claim 17 wherein the second memory includes:
a plurality of LUTs having a first state counter for selecting outputs from the plurality of LUTs;
a multiplexer for selecting one of the plurality of LUTs using a second state counter.
29. A system for processing a signal as recited in claim 17 wherein the input symbol set includes I and Q components and wherein the second memory is configured to store a plurality of outputs for possible I and Q components of the input symbol set and wherein the second memory is configured to output selected I and Q component outputs that correspond to the I and Q components of the input symbol set.
30. A system for processing a signal as recited in claim 17 further comprising a processor configured to encode a plurality of inputs to generate the encoded data.
31. A system for processing a signal as recited in claim 17 wherein the plurality of input symbols has a lower clock rate than the plurality of output samples.
32. A system for processing a signal including: an input for receiving encoded data including a plurality of input symbols; a first memory for storing an input symbol set derived from the plurality of input symbols; a second memory configured to store a plurality of interpolated output samples; wherein the plurality of time shifted output samples are obtained by looking up the input symbol set; and wherein the second memory includes a plurality of lookup tables (LUTs) and wherein the entries in each of the plurality of LUTs corresponds to interleaved output samples.