How to Create a Custom QAM Symbol Map Using Modulation Toolkit Primary Software: LabVIEW Toolkits>>Modulation ToolkitPrimary Software Version: 3.1 Primary Software Fixed Version: N/A Secondary Software: N/A
Problem: How do you use Modulation Toolkit to Create a Custom QAM Symbol Map? Solution: “Generate System Parameters.vi” in LabVIEW allows the user to either accept a default QAM symbol map, or to create a custom QAM symbol map in order to map bit patterns and IQ complex plane values differently. This polymorphic VI has two options for each of the modulation schemes: M and Map. Use M to auto-generate the symbol map or use Map to define your own. To find more information, right click this VI and select Help, then select the modulation type you would like to use. For example, selecting QAM symbol value array, we have the following explanation: This VI expects a two-dimensional, square array of integers as input for the symbol values control. 4-QAM expects a 2×2 array (2 rows, 2 columns), 16-QAM expects a 4×4 array, and so on. The integers 0 through (M–1) must all be included once (only) in the symbol values array, where M is the M-ary number of the modulation. The binary representation (LSB first convention) of the integers represents the bit pattern that is mapped to the corresponding symbol location in the symbol values array. For example, for 4-QAM, if you specify the symbol values array as [3 1] [0 2], the output QAM symbol map is [(–0.707 – 0.707i), (0.707 + 0.707i), (0.707 – 0.707i), (–0.707 + 0.707i)]. There is a simple example attached to this knowledge base that illustrates this written example. You can find more information about digital modulation in the attached link. Related Links: Developer Zone Tutorial: RF and Communications Fundamentals- Developer Zone Attachments:
Report Date: 01/10/2007 Last Updated: 05/07/2007 Document ID: 459J9KJX |
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