N5161A/62A/81A/82A/83A MXG Signal Generators User's Guide

Custom Digital Modulation (Option 431)Differential EncodingRefer to Figure 11- 20 on page 286. The graphic display can provide a useful troubleshooting tool(in this case, it indicates that a coefficient value is missing, resulting in an improper Gaussianresponse).4. Press Return.5. Highlight coefficient 15.6. Press 1 > Enter.Storing the Filter to MemoryThe maximum file name length is 23 characters (alphanumeric and special characters).1. Press Load/Store > Store To File.2. Name the file NEWFIR2.3. Press Enter.The contents of the current FIR table editor are stored to a file in non–volatile memory and thecatalog of FIR files is updated to show the new file.Differential EncodingDifferential encoding is a digital–encoding technique whereby a binary value is denoted by a signalchange rather than a particular signal state. Using differential encoding, binary data in anyuser–defined I/Q or FSK modulation can be encoded during the modulation process via symbol tableoffsets defined in the Differential State Map.For example, consider the signal generator’s default 4QAM I/Q modulation. With a user–definedmodulation based on the default 4QAM template, the I/Q Values table editor contains data thatrepresent four symbols (00, 01, 10, and 11) mapped into the I/Q plane using two distinct values,1.000000 and −1.000000. The following illustration shows the 4QAM modulation in the I/Q Valuestable editor.Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 287