Phase persistent agile signal source method, apparatus, and computer program product

A phase persistent agile signal source apparatus comprising:

• an equivalent accumulator;
• and
• a direct digital synthesizer (DDS) communicatively connected to the equivalent phase accumulator and having a clock rate,
• wherein said phase persistent agile signal source apparatus is configured to operate at a sub-multiple of the clock rate to phase track an output frequency of the DDS to maintain a time continuous phase of an output signal having an output frequency of the DDS when the DDS is programmed to another output frequency and then back to the original frequency, and
• wherein said equivalent accumulator further comprises:
• a least significant bit (LSB) accumulator a programmable register to program a frequency tuning word;
• and
• provides an equivalent frequency least significant bit;
• provides a DDS update rate;
• and
• generates a coherent phase of the LSB accumulator.

A computer program product including a computer readable medium with phase persistent agile signal source instructions embodied thereon for carrying out steps comprising:

• providing a direct digital synthesizer (DDS) clock rate;
• providing a frequency tuning word (FTW) for a desired output frequency;
• providing a DDS update for a desired DDS update rate;
• providing an equivalent frequency least significant bit (LSB) for the desired DDS update rate;
• providing a current phase of an LSB accumulator;
• and
• generating a coherent phase of the desired output frequency based on the DDS clock rate, FTW, DDS update rate to the DDS, equivalent LSB for the desired DDS update rate, and current phase of the LSB accumulator to maintain a time continuous phase of an output signal with the desired output frequency when the DDS is programmed to another output frequency and then back to the desired output frequency.