Pilot Tracking (DOCSIS 4.0 Downstream)
When demodulating a DOCSIS signal frame, the equalizer response computed from the PLC preamble and pilots is used to correct many imperfections in the signal. Because the equalizer response is not perfect, pilot tracking is used to correct for imperfections in the equalizer response and for imperfections that change over the length of the signal.
Pilot subcarriers transmit with a known data sequence. This information is used to determine the difference, or error, between an ideal signal and the actual received signal. Because the data is complex, the VSA calculates phase, amplitude, and timing error data. The error data can then be used to correct both pilot and data subcarrier imperfections, producing a more accurate demodulation.
| Parameter | Description |
|---|---|
| Track Amplitude |
When Track Amplitude is selected, the VSA applies pilot subcarrier amplitude error correction to the pilot and data subcarriers. |
| Track Phase |
When Track Phase is selected, the VSA applies pilot subcarrier phase error correction to the pilot and data subcarriers. |
| Track Timing |
When Track Timing is selected, the VSA applies pilot subcarrier timing error correction (frequency offset correction) to the pilot and data subcarriers. |
Trace Data
See Also
