Where can I read more about "slow search" methods for symbol synchronization based on FFT for extracting a clock signal from the modulated signal?
I have read here (8.7 Symbol synchronization)
One method of synchronization is to extract a harmonic of the symbol frequency from the received signal. Then a local symbol clock can be synchronized by methods that are very similar to the phase-locked loops used to recover the carrier phase. If necessary, a start-up procedure, such as one that uses a slow search, can be used for initialization. Synchronization is then maintained by locking a feedback loop to a clock signal that is extracted from the modulated waveform.
Then here I found a diagram which seems to be the kind of algorithm I am looking for:
The timing tone can be extracted by ... computing DFT at the symbol frequency (i.e., a single point of the DFT output is needed for each data block)
There must be more literature about this technique? I am not interested in high-performance methods for synchronization, but rather recovering the clock signal by any means without conserving memory or processing time.
I figure the basic technique is to
- Pass the signal through a matched filter
- "Condition" the signal (and make it purely real) by computing the magnitude (as in the diagram)
- Passing the signal through a DFT computation
- Searching the DFT bins for the highest power frequency
- Use the discovered frequency of the DFT bin to generate a local timing signal
- Use the discovered phase of the DFT bin (as in the diagram) to adjust the local timing signal offset
