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Made a quick-hack attempt at PLL synchronisation. Which doesn't work.

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This commit is contained in:
Thomas Harte 2016-07-14 07:31:23 -04:00
parent ac1bc588dd
commit d8d3464c56
1 changed files with 15 additions and 5 deletions
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20
Storage/Disk/DigitalPhaseLockedLoop.cpp
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@ -44,20 +44,30 @@ void DigitalPhaseLockedLoop::run_for_cycles(unsigned int number_of_cycles)
void DigitalPhaseLockedLoop::add_pulse()
{
// TODO: linear regression to adjust _current_window_length and _next_pulse_time
unsigned int *const _pulse_history_array = _pulse_history.get();
// attempt a phase correction by means of adjusting the window length
int total_offset = 0;
for(size_t pulse = 0; pulse < _length_of_history; pulse++)
{
total_offset += _pulse_history_array[pulse] % _current_window_length;
}
_current_window_length += (unsigned int)(((total_offset - (int)(_length_of_history*_current_window_length >> 1)) >> 2) / (int)_length_of_history);
if(_current_window_length < _clocks_per_bit - _tolerance) _current_window_length = _clocks_per_bit - _tolerance;
if(_current_window_length > _clocks_per_bit + _tolerance) _current_window_length = _clocks_per_bit + _tolerance;
printf("Total across %d samples is %d; adjusted length to %d\n", _length_of_history, total_offset, _current_window_length);
// therefore, there was a 1 in this window
_window_was_filled = true;
if(_delegate) _delegate->digital_phase_locked_loop_output_bit(1);
// shift history one to the left, subtracting the outgoing pulse from
unsigned int *const _pulse_history_array = _pulse_history.get();
unsigned int outgoing_pulse_time = _pulse_history_array[0];
// shift history one to the left, storing new value; act as though the outgoing pulse were exactly halfway through its
// window for adjustment purposes
unsigned int outgoing_pulse_time = _pulse_history_array[0] + (_current_window_length >> 1);
for(size_t pulse = 1; pulse < _length_of_history; pulse++)
{
_pulse_history_array[pulse - 1] = _pulse_history_array[pulse] - outgoing_pulse_time;
_pulse_history_array[pulse - 1] = _pulse_history_array[pulse] - _current_window_length;
}
_next_pulse_time -= outgoing_pulse_time;
_pulse_history_array[_length_of_history-1] = _next_pulse_time;