Git-Mirrors/portapack-mayhem
1
0
Fork 0
mirror of https://github.com/eried/portapack-mayhem.git synced 2024-10-01 01:26:06 -04:00
Code Issues Packages Projects Releases Wiki Activity

Enhancements to clock recovery

Browse Source 
Linearly interpolate input and delayed samples, based on phase of internal symbol clock.
This commit is contained in:
Jared Boone 2015-09-02 19:19:43 -07:00
parent 144b121b0e
commit 934936d3f6
1 changed files with 10 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
firmware/baseband/clock_recovery.hpp
View File

@ -38,13 +38,15 @@ public:
) {
const bool phase_0 = (phase_last >> 31) & (!(phase >> 31));
const bool phase_180 = (!(phase_last >> 31)) & (phase >> 31);
phase_last = phase;
phase += phase_increment + phase_adjustment;
if( phase_0 || phase_180 ) {
t2 = t1;
t1 = t0;
t0 = in;
const uint32_t phase_boundary = phase_180 ? (1U << 31) : 0;
const float alpha = (phase_boundary - phase_last) / float(phase_increment + phase_adjustment);
const float t = last_sample + alpha * (in - last_sample);
t0 = t;
}
if( phase_0 ) {
@ -59,6 +61,10 @@ public:
// Correct phase (don't change frequency!)
phase_adjustment = -phase_increment * error_filtered / 200.0f;
}
phase_last = phase;
phase += phase_increment + phase_adjustment;
last_sample = in;
}
private:
@ -66,6 +72,7 @@ private:
uint32_t phase_last { 0 };
uint32_t phase_adjustment { 0 };
uint32_t phase_increment { 0 };
float last_sample { 0 };
float t0 { 0 };
float t1 { 0 };
float t2 { 0 };