From 3895b13662ae154417e086cc4d35ef91839771bf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Bourdeauducq?= <sb@m-labs.hk>
Date: Sat, 28 Dec 2024 19:05:02 +0800
Subject: [PATCH] use negative frequency for demod

---
 sndlock.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sndlock.cpp b/sndlock.cpp
index 4470ea3..8fb2ae1 100644
--- a/sndlock.cpp
+++ b/sndlock.cpp
@@ -108,7 +108,7 @@ static void dsp_thread()
                         sample += (double)buf_in[SND_RCHAN*j+k];
                     std::complex<double> rotated;
                     rotated = sample*std::polar(scale, phase_in[i]*2.0*M_PI/(double)UINT32_MAX);
-                    phase_in[i] += ftw[i];  // wraps on underflow
+                    phase_in[i] -= ftw[i];  // wraps on underflow
 
                     lpf_y[i] += (rotated - lpf_y[i])*lpf_k[i];
                     double mag = std::abs(lpf_y[i]);