RTTY demod: Fix so mark is high RF freq. Fix squelch.

plugins/channelrx/demodrtty/readme.md

@@ -79,7 +79,12 @@ Specifies whether bits are transmitted least-significant-bit first (LSB) or most
 
 <h3>14: Mark/Space Frequency</h3>
 
-When unchecked, the mark frequency is the higher frequency, when checked the space frequency is higher.
+When unchecked, the mark frequency is the higher RF frequency, when checked the space frequency is higher.
+
+This should be unchecked when transmitter is using LSB AFSK and checked for USB AFSK and DWD
+[1](https://www.dwd.de/EN/specialusers/shipping/broadcast_en/brodcast_rtty_1_052014.pdf?__blob=publicationFile&v=1)
+[2](https://www.dwd.de/EN/specialusers/shipping/broadcast_en/broadcast_rtty_2_052014.pdf?__blob=publicationFile&v=1)
+shipping weather broadcasts.
 
 <h3>15: Suppress CR LF</h3>
 

plugins/channelrx/demodrtty/rttydemodsink.cpp

@@ -154,8 +154,8 @@ void RttyDemodSink::processOneSample(Complex &ci)
     m_expIdx = (m_expIdx + 1) % m_expLength;
     //Complex exp = m_exp[m_sampleIdx];
     //qDebug() << "IQ " << real(ci) << imag(ci);
-    Complex corr1 = ci * exp;
-    Complex corr2 = ci * std::conj(exp);
+    Complex corr1 = ci * std::conj(exp);    // Conj is high/mark freq (as for matched filter, we need to time reverse and take conjugate)
+    Complex corr2 = ci * exp;               // Low/space freq
 
     // Filter
     Real abs1, abs2;
@@ -238,6 +238,8 @@ void RttyDemodSink::processOneSample(Complex &ci)
             m_clockCount = 0;
             m_clock = false;
             m_cycleCount = 0;
+            m_rssiMagSqSum = 0.0;
+            m_rssiMagSqCount = 0;
         }
     }
     else