Adding initial DSC support.

csdr/chain/digimodes.py

@@ -3,7 +3,7 @@ from csdr.module.msk144 import Msk144Module, ParserAdapter
 from owrx.audio.chopper import AudioChopper, AudioChopperParser
 from owrx.aprs.kiss import KissDeframer
 from owrx.aprs import Ax25Parser, AprsParser
-from pycsdr.modules import Convert, FmDemod, Agc, TimingRecovery, DBPskDecoder, VaricodeDecoder, RttyDecoder, BaudotDecoder, Lowpass, MFRttyDecoder, CwDecoder, SstvDecoder, FaxDecoder, SitorDecoder, Ccir476Decoder, Shift
+from pycsdr.modules import Convert, FmDemod, Agc, TimingRecovery, DBPskDecoder, VaricodeDecoder, RttyDecoder, BaudotDecoder, Lowpass, MFRttyDecoder, CwDecoder, SstvDecoder, FaxDecoder, SitorDecoder, Ccir476Decoder, DscDecoder, Ccir493Decoder, Shift
 from pycsdr.types import Format
 from owrx.aprs.direwolf import DirewolfModule
 from owrx.sstv import SstvParser
@@ -250,3 +250,37 @@ class SitorBDemodulator(SecondaryDemodulator, SecondarySelectorChain):
         loop_gain = self.sampleRate / self.getBandwidth() / 5
         self.replace(2, Lowpass(Format.FLOAT, cutoff))
         self.replace(3, TimingRecovery(Format.FLOAT, secondary_samples_per_bit, loop_gain, 10))
+
+
+class DscDemodulator(SecondaryDemodulator, SecondarySelectorChain):
+    def __init__(self, baudRate, bandWidth, invert=False):
+        self.baudRate = baudRate
+        self.bandWidth = bandWidth
+        self.invert = invert
+        # this is an assumption, we will adjust in setSampleRate
+        self.sampleRate = 12000
+        secondary_samples_per_bit = int(round(self.sampleRate / self.baudRate))
+        cutoff = self.baudRate / self.sampleRate
+        loop_gain = self.sampleRate / self.getBandwidth() / 5
+        workers = [
+            Agc(Format.COMPLEX_FLOAT),
+            FmDemod(),
+            Lowpass(Format.FLOAT, cutoff),
+            TimingRecovery(Format.FLOAT, secondary_samples_per_bit, loop_gain, 10),
+            Ccir493Decoder(fec=True, invert=invert),
+            DscDecoder(),
+        ]
+        super().__init__(workers)
+
+    def getBandwidth(self) -> float:
+        return self.bandWidth
+
+    def setSampleRate(self, sampleRate: int) -> None:
+        if sampleRate == self.sampleRate:
+            return
+        self.sampleRate = sampleRate
+        secondary_samples_per_bit = int(round(self.sampleRate / self.baudRate))
+        cutoff = self.baudRate / self.sampleRate
+        loop_gain = self.sampleRate / self.getBandwidth() / 5
+        self.replace(2, Lowpass(Format.FLOAT, cutoff))
+        self.replace(3, TimingRecovery(Format.FLOAT, secondary_samples_per_bit, loop_gain, 10))

owrx/dsp.py

@@ -670,6 +670,9 @@ class DspManager(SdrSourceEventClient, ClientDemodulatorSecondaryDspEventClient)
         elif mod == "sitorb":
             from csdr.chain.digimodes import SitorBDemodulator
             return SitorBDemodulator(100, 170)
+        elif mod == "dsc":
+            from csdr.chain.digimodes import DscDemodulator
+            return DscDemodulator(100, 170)
         elif mod == "cwdecoder":
             from csdr.chain.digimodes import CwDemodulator
             return CwDemodulator(75.0)

owrx/modes.py

@@ -139,6 +139,7 @@ class Modes(object):
         DigitalMode("rtty450", "RTTY-450 (50N)", underlying=["usb", "lsb"]),
         DigitalMode("rtty85", "RTTY-85 (50N)", underlying=["usb", "lsb"]),
         DigitalMode("sitorb", "SITOR-B", underlying=["usb"]),
+        DigitalMode("dsc", "DSC", underlying=["usb"]),
         WsjtMode("ft8", "FT8"),
         WsjtMode("ft4", "FT4"),
         WsjtMode("jt65", "JT65"),