diff --git a/owrx/audio/chopper.py b/owrx/audio/chopper.py
index cb910fd..d9c8851 100644
--- a/owrx/audio/chopper.py
+++ b/owrx/audio/chopper.py
@@ -74,5 +74,5 @@ class AudioChopper(threading.Thread, Chain, ProfileSourceSubscriber):
 
     def send(self, profile, line):
         data = self.parser.parse(profile, line)
-        if data is not None:
+        if data is not None and self.writer is not None:
             self.writer.write(pickle.dumps(data))
diff --git a/owrx/modes.py b/owrx/modes.py
index 6bb292f..b6c73e4 100644
--- a/owrx/modes.py
+++ b/owrx/modes.py
@@ -10,8 +10,8 @@ class Bandpass(object):
         self.high_cut = high_cut
 
 
-class Mode(object):
-    def __init__(self, modulation, name, bandpass: Bandpass = None, requirements=None, service=False, squelch=True):
+class Mode:
+    def __init__(self, modulation: str, name: str, bandpass: Bandpass = None, requirements=None, service=False, squelch=True):
         self.modulation = modulation
         self.name = name
         self.requirements = requirements if requirements is not None else []
@@ -44,13 +44,16 @@ class DigitalMode(Mode):
         super().__init__(modulation, name, bandpass, requirements, service, squelch)
         self.underlying = underlying
 
+    def get_underlying_mode(self):
+        return Modes.findByModulation(self.underlying[0])
+
     def get_bandpass(self):
         if self.bandpass is not None:
             return self.bandpass
-        return Modes.findByModulation(self.underlying[0]).get_bandpass()
+        return self.get_underlying_mode().get_bandpass()
 
     def get_modulation(self):
-        return Modes.findByModulation(self.underlying[0]).get_modulation()
+        return self.get_underlying_mode().get_modulation()
 
 
 class AudioChopperMode(DigitalMode, metaclass=ABCMeta):
diff --git a/owrx/service/__init__.py b/owrx/service/__init__.py
index 2206924..2a8d160 100644
--- a/owrx/service/__init__.py
+++ b/owrx/service/__init__.py
@@ -3,7 +3,6 @@ from owrx.source import SdrSourceEventClient, SdrSourceState, SdrClientClass
 from owrx.sdr import SdrService
 from owrx.bands import Bandplan
 from csdr.output import Output
-from csdr import Dsp
 from owrx.wsjt import WsjtParser
 from owrx.aprs import AprsParser
 from owrx.js8 import Js8Parser
@@ -14,7 +13,12 @@ from owrx.property import PropertyLayer, PropertyDeleted
 from js8py import Js8Frame
 from abc import ABCMeta, abstractmethod
 from owrx.service.schedule import ServiceScheduler
-from owrx.modes import Modes
+from owrx.service.chain import ServiceDemodulatorChain
+from owrx.modes import Modes, DigitalMode
+from typing import Union
+from csdr.chain.demodulator import BaseDemodulatorChain, SecondaryDemodulator, FixedAudioRateChain
+from csdr.chain.analog import NFm, Ssb
+from csdr.chain.digimodes import AudioChopperDemodulator
 
 import logging
 
@@ -294,21 +298,46 @@ class ServiceHandler(SdrSourceEventClient):
             output = Js8ServiceOutput(frequency)
         else:
             output = WsjtServiceOutput(frequency)
-        d = Dsp(output)
-        d.nc_port = source.getPort()
-        center_freq = source.getProps()["center_freq"]
-        d.set_offset_freq(frequency - center_freq)
-        d.set_center_freq(center_freq)
+
         modeObject = Modes.findByModulation(mode)
-        d.set_demodulator(modeObject.get_modulation())
-        d.set_bandpass(modeObject.get_bandpass())
-        d.set_secondary_demodulator(mode)
-        d.set_audio_compression("none")
-        d.set_samp_rate(source.getProps()["samp_rate"])
-        d.set_temporary_directory(CoreConfig().get_temporary_directory())
-        d.set_service()
-        d.start()
-        return d
+        if not isinstance(modeObject, DigitalMode):
+            logger.warning("mode is not a digimode: %s", mode)
+            return None
+
+        demod = self._getDemodulator(modeObject.get_modulation(), source.getProps())
+        secondaryDemod = self._getSecondaryDemodulator(modeObject.modulation)
+        center_freq = source.getProps()["center_freq"]
+        sampleRate = source.getProps()["samp_rate"]
+        shift = (center_freq - frequency) / sampleRate
+        bandpass = modeObject.get_bandpass()
+
+        chain = ServiceDemodulatorChain(demod, secondaryDemod, sampleRate, shift)
+        chain.setBandPass(bandpass.low_cut, bandpass.high_cut)
+        chain.setReader(source.getBuffer().getReader())
+        return chain
+
+    # TODO move this elsewhere
+    def _getDemodulator(self, demod: Union[str, BaseDemodulatorChain], props):
+        if isinstance(demod, BaseDemodulatorChain):
+            return demod
+        # TODO: move this to Modes
+        demodChain = None
+        if demod == "nfm":
+            demodChain = NFm(props["output_rate"])
+        elif demod in ["usb", "lsb", "cw"]:
+            demodChain = Ssb()
+
+        return demodChain
+
+    # TODO move this elsewhere
+    def _getSecondaryDemodulator(self, mod):
+        if isinstance(mod, SecondaryDemodulator):
+            return mod
+        # TODO add remaining modes
+        if mod in ["ft8", "wspr", "jt65", "jt9", "ft4", "fst4", "fst4w", "q65"]:
+            return AudioChopperDemodulator(mod, WsjtParser())
+        return None
+
 
 
 class WsjtHandler(object):
diff --git a/owrx/service/chain.py b/owrx/service/chain.py
new file mode 100644
index 0000000..c275ae9
--- /dev/null
+++ b/owrx/service/chain.py
@@ -0,0 +1,21 @@
+from csdr.chain import Chain
+from csdr.chain.selector import Selector
+from csdr.chain.demodulator import BaseDemodulatorChain, SecondaryDemodulator, FixedAudioRateChain
+
+
+class ServiceDemodulatorChain(Chain):
+    def __init__(self, demod: BaseDemodulatorChain, secondaryDemod: SecondaryDemodulator, sampleRate: int, shiftRate: float):
+        # TODO magic number... check if this edge case even exsists and change the api if possible
+        rate = secondaryDemod.getFixedAudioRate() if isinstance(secondaryDemod, FixedAudioRateChain) else 1200
+
+        self.selector = Selector(sampleRate, rate, shiftRate)
+
+        workers = [
+            self.selector,
+            demod,
+            secondaryDemod
+        ]
+        super().__init__(workers)
+
+    def setBandPass(self, lowCut, highCut):
+        self.selector.setBandpass(lowCut, highCut)