From 063023564bf5d930b643cf7457e1d27d168869a6 Mon Sep 17 00:00:00 2001
From: Jakob Ketterl <jakob.ketterl@gmx.de>
Date: Tue, 22 Aug 2023 19:41:24 +0200
Subject: [PATCH] add empty demodulator (for modes that don't produce any
 usable audio)

---
 csdr/chain/analog.py   | 11 +++++++++++
 csdr/chain/dump1090.py |  0
 owrx/adsb/dump1090.py  |  0
 owrx/dsp.py            |  3 +++
 4 files changed, 14 insertions(+)
 create mode 100644 csdr/chain/dump1090.py
 create mode 100644 owrx/adsb/dump1090.py

diff --git a/csdr/chain/analog.py b/csdr/chain/analog.py
index 6bb277f0..2a2341e6 100644
--- a/csdr/chain/analog.py
+++ b/csdr/chain/analog.py
@@ -74,3 +74,14 @@ class Ssb(BaseDemodulatorChain):
             Agc(Format.FLOAT),
         ]
         super().__init__(workers)
+
+
+class Empty(BaseDemodulatorChain):
+    def __init__(self):
+        super().__init__([])
+
+    def getOutputFormat(self) -> Format:
+        return Format.FLOAT
+
+    def setWriter(self, writer):
+        pass
diff --git a/csdr/chain/dump1090.py b/csdr/chain/dump1090.py
new file mode 100644
index 00000000..e69de29b
diff --git a/owrx/adsb/dump1090.py b/owrx/adsb/dump1090.py
new file mode 100644
index 00000000..e69de29b
diff --git a/owrx/dsp.py b/owrx/dsp.py
index 5b5aa5e0..b112b38a 100644
--- a/owrx/dsp.py
+++ b/owrx/dsp.py
@@ -554,6 +554,9 @@ class DspManager(SdrSourceEventClient, ClientDemodulatorSecondaryDspEventClient)
         elif demod == "freedv":
             from csdr.chain.freedv import FreeDV
             return FreeDV()
+        elif demod == "none":
+            from csdr.chain.analog import Empty
+            return Empty()
 
     def setDemodulator(self, mod):
         self.chain.stopDemodulator()