add am demodulator chain

csdr/chain/am.py

@@ -0,0 +1,23 @@
+from csdr.chain import Chain
+from csdr.chain.demodulator import Demodulator
+from pycsdr.modules import AmDemod, DcBlock, Agc, Convert
+from pycsdr.types import Format
+
+
+class Am(Demodulator):
+    def __init__(self):
+        workers = [
+            AmDemod(),
+            DcBlock(),
+            # empty chain as placeholder for the "last decimation"
+            Chain(),
+            Agc(Format.FLOAT),
+            Convert(Format.FLOAT, Format.SHORT),
+        ]
+
+        super().__init__(*workers)
+
+    def setLastDecimation(self, decimation: Chain):
+        # TODO: build api to replace workers
+        # TODO: replace placeholder
+        pass